Comparison in the ITS-2,or second internal transcribed spacer, among the different geographic isolates of Strongyloides stercoralis
Yoon, John J.
MetadataShow full item record
The phylum Nematoda or round worms comprises numerous free-living and parasitic species. The free-living forms are distributed ubiquitously in soil and water. The parasitic species live in annelids, arthropods, mollusks, plants, and vertebrates. It is estimated that over 80,000 species are parasites of vertebrates. Species parasitic in humans range in length from 2.0 mm (Strongyloides stercoralis) to over a meter (Dracunculus medinensis). The sexes are usually separate. The male, which is smaller than the female, usually has a curved posterior end and, in some species, copulatory spicules and a bursa (Brown, 1975). This study is focused on Strongyloides stercoralis, a member of the Order Rhabditata. The specific diseases that can be caused by S. stercoralis are Strongyloiidiasis, and Chochin-China diarrhea. The distribution of S. stercoralis is worldwide, but human infection is especially prevalent in tropical and warm areas. However, endemic cases of Strongyloidiasis were noted in some mental institutions of the United States. Humans are the principal host of Strongyloides stercoralis, but it also can infect other primates, as well as dogs, cats, and some other mammals. The males usually die early during the life cycle. The pathogenetic parasitic female, measuring around 2.20 mm by 0.04 mm, penetrates the mucosa of the intestinal villi, and lays eggs. The adult worms also can be found in the submucosa of the duodenum and jejunum (Brown, 1975).