The United States has recorded the largest outbreak in Michigan’s history of an infection caused by the intestinal parasite Cyclospora. Nearly 1,000 people have been infected with the parasitic disease, which can cause prolonged watery diarrhea, according to Medical Xpress.

According to state health authorities, 992 cases have been reported so far, with around 40 patients requiring hospitalization. No deaths have been recorded, and the source of the outbreak remains unknown.

Investigations into similar cases are also ongoing in 28 other US states. In neighboring Ohio, near the Michigan border, the number of infections is also increasing: more than 300 cases have been reported in Lucas County alone, while northwestern Ohio has recorded more than 500 cases.

Michigan authorities first reported the outbreak at the end of June, when just over 170 cases had been identified. The state typically records around 50 cyclospora cases per year, making the current surge unprecedented.

Cyclospora is a microscopic parasite that infects the human intestine. It causes a disease known as cyclosporiasis, with the main symptom being prolonged watery diarrhea that may occur frequently and sometimes in severe episodes. Other symptoms may include abdominal pain, nausea, loss of appetite, fatigue, and weight loss.

In most cases, the infection is not life-threatening and can be treated with antibiotics. Outbreaks are more common in late spring and summer because the parasite survives well in warm conditions.

People become infected when the parasite enters the body through contaminated food or water. Previous outbreaks have been linked to fruits, vegetables, and leafy greens that may have come into contact with water contaminated with sewage.

However, identifying the source of such outbreaks is extremely difficult. Cyclospora is hard to detect using standard foodborne illness testing methods, and the parasite remains poorly understood in laboratory studies.