Cercarial dermatitis in central India: an emerging health problem among tribal communities

Abstract

Although cercarial dermatitis is an emerging disease world-wide, cases of such dermatitis may often go undiagnosed, especially in communities that are affected by various skin infections. Between August 2001 and July 2002, 1336 individuals from tribal villages in central India were examined for dermatitis. Skin scrapings were collected and examined for Sarcoptes scabiei and each subject's response to antiscabies treatment was recorded. Freshwater snails were collected from the local ponds used for bathing, and examined for cercariae. The recorded prevalence of dermatitis ranged between 2.1% and 12.5% during the study year, peaking at the end of winter (February-March) and during the rainy season (August-October). Snail positivity for cercariae peaked in the rainy season. The prevalence and the severity of dermatitis were both higher in children than in adults. As most recorded cases of dermatitis were associated with a rash that developed soon after bathing in the local pond, all the skin scrapings were negative for itch mites, and the response to antiscabies treatment was poor, most if not all of the dermatitis observed was probably cercarial. Cercarial dermatitis therefore appears to be a significant health problem among the tribal populations of central India.

Avian Schistosomes and Outbreaks of Cercarial Dermatitis

“…Most reported cases of dermatitis caused by the genus Schistosoma are from parasites that infect domesticated work animals, such as cattle and buffalo, mainly in Asia. For example, in countries such as India and Nepal, the species Schistosoma turkestanicum, Schistosoma nasale, Schistosoma indicum, and Schistosoma spindale are often implicated in outbreaks of dermatitis (29)(30)(31)(32)(33)(34)(35)(36)(37)(38). This relationship may not be a surprise, as bovids are the definitive host, and the people in these areas depend upon these animals for their livelihood in farming.…”

Schistosome Infections: An Indian Perspective

“…Although it is an emerging water-borne non-communicable disease prevalent among rural and tribal population of India, it is often neglected, unrecognized and under-reported owing to lack of access to adequate diagnostic & health care facilities [5]. Usually non-human schistosomes (birds and animal schistosome) are mainly attributed to this intense inflammatory pruritic skin condition.…”

“…When cercaria of these parasites emerge from their snail hosts and penetrate skin of patients, they induce inflammatory response to eliminate parasites trapped in the skin [12]. In a recent study, the prevalence of it varied from 2.1% and 12.5% during the year with highest infection rate during winter and the rainy season [5]. Agarwal et al, have reported incidence of cercarial rash in Jabalpur, Madhya Pradesh which was unrecognized and misinterpreted by health practitioners and local people [39].…”

“…The non-existence of intermediate host of anthropophilic schistosomes in India is believed to be the principal reason which precludes the natural lifecycle of these schistosomes in Indian subcontinent [2]. However, at least three endemic foci of human schistosomiasis had been described in India previously and sporadic autochthonous cases and cercarial dermatitis are also not uncommon [5][6][7][8]. Moreover, several unique schistosome species of animals are prevalent in India [3].…”

Real-Time PCR and Sequencing Assays for Rapid Detection and Identification of Avian Schistosomes in Environmental Samples

“…n recent years, waterborne outbreaks of cercarial dermatitis, also known as swimmer's itch, have increasingly been reported worldwide (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). Cercarial dermatitis is caused by free-swimming cercariae of avian and mammalian schistosomes emerging from snails that penetrate and die within human skin, causing an inflammatory immune response (12).…”