Acute renal failure following multiple wasp bites

Wasps and bees descend from order Hymenoptera. All social wasps belong to family Vespidae and Vespa affinis affinis (Hornet or “Debara”) is the species found in Sri Lanka. Other stinging hymenopterans in Sri Lanka are Hive honeybee or “Mee massa” (Apis cerana), Giant honeybee or “Bambara” (Apis dorsata) and Little honeybee or “Danduwel massa” (Apis florea) and they belong to family Apidae. Acute renal failure is a rare clinical manifestation of hymenopteran bites.


Introduction
Wasps and bees descend from order Hymenoptera.All social wasps belong to family Vespidae and Vespa affinis affinis (Hornet or "Debara") is the species found in Sri Lanka.Other stinging hymenopterans in Sri Lanka are Hive honeybee or "Mee massa" (Apis cerana), Giant honeybee or "Bambara" (Apis dorsata) and Little honeybee or "Danduwel massa" (Apis florea) and they belong to family Apidae.Acute renal failure is a rare clinical manifestation of hymenopteran bites.

Case report
A 65 year old woman and her 1 year 2 month old grand daughter were attacked by a swarm of wasps while inside a small jungle in Jayanthipura, Polonnaruwa.About 10 bite marks were identified over the head, face and upper trunk of the baby, on admission to Base Hospital Polonnaruwa.She developed a mild urticarial rash, and during the second day became progressively drowsy and had a short lasting convulsion.
Baby had been anuric for 24 hours, when transferred to Teaching Hospital Peradeniya (THP).She was drowsy, ill, pale and had generalized oedema.The blood pressure was 130/80 mmHg.She remained markedly oliguric.Blood urea and serum creatinine increased to 34mmol/l and 300µmol/l respectively.Peritoneal dialysis was started on the 4 th day following bites and continued for further three days with intense supportive care.She went into a diuretic phase on day 9 and renal functions normalized after 1 month.
Previously she had been quite healthy and active without any significant ailments.During the present illness she did not have anaphylaxis or hypotension and there were no bleeding manifestations, jaundice, red coloured urine or features of rhabdomyolysis such as limb immobility, muscle pain or tenderness.Urinalysis ___________________________________________ 1 Senior Registrar in Paediatric Nephrology, Teaching Hospital, Peradeniya.did not reveal albumin, red blood cells or casts.Urine cultures were sterile.Her haemoglobin was 90g/l, but blood picture did not reveal evidence of haemolysis and leucocyte and platelet counts were within normal ranges.Serum potassium did not increase beyond 5mmol/l.Liver enzymes were not elevated.Ultrasound scan of the abdomen showed evidence of renal parenchymal disease, but no structural abnormalities were noted.Renal biopsy performed on day 7 following the bites (figure 1 A-C) showed features of acute tubular necrosis (ATN).In the absence of any other aetiologies, a diagnosis of acute renal failure with ATN, due to multiple wasp bites was made.

Discussion
A spectrum of clinical manifestations ranging from nonspecific skin lesions to anaphylactic shock can occur, in a previously sensitized person, following even a single hymenopteran bite 1 .An unexposed person can get cellular damage due to systemic envenomation following multiple bites.Toxins like histamine, serotonin, wasp kinin, phosphlipase A 2 , mellitin and hyaluronidase are responsible for the latter 1,3 .
Toxaemia can lead to intravascular haemolysis, thrombolysis, disseminated intra vascular coagulation (DIC), rhabdomyolisis, centrilobular necrosis of liver, ATN of kidney and sub endocardial necrosis 1,2,3 .Although toxins of 500 stings are estimated to be capable of killing an adult, as few as 30 stings can cause fatal envenomation in children 1,3 .
ARF can result from direct toxicity or following haemolysis, rhabdomyolysis or DIC.Circulatory compromise due to anaphylaxis or dehydration can cause pre renal type of ARF.ATN is the histological end result of these pathologies and acute tubularinterstitial nephritis (ATIN) also can occur in combination 1,3,5 .Thiruventhiran and et al had analyzed 24 cases of ARF due to hymenopteran bites and all have had evidence of haemolysis and/or rhabdomyolysis.Pigment casts in tubules also had been noted, in addition to ATN, of the biopsied patients of this series, supporting pigment nephropathy secondary to haemoglobinurea or myoglobinuria, to be the likely patho-mechanism of renal damage 1 .The mechanism of injury may be related to dissociation of heamoglobin/myoglobin to ferrihaemate-tubular toxin, precipitation of pigments in tubular lumen and vasoconstriction.
The most probable cause of ATN of our patient is direct kidney damage by circulatory toxins.A few cases had been reported previously having same pathomechanism 3 .Our patient benefited by early institution of peritoneal dialysis and the intense supportive care.Some cases with ATN treated with steroids have had a good out come 5 .Steroids may hasten renal recovery by preventing interstitial fibrosis.Early recovery had been noted in some other patients with ARF with haemolysis and/or rhabdomyolysis who had been treated with forced alkaline diuresis, early in the course 1,2 .Alkaline diuresis might inhibit dissociation and precipitation of pigments.
In conclusion, it is important, not only to provide medical care as soon as possible to patients with multiple hymenopteran bites, but also to anticipate major clinical problems due to systemic envenomation in the days to come.Peritoneal dialysis and intense supportive care are the mainstay of treatment for ARF.Steroids and alkaline diuresis might be effective in cases with interstitial nephritis and pigment nephropathy respectively.

2
Professor of Pathology, 3 Senior Lecturer in Paediatrics, Faculty of Medicine, University of Peradeniya (Received on 11 September 2006.Accepted on 02 October 2006)

Figure
Figure 1A -A granuloma has formed following a ruptured distal tubule.(H and E stain)

Figure 1 C
Figure 1 C -Histologically normal glomeruli excluded a glomerular pathology (H and E stain)