Cyclosporiasis (Cyclospora cayetanensis) gastroenteritis

Case definition:

• a person with diarrhoea and the identification of Cyclospora cayetanensis oocysts in a stool sample (Multiple specimens may be required as cases may not shed sufficient oocysts in stools)

Cause:Cyclospora cayetanensis, a protozoan parasite

Reservoir: Humans

Epidemiology:

• cases are usually associated with travel to Central or South America, the Caribbean islands, Indian subcontinents and South East Asia
• infection occurs worldwide however the parasite is not endemic in the UK. Since 2015, large outbreaks have been reported in the UK from travellers returning from Mexico

Transmission:

• direct person-to-person spread is unlikely
• cyclospora cayetanensis is transmitted by ingesting infective oocysts. Oocysts are excreted in faeces of human hosts in a non-infective form. They must then sporulate (mature) over 7-15 days in the environment to become infective
• ingestion of sporulated oocysts from sources such as drinking water, and fresh foods cause infection
• outbreaks linked to imported fresh berries, herbs and salad leaves have been documented in developed countries

Incubation period: Usually 7 days (range 1-14 days)

Clinical presentation:

• watery diarrhoea which may be prolonged
• other symptoms often include abdominal pain, fatigue, nausea, flatulence, weight loss and loss of appetite. Vomiting, headache and fever may also occur
• some cases may be asymptomatic

Infectivity: Direct person-to-person spread is unlikely

Notes (1):

• immunocompromised cases may remain infected for several months, but treatment will clear infection
• in a cluster/outbreak situation, a travel history should be sought and if none, a detailed food history (including raw fruits, salads, herbs and imported foods) should be undertaken

Reference:

• PHE (2019). Recommendations for the Public Health Management of Gastrointestinal Infections