Scabies is a skin disease caused by infestation with a tiny mite (Sarcoptes scabiei) that burrows under the skin and is transmitted through close personal contact [1]. The direct effect of scabies is debilitating itching, leading to scratching, which is in turn followed by complications due to bacterial infection of the skin, ranging from impetigo, abscesses and cellulitis, through to septicaemia and even death [1]. Bacterial infections secondary to scabies can also lead to more serious sequelae associated with group A streptococcal infection such as rheumatic fever and glomerulonephritis [2–6].

Scabies and its complications are considered endemic in most Pacific Island countries and in many other tropical countries including in Africa largely on the basis of anecdotal reporting. Prevalence surveys of scabies have been conducted in localized areas of a limited number of countries [7–14]. These studies have generally confirmed high levels of scabies in these locations but none have been national that we are aware of, and have not been sufficiently broad-based to provide the basis for developing and informing national disease control strategies.

Scabies was recently added to the World Health Organization’s list of Neglected Tropical Diseases, but has generally not been recognised as a public health priority in most developing countries, perhaps because of the absence of large scale surveys to fully define its extent and risk factors [3]. In order to provide comprehensive information on the prevalence of scabies and impetigo and the effect of demographic risk factors in a country believed to be highly endemic for these conditions, we undertook a national prevalence survey in Fiji.

A total of 75 sites were included in the survey, with a median proportion of 82% of the official resident population examined in each village, with an overall participation rate of 78.2%. In 72 of the villages the proportion examined was 60% or more. A total of 10,887 study participants were enrolled. As shown in Table 1, the demographic characteristics of the study sample were broadly comparable to that of the 2007 census population in regard to age and ethnicity, but there was substantial over-representation of younger age groups (54% of the sample was aged less than 15 years compared to 29% from census data), and of people from the Northern division of Fiji (40.0% of the sample vs. 16.2% from census data).

Scabies was observed in 2,564 participants (23.6%) of the population surveyed (Table 2). Prevalence was highest in children aged five to nine years (43.7%, adjusted odds ratio, OR, 3.7 when compared to those aged over 49 years, Fig. 1). Scabies was nearly twice as common in iTaukei Fijians (24.7%, adjusted OR 2.7 when compared to the Indo-Fijian population). Scabies was most prevalent in people living in the Northern division (28.5%), in people living in rural areas (25.6%) and in females (24.8%). Taking into account the census distribution of age and geographical location by direct adjustment, the estimated national prevalence of scabies was 18.5% (95% CI 14.7–22.9). There were no cases of crusted scabies detected in this study.

The prevalence of impetigo was also high, with lesions observed in 19.6% of participants (Table 3). Impetigo followed a similar age distribution to scabies, being more common in children aged five to nine years (34.2%, adjusted OR 2.2). Similar to scabies, impetigo prevalence was twice as high in the iTaukei Fijians (22.8%, adjusted OR 2.4), in females (20.5%), in people living in rural areas (21.4%) and in the Northern division (23.7%). When taking into account the census distribution of age and geographical location the national prevalence of impetigo was 18.5% (95% CI 12.3–20.2). The majority of impetigo lesions were mild (53.5%) and flat/dry (54.8%), although severe cases were not uncommon (16.2%) and over a quarter of the sores were purulent (26.6%, Table 4).

The presence of impetigo was strongly associated with a diagnosis of scabies (relative risk, RR, 58.6, 95% CI 48.7–70.5). The population attributable risk of scabies as a cause of impetigo based on the national survey was 93.1%.

Study participants who reported a previous diagnosis of scabies (n = 2923, 26.9%) were more likely to have scabies infestation at the time of the survey (51.4%) compared to those who did not recall a prior scabies diagnosis (13.3%, RR 3.4, 95% CI 3.2–3.6). Similarly, participants reporting prior treatment (n = 1586, 14.6%) had a higher prevalence of scabies than those who did not (RR 2.7, 95% CI 2.6–2.9). Of those who reported prior treatment, the most common treatment was topical cream of an unspecified type (39.1%) followed by various local plant-based treatments (36.9%) and benzyl benzoate (12.8%). At the time of the survey, permethrin cream was unavailable through the publicly funded clinics and could only be purchased through private pharmacies. Ivermectin, an oral treatment for scabies, is not available in Fiji.

This study is the first national survey of scabies and impetigo prevalence conducted in any country and indeed the only one that we are aware of that is based on a rigorous sampling methodology and covers a substantial population and geographic area. Our survey confirms that scabies and impetigo are widespread problems in Fiji. While we observed that children are the most affected population group, no age group is free of scabies or impetigo, and there is an indication that prevalence increases after middle age. Scabies and impetigo are highly prevalent across all geographical divisions and both genders and in both the main ethnic groups.

High levels of scabies and related bacterial infections have previously been documented in tropical countries with low or medium socio-economic status and in disadvantaged populations, particularly in countries in the Pacific region [21]. However, all previous studies were conducted in smaller, localised areas, such as single provinces, schools or villages [21]. Prior reviews of the prevalence of scabies and impetigo have consistently documented high levels of both diseases in school-aged children [9,21]. Only a limited number of studies have described the tendency for scabies to reappear in older age groups, as we observed [7,14,22]. A possible explanation for this apparent phenomenon is that under the typical family structure in these countries, older community members frequently care for children, and are thereby exposed to a heightened risk of transmission of scabies from children. A further possible explanation is that repeated infestation in childhood leads to protective immunity in adulthood but this wanes in the elderly, although there are very few data to support this hypothesis. Consistent with our findings, previous studies in Fiji have documented that scabies and impetigo are most prevalent in the iTaukei Fijian population [8,14,21]. The reason for this is not clear but may be possibly linked to a higher number of children per family and the tendency to live in single-room houses. Other bacterial infections including pneumonia, invasive streptococcal and staphylococcal infections, and rheumatic heart disease have been observed to be more common in iTaukei Fijians [6,23–25].

Impetigo is common in Fiji. Over 15% of participants in this study had more than 20 impetigo lesions and over one quarter of participants had purulent lesions. This study clearly documents that scabies is the main driver of bacterial skin infection in Fiji with scabies contributing 93% of the risk of impetigo. This striking finding has considerable implications for public health efforts to control impetigo; that is, successful control measures directed at scabies would likely translate into significant reductions in the burden of impetigo.

The survey had a number of methodological limitations. Our sample had an over-representation of younger children and an under-representation of older people, possibly due to sampling of areas with primary or secondary schools in proximity of the selected sites, and the relative absence of adults due to regional work commitments. Further, there may have been weaknesses in the diagnosis of scabies and impetigo. Although diagnosis was entirely clinical, and did not use a microscope or scraping of scabies mites, we employed senior nurses, who received intensive training in relevant methods, and were paired to conduct the examination. However no further validation was conducted and we did not conduct any bacteriology tests to confirm the presence of bacterial infection of impetigo lesions.

The Fiji Ministry of Health received a preliminary report of this survey Romani [10], and has since undertaken a number of measures to increase community and health care worker awareness and knowledge of scabies. The Government’s Integrated Management of Childhood Illness guidelines now include an assessment and treatment guide for skin health with a focus on scabies and bacterial skin infection [19]. Education about scabies has been conducted through the hospitals, clinics and health centres.

This large, nationwide survey of scabies and impetigo provides comprehensive data on the prevalence of these diseases in Fiji indicating that one-fifth of the population is affected at any one time, and that nearly 50% of school-aged children are affected. This tremendous burden of disease at a population level strongly supports the need for investment into research to investigate the best strategies for public health control of scabies in communities where resources are limited and scabies and it complications endemic. Our data suggest that an effective public health control measure for scabies will also likely lead to a considerable reduction in the burden of impetigo.