# Food and Drinking Water as Sources of Pathogenic Protozoans: An Update
## 9 Cyclospora cayetanensis
### Epidemiology of C. ayetanensis  
Latin America, Central and Southeast Asia, the Middle East, and North Africa are hotspots of endemicity for _C. ayetanensis_, where it caused several outbreaks linked to the consumption of fresh fruits, berries, leafy greens, and aromatic herbs. Since _C. ayetanensis_ is highly resistant to disinfectants used in the food industry, the contamination of fresh vegetables and fruits persists even after sanitation [6].  
In the USA, outbreaks of cyclosporiasis linked to berries, cilantro, basil, and, more recently, ready-to-eat bagged salads have been documented since the 1990s and have affected thousands of individuals annually in the past decade [237]. The first outbreak was reported in Chicago and was possibly linked to a hospital water supply [242]. From 2018 to 2022 annual summertime outbreaks became regular in people with no recent international travel history [235; 243]. Between May and August 2021, 1123 laboratory-confirmed cases occurred in 36 states, and 561 isolates were distinguished in 31 temporal genetic clusters (TGC). Ten of these were associated with epidemiological clusters. Two of these were multistate and were linked to lettuce from a single brand, and to lettuce not associated with a brand, respectively, as inferred by isolate typing and patient interviews [242].  
In a case-control study of an outbreak in Canada, with 87 cases and 1 hospitalization, blackberries imported from Mexico were identified as the most probable source of infection. In South Korea, the first reported outbreak of cyclosporiasis occurred among travelers returning from Nepal, and it was probably caused by infected vegetables, water, or fruits from the visited country [237].  
In Europe and Australia, most of the reported cases of cyclosporiasis were linked to international travel to endemic areas. A foodborne outbreak in Stockholm, Sweden, was linked to sugar snap peas imported from Guatema, and a foodborne outbreak in Germany was epidemiologically traced to lettuce and herbs from Germany, France, and Italy; the contamination of food crops probably derived from agricultural workers who had no access to sanitary facilities [243].  
The prevalence of _C. ayetanensis_ among populations reported in different studies varied greatly. In China, it was 0.2% among patients with diarrheal illnesses in Zhenjiang City, Shanghai Municipality and 10.0% in Yongfu County and in southeast China among workers in a laboratory animal facility. In children younger than 5 years in African countries, the prevalence of _C. ayetanensis_ was 3.3% in Gabon, 2.7%, in Ghana, and 0.9%-1.5% in Tanzania. In Iraq, the prevalence of _C. ayetanensis_ varied between 1.0% in a hospital in Baqdad and 14.5% in rural areas, and a high rate of infection was observed in children of 1-9 years of age (25.8%) and in the age group 10-29 years (21.8%-16.6%), while it comprised between 1.0 and 3.0% in older individuals. In Thailand, _C. ayetanensis_ was not detected by molecular methods in 254 schoolchildren in Ratchaburi Province [237].  
A significantly higher prevalence of 8.7% was reported in Ghana in HIV-positive individuals compared to 1.2% in HIV-negative individuals. The prevalence reached 13.6% in patients with CD4+ T cell counts below 200 cells/\(\upmu\)L. A pooled prevalence of _C. cayetanensis_ infection of 3.9% was estimated in HIV-infected individuals in northwestern Iran [244]. In patients with gastroenteritis from Sweden, the parasite was only detected in 2 of 803 fecal samples by microscopy and real-time PCR. The incidence and suspected origin of those infections were unknown [245]. In Venezuela, cyclosporiasis was associated with poverty and soil transmission [246].