Evidence for an African Cluster of Human Head and Body Lice with Variable Colors and Interbreeding of Lice between Continents

BACKGROUND: Human head lice and body lice have been classified based on phenotypic characteristics, including geographical source, ecotype (preferred egg laying site hair or clothes), shape and color. More recently, genotypic studies have been based on mitochondrial genes, nuclear genes and intergenic spacers. Mitochondrial genetic analysis reclassified lice into three genotypes (A, B and C). However, no previous study has attempted to correlate both genotypic and phenotypic data. MATERIALS AND METHODS: Lice were collected in four African countries: Senegal, Burundi, Rwanda and Ethiopia and were photographed to compare their colors. The Multi-Spacer-Typing (MST) method was used to genotype lice belonging to the worldwide Clade A, allowing a comparison of phenotypic and genotypic data. RESULTS: No congruence between louse color and genotype has been identified. Phylogenetic analysis of the spacer PM2, performed including lice from other sources, showed the existence of an African cluster of human lice. However, the analysis of other spacers suggested that lice from different areas are interbreeding. CONCLUSIONS: We identified two geotypes of Clade A head and body lice including one that is specifically African, that can be either black or grey and can live on the head or in clothing. We also hypothesized that lice from different areas are interbreeding

False positive circumsporozoite protein ELISA: a challenge for the estimation of the entomological inoculation rate of malaria and for vector incrimination

<p>Abstract</p> <p>Background</p> <p>The entomological inoculation rate (EIR) is an important indicator in estimating malaria transmission and the impact of vector control. To assess the EIR, the enzyme-linked immunosorbent assay (ELISA) to detect the circumsporozoite protein (CSP) is increasingly used. However, several studies have reported false positive results in this ELISA. The false positive results could lead to an overestimation of the EIR. The aim of present study was to estimate the level of false positivity among different anopheline species in Cambodia and Vietnam and to check for the presence of other parasites that might interact with the anti-CSP monoclonal antibodies.</p> <p>Methods</p> <p>Mosquitoes collected in Cambodia and Vietnam were identified and tested for the presence of sporozoites in head and thorax by using CSP-ELISA. ELISA positive samples were confirmed by a <it>Plasmodium </it>specific PCR. False positive mosquitoes were checked by PCR for the presence of parasites belonging to the Haemosporidia, Trypanosomatidae, Piroplasmida, and Haemogregarines. The heat-stability and the presence of the cross-reacting antigen in the abdomen of the mosquitoes were also checked.</p> <p>Results</p> <p>Specimens (N = 16,160) of seven anopheline species were tested by CSP-ELISA for <it>Plasmodium falciparum </it>and <it>Plasmodium vivax </it>(Pv210 and Pv247). Two new vector species were identified for the region: <it>Anopheles pampanai </it>(<it>P. vivax</it>) and <it>Anopheles barbirostris </it>(<it>Plasmodium malariae</it>). In 88% (155/176) of the mosquitoes found positive with the <it>P. falciparum </it>CSP-ELISA, the presence of <it>Plasmodium </it>sporozoites could not be confirmed by PCR. This percentage was much lower (28% or 5/18) for <it>P. vivax </it>CSP-ELISAs. False positive CSP-ELISA results were associated with zoophilic mosquito species. None of the targeted parasites could be detected in these CSP-ELISA false positive mosquitoes. The ELISA reacting antigen of <it>P. falciparum </it>was heat-stable in CSP-ELISA true positive specimens, but not in the false positives. The heat-unstable cross-reacting antigen is mainly present in head and thorax and almost absent in the abdomens (4 out of 147) of the false positive specimens.</p> <p>Conclusion</p> <p>The CSP-ELISA can considerably overestimate the EIR, particularly for <it>P. falciparum </it>and for zoophilic species. The heat-unstable cross-reacting antigen in false positives remains unknown. Therefore it is highly recommended to confirm all positive CSP-ELISA results, either by re-analysing the heated ELISA lysate (100°C, 10 min), or by performing <it>Plasmodium </it>specific PCR followed if possible by sequencing of the amplicons for <it>Plasmodium </it>species determination.</p

Etude phénotypique et génotypique du pou de tête et du pou de corps de l'homme

L'objectif de la thèse était d'enrichir les connaissances sur les poux de tête et les poux de corps de l'homme. Les poux de tête vivent et pondent leurs œufs à la base des cheveux et sont très répandus chez les enfants dans les écoles. Les poux de corps vivent dans les vêtements et infestent les personnes de milieux sociaux très défavorisés ne permettant pas une hygiène vestimentaire adéquate. Les poux de corps sont vecteurs de trois grandes maladies : le typhus épidémique, la fièvre des tranchées et la fièvre récurrente à poux. Ces insectes hématophages sont étudiés depuis des décennies afin de déterminer si ils constituent deux écotypes de la même espèce ou deux espèces distinctes. Avant l'avènement des techniques de biologie moléculaire, la taxonomie des poux était basée sur leur morphologie et leur biologie. Bien que les différences biologiques décrites entre les poux de tête et les poux de corps ne sont pas toujours cohérentes, il est légitime de penser que leur séparation physique puisse mener à une différenciation spécifique. Certaines études expérimentales ont cependant montré certains cas de migrations de poux de tête vers les vêtements et inversement. Puis, grâce au séquençage du génome du pou, beaucoup de progrès ont été réalisés ces dernières années sur leur phylogénie. Ainsi, sur base de l'ADN mitochondrial, les poux de l'homme sont séparés en trois Clades phylogénétiques : le Clade A qui comprend à fois des poux de tête et des poux de corps et les Clade B et C qui comprennent uniquement des poux de tête.The objective of this thesis work was to increase the knowledge of human head lice and body lice. Head lice live and lay their eggs at the base of hair shaft and are found frequently in school going children. Body lice live in clothes and are usually associated with low income persons that do not have adequate clothes hygiene. Body lice are the vector of three major diseases: epidemic typhus, trench fever and relapsing fever. These blood feeding insects have been studied over the past decades to determine whether they are two ecotypes of the same species or two distinct species. Before the advent of molecular biology, taxonomical classification of lice was based on their morphology and biological activities. Although described biological differences between head lice and body lice are not always consistent, their physical separation could lead to species differentiation. However, some experimental studies have shown that in certain cases head lice could migrate to the clothes and vice versa. In the recent years many progress were made in the body louse genome sequencing, and further their phylogenetic classification. Thus, on the basis of mitochondrial DNA, human lice are classified into three phylogenetic clades: Clade A that comprise both head lice and body lice and the Clades B and C that comprise only head lice. This phylogenetic organization clustered into three clades surprisingly shows that head lice of Clade A are closer to body lice than to head lice of Clade B or C. Since body lice serve as vectors of several diseases, in view of this, it is crucial to understand human lice epidemiology

Etude phénotypique et génotypique du pou de tête et du pou de corps de l'homme

L'objectif de la thèse était d'enrichir les connaissances sur les poux de tête et les poux de corps de l'homme. Les poux de tête vivent et pondent leurs œufs à la base des cheveux et sont très répandus chez les enfants dans les écoles. Les poux de corps vivent dans les vêtements et infestent les personnes de milieux sociaux très défavorisés ne permettant pas une hygiène vestimentaire adéquate. Les poux de corps sont vecteurs de trois grandes maladies : le typhus épidémique, la fièvre des tranchées et la fièvre récurrente à poux. Ces insectes hématophages sont étudiés depuis des décennies afin de déterminer si ils constituent deux écotypes de la même espèce ou deux espèces distinctes. Avant l'avènement des techniques de biologie moléculaire, la taxonomie des poux était basée sur leur morphologie et leur biologie. Bien que les différences biologiques décrites entre les poux de tête et les poux de corps ne sont pas toujours cohérentes, il est légitime de penser que leur séparation physique puisse mener à une différenciation spécifique. Certaines études expérimentales ont cependant montré certains cas de migrations de poux de tête vers les vêtements et inversement. Puis, grâce au séquençage du génome du pou, beaucoup de progrès ont été réalisés ces dernières années sur leur phylogénie. Ainsi, sur base de l'ADN mitochondrial, les poux de l'homme sont séparés en trois Clades phylogénétiques : le Clade A qui comprend à fois des poux de tête et des poux de corps et les Clade B et C qui comprennent uniquement des poux de tête.The objective of this thesis work was to increase the knowledge of human head lice and body lice. Head lice live and lay their eggs at the base of hair shaft and are found frequently in school going children. Body lice live in clothes and are usually associated with low income persons that do not have adequate clothes hygiene. Body lice are the vector of three major diseases: epidemic typhus, trench fever and relapsing fever. These blood feeding insects have been studied over the past decades to determine whether they are two ecotypes of the same species or two distinct species. Before the advent of molecular biology, taxonomical classification of lice was based on their morphology and biological activities. Although described biological differences between head lice and body lice are not always consistent, their physical separation could lead to species differentiation. However, some experimental studies have shown that in certain cases head lice could migrate to the clothes and vice versa. In the recent years many progress were made in the body louse genome sequencing, and further their phylogenetic classification. Thus, on the basis of mitochondrial DNA, human lice are classified into three phylogenetic clades: Clade A that comprise both head lice and body lice and the Clades B and C that comprise only head lice. This phylogenetic organization clustered into three clades surprisingly shows that head lice of Clade A are closer to body lice than to head lice of Clade B or C. Since body lice serve as vectors of several diseases, in view of this, it is crucial to understand human lice epidemiology

Evidence that head and body lice on homeless persons have the same genotype.

Human head lice and body lice are morphologically and biologically similar but have distinct ecologies. They were shown to have almost the same basic genetic content (one gene is absent in head lice), but differentially express certain genes, presumably responsible for the vector competence. They are now believed to be ecotypes of the same species (Pediculus humanus) and based on mitochondrial studies, body lice have been included with head lice in one of three clades of human head lice (Clade A). Here, we tested whether head and body lice collected from the same host belong to the same population by examining highly polymorphic intergenic spacers. This study was performed on lice collected from five homeless persons living in the same shelter in which Clade A lice are prevalent. Lice were individually genotyped at four spacer loci. The genetic identity and diversity of lice from head and body populations were compared for each homeless person. Population genetic structure was tested between lice from the two body regions and between the lice from different host individuals.We found two pairs of head and body lice on the same homeless person with identical multi locus genotypes. No difference in genetic diversity was found between head and body louse populations and no evidence of significant structure between the louse populations was found, even after controlling for a possible effect of the host individual. More surprisingly, no structure was obvious between lice of different homeless persons.We believe that the head and body lice collected from our five subjects belong to the same population and are shared between people living in the same shelter. These findings confirm that head and body lice are two ecotypes of the same species and show the importance of implementing measures to prevent lice transmission between homeless people in shelters

Bartonella quintana in head lice from Senegal

Head and body lice are strict, obligate human ectoparasites with three mitochondrial clades (A, B, and C). Body lice have been implicated as vectors of human diseases, and as the principal vectors of epidemic typhus, relapsing fever, and Bartonella quintata-associated diseases (trench fever, bacillary angiomatosis, endocarditis, chronic bacteremia, and chronic lymphadenopathy). Using molecular methods (real-time and traditional PCR), we assessed the presence of Bartonella quintana DNA in black head lice collected from three locations in Senegal. DNA from B. quintana was identified in 19 lice (6.93%) collected from 7 patients (7%) in Dakar. B. quintana-positive lice collected from three subjects were identified as clades C and A

Pictures of lice.

<p>Pictures of lice.</p