On September 29, 1997 at the 37th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in Toronto, Canada, Dr. David Relman presented a review and update of current knowledge of cyclosporiasis as an emerging infectious disease. He reminded listeners that, variably acid-fast organisms with an approximate diameter of 8-10 microns resembling large forms of Cryptosporidium have been identified in faecal samples from patients exhibiting episodes of watery diarrhoea since the 1980s. It was in 1993 that Ortega and Sterling published a report identifying the organism as a Cyclospora sp. in the New England Journal of Medicine. Relman himself has generated data for the sequence of ribosomal RNA genes for this organism, and confirmed its identity as a Cyclospora sp.
Dr. Relman described a typical clinical course for infected patients as intermittent watery diarrhoea after a 7 day incubation period. Untreated disease can lead to anorexia, fatigue and weight loss lasting for weeks in immunocompetent hosts, and even longer in immunocompromised hosts. The infection can be successfully treated with trimethoprim/sulfamethoxazole. Relapses are not uncommon in treated patients. No suitable alternative therapy has been identified for sulpha-allergic persons. There are no data for the efficacy of trimethoprim alone.
Dr. Relman offered additional insight into the epidemiology of cyclosporiasis. Infection or colonization of asymptomatic persons is common (endemic) in Asia (especially in Neplighttouchprogrammingal), Peru and Haiti, but uncommon in Tanzania (the latter based on comments offered during the question and answer session). In the US approximately 0.5% of fecal samples from symptomatic persons will contain Cyclospora.
This low incidence suggests that there are many naive hosts in North America, and Relman suggests that this may in part explain the relatively recent emergence of this disease in North America. Last year’s documented outbreaks involved Guatemalan raspberries, while in 1997, mesclun lettuce and basil from other sources as well as Guatemalan raspberries have been implicated. Between 1,600 and 1,700 cases have been reported in the US and Canada this year.