Cyclospora

(endorsed 2011)

Guideline

No guideline value has been set for Cyclospora in drinking water and its inclusion in routine monitoring programs is not recommended.

A multiple barrier approach from catchment to tap is recommended to minimise the risk of contamination. Protecting catchments from human and animal wastes is a priority. Operation of barriers should be monitored to ensure effectiveness and that microbial health-based targets are being met.

General description

Cyclospora cayetanensis is a single-cell, obligate, intracellular, coccidian protozoan parasite. It produces thick-walled oocysts of 8-10 µm in diameter that are excreted in the faeces of infected individuals. Humans are the only host identified. The unsporulated oocysts are excreted in faecal material and undergo sporulation, which is complete in 7-12 days, depending on environmental conditions. Only the sporulated oocysts are infectious.

C. cayetanensis is an emerging pathogen, having first been identified as a human pathogen in the 1970s and 1980s (Herwaldt 2000). The organism increased in profile following several food-borne outbreaks in the United States in the 1990s. It has also been associated with waterborne outbreaks (Herwaldt 2000).

C. cayetanensis is transmitted by the faecal-oral route. Person-to-person transmission is virtually impossible, because the oocysts must sporulate outside the host to become infectious. The primary sources of infection are contaminated water and food.

The origin of organisms in food-borne outbreaks has generally not been established, but contaminated water has been implicated in several cases. Drinking water has also been implicated as a cause of outbreaks. The first report was among staff of a hospital in Chicago, USA, in 1990 (Herwaldt 2000, WHO 2002). The infections were associated with drinking tap water that had possibly been contaminated with stagnant water from a rooftop storage reservoir. In Nepal, infection of 12 of 14 soldiers was linked to drinking water consisting of a mixture of river and municipal water (Herwaldt 2000, WHO 2002). In 2005 a waterborne outbreak of cryptosporidiosis and cyclosporiasis was reported in Turkey (Aksoy et al. 2007).

There is limited information on the prevalence of Cyclospora in water environments. The cysts could be environmentally persistent in a similar fashion to other protozoan cysts but there are no data on survival in the environment. Cyclospora has been detected in sewage and water sources (Herwaldt 2000, WHO 2002, Dowd et al. 2003).

Australian significance

There have been no outbreaks recorded in Australia. Sporadic cases in Australia are typically associated with travellers’ diarrhoea (Pinge-Suttor et al. 2004). This is consistent with the cause of sporadic cases in regions such as North America and Europe (Sterling and Ortega 1999, WHO 2002).

Preventing contamination of drinking water

Control measures applied to other infectious protozoa will also reduce risks associated with Cyclospora. The likely source of Cyclospora is human faecal waste, and prevention of contamination of water sources is a priority. There is little information on the removal and/or inactivation of Cyclospora by water and wastewater treatment processes. Oocysts are intermediate in size between Cryptosporidium oocysts and Giardia cysts, and removal by physical processes such as filtration should be similar. There is little information on sensitivity to disinfection.

Method of identification and detection

No specific method has been developed for concentration of Cyclospora from water. However, methods developed for Cryptosporidium and Giardia should be effective. Identification is based on light microscopy and acid-fast staining of smears. Autofluoresence of Cyclospora has also been used to facilitate detection by microscopy (Herwaldt 2000, WHO 2002).

Health considerations

Sporozoites are released from the oocysts when ingested and they penetrate epithelial cells in the small intestine of susceptible individuals. Clinical symptoms of cyclosporiasis include watery diarrhoea, abdominal cramping, weight loss, anorexia, myalgia and occasionally vomiting and/or fever. Relapsing illness often occurs.

Derivation of guideline

No guideline value is proposed for Cyclospora. The focus should be on monitoring of control measures, including prevention of contamination by human waste and (where used) filtration. Escherichia coli is not a reliable indicator for the presence/absence of Cyclospora.

References

Aksoy U, Akisu C, Sahin S, Usluca S, Yalcin G, Kuralay F (2007). First reported waterborne outbreak of cryptosporidiosis with Cyclospora co-infection in Turkey. Eurosurveillance 12(7).

Dowd SE, John D, Eliopolus J, Gerba CP, Naranjo J, Klein R, López B, de Mejía M, Mendoza CE, Pepper IL (2003). Confirmed detection of Cyclospora cayetanensis, Encephalitozoon intestinalis and Cryptosporidium parvum in water used for drinking. Journal of Water and Health, 1:117-123.

Herwaldt BL (2000). Cyclospora cayetanensis: A review, focusing on the outbreaks of cyclosporiasis in the 1990s. Clinical Infectious Diseases, 31:1040-1057.

Pinge-Suttor V, Douglas C, Wettstein A (2004). Cyclospra infection masquerading as coeliac disease. Medical Journal of Australia, 180(6):295-296.

Sterling CR, Ortega YR (1999). Cyclospora: an enigma worth unravelling. Emerging Infectious Diseases, 5(1):48-53.

WHO (World Health Organization) (2002). Protozoan parasites (Cryptosporidium, Giardia, Cyclospora). In: Guidelines for Drinking-Water Quality, 2nd edition, Addendum: Microbiological agents in drinking water. World Health Organization, Geneva, pp. 70-118.