Pediculus humanus capitis, the head louse, is an obligate blood-sucking ectoparasite that occurs in six divergent mitochondrial clades (A, D, B, F, C and E). Several studies reported the presence of different pathogenic agents in head lice specimens collected worldwide. These findings suggest that head louse could be a dangerous vector and a serious public health problem. Herein, we aimed to study the mitochondrial genetic diversity, the PHUM540560 gene polymorphisms profile of head lice collected in Guinea, as well as to screen for their associated pathogens. In 2018, a total of 155 head lice were collected from 49 individuals at the Medicals Centers of rural (Maférinyah village) and urban (Kindia city) areas, in Guinea. Specimens were subjected to a genetic analysis and pathogens screening using molecular tools. Results showed that all head lice belonged to eight haplotypes in the E haplogroup, with six newly identified for the first time. The study of the PHUM540560 gene polymorphisms of our clade E-head lice revealed that 82.5% exhibited the same polymorphism profile as the previously reported clade A-body lice. Screening for targeted pathogens revealed the presence of Acinetobacter spp., while sequencing highlighted the presence of several species, including Acinetobacter baumannii, Acinetobacter nosocomialis, Acinetobacter variabilis, Acinetobacter towneri and for the first time Acinetobacter haemolyticus. Our study is the first to report the existence of the Guinean haplogroup E, the PHUM540560 gene polymorphism profile as well as the presence of Acinetobacter species in head lice collected from Guinea.

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Background The human louse (Pediculus humanus) is a haematophagous ectoparasite that is intimately related to its host. It has been of great public health concern throughout human history. This louse has been classified into six divergent mitochondrial clades (A, D, B, F, C and E). As with all haematophagous lice, P. humanus directly depends on the presence of a bacterial symbiont, known as “Candidatus Riesia pediculicola”, to complement their unbalanced diet. In this study, we evaluated the codivergence of human lice around the world and their endosymbiotic bacteria. Using molecular approaches, we targeted lice mitochondrial genes from the six diverged clades and Candidatus Riesia pediculicola housekeeping genes. Methods The mitochondrial cytochrome b gene (cytb) of lice was selected for molecular analysis, with the aim to identify louse clade. In parallel, we developed four PCR primer pairs targeting three housekeeping genes of Candidatus Riesia pediculicola: ftsZ, groEL and two regions of the rpoB gene (rpoB-1 and rpoB-2). Results The endosymbiont phylogeny perfectly mirrored the host insect phylogeny using the ftsZ and rpoB-2 genes, in addition to showing a significant co-phylogenetic congruence, suggesting a strict vertical transmission and a host–symbiont co-speciation following the evolutionary course of the human louse. Conclusion Our results unequivocally indicate that louse endosymbionts have experienced a similar co-evolutionary history and that the human louse clade can be determined by their endosymbiotic bacteria. Graphical Abstract

Pediculus humanus capitis, the head louse, is an obligate blood-sucking ectoparasite that occurs in six divergent mitochondrial haplogroups (A, D, B, F, C and E), each exhibiting a particular geographic distribution. A few years ago, several studies reported the presence of different pathogenic agents in head lice specimens from different clades collected worldwide. These findings suggest that head louse could be a vector for dangerous diseases and therefore a serious public health problem. Herein, we aimed to study the mitochondrial genetic diversity, the PHUM540560 gene polymorphisms profile of head lice collected in Guinea, as well as to screen for the pathogens present in these lice. In 2018, a total of 155 head lice were collected from 49 individuals at the Medicals Centers of rural (Maférinyah village) and urban (Kindia city) areas, in Guinea. All head lice were subjected to genetic analysis and screened for the presence of several pathogens using molecular tools. The results showed that all head lice belonged to the haplogroups C/E using the duplex qPCR which detects both clades. Standard PCR and sequencing revealed that all specimens belonged to the haplogroup E, including 8 haplotypes, whither 6 new identified for the first time in this study. The study of the PHUM540560 gene polymorphisms in our Guinean head lice revealed that 7/40 (17.5%) of our tested samples exhibit three different polymorphism profiles compared to the clade A-head lice PHUM540560 gene profile, while the remaining specimens 33/40 (82,5%) showed the same PHUM540560 gene polymorphism profile as the previously reported clade A-body lice. Molecular investigations of the targeted pathogens revealed only the presence of Acinetobacter species in 9% of our samples using real time PCR. Sequencing results identified highlighted the presence of several Acinetobacter species, including Acinetobacter baumannii (14.3%), Acinetobacter nosocomialis (14.3%), Acinetobacter variabilis (14.3%), Acinetobacter haemolyticus (7.2%), Acinetobacter towneri (7.2%). Furthermore, a candidate new species of Acinetobacter sp. (7.2%) was detected. Positive specimens were collected from 24,5% individuals in Maférinyah. We also investigated in our study the carbapenem’s-resistant profile of A. baumannii, none of our specimens were positive for the following resistance genes blaOXA-21, blaOXA-24 and blaOXA-58. To the best of our knowledge, our study is the first to report the existence of the Guinean haplogroup E, the PHUM540560 gene polymorphism profile as well as the presence of Acinetobacter species in head lice collected from Guinea.

Background Louse-borne trench fever caused by Bartonella quintana is a neglected public health concern, known to be transmitted from body louse faeces via scratching. No viable B. quintana have ever been isolated from head lice before; therefore, their role as a vector is still poorly understood. Methods In Senegal, the implementation of a permanent local surveillance system in a Point-of-Care laboratory (POC) allows the monitoring of emerging diseases. Here, we used culture as well as molecular and genomic approaches to document an outbreak of trench fever associated with head lice in the village of Ndiop. Head lice and blood samples were collected from febrile patients between November 2010 and April 2015. Genomes of two isolated strains of B. quintana were sequenced and analysed. Results A total of 2,289 blood samples were collected in the 2010-2015 period. From 2010-2013, B. quintana DNA was detected by PCR in 0.25% (4/1,580). In 2014, 228 blood samples were collected, along with 161 head lice from five individuals. B. quintana DNA was detected in 4·4% (10/228) of blood samples, and in lice specimens collected from febrile patients (61·7%, 50/81) and non-febrile patients (61·4%, 43/70). Two B. quintana strains were isolated from blood and head lice from two different patients. Genomic sequence analysis showed 99·98% overall similarity between both strains. Conclusion The presence of live B. quintana in head lice, and the genetic identity of strains from patients’ blood and head lice during a localised outbreak in Senegal, supports the evidence of head lice vectorial capacity.

Background: The human louse is one of the most ancient haematophagous ectoparasites that is related intimately to its host and has been of great concern to public health throughout human history. Previously, Pediculus humanus was classified within six divergent mitochondrial clades (A, D, B, F, C and E). Like all haematophagous lice, P. humanus directly depends on the presence of bacterial symbionts, known as “Candidatus Riesia pediculicola”, to complement their unbalanced diet. In this study, we evaluated the coevolution of human lice around the world and their endosymbiotic bacteria. Using molecular approaches, we targeted lice mitochondrial genes from the six diverged clades and Candidatus R. pediculicola housekeeping genes. Methods: A total of 126 lice were selected for molecular analysis of the cytb gene for lice clade determination. In parallel, four PCR primer pairs were developed targeting three housekeeping genes of Candidatus R. pediculicola: ftsZ, groEL and two regions of the rpoB gene (rpoB-1 and rpoB-2).Results: The endosymbiont phylogeny perfectly mirrored the host insect phylogeny, using the ftsZ and rpoB-2 genes, suggesting a strict vertical transmission and a host-symbiont co-speciation following the evolutionary course of the human louse. Conclusion: Our results unequivocally indicate that lice endosymbiont have experienced a similar co-evolutionary history, and that the human louse clade can be determined by their endosymbiotic bacteria.