NECATOR-AMERICANUS (NEMATODA, ANCYLOSTOMATIDAE) FROM AFRICA AND MALAYSIA HAVE DIFFERENT ITS-2 RDNA SEQUENCES

The nucleotide sequences of the second internal transcribed spacer of rDNA were determined for adult worms of Necator americanus originating from Togo (Africa) and Sarawak (Malaysia). The length of the sequence s of specimens from Togo (325 bp) were shorter than those from Sarawak (327 bp). There were six fixed genetic differences in the aligned seq uences of N. americanus from Sarawak and Togo, excluding one or two po lymorphic sites within the sequence of N. americanus from each geograp hical region. These findings suggest that there is either population v ariation in the sequence of N. americanus, or that N. americanus from the two countries may represent genetically distinct but morphological ly similar (i.e. cryptic) species, however, comparison of the sequence differences among other hookworm species supports the latter conclusi on. (C) 1998 Australian Society for Parasitology. Published by Elsevie r Science Ltd.