Abstract

Cyclosporiasis is a disease caused by infection with "Cyclospora cayetanensis", a pathogenic protozoan transmitted by feces or feces-contaminated food and water. Outbreaks have been reported due to contaminated fruits and vegetables. It is not spread from person to person, but can be a hazard for travelers as a cause of diarrhea.

Mode of infection

When an oocyst of "Cyclospora cayetanensis" enters the small intestine, it invades the mucosa, where it incubates for about one week. After incubation, the infected person begins to experience severe watery diarrhea, bloating, fever, stomach cramps, and muscle aches.

The parasite particularly affects the jejunum of the small intestine. Of nine patients in Nepal who were diagnosed with this illness, all had inflammation of the lamina propria along with an increase of plasma in the lamina propria. Of this sample, Oocysts were observed in the duodenal aspirates.

Oocysts are often present in the environment as a result of using contaminated water or human feces as fertilizer. Cyclosporiasis primarily affects humans and primates.

Diagnosis and treatment

Diagnosis can be difficult due to the lack of recognizable oocysts in the feces. PCR-based DNA tests and acid-fast staining can help with identification. The infection is often treated with trimethaprine-sulfamethaxozol [Bactrim, co-trimoxazole], because traditional anti-protozoal drugs are not sufficient. To prevent transmission, food should be cooked thoroughly and drinking water from streams should be avoided while outdoors.

Vaccine research

There is no vaccine to control "Cyclospora" infection in humans at present, but one is available for reduction of fetal losses in sheep.

Epidemiology

The first recorded cases of Cyclospora in humans were as recent as 1977, 1978, and 1979. They were reported by Ashford, a British parasitologist who discovered 3 cases while working in Papua New Guinea. Ashford found that the parasite had very late sporulation, from 8–11 days, making the illness difficult to diagnose. When examining feces, the unsporulated oocysts can easily be mistaken for fungal spores, and thus can be easily overlooked.

During the first cases discovered in the early 1980s, Cyclospora was identified as one of the most important opportunistic infections among AIDS patients.

Although it was initially thought that "Cyclospora" was confined to tropical and subtropical regions of the world, occurrences of Cyclosporiasis are becoming more frequent in North America. According to the Centers for Disease Control and Prevention, a U.S. government public health agency, there have been 11 documented "Cyclospora" outbreaks in the U.S. and Canada since the 1990s. The CDC also recorded 1,110 laboratory-confirmed sporadic instances of "Cyclosporiasis". Between June and August 2013, multiple independent outbreaks of the disease in the U.S. sickened at least 631 people across 25 states. Investigations later identified a bagged salad mixture as the cause of the outbreak in Iowa and Nebraska.

In 2015, the CDC was notified of 546 ill persons with confirmed "Cyclospora" infection across 31 states. Cluster investigations in Texas, where the greatest number of infections was reported, suspected contaminated cilantro as the culprit.