Genotyping specimens of human lice from a centenary entomological collection

Abstract

Pediculus humanus has been infesting humans since their origin. This obligatory hematophagous and monoxenic parasite has co-evolved with its hosts, carrying genetic information that reflects this long evolutionary history. The ecotypes of P. humanus are divided into six phylogenetic clades (A-F) with distinct geographical distributions. Paleoparasitological studies have revealed a high lice infestation rate in mummies from various chronological periods and cultures worldwide. In this study, we conducted a paleogenetic analysis of head lice specimens from the Entomological Collection of Oswaldo Cruz Institute, collected in Suriname in 1941, to investigate the P. humanus mitochondrial haplotypes that were circulating in that population at that time. Ancient DNA was extracted from adult lice specimens, and paleogenetic analysis was performed using PCR-Sanger sequencing targeting the mitochondrial cytochrome b (cytb) gene. Our results identified sequences belonging to the cosmopolitan clade A, specifically the haplotype A17. A17 is the second largest cosmopolitan haplotype within clade A, with representatives found across all continents, but never found in South America. In 1941, Suriname, as part of the Kingdom of the Netherlands, experienced various socio-political changes and movements of populations due to World War II. This finding reflects both the colonial activities of that time and the global conflicts influencing human migrations. Specimens housed in collections for many decades often exhibit degraded DNA due to preservation techniques being inappropriate for molecular studies, posing challenges for genetic analysis. Our findings highlight the importance of biological collections as valuable repositories of genetic information that can shed light on the past distributions and interactions of parasitic species.