Human Lice (Phthiraptera) Infestations in Africa: A Review of Prevalence, Genetic Diversity, Associated Pathogens, Pediculicide Resistance, and the Implications for Public Health

Abstract

Purpose of Review Pediculosis, classified as a neglected tropical disease, remains widely prevalent across much of Africa, imposing substantial health burdens and significant social consequences across diverse socioeconomic strata. This review aims to provide up-to-date information on human lice infestations and offer recommendations for future research directions.Recent Finding Prevalence of 0.6 − 79% human infestations with Pediculus humanus capitis, and Pediculus humanus huma-nus has been reported in 27 African countries. Phylogenetic and haplotype analyses of mitochondrial genes reveal high genetic diversities among the African lice populations. Clades A head lice were the most prevalent, followed by the D, C and E clades. Interestingly, clade E body lice were reported for the first time in Africa. The DNA of several pathogens of public health importance; Bartonella, Borrelia, Rickettsia, Coxiella, Yersinia, Acinetobacter, Anaplasma, and Ehrlichia species were detected in both head and body lice. The vector capacity of both lice for some of these pathogens were demonstrated experi-mentally or circumstantially during outbreak investigations, highlighting the potential role of head lice in disease transmis-sion. Of note, the DNA of Acinetobacter baumannii was detected in Pthirus pubis suggestive of the ubiquitous nature of this pathogen and the potential public health impact of pubic lice. The use of local formulations or unconventional products for the treatment of human lice predominates in most of Africa. Pyrethroid resistance associated with the M815I, T917I, and L920F mutations in the voltage-sensitive sodium channel (VSSC) α-subunit gene, as well as ivermectin resistance linked to mutations in the glutamate-gated chloride channel (GluCl), has been reported in a limited number of African countries.Summary Inadequate healthcare facilities and economic constraint tends to facilitate the widespread human lice infestation in Africa. The detection of a broad variety of pathogens constitute threats to human health and social well-being. In-depth studies to assess the socio-economic impact, elucidate pediculicides resistance profile and the adoption of a standardized treatment approach for human lice on the continent are needed.