Cyclospora infection: a review

Cyclospora is a coccidian parasite responsible for a syndrome of acute and chronic diarrhoea. The organism first come to worldwide attention in 1990 following the publication of three reports. The largest series of cases and the first clinical description of the illness associated with this organism came from Kathmandu where travellers and expatriates were noted to have prolonged diarrhoea with a previously undescribed organism. The organism has been identified as a coccidian both by observation of sporulation and subsequent molecular phylogenetic analysis. Cyclospora organisms appear as non-refractile double-walled spheres, 8-10 microns in diameter. The organism floats in Sheather's sucrose solution and appears variably red on the modified acid-fast stain. It can also be identified on plain wet mounts. Since its first description, Cyclospora has been noted in an increasing number of countries throughout the world. Water-borne transmission has been implicated in several studies. There is a distinct seasonality in Cyclospora outbreaks and cases. In Nepal, the organism has occurred in virtually identical seasonal outbreaks since 1989. The clinical illness associated with Cyclospora is characterized by diarrhoea, nausea, anorexia and weight loss, which may persist for weeks to months if untreated. Evidence of malabsorption of D-xylose has been noted and small bowel biopsies revealed moderately severe villous atrophy and crypt hyperplasia. Successful treatment with trimethoprim-sulfamethoxazole has been identified, but to date no alternative treatment exists for the sulfa allergic patient.