Current research on human louse biology has focused on the longstanding debate about speciation of head and body lice but using new tools of DNA and enzyme analysis. These studies have indicated that head and body lice from the same geographical zone may be more closely allied than insects inhabiting the same ecological niche in other regions. However, the majority of research over the past decade has involved clinical aspects including transmission, treatment, and the appearance and

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... ion of resistant strains within populations of lice. Despite advances, there is a need for a better understanding of louse biology, as existing therapies fail and lice remain potential vectors of disease for millons of people. Recent investigations (3, 52, 53) at the subcellular level have begun to provide information to elucidate this long-term question. Examination of mitochondrial DNA from both head and body lice from nine countries found 10 haplotypes that differed by between one and five base pairs at 11 nucleotide positions. Of these, three haplotypes were shared between head and body lice and, although tests of frequency of these haplotypes found significant differences between the two forms of lice, greater differences were found between lice from different countries. The constructed phylogeny suggested that head and clothing lice are conspecific and not Annu. Rev. Entomol. 2004.49:457-481. Downloaded from arjournals.annualreviews.org by Ian Burgess on 02/04/05. For personal use only. HUMAN LICE