"The Illinois Department of Public Health (IDPH) has received confirmation of approximately 90 cases of cyclosporiasis, an intestinal illness caused by the microscopic Cyclospora parasite. Cases have been reported in counties across Illinois with people becoming ill starting in mid-May. The initial investigation indicates a link to consumption of McDonald’s salads produced for McDonald’s restaurants. Approximately one-fourth of Illinois cases reported eating salads from McDonald’s in the days before they became ill. The Iowa Department of Health has noted a similar increase in cases." It is now suggested in some media items that there are 100 cases.
The FDA has already issued product recall alerts in the last month for Cyclospora ... Del Monte Fresh Produce N.A., Inc. ("Del Monte Fresh") announced on June 15th 2018 a voluntary recall of a limited quantity of 6 oz., 12 oz. and 28 oz. vegetable trays containing fresh broccoli, cauliflower, celery sticks, carrots, and dill dip sold to select retailers in Illinois, Indiana, Iowa, Michigan, Minnesota and Wisconsin - linked to food produced in the previous two weeks. As of July 13, 2018, the CDC has reported 227 laboratory-confirmed cases of cyclosporiasis in people from IA, MN, WI and MI who reportedly consumed the vegetable trays.
These incidents remind me of the problem in the US with the 2013 multistate outbreaks of Cyclospora cayetanensis infections associated with fresh salad mix - the source was cilantro or as known in the UK coriander. There were 636 cases of illness in this outbreak.
A further outbreak associated with a lunch i.e. food service in Germany in 2000 was linked to leafy salads or herbs; imported sugar snap peas in Sweden in 2009; and raspberries in the US in 2000 and in multiple previous years. For a full list from the CDC see U.S. Foodborne Outbreaks of Cyclosporiasis—2000–2016
In the past what has been linked to Cyclospora outbreaks - contaminated irrigation water or water used for spraying crops; people picking crops that were carriers of Cyclospora - in fact in many less economically developed countries Cyclospora is one of the top causes of infant/child gastroenteritis. Basically it is the faecal-oral route of contamination once again probably with water as the route of transmission - we will have to wait and see if this is the case with the 2018 cases.
This incident made me reflect on John Snow - one of the first epidemiologists who 170 years ago studied the sources of Cholera in London and identified the water source where the outbreak originated - faecal-oral route once more. Check out his mapping of the outbreak here.