US health officials are warning that symptoms many people dismiss as a routine summer stomach bug could actually be cyclosporiasis, a foodborne parasitic illness, amid one of the largest outbreaks of its kind on record. Doctors say the condition is easily mistaken for a typical gastrointestinal upset, meaning cases can go undiagnosed and untreated unless specifically tested for, which matters because effective treatment requires a particular antibiotic rather than standard stomach bug remedies.

The Centers for Disease Control and Prevention says cases have been confirmed or are under investigation across 34 states, with the total nearing 7,000. CDC Deputy Director Gwen Biggerstaff said symptoms such as diarrhoea and cramping can become severe, and urged anyone affected to consult a doctor about testing and antibiotic treatment rather than assuming it will pass on its own. The agency says it expects to identify the source of the outbreak soon.