Cyclospora cayetanensis is a widespread infectious parasite. It is most commonly found in tropical regions of South America, Africa, and Asia, though it frequently appears in other regions on imported food products. The parasite thrives in human feces, and infection is usually due to eating unwashed foods or accidentally drinking contaminated water. People who acquire Cyclospora cayetanensis infections typically experience a range of digestive symptoms including violent diarrhea, nausea and vomiting. Illness can last for two months or longer without treatment, though antibiotics are available in most regions that can relieve symptoms in as little as one week.
People who live in or travel to highly-populated tropical communities are at the highest risk of Cyclospora cayetanensis infection. Rates are the highest in crowded regions with poor sanitation and little access to medical care or education. Young children develop severe infections more often than adults because their immune systems are not mature enough to combat the parasite. While Cyclospora cayetanensis is not native to cooler climates in the United States or Europe, outbreaks can still occur when the parasite is transported with goods, food products, or returning travelers.
Single-celled Cyclospora cayetanensis spores begin their life cycle in human waste. They enter human hosts when contaminated dirt, water, or food is consumed. Spores attach to the walls of the digestive tract and begin to reproduce prolifically. Within a week of infection, a person may experience several episodes of watery or bloody diarrhea a day. Nausea, vomiting, severe stomach cramps, and fatigue are common, and flu-like symptoms of joint pain, fever, and headache can develop if dehydration occurs.
Parasites can thrive in a host's digestive tract for up to nine weeks, during which time some spores are expelled through feces to seek out new hosts. When a doctor or hospital is available, treatment should be sought as soon as possible to avoid complications and to help prevent an epidemic. A doctor can confirm the presence of Cyclospora cayetanensis in the body by analyzing blood and stool samples.
Treatment usually consists of a one- or two-week course of an antibiotic called trimethoprim-sulfamethoxazole. Drinking plenty of fluids and resting are important to prevent complications of dehydration. Patients with severe symptoms may be hospitalized to receive intravenous fluids and drugs. At the hospital or doctor's office, health care workers can also provide helpful tips for preventing future infections, such as washing hands regularly, sterilizing fruits and vegetables, and only drinking bottled water in at-risk regions.