Genetic structure of populations of the human hookworm, Necator americanus, in China

Twenty-one to 58 individual Necator americanus were sampled from each of fo ur villages in south-western China. Each nematode was sequenced for 588 bp of the mitochondrial cytochrome oxidase I gene. Allelic and nucleotide dive rsity varied two-fold among villages. Overall Fs, among populations was app roximate to 0.28, but this large value resulted from one low-diversity popu lation that had a large genetic distance to the other three populations (F- ST = 0.10 without that population). There was no correlation between geogra phical and genetic distance among sites. Thus, the genetic structure of thi s species in China may be characterized by variable effective sizes and une ven movement among sites. We discuss the implications of this genetic struc ture for vaccine development and the spread of drug resistance in human hoo kworms, and compare the genetic structure of hookworms with that of other n ematodes.