COLONIC STRONGYLOIDES STERCORALIS INFECTION

Strongyloides stercoralis is a nematode infection which predominantly involves the small bowel. Spillover infection to the colon does occur, but is uncommon and is usually associated with an immunocompromised host. Individuals with infection confined to the intestinal tract are often asymptomatic but may have abdominal pain, weight loss, diarrhea, and other nonspecific complaints. In such cases the only sign of infection is an increased peripheral blood eosinophil count but should not be relied upon.Strongyloidiasis is endemic in rural areas of tropical and subtropical regions in these areas, the overall regional prevalence may exceed 25 percent. In addition, strongyloidiasis occurs sporadically in temperate areas such as North America, southern Europe, Japan, and Australia. An estimated 30?100 million people are infected worldwide precise data on prevalence are unknown in endemic countries (WHO)(1,2). Strongyloidiasis is transmitted through direct penetration of human skin by infective larvae when in contact with soil walking barefoot is therefore a major risk factor for acquiring the infection. Strongyloides spp. larvae penetrate the human host and reach the intestine where they mature into adults and produce eggs the eggs hatch in the gut lumen and yield larvae that are evacuated in faeces. The peculiarity of this worm is that some larvae are not excreted but reinvade the intestine or perianal skin to perpetuate the infection (?autoinfection cycle?).(2) The larvae mature into adult worms that burrow into the mucosa of the duodenum and jejunum. Adult worms may live for up to five years. In the apparent absence of male adults, pathogenic adult females produce eggs, from which noninfectious larvae (rhabditiform larvae) develop within the lumen of the gastrointestinal (GI) tract. The rhabditiform larvae (picture 1) are generally passed in the stool. The duration of the cycle from dermal penetration of filariform larvae to appearance of rhabditiform larvae in the stool is approximately three to four weeks. (2, 3)