US investigates source as Cyclospora outbreak surpasses 2,800 cases across 31 States

More than 2,800 people have been infected in a growing outbreak of cyclosporiasis. It is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis, prompting health authorities across the United States to intensify efforts to identify the source. The outbreak has spread across 31 states, with Michigan reporting the largest number of cases.

The US Centres for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) are investigating whether the contaminated fresh produce is responsible, although no specific food item or supplier has yet been confirmed.

Cyclosporiasis is most commonly spread by consuming contaminated food or water with the parasite. Health experts say fresh produce such as leafy greens, herbs, berries and other fruits and vegetables are among the foods most often linked to outbreaks because they are frequently eaten raw. Unlike many other foodborne illnesses, the parasite is not usually passed directly from person-to-person because it must first mature in the environment before it becomes infectious.

According to reports, symptoms usually develop between two days and two weeks after exposure. They can include severe watery diarrhoea, frequent bowel movements, stomach cramps, bloating, nausea, vomiting, fatigue, loss of appetite, weight loss and, in some cases, a low-grade fever.

Without treatment, the illness can last for several weeks or even months, with symptoms sometimes returning after improving.

Doctors have said that most healthy people recover completely, but the infection can be more serious for young children, older adults and people with weakened immune systems because prolonged diarrhoea can lead to dehydration. The standard treatment is an antibiotic known as trimethoprim-sulfamethoxazole. Although, healthcare providers may recommend alternative care for patients who cannot take medication.

Investigators have not yet identified the exact source of the current outbreak, but Michigan health officials say lettuce and other salad greens are being examined as possible sources. Past outbreaks in the United States have also been linked to imported fresh produce, including basil, cilantro, raspberries and snow peas.

Health authorities are now urging the public to wash fresh fruits and vegetables thoroughly, practise good hand hygiene and seek medical attention if severe or persistent diarrhoea develops. While most reported cases are in the United States, Cyclospora infections occur worldwide and are more common in tropical and subtropical regions, particularly during seasonal outbreaks.