Many parasitic helminths are of major socio-eco- sequence of the second internal transcribed spacer
nomic importance due to the diseases they cause in (ITS-2) of rDNA provides genetic markers for the
humans and animals. Being able to accurately identify identification of parasitic nematodes to species.3–8 We
a parasite at any stage of its development is central have employed PCR-linked restriction fragment length
to diagnosis of infection, and has important im- polymorphism (PCR-RFLP) and direct cycle seplications
for studying parasite epidemiology and quencing methods to characterize parasites by their
controlling disease. However, the accurate iden- ITS-2 sequence.9,10 Although valuable, these methods
tification of parasite stages (particularly ova and lar- have limitations in that they can be relatively lavae)
to the species level is frequently not possible borious and time consuming to perform when large
using morphological characters. numbers of samples are to be examined, and they do
DNA technology has provided alternative strategies not always accurately resolve sequence variation.
for parasite identification where morphological fea- Mutation scanning methods are now widely used
tures are of limited value.1 Ribosomal (r)DNA can in fields of biomedical research to screen for variation
provide useful genetic markers as it is generally con- in gene sequences,11 but they have not been exploited
sidered that rDNA maintains sequence homogeneity in the field of molecular helminthology. Single-strand
within a species.2 We have recently shown that the conformation polymorphism (SSCP) is a simple