PLoS Negl Trop Dis plos plosntds PLOS Neglected Tropical Diseases 1935-2735 Public Library of Science San Francisco, CA USA 10.1371/journal.pntd.0011242 PNTD-D-22-01606 Research Article Biology and life sciencesPsychologyBehaviorSedentary behavior Social sciencesPsychologyBehaviorSedentary behavior Biology and life sciencesBiochemistryGlycobiologyGlycoproteinsFibrinogen Medicine and health sciencesMedical conditionsTropical diseasesNeglected tropical diseasesSnakebite Medicine and health sciencesHealth careHealth care facilities Medicine and health sciencesClinical medicineSigns and symptomsHemorrhage Medicine and health sciencesVascular medicineHemorrhage Medicine and health sciencesDermatologyBlisters Medicine and health sciencesPharmacologyAdverse reactions Biology and life sciencesOrganismsEukaryotaAnimalsVertebratesAmniotesReptilesSquamatesSnakes Biology and life sciencesZoologyAnimalsVertebratesAmniotesReptilesSquamatesSnakes Effect of the time to antivenom administration on recovery from snakebite envenoming-related coagulopathy in French Guiana Time to antivenom administration in snakebite envenoming in French Guiana Houcke Stéphanie Data curation Methodology Writing – original draft 1 Pujo Jean Marc Conceptualization Methodology Writing – original draft 2 Vauquelin Segolene Data curation Writing – original draft 1 Lontsi Ngoula Guy Roger Data curation 1 Matheus Severine Data curation Writing – original draft 1 NkontCho Flaubert Conceptualization Validation 3 Pierre-Demar Magalie Conceptualization Validation 4 5 Gutiérrez José María Conceptualization Validation Writing – review & editing 6 Resiere Dabor Conceptualization Methodology Validation Writing – review & editing 7 Hommel Didier Conceptualization Formal analysis Methodology Supervision Validation Visualization Writing – original draft 1 https://orcid.org/0000-0002-5663-0349 Kallel Hatem Conceptualization Data curation Formal analysis Methodology Software Supervision Validation Visualization Writing – original draft Writing – review & editing 5 * Intensive Care Unit, Cayenne General Hospital, Cayenne, French Guiana, France Emergency department, Cayenne General Hospital, Cayenne, French Guiana, France Pharmacy department, Cayenne General Hospital, Cayenne, French Guiana, France Laboratory department, Cayenne General Hospital, Cayenne, French Guiana, France Tropical Biome and immunopathology CNRS UMR-9017, Inserm U 1019, Université de Guyane, Cayenne, French Guiana, France Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica Intensive Care Unit, Martinique University Hospital, Martinique, France Monteiro Wuelton M. Editor Fundação de Medicina Tropical Doutor Heitor Vieira Dourado, BRAZIL

The authors have declared that no competing interests exist.

 * E-mail: Kallelhat@yahoo.fr 24 4 2023 4 2023 17 4 e0011242 22 12 2022 14 3 2023 2023 Houcke et al This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Background

Snakebite (SB) envenoming is an acute emergency requiring an early care delivery. We aimed to search for the time to reach healthcare facilities in various regions of French Guiana (FG) and to assess the impact of time to antivenom (AV) on the correction of coagulation parameters in these patients.

 Methodology

This is a prospective observational study conducted in Cayenne General Hospital between January 1st, 2016, and July 31st, 2022. We included all patients hospitalized for SB envenoming less than 48h after the bite, and receiving antivenom (AV). We assessed the time lapse between SB and medical attention and the time needed to return of the coagulation parameters to normal.

 Principal findings

Overall, 119 patients were investigated, and 48.7% were from remote areas. The median time from SB to AV therapy was 09:15 h (05:32–17:47). The time was longer in patients from remote rural locations. AV was dispensed within the first six hours after the SB in 45 cases (37.8%). Time from SB to reaching normal plasma fibrinogen concentration was 23:27 h (20:00–27:10) in patients receiving AV≤6h vs. 31:23 h (24:00–45:05) in those receiving AV>6h (p<0.001). Whereas, the time from AV administration to reach normal fibrinogen dosage was similar in the two groups.

 Conclusions

Patients from rural settings in FG suffer from a delay in AV administration after SB envenoming leading to an extended time in which patients are coagulopathic. Once AV is administered, clotting parameters recover at a similar rate. Supplying remote healthcare facilities with AV and with medical teams trained on its use should be planned.

 Author summary

Snakebite envenoming is a public health concern in the Amazon region. It represents an acute medical emergency needing early care such as stroke, severe trauma, myocardial infarction, etc. Antivenoms are the most effective treatment of snakebite envenomings. They are part of the WHO List of essential medicines and should be available in any primary health care where snakebite victims are managed. In this context, less than 6 hours delay between the snakebite and the antivenom administration is needed for a maximal chance to prevent and reverse most of the toxic effects of the snake venom.

 The authors received no specific funding for this work. PLOS Publication Stage vor-update-to-uncorrected-proof Publication Update 2023-05-04 Data Availability All data used to draw the conclusions outlined in our manuscript are available and freely accessible from the Supporting Information file (S1 Data).

In French Guiana, like in the Amazon region, antivenoms are available in hospital settings but not in remote healthcare facilities. This leads to extended delays in antivenom administration and, consequently, lesser chances for envenomed victims.

Health authorities should promote supplying primary health care facilities with antivenoms for the optimal management of snakebite victims and an increased chance to reverse the envenoming signs. Moreover, time to antivenom should be considered as an indicator of equality and equity of access to health care for people living in remote and rural communities.

Introduction

Snakebite (SB) envenoming is a public health concern in the Amazon region [1]. It is a frequent event in French Guiana (FG), where, on average, 90 snakebite envenomings are recorded yearly [1–3]. Typically, the first signs of envenoming appear within half an hour after the bite, and early treatment by antivenom (AV) is recommended to prevent serious complications [3]. In 2017, the French Health Authority decided the use of AV in FG. The AV chosen was the Antivipmyn Tri, deemed effective against most of the snakes encountered in the region [4]. However, the efficacy of this AV remains controversial [2,5,6], and one of the causes of poor efficacy in some cases might be a delayed AV administration. It is noteworthy that AV is available only in the three territorial hospitals, all located along the coastline of FG. While there are 18 remote health centers scattered along the borders with Brazil and Suriname, none of them is provided with AV. Meanwhile, most of the time, the rapid access to the emergency department depends on air means managed by the Regional Call Center for Emergencies based in Cayenne.

The WHO defined SB envenoming as an acute emergency requiring an early care delivery [7]. Indeed, early AV use (within the first 6h of envenoming) in South America and Martinique has been reported to be associated with a better outcome [8–11]. In the Brazilian Amazon, a study of 9,191 SB cases found that a delay of six or more hours in medical care was associated with increased severity of envenoming [12]. However, in FG, twenty percent of the whole population (estimated in 2018 at 296,700 inhabitants in the legal situation) lives in remote areas in the middle of tropical rainforests that are only accessible by boat or plane. Consequently, patients can take several hours before hospital admission and AV administration. In two recent studies in FG the average time from SB to AV administration was 11:00 h (6:00–20:00) and 09:00 h (05:22–20:40), respectively [2,6].

We conducted this study to search for the time lapse for reaching medical attention in various settings in FG, and to assess the impact of time to AV administration after the bite on the recovery of SB related coagulopathy and other clinical and laboratory parameters.

 Methods Ethics statement

Our study is an observational, non-interventional work. The antivenom used is authorized “compassionally” by the French Agency for Drug Safety (code product: 3400893189627). The hospital’s institutional review board (Direction qualité du Centre Hospitalier de Cayenne) and the Cayenne Hospital ethics committee (Comité d’éthique du Centre Hospitalier de Cayenne) approved the protocol of antivenom administration and blood test dosages (Ref: UF3700/17’, version “b”). We informed all patients about the hospital protocol on the management of SB and that the data collected would be used in research programs. Formal verbal consent was obtained from all patients or parent/guardian (when patients are <18 years or unable to consent) and was reported in the patient’s medical file. In addition, at admission to our hospital, an information booklet was distributed to all patients or their relatives stating that their data can be used for research purposes and that they can oppose to this use. The database has been registered at the Commission Nationale de l’Informatique et des Libertés (registration n° 2217025v0), in compliance with French law on electronic data sources.

 Study design

Our study is prospective and observational. It was conducted in Cayenne General Hospital between January 1st, 2016, and July 31st, 2022. We included all patients hospitalized with clinical and biological signs of SB envenoming lasting less than 48 hours after the bite, regardless of the grade of envenoming, and receiving antivenom. We excluded all patients hospitalized for SB envenoming lasting more than 48 hours after the bite, those who did not receive antivenom, and those who did not present clinical or biological signs of envenoming.

The study design and the regional AV protocol were previously described [2]. The AV used is Antivipmyn Tri, manufactured and marketed since 2008 by Instituto Bioclon, Mexico. Antivipmyn Tri is a freeze-dried F(ab’)2 polyvalent antivenom produced by Instituto Bioclon, in Mexico-Mexico Registry N 58583 SSA IV. It is prepared by immunizing horses with venoms of Bothrops asper, Crotalus durissus terrificus, and Lachesis muta. According to the manufacturer, it is indicated for the treatment of envenoming by vipers, such as Bothrops atrox, Bothrops brazili, Bothrops asper, Bothrops neuwiedii, Bothrops alternatus, Bothrops jararacussu, Bothrops venezuelensis, Bothrops pictus, Crotalus durissus terrificus, Crotalus durissus durissus, Lachesis stenophrys, Lachesis muta muta, Sistrurus spp., and Agkistrodon spp. The protocol of Antivipmyn Tri used was already described (6 vials whatever the grade of envenoming), and its efficacy was already studied [2,13].

In all envenomed patients, we collected epidemiological and clinical data, including the geographic zone where the bite occurred, age and gender of patients, the date and time of the bite, the anatomical site of the bite, the snake identification, the grade of severity of envenoming, the clinical manifestations and laboratory tests at admission and during the hospital stay, the date and time of hospital admission and AV administration, and the adverse reactions to AV.

 Definitions

The culprit snake was identified based on the patient description, photographs, or on the physical examination of the captured snake. The grade of envenoming was assessed according to the conclusions of the international symposium held in French Guiana in 2017 [3]. It was evaluated at patient admission to the medical service and at hospital discharge (referring to the case evaluation along the whole evolution). The grading system is based on three grades (I: mild, II: moderate, and III: severe) including a large number of signs and symptoms (Table 1).

10.1371/journal.pntd.0011242.t001 The grading system for classifying the severity of envenoming.
Grade
I II III
Coagulation disorder* + + +
Local signs Pain + + +
Swelling Not exceeding elbow or knee Exceeding elbow or knee Beyond the root of the limb
Blister - + +
Necrosis - - +
Local bleeding - + +
Systemic bleeding - - +
Systemic manifestations (Hypotension, Renal failure, Coma, Respiratory failure) - - Organ failure

*Based on results of the 20-min whole blood clotting test and laboratory analysis.

Worsening skin lesions refer to expanding local edema, necrosis, or blisters over 24 hours of surveillance. Expanding cutaneous edema refers to enlargement of the edema zone by more than 5 cm in size. Expanding necrosis refers to enlargement of the necrosis zone by more than 5 cm in size. Expanding blisters refers to the development of new blisters. Expanding skin manifestation is tracked by drawing a line around the lesion area with a marker and checking whether the lesion extends past the line after 24 hours of medical observation. Acute kidney injury is characterized according to the definition of Kidney Disease Improving Global Outcomes (KDIGO) definition [14]. Fibrinogen was measured by chronometric determination (Closs method) with a threshold of detection of 0.35 g/L. Detectable fibrinogen is defined as a fibrinogen concentration higher than the threshold of detection of the dosage technique. Defibrinogenation is defined by a fibrinogen level <1 g/L (normal range: 2–4 g/L). Thrombocytopenia is defined by a platelet count < 150 G/L. Rhabdomyolysis is defined by a serum creatine kinase (CK) activity > 500 IU/L (normal range: 39–308 IU/L). Hemolysis is defined by an increased serum lactate dehydrogenase (normal range: 105–333 IU/L), increased unconjugated bilirubin (normal range: 0.2–0.8 mg/dL), and decreased haptoglobin levels (normal range: 41–165 mg/dL) in serum [15]. Presence of schistocytes is considered significant when detected at more than 1% on the blood smear test. Coagulation disorders are defined by International Normalized Ratio (INR) >2 (normal range: 0.8–1.2), activated partial thromboplastin time (aPTT) > 1.5, Prothrombin time and concentration of coagulation factors < 60%. Coagulation factors are dosed only when the prothrombin time is less than 60%. According to the hospital protocol, laboratory tests were performed every 6 hours from hospitalization until recovery of the coagulation disorders (fibrinogen >1.5 g/L).

The time to treatment (the interval between the SB and the initiation of medical care) was classified as early (≤6h) or delayed (>6h). Adverse reactions to AV were classified as ‘mild’ or ‘severe’ [16,17]. Worsening of clinical manifestations is defined as a progression to a higher grade of envenoming. Patients are hospitalized in ICU until recovery of the coagulation disorders. Then, they are transferred to the surgical ward and followed until day 8 from the bite or until recovery of the skin lesion, when it takes more time to heal. After that, patients are followed in the outpatient clinic one week after the hospital discharge.

 Data analysis

We created a data file with the patient’s and snake’s information, and we performed a descriptive analysis using Excel (2007) and IBM SPSS Statistics for Windows, version 24 (IBM Corp., Armonk, NY, USA). Results are reported as the median and inter-quartile range (IQR), mean and standard deviation, or numbers with percentages. Time is expressed as hours and minutes (hh: mn). To compare qualitative variables, we used the Fisher exact test. To compare quantitative variables, we used the Mann–Whitney U-test. The significance level was set at p ≤ 0.05. We used Kaplan-Meier analysis to compare the time needed to achieve normal fibrinogen dosage between the early and the late AV groups. The significance level was set at Log-Rank ≤ 0.05.

 Results

During the study period, 198 patients were admitted to the emergency department of Cayenne General Hospital with a diagnosis of SB envenoming (on average, 35 cases per year). Of them, 111 patients (56%) were transferred from remote rural healthcare centers.

Fig 1 shows the primary sites of consultation, the time from SB to the hospital (one-trip access time by helicopter), and the median and interquartile range of time from the SB to AV therapy according to the geographic region where the SB occurred. Among patients admitted for SB, 119 (60%) reached the inclusion criteria and were analyzed in our study (Fig 2).

10.1371/journal.pntd.0011242.g001 Place of the initial medical care (black and blue dots), number of cases registered at each place (in parentheses), the one-way time to medical evacuation of envenomed patients to Cayenne hospital by helicopter (minutes indicated in the arrows), and the time to receive AV (hours and minutes, with the corresponding quartiles in parentheses).

The base layer of the map was drawn by hand from the U.S. Geological Survey (http://www.usgs.gov).

 10.1371/journal.pntd.0011242.g002 The flow-chart of the study.

The median age of included patients was 41 years (IQR: 27–53), and 67.2% were male. The median time from the SB to hospitalization was 6:13 h (IQR: 1:33–18:10). The median time from the SB to AV therapy was 9:15 h (IQR: 5:32–17:47). The responsible snake was identified in 52 cases (43.7%). It was Bothrops atrox in 51 cases and B. bilineatus in one case. A higher proportion of patients first attended in remote rural health centers had a delayed (>6h) administration of antivenom as compared to those first attended in urban centers (Table 1).

The main clinical signs and symptoms at admission were edema (97.5%), pain (99.2%), blister (10.1%), local hemorrhage (12.6%), acute kidney injury (17.6%), and systemic bleeding (10.9%). The only parameter showing a statistical difference between the two groups (early and delayed AV) was the local hemorrhage (24.4 vs. 5.4%, p = 0.002). The elapsed time from SB to the development of systemic bleeding was 1h (0–4) as per information provided by the patients. During evolution, infection was recorded in 26.1% of cases. Clinical progression of symptoms was recorded in 30 patients (25.2%). It was responsible for envenoming-grade progression in 12/119 cases (10.1%). Table 2 summarizes the epidemiological and clinical parameters of patients.

10.1371/journal.pntd.0011242.t002 Epidemiological and clinical parameters at admission.
Total Early AV Delayed AV p
Parameter Nb Result Nb Result Nb Result
Age, years 119 41 (27–53) 45 38 (25–57) 74 42 (30–53) 0.530
Male gender 119 80 (67.2%) 45 29 (64.4%) 74 51 (68.9%) 0.614
BMI, Kg/m2 73 23.8 (21.2–26.3) 32 23.8 (21.4–26.1) 41 23.8 (21.2–26.4) 0.960
Past medical history 119 30 (25.2%) 45 14 (31.1%) 74 16 (21.6%) 0.248
Arterial hypertension 119 10 (8.4%) 45 6 (13.3%) 74 4 (5.4%) 0.131
Alcohol abuse 119 4 (3.4%) 45 1 (2.2%) 74 3 (4.1%) 0.591
First attended in a remote health center 119 58 (48.7%) 45 12 (26.7%) 74 46 (62.2%) 0.000
Snake identification 119 52 (43.7%) 45 28 (62.2%) 74 24 (32.4%) 0.001
Time from SB to hospitalization 119 06:13 (01:33–18: 10) 45 01:30 (00:45–03:00) 74 09:44 (06:03–21:36) 0.000
Grade of envenoming on admission
Grade I 119 60 (50.4%) 45 23 (51.1%) 74 37 (50%) 0.219*
Grade II 119 31 (26.1%) 45 15 (33.3%) 74 16 (21.6%) 0.064$
Grade III 119 28 (23.5%) 45 7 (15.6%) 74 21 (28.4%) 0.110£
Progression of the grade of envenoming# 119 12 (10.1%) 45 4 (8.9%) 74 8 (10.8%) 0.736
From grade I to grade II 58 7 (12.1%) 23 3 (13%) 35 4 (11.4%) 0.853
From grade I to grade III 53 2 (3.8%) 20 0 (0%) 33 2 (6.1%) 0.521
From grade II to grade III 31 3 (9.7%) 15 1 (6.7%) 16 2 (12.5%) 0.583
Symptoms related to grade progression
Expanding local edema 12 10 (83.3%) 4 3 (75%) 8 7 (87.5%) 0.584
Expanding blisters 12 3 (25%) 4 2 (50%) 8 1 (12.5%) 0.157
Clinical parameters during hospitalization
Local edema 119 116 (97.5%) 45 45 (100%) 74 71 (95.9%) 0.171
Local hemorrhage 119 15 (12.6%) 45 11 (24.4%) 74 4 (5.4%) 0.002
Necrosis 119 14 (11.8%) 45 3 (6.7%) 74 11 (14.9%) 0.178
Blisters 119 12 (10.1%) 45 5 (11.1%) 74 7 (9.5%) 0.772
Pain 119 118 (99.2%) 45 45 (100%) 74 73 (98.6%) 0.434
Worsening skin lesions# 119 30 (25.2%) 45 11 (24.4%) 74 19 (25.7%) 0.881
Expanding local edema 119 27 (22.7%) 45 10 (24.4%) 74 17 (21.6%) 0.924
Expanding blisters 119 5 (4.2%) 45 2 (4.4%) 74 3 (4.1%) 1.000
Expanding necrosis 119 3 (2.5%) 45 0 (0%) 74 3 (4.1%) 0.289
Acute kidney injury at admission 119 21 (17.6%) 45 6 (13.3%) 74 15 (20.3%) 0.336
Time from renal injury to normal renal parameters, days 21 5 (2–10) 6 9 (3–10) 15 3 (2–8) 0.288
Systemic bleeding 119 13 (10.9%) 45 4 (8.9%) 74 9 (12.2%) 0.579

Nb: the number of cases in whom the parameter was analyzed, Values are expressed as number and percentages or median and interquartile range, BMI: Body Mass Index$: grade II vs. III

£: grade III vs. I and II *, grade I vs. III

# refers to the progression of symptoms during hospitalization.

Antivenom was administered within the six first hours in 45 patients (37.8%) and was delayed more than six hours in 74 patients (62.2%). Early AV administration concerned 23/60 (38.3%), 15/31 (48.4%), and 7/28 (25%) in grade I, II, and III patients, respectively. It concerned 33/61 (54.1%) and 12/58 (20.7%) patients coming from the coastline and consulting at the emergency department, and patients from the remote rural zones and consulting at the remote healthcare centers, respectively. Early adverse reaction during AV administration was observed in 15 patients (12.6%). It was mild in 11 patients (11%) and severe in 4 patients (3.4%). Symptomatic management was based on analgesics (100%), fluid infusion (59.7%), blood components transfusion (4.2%), and dialysis (2.5%). Surgery was required for 27 patients (22.7%), and necrosectomy was performed on 12 (44.4%) of them. The delay from admission to surgery was 7 days (IQR: 5–9). Table 2 summarizes the management and outcome of the patients. When comparing early and delayed AV groups, several parameters showed a significant difference, i.e., duration under dialysis (three patients in the delayed AV group required dialysis), fluid infusion, antibiotics at admission, and length of hospital stay, while no significant difference was found in the other examined parameters (Table 3).

10.1371/journal.pntd.0011242.t003 Management and outcome of patients.
Total Early AV Delayed AV p
Parameter Nb Result Nb Result Nb Result
Dialysis 119 3 (2.5%) 45 0 (0%) 74 3 (4.1%) 0.289
Duration under dialysis, days 3 7 (6–55) 0 - 3 7 (6–55) -
Fluid infusion 119 71 (59.7%) 45 32 (71.1%) 74 39 (52.7%) 0.047
Fluid infusion volume, ml 71 1000 (1000–2000) 32 1000 (1000–1500) 39 1000 (1000–2000) 0.633
Antibiotics at admission 119 42 (35.3%) 45 10 (22.2%) 74 32 (43.2%) 0.020
Time from SB to AV 119 9:15 (5:32–17:47) 45 5:00 (4:00–6:00) 74 12:50 (9:16–23:00) 0.000
Adverse reaction to AV 119 15 (12.6%) 45 5 (11.1%) 74 10 (13.5%) 0.702
Blood transfusion 119 5 (4.2%) 45 2 (4.4%) 74 3 (4.1%) 0.918
Surgery 119 27 (22.7%) 45 9 (20%) 74 18 (24.3%) 0.585
Time from admission to surgery, days 27 7 (4–9) 9 5 (4–6) 18 7 (6–9) 0.062
Necrosectomy 27 12 (44.4%) 9 3 (33.3%) 18 9 (50%) 0.411
Infection 119 31 (26.1%) 45 9 (20%) 74 22 (29.7%) 0.241
Length of hospital stay, days 119 7 (5–11) 45 6 (4–10) 74 8 (5–13) 0.038

Nb: the number of cases in whom the parameter was analyzed, Values are expressed as number and percentages or median and interquartile range

Table 4 summarizes the biological abnormalities recorded at admission and during hospitalization. Biological parameters at admission showed defibrinogenation in all cases, thrombocytopenia in 31 cases (26.1%), hemolysis in 44 cases (37%), and rhabdomyolysis in 15 cases (12.6%). International Normalized Ratio was >2 in 105 cases (88.2%), and activated partial thromboplastin time (aPTT) was >1.5 in 71 cases (59.7%). When comparing the two groups, i.e., early (<6h) and delayed (>6h) AV administration, time from SB to the normalization of several clotting parameters (fibrinogen, INR, aPTT, factor II, and factor V) was shorter in patients receiving AV within the first six hours after the SB (Table 3). In contrast, no difference was observed regarding recovery of these parameters when comparing the time lapse between AV administration and recovery (Table 3). The rate of patients with a detectable fibrinogen dosage (>0.35 g/L) at admission was higher in the late AV group (35.6% vs. 15.6%; p = 0.018). Fig 3 shows the time from SB and AV administration to the normal value of fibrinogen, Factor II, and Factor V according to the time of AV initiation (≤6h vs. >6h). Fig 4 shows the time from SB and AV administration to the normal value of fibrinogen according to the delay in AV administration (≤6h vs. >6h). As a general trend, the time to correct alterations in some clotting factors and INR after the SB is more prolonged in the delayed AV group, although when the analysis was done from the time of AV administration, no significant difference was observed between the groups. Thus, once AV is administered, clotting alterations recover at a similar rate between the groups.

10.1371/journal.pntd.0011242.t004 Biologic abnormalities recorded at admission and during hospitalization.
Total Early AV Delayed AV p
Parameter Nb Result Nb Result Nb Result
Rhabdomyolysis 119 15 (12.6%) 45 3 (6.7%) 74 12 (16.2%) 0.161
Hemolysis 119 44 (37%) 45 16 (35.6%) 74 28 (37.8%) 0.803
Time from SB to resolved hemolysis 34 24:44 (20:15–37:07) 13 21:00 (16:20–25:24) 21 27:00 (24:00–46:00) 0.008
Presence of schistocytes 31 3 (9.7%) 13 1 (7.7%) 18 2 (11.1%) 1.000
Defibrinogenation 119 119 (100%) 45 45 (100%) 74 74 (100%) -
Time from SB to normal fibrinogen 112 26:55 (22:00–36:02) 45 23:27 (20:00–27:10) 67 31:23 (24:00–45:05) 0.000
Time from AV to normal fibrinogen 112 15:52 (11:58–21:55) 45 18:00 (14:26–21:54) 67 14:10 (10:16–22:10) 0.069
Fibrinogen dosage>0.35 g/L on admission 118 33 (28%) 45 7 (15.6%) 73 26 (35.6%) 0.018
INR>2 119 105 (88.2%) 45 43 (95.6%) 74 62 (83.8%) 0.053
Time from SB to normal INR 98 23:17 (17:31–34:37) 41 18:30 (16:14–30:30) 57 25:30 (19:51–41:00) 0.006
Time from AV to normal INR 98 12:00 (09:17–17:24) 41 12:10 (11:14–17:07) 57 11:58 (07:00–17:30) 0.137
aPTT>1.5 119 71 (59.7%) 45 34 (75.6%) 74 37 (50%) 0.006
Time from SB to normal aPTT 70 17:24 (13:26–24:00) 33 13:45 (11:00–17:18) 37 21:37 (16:30–29:20) 0,000
Time from AV to normal aPTT 70 08:45 (05:31–11:55) 33 09:21 (05:40–11:43) 37 08:10 (05:10–12:20) 0.888
Thrombocytopenia 119 31 (26.1%) 45 11 (24.4%) 74 20 (27%) 0.756
Time from SB to normal platelet count 24 66:30 (31:37–122:51) 10 55:45 (34:15–115:08) 14 68:05 (30:32–112:02) 0.861
Time from AV to normal platelet count 24 57:34 (17:50–111:51) 10 47:00 (19:57–110:32) 14 57:34 (12:22–96:45) 0.558
Abnormal Factor II 107 53 (49.5%) 45 23 (51.1%) 62 30 (48.4%) 0.781
Time from SB to normal FII 29 32:35 (17:40–41:50) 13 20:15 (16:10–27:00) 16 37:35 (32:28–48:45) 0.010
Time from AV to normal FII 29 17:15 (09:30–25:10) 13 14:40 (09:30–20:13) 16 20:45 (13:15–25:50) 0.211
Abnormal Factor V 108 66 (61.1%) 45 33 (73.3%) 63 33 (52.4%) 0.028
Time from SB to normal FV 47 24:50 (17:50–35:10) 24 18:28 (15:20–25:15) 23 31:30 (24:45–38:20) 0.000
Time from AV to normal FV 47 14:00 (09:55–21:00) 24 12:05 (09:19–16:15) 23 17:30 (11:25–22:30) 0.154
Abnormal Factor VII 107 36 (33.6%) 45 13 (28.9%) 62 23 (37.1%) 0.375
Time from SB to normal FVII 13 28:00 (18:00–44:50) 4 41:15 (22:59–62:25) 9 28:00 (18:00–41:50) 0.643
Time from AV to normal FVII 13 15:20 (08:30–26:50) 4 30:43 (08:27–54:10) 9 15:20 (08:30–16:30) 0.355
Abnormal Factor X 104 27 (26%) 44 11 (25%) 60 16 (26.7%) 0.848
Time from SB to normal FX 11 32:10 (18:30–35:10) 4 21:28 (11:49–33:35) 7 33:40 (26:05–35:10) 0.345
Time from AV to normal FX 11 19:30 (09:13–24:20) 4 16:58 (08:19–27:46) 7 19:30 (10:03–22:25) 0.850

Nb: the number of cases in whom the parameter was analyzed, Values are expressed as number and percentages or median and interquartile range, SB: snakebite, AV: antivenom, INR: International Normalized Ratio, aPTT: activated partial thromboplastin time

 10.1371/journal.pntd.0011242.g003 <p>Time from SB (Plot A) and antivenom administration (Plot B) to the normal value of fibrinogen, Factor II, and Factor V according to the time between SB and antivenom administration (≤6h <italic>vs</italic>.>6h). The number of cases in whom the parameter was analyzed (Total, Early/Delayed) was: factor II (29, 13/16), factor V (47, 24/23), fibrinogen (112, 45/67). (Values are presented as mean and 95%CI).</p> </caption> <graphic mimetype="image" position="float" xlink:href="info:doi/10.1371/journal.pntd.0011242.g003" xlink:type="simple"/> </fig> <fig id="pntd.0011242.g004" position="float"> <object-id pub-id-type="doi">10.1371/journal.pntd.0011242.g004</object-id> <label>Fig 4</label> <caption> <title/> <p>Time from SB (Plot A) and antivenom administration (Plot B) to the normal value of fibrinogen concentration according to the time between SB and antivenom administration [≤6h (red line, n = 45) <italic>vs</italic>. >6h (blue line, n = 67)].</p> </caption> <graphic mimetype="image" position="float" xlink:href="info:doi/10.1371/journal.pntd.0011242.g004" xlink:type="simple"/> </fig> </sec> </sec> <sec id="sec012" sec-type="conclusions"> <title>Discussion

Our study shows that patients from rural areas in French Guiana took a longer time to receive AV after SB as compared to patients suffering the bite in locations close to Cayenne. Also, it shows that patients receiving AV within the first 6h after the SB were more likely to have a shorter time to normalize clotting parameters. However, the time between AV administration and recovery of clotting parameters was similar for the two groups.

Snakebite envenoming is an acute emergency requiring an early care delivery [7], including the early use of AV, ideally within the first six hours of envenoming [8–10]. In this context, our study emphasizes the vast difference in time to receive AV in French Guiana according to the geographic region where the bite occurred. Patients in remote zones must attend the closest local healthcare center before being evacuated to Cayenne to receive the AV. However, the time for medical evacuation of patients is variable, since it depends on the helicopter availability and weather conditions. This disparity in time from SB to AV allowed us to compare an early AV group (≤6h from SB) and a delayed AV group (>6h). In similar contexts, most studies showed higher effectiveness of AV when administered early after the SB with significant improvement in clinical and biological parameters and better outcomes [11,18,19]. Thus, reducing the delay in treatment should be principally based on providing remote healthcare centers with AV. The critical point is that AV must go to patients, instead of patients having to travel long distances to receive antivenom. In French Guiana, two recent studies investigated the effectiveness of Antivipmyn Tri in the treatment of SB [2,6]. Heckmann et al. reported a median time from the SB to AV of 11h (IQR: 6–20), and only 11 patients received the AV before the sixth hour [6]. In another study, Resiere et al. found that the median time from the SB to AV was 9h (IQR: 5–21) [2].

French Guiana is a 83.534 km2 department with an estimated population of 283,540 inhabitants. On average, 80% of the population lives in the coastal zone, and in suburban areas [20]. The remaining 20% live in remote areas where the huge disparities in healthcare availability and access to the nearest health care facility might be counted in hours or (sometimes) in days. Indeed, the one-trip access time to the nearest hospital can be about 10 to 20 min in the urban locations (by car), and it can go up to 100 min in isolated zones (by helicopter) [21]. In our study, there were two groups, i.e., patients from urban and suburban sites, and those from remote areas. In the urban and suburban groups, patients came directly to the ED and benefited from an early AV treatment (median time <3h). In the remote sites group, patients attended to the local healthcare center before being transferred to Cayenne hospital. Sometimes, patients must go through the forest or rivers to reach the healthcare center extending the delay in hospitalization and AV therapy (median time up to 19h). Consequently, the availability of AV in remote health centers is essential to shorten the delay to treatment. Once AV is administered in these remote health facilities, patients can be transferred to the hospital for further monitoring and care. These differences in time to attend a health facility and receive appropriate treatment are typical examples of inequitable access to care in the Guianese population. Similar reports from the Brazilian Amazon region were published, describing the limited access to health facilities and to antivenoms in the remote rural populations and rising the need for public health interventions [19,22,23]. In contrast, in a recent study in Costa Rica, Montoya-Vargas et al. [24] interviewed 96 pharmacists from 55 different healthcare facilities to investigate the way AV are managed by the public health system. Overall, participants reported AV availability at all levels of care and patients take less than 3h to medical assistance in the majority of cases. In FG, the AV is administered under a “compassionate” authorization for use by the French Agency for Drug Safety (Agence Française de Sécurité des Médicaments). This system allows the use of drugs without marketing authorization in France under specific conditions. It prohibits stocking the drug in remote health care centers and including patients in clinical trials. Currently, we are working together with the hospital pharmacists, the French Guiana Health Authority, and the French Agency for Drug Safety to get derogatory advice to provide remote health care centers with AV. European and French laws require that AV be administered by a nurse supervised by a doctor who can manage adverse reactions including anaphylactic shock. Thus, some French Guiana HCCs are planned to be provided by emergency doctors and trained nurses for AV administration and urgent snake-bitten patients’ management.

AV should be administered in a health facility where acute adverse reactions can be treated. For this, before introducing AV in remote areas, some points have to be resolved. The first is to establish a management procedure for AV supplying and storage in remote areas to avoid disruption. In the case of liquid antivenoms, the maintenance of the cold chain must be ensured. Second, the validation of a protocol for AV use, including the method to grade the severity of envenomings, the prerequisites for AV administration, the duration of the monitoring before and after the immunotherapy, the modalities of preparation and injection of the AV, and the protocol to follow in the event of adverse effects. The criteria for evacuation to a hospital setting and the degree of emergency concerning the transfer time should be carefully considered. Indeed, non-predictable adverse effects can be observed during AV administration requiring close monitoring during the therapy and over [2,6]. Overall, an optimal approach to manage SB envenoming in FG must include antivenom availability and trained staff in remote healthcare facilities [20]. Furthermore, hospitals and healthcare authorities should promote comparative studies on the safety and efficacy of different AVs available in the region.

In agreement with previous studies in French Guiana, B. atrox was responsible for the majority of bites when the culprit snake was identified [2]. Likewise, the main clinical manifestations observed in patients included in this study were similar to those described in earlier works for B. atrox, i.e., local edema and pain, local hemorrhage, blisters, systemic bleeding and acute kidney injury [2,25]. The frequency of early adverse reactions to AV administration was low (12.6%), in agreement with previous studies in FG using this antivenom [2,6].

In our study, we compared the evolution of patients receiving AV within the first 6h after the bite with those receiving it at later time intervals, with emphasis on coagulopathy. The time from SB to correct coagulation disorders was more prolonged in the delayed AV group, thus highlighting the higher risk of these patients to suffer hemorrhage and other systemic complications. Previous studies in FG evaluated the restoration of clotting parameters comparing patients who received this AV and those who did not. Heckman et al. [6] described that the time from SB to reach fibrinogen concentration of 100 mg/dL was similar for the two groups (22 and 24h), although the fibrinogen recovery was faster beyond 30h in the AV group. In contrast, Resiere et al. [2] reported significant differences, since patients receiving AV reached 100 mg/dL fibrinogen concentration 25:30 h after SB, while this time was 47:00 h in those who did not receive AV.

On the other hand, when the time lapse from AV administration to recovery of clotting parameters was analyzed in our study, no significant difference was observed between the groups. Thus, once AV is administered, recovery from coagulation disturbances had an overall similar time course in the two groups. The time lapse to reach normal fibrinogen concentration after AV administration in our study was 15:52 h (11:58–21:55). The time of recovery from hypofibrinogenemia after AV administration in envenomings by B. atrox in Brazil and Bothrops asper in Colombia was estimated at 48h and 12-24h, respectively [25,26]. Thrombocytopenia is another common manifestation of B. atrox envenomings, and was observed in 26.1% of the patients included in this study. Interestingly, no significant differences were observed between the two groups in the time from SB or from AV administration required to recover normal platelet counts. It is necessary to further explore, at the preclinical and clinical levels, the ability of the current and other AVs to neutralize this relevant effect.

Following SB by B. atrox, the plasma fibrinogen concentration rapidly drops to very low levels due to venom-induced consumption coagulopathy. Two simultaneous processes determine the recovery of fibrinogen levels, i.e., the neutralization of venom procoagulant enzymes by AV and the replenishment of fibrinogen by the liver. Thus, it is hypothesized that in the delayed AV group there has been an increased synthesis of fibrinogen before AV administration (Fig 5). This hypothesis is supported by the finding that the percentage of patients with a detectable fibrinogen level at admission was higher in the late AV group than in the early AV group. However, despite the ongoing synthesis of fibrinogen by the liver, the neutralization of procoagulant toxins by AV is required to speed the recovery of coagulation parameters, as evidenced in previous studies with viperid SB envenomings in which patients receiving and not receiving AV were compared [2,27,28].

10.1371/journal.pntd.0011242.g005 Scheme of the proposed fibrinogen concentration kinetics following SB by <italic>B</italic>. <italic>atrox</italic>.

Venom induces a consumption coagulopathy, associated with a drastic drop in plasma fibrinogen concentration. After a time lapse, fibrinogen concentration starts to increase as a result of synthesis by the liver. Once AV is administered, venom toxins are neutralized and fibrinogen levels continue to increase until reaching normal concentration.

Our study has several limitations. First, it is an observational study with a small sample. Second, it includes patients with grade I envenoming (46.4%), limiting the evaluation of time to AV on systemic effects and skin necrosis and blisters. Indeed, in some not frequent outcomes, sample size may not be sufficient to show statistical significance in the comparison between groups. Third, snake identification was made in only 47.3% of cases. Identification was based on the patient’s description, photographs, or on physical examination of the captured snake. In this context, we recommend against bringing and/or killing the snake in order not to increase the risk of new accidents. Additionally, the genus Bothrops, mainly B. atrox is reported to be the principal etiological agent of SB envenoming causing the vast majority of bites and fatalities in the Amazon region [1,25].

 Conclusion

Our results show that there is a delay in AV administration in many SB cases in FG. Such delay extends the time lapse in which patients are coagulopathic, hence increasing the risk of bleeding and related clinical complications. Accordingly, the time lost to administer AV is proportional to the time needed to normalize coagulation parameters. Once AV is administered, the time lapse to recover clotting parameters is similar regardless of the delay in the onset of AV infusion. Supplying remote healthcare facilities with AV with medical teams trained on its use and on the management of related adverse effects should be planned for better and optimal SB-envenoming care in FG.

 Supporting information Is: Snakebites database registered in Cayenne Hospital.

(XLSX)

 References Resiere D, Monteiro W, Houcke S, Pujo JM, Mathien C, Mayence C, et al. Bothrops Snakebite Envenomings in the Amazon Region. Curr Trop Med Rep (2020) 7: 48–60 Resiere D, Houcke S, Pujo JM, Mayence C, Mathien C, NkontCho F, et al. Clinical Features and Management of Snakebite Envenoming in French Guiana. Toxins (Basel). (2020) doi: 10.3390/toxins12100662 33086750 Kallel H, Hommel D, Mehdaoui H, Megarbane B, Resiere D, Snakebites in French Guiana: Conclusions of an international symposium. Toxicon (2018) 146: 91–94 doi: 10.1016/j.toxicon.2018.04.003 29621524 Boels D, Harry P, de Haro L, Darsonval A, Quistinic P, Clerc M-A,et al. La banque des sérums antivenimeux (BSA) et la prise en charge des envenimations par serpents exotiques en France. Urgence Pratique (2009) 41–44 Resiere D, Arias AS, Villalta M, Rucavado A, Brouste Y, Cabié A, et al. Preclinical evaluation of the neutralizing ability of a monospecific antivenom for the treatment of envenomings by Bothrops lanceolatus in Martinique. Toxicon (2018) 148: 50–55 doi: 10.1016/j.toxicon.2018.04.010 29654867 Heckmann X, Lambert V, Mion G, Ehrhardt A, Marty C, Perotti F, et al. Failure of a Mexican antivenom on recovery from snakebite-related coagulopathy in French Guiana. Clin Toxicol (Phila) (2020) 1–7 Minghui R, Malecela MN, Cooke E, Abela-Ridder B, WHO’s Snakebite Envenoming Strategy for prevention and control. The Lancet Global Health (2019) 7: e837–e838 doi: 10.1016/S2214-109X(19)30225-6 31129124 Silveira PV, Nishioka S de A, South American rattlesnake bite in a Brazilian teaching hospital. Clinical and epidemiological study of 87 cases, with analysis of factors predictive of renal failure. Trans R Soc Trop Med Hyg (1992) 86: 562–564 doi: 10.1016/0035-9203(92)90114-r 1475835 Thomas L, Tyburn B, Ketterlé J, Biao T, Mehdaoui H, Moravie V, et al.Prognostic significance of clinical grading of patients envenomed by Bothrops lanceolatus in Martinique. Transactions of the Royal Society of Tropical Medicine and Hygiene (1998) 92: 542–545 Bucaretchi F, Herrera SRF, Hyslop S, Baracat ECE, Vieira RJ, Snakebites by Crotalus durissus ssp in children in Campinas, São Paulo, Brazil. Rev Inst Med Trop Sao Paulo (2002) 44: 133–138 Magalhães SFV, Peixoto HM, Freitas LRS de, Monteiro WM, Oliveira MRF de, Snakebites caused by the genera Bothrops and Lachesis in the Brazilian Amazon: a study of factors associated with severe cases and death. Rev Soc Bras Med Trop (2022) 55: e05582021 doi: 10.1590/0037-8682-0558-2021 35894402 Feitosa EL, Sampaio VS, Salinas JL, Queiroz AM, da Silva IM, Gomes AA, et al. Older Age and Time to Medical Assistance Are Associated with Severity and Mortality of Snakebites in the Brazilian Amazon: A Case-Control Study. PLoS ONE (2015) 10: e0132237 doi: 10.1371/journal.pone.0132237 26168155 Chippaux J-P, Les envenimations ophidiennes en Guyane Française. Med Trop (2002) 62: 177–184 Khwaja A KDIGO clinical practice guidelines for acute kidney injury. Nephron Clin Pract (2012) 120: c179–184 Phillips J, Henderson AC, Hemolytic Anemia: Evaluation and Differential Diagnosis. Am Fam Physician (2018) 98: 354–361 30215915 Mendonça-da-Silva I, Magela Tavares A, Sachett J, Sardinha JF, Zaparolli L, Gomes Santos MF, et al. Safety and efficacy of a freeze-dried trivalent antivenom for snakebites in the Brazilian Amazon: An open randomized controlled phase IIb clinical trial. PLoS Negl Trop Dis (2017) 11: e0006068 doi: 10.1371/journal.pntd.0006068 29176824 de Silva HA, Ryan NM, de Silva HJ, Adverse reactions to snake antivenom, and their prevention and treatment. Br J Clin Pharmacol (2016) 81: 446–452 doi: 10.1111/bcp.12739 26256124 Mise YF, Lira-da-Silva RM, Carvalho FM, Time to treatment and severity of snake envenoming in Brazil. Rev Panam Salud Publica (2018) 42: e52 doi: 10.26633/RPSP.2018.52 31093080 Alves EC, Sachett J de AG, Sampaio VS, Sousa JD de B, Oliveira SS de, Nascimento EF do, et al. Predicting acute renal failure in Bothrops snakebite patients in a tertiary reference center, Western Brazilian Amazon. PLoS ONE (2018) 13: e0202361 doi: 10.1371/journal.pone.0202361 30118505 L’essentiel sur… la Guyane | Insee. https://www.insee.fr/fr/statistiques/4313999. Accessed 2 Dec 2022 Baert X, Charrier R,Kempf N, L’accès aux soins à l’épreuve des grands espaces guyanais—Insee Dossier Guyane—6. https://www.insee.fr/fr/statistiques/3181903. Accessed 9 Aug 2020 Cristino JS, Salazar GM, Machado VA, Honorato E, Farias AS, Vissoci JRN, et al. A painful journey to antivenom: The therapeutic itinerary of snakebite patients in the Brazilian Amazon (The QUALISnake Study). PLOS Neglected Tropical Diseases (2021) 15: e0009245 doi: 10.1371/journal.pntd.0009245 33661895 Fan HW, Monteiro WM, History and perspectives on how to ensure antivenom accessibility in the most remote areas in Brazil. Toxicon (2018) 151: 15–23 doi: 10.1016/j.toxicon.2018.06.070 29908262 Montoya-Vargas W, Gutiérrez JM, Quesada-Morúa MS, Morera-Huertas J, Rojas C, Leon-Salas A, Preliminary assessment of antivenom availability and management in the public health system of Costa Rica: An analysis based on a survey to pharmacists in public health facilities. Toxicon X (2022) 16: 100139 doi: 10.1016/j.toxcx.2022.100139 36325535 Silva de Oliveira S, Campos Alves E, Dos Santos Santos A, Freitas Nascimento E, Tavares Pereira JP, Mendonça da Silva I, et al. Bothrops snakebites in the Amazon: recovery from hemostatic disorders after Brazilian antivenom therapy. Clin Toxicol (Phila) (2020) 58: 266–274 doi: 10.1080/15563650.2019.1634273 31264481 Otero-Patiño R, Segura Á, Herrera M, Angulo Y, León G, Gutiérrez JM, et al. Comparative study of the efficacy and safety of two polyvalent, caprylic acid fractionated [IgG and F(ab′)2] antivenoms, in Bothrops asper bites in Colombia. Toxicon (2012) 59: 344–355 doi: 10.1016/j.toxicon.2011.11.017 22146491 Mion G, Larréché S, Benois A, Petitjeans F, Puidupin M, Hemostasis dynamics during coagulopathy resulting from Echis envenomation. Toxicon (2013) 76: 103–109 doi: 10.1016/j.toxicon.2013.09.003 24070638 Silva A, Scorgie FE, Lincz LF, Maduwage K, Siribaddana S, Isbister GK, Indian Polyvalent Antivenom Accelerates Recovery From Venom-Induced Consumption Coagulopathy (VICC) in Sri Lankan Russell’s Viper (Daboia russelii) Envenoming. Front Med (Lausanne) (2022) 9: 852651 doi: 10.3389/fmed.2022.852651 35321467 10.1371/journal.pntd.0011242.r001 Decision Letter 0 Monteiro Wuelton M. Section Editor 2023 Wuelton M. Monteiro This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Submission Version 0

16 Jan 2023

Dear Dr Kallel,

Thank you very much for submitting your manuscript "Effect of the time to antivenom administration on recovery from snakebite envenoming-related coagulopathy in French Guiana" for consideration at PLOS Neglected Tropical Diseases. As with all papers reviewed by the journal, your manuscript was reviewed by members of the editorial board and by several independent reviewers. In light of the reviews (below this email), we would like to invite the resubmission of a significantly-revised version that takes into account the reviewers' comments.

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Wuelton Monteiro

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Reviewer's Responses to Questions

Key Review Criteria Required for Acceptance?

As you describe the new analyses required for acceptance, please consider the following:

Methods

-Are the objectives of the study clearly articulated with a clear testable hypothesis stated?

-Is the study design appropriate to address the stated objectives?

-Is the population clearly described and appropriate for the hypothesis being tested?

-Is the sample size sufficient to ensure adequate power to address the hypothesis being tested?

-Were correct statistical analysis used to support conclusions?

-Are there concerns about ethical or regulatory requirements being met?

Reviewer #1: Methods:

Add more info regarding Antivipmyn Tri®. Type of antivenom (Fab?) and the snake venoms that it neutralizes. Add info also regarding number of recommended vials. Besides that, the methods are very detailed.

Reviewer #2: The study proposed an analysis of accidents that occurred in French Guiana with a difference between early and delayed 6-hour VA administration. This context is interesting since 6 hours is a gold standard for receiving VA and after this time the risk of complications gradually increases.

Regarding the classification of poisoning, the authors could describe how it is done according to the conclusions of the 131 international symposium held in French Guiana in 2017 cited in the method to make it clearer.

Given the local epidemiology, how was the species of snake involved in the accident defined? The antivenom used neutralizes venom of which genus/species? How many vials are used for each accident classification?

What is the maximum follow-up time for patients?

What were the patient exclusion criteria set at baseline?

What was the estimated number of cases in the period evaluated? Did the authors make a sample calculation?

Did the laboratory tests have a frequency and interval period to be performed?

Reviewer #3: This is an interesting study about the effect of the time to antivenom (AV) administration on recovery of the effects of snakebite envenoming in patients receiving AV early (in the first 6 hours after bite) or lately (6 hours or more after bite).

Objectives are clearly stated, and the study design is in accordance with the purposes. It is not described how the sample size was defined. It may be inferred that number of patients was obtained from the period outlined in the study. However, for some not frequent outcomes, sample size may not have been sufficient to show statistical significance in the comparison between groups, such as necrosis, blisters and dialysis. Authors indicate this limitation, suggesting the possibility of confounding factors, but do not explain which ones. Readers would benefit from greater detail in this respect.

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Results

-Does the analysis presented match the analysis plan?

-Are the results clearly and completely presented?

-Are the figures (Tables, Images) of sufficient quality for clarity?

Reviewer #1: The results are fine.

Reviewer #2: In line 206 the authors described that 52 patients had the snake identified, was it by photo or did they bring the snake? 51 snakes were Bothrops atrox and what was the other 1 species?

Line 211 Do the authors describe the main signs and symptoms of the patients, is this information from the patient's arrival at the hospital or at another time? The clinical information is in general, wouldn't it be better to divide into the group of early AV and delayed AV as in the rest of the results?

Table 1 has the definition of GRADE I, II and III, please describe clearly in the methodology to improve understanding of this classification.

In table 3, not all patients underwent all laboratory tests, some of these, for example Factor X: out of 104, only 11 were evaluated in the table for Time from SB to normal and Time from AV to normal FX. Why was information not presented on the 104 patients who had this abnormal value? Thus, the small number of results would not be good for conclusions and analyzes due to possible biases. Is this the correct interpretation or am I mistaken?

The fact of not having the monitoring of the abnormal exams of the 119 patients left me confused in the construction of figures 3 and 4, how many patients were considered to perform the graph calculations?

Reviewer #3: Statistical tests were correctly applied, but some numerical variables, such as fibrinogen and platelets, were not analyzed according to their medians. Authors preferred to convert them in discrete variables (number and percentage of patients with defibrinogenation, number and percentage of patients with thrombocytopenia). Would the comparison be different if variables se variables present different

Rhabdomyolysis and hemolysis were included as variables to be studied, but their meaning in Bothrops envenoming in FG was not discussed. Laboratory tests were performed but values of CK (for rhabdomyolysis), LDH, bilirubin and haptologlobin (for hemolysis) were omitted. May these parameters did not show difference between groups, but authors should give some explanation.

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Conclusions

-Are the conclusions supported by the data presented?

-Are the limitations of analysis clearly described?

-Do the authors discuss how these data can be helpful to advance our understanding of the topic under study?

-Is public health relevance addressed?

Reviewer #1: Yes, the conclusion support the study.

Reviewer #2: Some parameters were associated in the statistical analysis, such as the first visit in a remote area, snake identification and local hemorrhage. However, only remote area care was well discussed, could the authors include the other points mentioned in the discussion as well?

As for Factor V, aPTT, Defibrinogenation, I need clarification on the number of patients who completed the exams to issue a more correct opinion, as I was in doubt in interpreting the information in Table 3 and graphs 3 and 4.

Figure 5 and the explanation given in the text were very good, however, this would not be the appropriate place for this information. So I suggest that this be in the methodology section.

In the limitation of the study, the authors describe that the entry of GRADE I patients that limited the evaluation of the time to the effects of VA, could the authors how this limited the study? Were the patients discharged early, not allowing the collection of exams and clinical evaluation to monitor the complete recovery of parameters, or was there another reason? Regarding the limitation of the identification of the snake in 47.3% of the cases - in line 207 43.7% were described - the authors could have a moment in the discussion that the stimulus of bringing and/or killing the snake should not be done in order not to increase the risk of new accidents and that the classification of the type of snake responsible for the envenomation is carried out by the patient's clinic, that is, this should not be considered a limitation of the study.

Reviewer #3: It is interesting the theory proposed to explain the higher percentage of patients with fibrinogen levels > 0.35 g/L in those who received AV late, compared to those treated early. Despite the correct recommendation for AV administration in any circumstance of systemic envenoming, could grade I patients suggest spontaneous recovery of coagulopathy in patients mildly envenomed?

The availability of antivenom in remote health facilities is strongly emphasized as a key aspect to reduce morbidity and mortality of snakebite envenoming in rural and traditional populations. This is an important contribution of study and could be complemented with some discussion regarding the type of health professional to be responsible for the administration of antivenom. Should be a medical doctor? In places where this type of professional is not available, could a nurse of health agent administer AV? What about the risk of complications of an adverse reaction to antivenom if used in a primary care unit?

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Editorial and Data Presentation Modifications?

Use this section for editorial suggestions as well as relatively minor modifications of existing data that would enhance clarity. If the only modifications needed are minor and/or editorial, you may wish to recommend “Minor Revision” or “Accept”.

Reviewer #1: Minor revision

Reviewer #2: The authors need to clarify the laboratory results.

Reviewer #3: Line 139: "medical observation" is more appropriate than "surveillance"

Table 1: correct typing "snake identification"

Table 3: include legend, similarly to table 1 and 2.

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Summary and General Comments

Use this section to provide overall comments, discuss strengths/weaknesses of the study, novelty, significance, general execution and scholarship. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. If requesting major revision, please articulate the new experiments that are needed.

Reviewer #1: The article intitled Effect of the time to antivenom administration on recovery from snakebite envenoming- related coagulopathy in French Guiana is interesting. Although not novel (other studies have investigated the same) there is a lack of literature info regarding the snakebite treatment FG. The manuscript is easy to read; however, there are some grammar and other mistakes. I encourage authors read it again and have the article read by a native speaker as well. I really liked Figure 1, it is very explicative. For me the main results are in Figure 3. Is the group the pioneer to show that? Please check the literature and make it clear. Based on that, I also encourage a quick discussion regarding the hospital costs comparing the time the patient stay in the hospital (receiving early and late AV).

Minor issues:

Line 38, 43, 107, 208,etc: change hr to h (check all the manuscript)

Lines 39-40: to correct laboratory coagulation parameters? Maybe to return to normal levels of coagulation. Please rewrite.

Line 42: change sites to areas

Line 43: change it to The time

Line 58: remove comma before such

Line 66: a loss of chance???? Please rewrite

Line 194: medevac???? See 320 too.

Line 315: put together snakebite

Methods:

Add more info regarding Antivipmyn Tri®. Type of antivenom (Fab?) and the snake venoms that it neutralizes. Add info also regarding number of recommended vials.

Reviewer #2: The article is interesting mainly because it is a follow-up of patients, however some information is not clear to adequately respond to the objective of the study and understand the evolution of the clinical condition of the patients as described in the recommendations above.

Reviewer #3: (No Response)

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Reviewer #2: No

Reviewer #3: No

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Please note that, as a condition of publication, PLOS' data policy requires that you make available all data used to draw the conclusions outlined in your manuscript. Data must be deposited in an appropriate repository, included within the body of the manuscript, or uploaded as supporting information. This includes all numerical values that were used to generate graphs, histograms etc.. For an example see here: http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001908#s5.

Reproducibility:

To enhance the reproducibility of your results, we recommend that you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. Additionally, PLOS ONE offers an option to publish peer-reviewed clinical study protocols. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols

 10.1371/journal.pntd.0011242.r002 Author response to Decision Letter 0 Submission Version 1

6 Feb 2023

Submitted filename: Response to Nithya Venkatesan.docx

 10.1371/journal.pntd.0011242.r003 Decision Letter 1 Monteiro Wuelton M. Section Editor 2023 Wuelton M. Monteiro This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Submission Version 1

8 Feb 2023

Dear Dr Kallel,

Thank you very much for submitting your manuscript "Effect of the time to antivenom administration on recovery from snakebite envenoming-related coagulopathy in French Guiana" for consideration at PLOS Neglected Tropical Diseases. As with all papers reviewed by the journal, your manuscript was reviewed by members of the editorial board and by several independent reviewers. In light of the reviews (below this email), we would like to invite the resubmission of a significantly-revised version that takes into account the reviewers' comments.

We cannot make any decision about publication until we have seen the revised manuscript and your response to the reviewers' comments. Your revised manuscript is also likely to be sent to reviewers for further evaluation.

When you are ready to resubmit, please upload the following:

[1] A letter containing a detailed list of your responses to the review comments and a description of the changes you have made in the manuscript. Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out.

[2] Two versions of the revised manuscript: one with either highlights or tracked changes denoting where the text has been changed; the other a clean version (uploaded as the manuscript file).

Important additional instructions are given below your reviewer comments.

Please prepare and submit your revised manuscript within 60 days. If you anticipate any delay, please let us know the expected resubmission date by replying to this email. Please note that revised manuscripts received after the 60-day due date may require evaluation and peer review similar to newly submitted manuscripts.

Thank you again for your submission. We hope that our editorial process has been constructive so far, and we welcome your feedback at any time. Please don't hesitate to contact us if you have any questions or comments.

Sincerely,

Wuelton M. Monteiro, Ph.D.

Section Editor

PLOS Neglected Tropical Diseases

Wuelton Monteiro

Section Editor

PLOS Neglected Tropical Diseases

***********************

Figure Files:

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org.

Data Requirements:

Please note that, as a condition of publication, PLOS' data policy requires that you make available all data used to draw the conclusions outlined in your manuscript. Data must be deposited in an appropriate repository, included within the body of the manuscript, or uploaded as supporting information. This includes all numerical values that were used to generate graphs, histograms etc.. For an example see here: http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001908#s5.

Reproducibility:

To enhance the reproducibility of your results, we recommend that you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. Additionally, PLOS ONE offers an option to publish peer-reviewed clinical study protocols. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols

 10.1371/journal.pntd.0011242.r004 Author response to Decision Letter 1 Submission Version 2

18 Feb 2023

Submitted filename: Responses to reviewers comments.docx

 10.1371/journal.pntd.0011242.r005 Decision Letter 2 Monteiro Wuelton M. Section Editor 2023 Wuelton M. Monteiro This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Submission Version 2

14 Mar 2023

Dear Dr Kallel,

We are pleased to inform you that your manuscript 'Effect of the time to antivenom administration on recovery from snakebite envenoming-related coagulopathy in French Guiana' has been provisionally accepted for publication in PLOS Neglected Tropical Diseases.

Before your manuscript can be formally accepted you will need to complete some formatting changes, which you will receive in a follow up email. A member of our team will be in touch with a set of requests.

Please note that your manuscript will not be scheduled for publication until you have made the required changes, so a swift response is appreciated.

IMPORTANT: The editorial review process is now complete. PLOS will only permit corrections to spelling, formatting or significant scientific errors from this point onwards. Requests for major changes, or any which affect the scientific understanding of your work, will cause delays to the publication date of your manuscript.

Should you, your institution's press office or the journal office choose to press release your paper, you will automatically be opted out of early publication. We ask that you notify us now if you or your institution is planning to press release the article. All press must be co-ordinated with PLOS.

Thank you again for supporting Open Access publishing; we are looking forward to publishing your work in PLOS Neglected Tropical Diseases.

Best regards,

Wuelton M. Monteiro, Ph.D.

Section Editor

PLOS Neglected Tropical Diseases

Wuelton Monteiro

Section Editor

PLOS Neglected Tropical Diseases

***********************************************************

Reviewer's Responses to Questions

Key Review Criteria Required for Acceptance?

As you describe the new analyses required for acceptance, please consider the following:

Methods

-Are the objectives of the study clearly articulated with a clear testable hypothesis stated?

-Is the study design appropriate to address the stated objectives?

-Is the population clearly described and appropriate for the hypothesis being tested?

-Is the sample size sufficient to ensure adequate power to address the hypothesis being tested?

-Were correct statistical analysis used to support conclusions?

-Are there concerns about ethical or regulatory requirements being met?

Reviewer #2: The description of the sample and the evaluated patients was better described and is more coherent with the objectives and results.

**********

Results

-Does the analysis presented match the analysis plan?

-Are the results clearly and completely presented?

-Are the figures (Tables, Images) of sufficient quality for clarity?

Reviewer #2: The authors added information and tables that clarified the information from the results.

**********

Conclusions

-Are the conclusions supported by the data presented?

-Are the limitations of analysis clearly described?

-Do the authors discuss how these data can be helpful to advance our understanding of the topic under study?

-Is public health relevance addressed?

Reviewer #2: It's adequate.

**********

Editorial and Data Presentation Modifications?

Use this section for editorial suggestions as well as relatively minor modifications of existing data that would enhance clarity. If the only modifications needed are minor and/or editorial, you may wish to recommend “Minor Revision” or “Accept”.

Reviewer #2: Accept

**********

Summary and General Comments

Use this section to provide overall comments, discuss strengths/weaknesses of the study, novelty, significance, general execution and scholarship. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. If requesting major revision, please articulate the new experiments that are needed.

Reviewer #2: The authors met most of the recommendations and the manuscript is significantly improved.

**********

PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

 10.1371/journal.pntd.0011242.r006 Acceptance letter Monteiro Wuelton M. Section Editor 2023 Wuelton M. Monteiro This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

20 Apr 2023

Dear Dr Kallel,

We are delighted to inform you that your manuscript, "Effect of the time to antivenom administration on recovery from snakebite envenoming-related coagulopathy in French Guiana," has been formally accepted for publication in PLOS Neglected Tropical Diseases.

We have now passed your article onto the PLOS Production Department who will complete the rest of the publication process. All authors will receive a confirmation email upon publication.

The corresponding author will soon be receiving a typeset proof for review, to ensure errors have not been introduced during production. Please review the PDF proof of your manuscript carefully, as this is the last chance to correct any scientific or type-setting errors. Please note that major changes, or those which affect the scientific understanding of the work, will likely cause delays to the publication date of your manuscript. Note: Proofs for Front Matter articles (Editorial, Viewpoint, Symposium, Review, etc...) are generated on a different schedule and may not be made available as quickly.

Soon after your final files are uploaded, the early version of your manuscript will be published online unless you opted out of this process. The date of the early version will be your article's publication date. The final article will be published to the same URL, and all versions of the paper will be accessible to readers.

Thank you again for supporting open-access publishing; we are looking forward to publishing your work in PLOS Neglected Tropical Diseases.

Best regards,

Shaden Kamhawi

co-Editor-in-Chief

PLOS Neglected Tropical Diseases

Paul Brindley

co-Editor-in-Chief

PLOS Neglected Tropical Diseases