A historic surge of cyclosporiasis has swept across the US Midwest, with Michigan confirming more than 1,200 cases and at least 40 hospitalisations by early July—the largest outbreak of the parasitic intestinal infection in the state’s history. Neighbouring Ohio has recorded over 500 cases, and infections have been reported in at least 17 states, according to federal and state health agencies. The US Centers for Disease Control and Prevention (CDC) had logged 145 cases nationwide between 1 May and 16 June, but state-level data now points to thousands of illnesses, though no deaths have been linked to the outbreak. The source of contamination remains unidentified, and investigators are conducting traceback studies on fresh produce, which has been implicated in past cyclospora outbreaks.

Cyclospora cayetanensis, a single-celled parasite, infects the small intestine after ingestion of food or water contaminated with faecal matter. Symptoms typically appear within a week and include watery, often explosive diarrhoea, abdominal cramping, nausea, and fatigue; the illness can persist for weeks or relapse if untreated. The parasite is not transmitted directly between people. In response, the fast-food chain Taco Bell removed fresh ingredients such as lettuce, cilantro, and guacamole from its menu nationwide as a precaution, though no specific supplier or produce item has been identified as the outbreak vehicle. Health officials in Michigan recommend thorough washing of raw produce, cooking vegetables when possible, and discarding outer leaves of lettuce, while noting that washing alone may not eliminate the parasite.

Separately, the US National Park Service is investigating a cluster of unexplained illnesses among rafters who took multi-week trips through the Grand Canyon in May and June. Affected individuals reported fever, chills, fatigue, pneumonia, and severe joint pain; some required hospitalisation. Early speculation among epidemiologists cited in online forums points to mosquito-borne viruses such as dengue or chikungunya, though no pathogen has been confirmed. In New York City, health authorities are probing a Legionnaires’ disease outbreak in Manhattan’s Upper East Side, with 23 confirmed cases and 17 hospitalisations as of 6 July. The likely source is one or more cooling towers, and officials stress the bacteria is not spread through drinking water or person-to-person contact. Across the Atlantic, Swedish municipalities are recording a seasonal rise in swimmer’s itch, a self-limiting rash caused by avian schistosome parasites that burrow into the skin in warm, shallow freshwater. While not notifiable, the condition has prompted calls for public reporting to help local authorities issue warnings.

The cyclospora investigation now hinges on epidemiological interviews and supply-chain traceback to pinpoint a common food source, a process that can take weeks. For the Grand Canyon cluster, NPS and Arizona health officials await laboratory results to rule in or out vector-borne viruses. New York’s cooling tower inspections and sampling are ongoing, with results expected to guide remediation orders. In Sweden, environmental health offices continue to rely on bathers’ reports to map the patchy distribution of cercariae, as standard water quality tests do not detect the parasite.