Low prevalence of scabies and impetigo in Dakar/Senegal: a cluster-randomised, cross-sectional survey

Background Scabies, a parasitic infection caused by Sarcoptes scabiei var. hominis, is a public health problem with significant morbidity worldwide, particularly in low-resource countries. Impetigo, a complication of scabies infection, is a risk factor for sepsis, glomerulonephritis and possibly acute rheumatic fever. Currently, the majority of epidemiological data has been collected in rural populations in the Pacific with limited applicability to urban populations in sub-Saharan Africa, where scabies is also believed to be a problem. To inform future public health programs more reliable information about the burden of disease is required. Methodology/Principal Findings In July/August 2022 we conducted a cross sectional, cluster-randomised, household survey in Pikine/Dakar using the ‘International Association for the Control of Scabies (IACS)’ criteria to diagnose scabies and impetigo. All participants underwent a standardised clinical examination by post-graduate dermatology students. For those diagnosed with scabies an age-adapted ‘Dermatology Life Quality Index (DLQI)’ questionnaire was filled. We recruited and examined 1697 participants detecting 27 cases of scabies (prevalence: 1.6%, 95% CI 0.8-3.2), mostly in school aged children. 10 participants suffered from impetigo (prevalence: 0.6%, 95% CI 0.3-1.3), 5 of which were dually infected with scabies. Risk factors for scabies infection were young age, male gender and koranic school attendance. Scabies had a large effect on the lives of 7 out of 22 cases (31.8%), who had DLQI questionnaires filled. Conclusions/Significance This study adds to the mapping of the burden of scabies across Africa to support public health action. With a low prevalence of scabies that is concentrated amongst poor households and children attending koranic schools a focused public health approach targeting koranic schools and poor households seems to be most appropriate in this community. Author’s Summary Caused by a mite, scabies is a very common skin infection transmitted between humans. It most commonly affects children in tropical countries and causes a severe itch leading to emotional distress and sometimes bacterial infections than can lead to severe illness. Despite efforts in the past to reduce the burden from scabies at a population level a lack of knowledge about the distribution of the parasite hampers the design and implementation of larger control programs. In Africa, little is known about the burden and distribution of scabies, particularly in urban centres. This study surveyed inhabitants of Dakar for scabies and bacterial skin infections. We randomly selected groups of houses in a low socio-economic status neighbourhood and invited all inhabitants of these houses for an interview and for a brief skin examination. Of 1697 participants only 27 (1.6%) were found to have scabies, 5 of whom also suffered from impetigo, a bacterial skin infection. Most people with scabies were pupils in koranic schools suggesting they may be the setting of ongoing transmission. Further studies need to find reasons for the high burden amongst these pupils and how best to reduce the burden in these schools.