Differentiation of Oesophagostomum bifurcum from Necator americanus by PCR using genetic markers in spacer ribosomal DNA

Oesophagostomiasis in humans due to infection with Oesophagostomum bifurcum (nodular worm) is of major human health significance in northern Togo and Ghana where Necator americanus (human hookworm) also exists at high prevalence. However, very little is known about the transmission patterns of O. bifurcum, partly due to the difficulty in differentiating O. bifurcum from N. americanus at some life-cycle stages using morphological features. To overcome this limitation, a molecular approach utilizing genetic markers in the second internal transcribed spacer (ITS-2) of ribosomal (r) DNA was developed. The ITS-2 sequence of each species was determined, and specific oligonucleotide primers were designed to the regions of greatest sequence difference between the species. Utilizing these primers, rapid PCR assays were developed for the specific amplification of DNA of O. bifurcum or N. americanus, which have the potential to confirm the identity of eggs from faeces and larvae from the intestine or environment. The application of species-specific PCR has important implications for studying the epidemiology and population biology of O. bifurcum.