Emerging pathogen Cyclospora cayetanensis infection in Nepal.

Cylospora cayetanensis, an emerging parasitic pathogen of human is being increasingly recognized throughout the world, however the means of transmission and the possibility of a reservoir host remain an enigma. A longitudinal study on cyclosporiasis in different parts of Nepal was carried out from April, 1995 until November, 2000. Fecal specimens were collected from symptomatic and asymptomatic patients. The data shows a distinct seasonality with the highest infection rates occurring during the summer and rainy season of the year. Attempts have been made to determine the sources of infection and possible reservoir hosts. Stools were examined from nearly 700 animals such as chickens, pigs, buffalos, cows, dogs, cats, monkeys, rats, mice and pigeons. In addition, vegetable farms around the Kathmandu Valley were examined during the seasonal high and low periods of transmission. C. cayetanensis-like oocysts were found in sewage water and from vegetable washings on five occasions during June, July, August, October, and November. Similarly, C. cayetanensis-like oocysts were recovered from mice, rats, chickens, and dogs. These results suggest that these sources may be important in the transmission of this parasitosis. However, further studies will be required to obtain definitive answers on transmission.