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

Abstract

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 to detect 27 cases of scabies (prevalence: 1.6%, 95% CI 0.8-3.2), mostly in school aged children. Ten 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. Of those found to have scabies, in 7 out of 22 cases (31.8%) it had a large effect on their lives according to the 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.

Fig 1. Map of Pikine, a suburb of Dakar, the most Western point of Africa, showing the 27 randomly selected clusters, color-coded for different levels of scabies prevalence in the respective clusters, from which participants were recruited: Green: No scabies, blue: >0–2% scabies, yellow: >2–4% scabies, red: >4–8.5% scabies.

Map created in QGIS by the authors. The basemap is a custom download from OpenStreetMap (OSM). OSM is accessible under a CC-BY-SA-licence.

Fig 2. Flow chart of recruitment for scabies and impetigo survey in Pikine, a suburb of Dakar, Senegal.