Cyclosporiasis Detected in Mexico Travelers

Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. People can become infected with Cyclospora by consuming food or water contaminated with the parasite.

People living or traveling in countries where cyclosporiasis is endemic may be at increased risk for infection. During the summers of 2015 and 2016, the UK experienced large outbreaks of cyclosporiasis in travelers returning from Mexico. As the source of the outbreaks was not identified, there is the potential for a similar outbreak to occur in 2017 and indeed 78 cases had already been reported by July 27, 2017.

Scientists working with Health Protection Scotland (Glasgow, UK) were was informed of cyclosporiasis among travelers returning from Mexico. Subsequently, cases were also detected among residents of England, Wales, Jersey and Isle of Man. Individuals were considered a probable case of cyclosporiasis if they had a sample date between 1 June and 28 October 2016 and travelled to Mexico in the previous 14 days, and if oocysts were identified in stool specimens by a diagnostic laboratory. Confirmed cases were probable cases confirmed microscopically by a national reference laboratory. Between June 1 and October 28, 2016, a total of 440 cases were reported in the UK, of which 289 (66%) were confirmed.

Food and travel histories were collected, and 359 (82%) cases reported recent travel history to Mexico, four had travelled to four different countries, two reported no overseas travel and travel history was unavailable for the other 75 cases. The epidemiological investigations demonstrated that 231 (64%) of the travelers had visited Mexico and had stayed in the Riviera Maya and Cancun regions often in all-inclusive hotels. Despite extensive descriptive epidemiological investigations in the UK, a formal analytical epidemiological study was not conducted and no specific vehicle was identified.

To improve laboratory testing, reminders were sent to diagnostic laboratories to consider testing for Cyclospora in cases where individuals had compatible symptoms and travel history. Discussions were also held among UK parasitology reference laboratories to share their confirmatory methodologies (fluorescence and stained microscopy and/or polymerase chain reaction), to review the usefulness of quantitative PCR for monitoring assay development and performance, and consider methods for genotyping and progression of whole genome sequencing.

The authors concluded that the recurring seasonal increase of cyclosporiasis cases is of public health importance due to the detrimental effect that this infection has on symptomatic cases, both during and following travel. Based on the previous UK cyclosporiasis outbreaks, they recommend other European countries to assess, and increase if necessary, Cyclospora laboratory testing and reporting capacity, increase cyclosporiasis risk awareness among travelers to Mexico, report cyclosporiasis cases early, and collaborate in outbreak investigations to identify possible sources and to assess the extent of the outbreak. The study was published in the journal Eurosurveillance.

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