Impact of Scabies in Resource-Poor Communities
Impact of Scabies in Resource-Poor Communities
Treatment of scabies includes a variety of topical compounds such as permethrin, benzyl benzoate, malathion, and oral ivermectin. Usually topical compounds are used as first-line therapy, but in some countries ivermectin is registered for the treatment of scabies, and, owing to its easy application and low cost, commonly used as first-line therapy against scabies. As ivermectin kills a variety of parasites, intestinal helminths, and other ectoparasites (mainly head lice), this drug is increasingly used for mass treatment in endemic communities. Similar to topical compounds, treatment should be given to all household and other close contacts to avoid reinfestation of treated family members. We recommend a second ivermectin dose after 7–10 days, as eggs are not killed by this oral compound. In resource-poor settings, treatment of household members should be given priority over other measures with questionable effectiveness, like treatment of bed linen. There is no need for preventive treatment of companion animals, as sarcoptic mange in animals is caused by other Sarcoptes scabiei subtypes.
Control of scabies on the community level is clearly not an easy task. Some studies have shown that a reduction of scabies prevalence is feasible in endemic communities, by integrating mass therapy, community involvement, health education, training of health professionals, and ongoing surveillance. Intervention should also address socioemotional aspects such as stigma, using an integrated approach with professionals from different areas, and the community. Gilmore has recently suggested, based on statistical modeling, that frequent low-density treatment in an endemic community would bring more benefit than infrequent mass screening and treatments; however, this is based on theoretical assumptions. La Vincente et al.[1] have vividly described the difficulties that public health professionals in practice are facing to achieve sustainability of community control programs in remote aboriginal communities in Australia. Although treatment uptake of topical permethrin among children was about 70%, treatment levels of household contacts were low, especially in households with high scabies burden, with consequently ongoing transmission. In another Australian study, scabies prevalence was not reduced significantly within a community-based control program, based on treatment with topical permethrin for scabies and referral in case of secondary infection, but on the other hand pyoderma prevalence was reduced substantially.
Oral ivermectin has been proposed for community control of scabies, especially in settings in which compliance to topicals may pose a problem. The acceptance of ivermectin is usually very high. Ivermectin has been used in several hundreds of millions of individuals within the onchocerciasis and lymphatic filariasis control programs and is considered well tolerated. The drug has shown good efficacy against several parasitic infections other than filarial, such as soil-transmitted helminth infections, pediculosis, cutaneous larva migrans, and scabies. In fact, the 'beyond-lymphatic filariasis benefits' discussed within the Global Programme to Eliminate Lymphatic Filariasis, which delivered about 150 million ivermectin treatments, include a reduction of scabies, pediculosis, and soil-transmitted helminth infections in communities in which these diseases are endemic. A reduction of the transmission of soil-transmitted helminth infections and scabies in affected communities has also been perceived as an additional benefit within the ivermectin-based Onchocerciasis Control Program. Similarly in Nigeria, communities reported additional benefits of ivermectin mass treatment against onchocerciasis: about one-fourth reported to have expelled intestinal helminths after treatment with ivermectin, 19% improved body itching, and 17% reduced skin rash possibly because of scabies; others reported clearance of head lice infestations. We have observed during mass treatments in Brazil aiming at the reduction of ectoparasites that community members were referring to ivermectin as 'God's drug', as they had noticed that the skin did not itch any more, worms were expelled from the intestine, and head lice were falling off the head (J. Heukelbach, personal communication). This information spread quickly in the community, and as a consequence uptake of drugs was very high.
Scabies-related morbidity rapidly regressed after treatment with oral ivermectin in a Brazilian slum, with significantly decreased itching and less sleep disturbances after 1 week. In a study from the Solomon Islands, scabies prevalence, skin sores, and hematuria (as a marker for renal damage because of group A streptococci) reduced remarkably after ivermectin therapy.
However, the use of oral ivermectin is still a matter of debate. First of all, it is not registered in many countries for the indications of scabies, and also not recommended for use in children younger than 5 years and pregnant women. Second, a recent randomized controlled trial from Senegal, which compared two regimens, topical application of benzyl benzoate and oral ivermectin, has reported that only 25% of patients in the ivermectin group were considered cured, and as a consequence the study was finalized before its planned completion. Cure rate in the benzyl benzoate groups was 54–69%. Similarly, another recent trial from India reported lower efficacy of a single dose of ivermectin as compared to application of topical permethrin. These results from Senegal and India are in contrast to a series of trials comparing oral ivermectin with different topical compounds, which reported similar or superior therapeutic efficacy of ivermectin. As some of these trials were not controlled, and methods were not standardized, the results should be interpreted with care. Resistance may develop after repeated and prolonged treatment with oral ivermectin and topical compounds.
Specific Features of Scabies Control in Endemic Communities
Treatment of scabies includes a variety of topical compounds such as permethrin, benzyl benzoate, malathion, and oral ivermectin. Usually topical compounds are used as first-line therapy, but in some countries ivermectin is registered for the treatment of scabies, and, owing to its easy application and low cost, commonly used as first-line therapy against scabies. As ivermectin kills a variety of parasites, intestinal helminths, and other ectoparasites (mainly head lice), this drug is increasingly used for mass treatment in endemic communities. Similar to topical compounds, treatment should be given to all household and other close contacts to avoid reinfestation of treated family members. We recommend a second ivermectin dose after 7–10 days, as eggs are not killed by this oral compound. In resource-poor settings, treatment of household members should be given priority over other measures with questionable effectiveness, like treatment of bed linen. There is no need for preventive treatment of companion animals, as sarcoptic mange in animals is caused by other Sarcoptes scabiei subtypes.
Control of scabies on the community level is clearly not an easy task. Some studies have shown that a reduction of scabies prevalence is feasible in endemic communities, by integrating mass therapy, community involvement, health education, training of health professionals, and ongoing surveillance. Intervention should also address socioemotional aspects such as stigma, using an integrated approach with professionals from different areas, and the community. Gilmore has recently suggested, based on statistical modeling, that frequent low-density treatment in an endemic community would bring more benefit than infrequent mass screening and treatments; however, this is based on theoretical assumptions. La Vincente et al.[1] have vividly described the difficulties that public health professionals in practice are facing to achieve sustainability of community control programs in remote aboriginal communities in Australia. Although treatment uptake of topical permethrin among children was about 70%, treatment levels of household contacts were low, especially in households with high scabies burden, with consequently ongoing transmission. In another Australian study, scabies prevalence was not reduced significantly within a community-based control program, based on treatment with topical permethrin for scabies and referral in case of secondary infection, but on the other hand pyoderma prevalence was reduced substantially.
Oral ivermectin has been proposed for community control of scabies, especially in settings in which compliance to topicals may pose a problem. The acceptance of ivermectin is usually very high. Ivermectin has been used in several hundreds of millions of individuals within the onchocerciasis and lymphatic filariasis control programs and is considered well tolerated. The drug has shown good efficacy against several parasitic infections other than filarial, such as soil-transmitted helminth infections, pediculosis, cutaneous larva migrans, and scabies. In fact, the 'beyond-lymphatic filariasis benefits' discussed within the Global Programme to Eliminate Lymphatic Filariasis, which delivered about 150 million ivermectin treatments, include a reduction of scabies, pediculosis, and soil-transmitted helminth infections in communities in which these diseases are endemic. A reduction of the transmission of soil-transmitted helminth infections and scabies in affected communities has also been perceived as an additional benefit within the ivermectin-based Onchocerciasis Control Program. Similarly in Nigeria, communities reported additional benefits of ivermectin mass treatment against onchocerciasis: about one-fourth reported to have expelled intestinal helminths after treatment with ivermectin, 19% improved body itching, and 17% reduced skin rash possibly because of scabies; others reported clearance of head lice infestations. We have observed during mass treatments in Brazil aiming at the reduction of ectoparasites that community members were referring to ivermectin as 'God's drug', as they had noticed that the skin did not itch any more, worms were expelled from the intestine, and head lice were falling off the head (J. Heukelbach, personal communication). This information spread quickly in the community, and as a consequence uptake of drugs was very high.
Scabies-related morbidity rapidly regressed after treatment with oral ivermectin in a Brazilian slum, with significantly decreased itching and less sleep disturbances after 1 week. In a study from the Solomon Islands, scabies prevalence, skin sores, and hematuria (as a marker for renal damage because of group A streptococci) reduced remarkably after ivermectin therapy.
However, the use of oral ivermectin is still a matter of debate. First of all, it is not registered in many countries for the indications of scabies, and also not recommended for use in children younger than 5 years and pregnant women. Second, a recent randomized controlled trial from Senegal, which compared two regimens, topical application of benzyl benzoate and oral ivermectin, has reported that only 25% of patients in the ivermectin group were considered cured, and as a consequence the study was finalized before its planned completion. Cure rate in the benzyl benzoate groups was 54–69%. Similarly, another recent trial from India reported lower efficacy of a single dose of ivermectin as compared to application of topical permethrin. These results from Senegal and India are in contrast to a series of trials comparing oral ivermectin with different topical compounds, which reported similar or superior therapeutic efficacy of ivermectin. As some of these trials were not controlled, and methods were not standardized, the results should be interpreted with care. Resistance may develop after repeated and prolonged treatment with oral ivermectin and topical compounds.
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