Health officials are trying to pin down the source of an outbreak of Cyclosporiasis, a parasitic infection that causes long-lasting flu-like symptoms.
The Centers for Disease Control and Prevention (CDC) says it has been notified of 273 cases of the disease, including 21 hospitalizations, in 15 states.
The reports began on June 28, when two Iowa residents became ill. Since then, the CDC, Food and Drug Administration and state health departments have been trying to determine if the illnesses are related and whether there is a single source of infection.
The count includes laboratory-confirmed infections in people who had no history of recent travel outside the United States and Canada. This CDC map shows the number and location of reported cases.
Symptoms include sporadic episodes of diarrhea and low-grade fevers as well as weight loss, bloating, fatigue and occasional vomiting. Anyone whose mouth is unusually dry and who has little need to urinate and bouts of dizziness should seek medical attention.
The infection is generally spread through the feces of infected people, generally via contaminated food or water. Direct person-to-person transmission is unlikely, because the oocysts shed in feces must mature in the environment (outside the host) to become infective to someone else, the CDC said.
Cyclosporiasis appears to be most common in tropical and subtropical regions of the world. Outbreaks in the United States and Canada have been linked to various types of imported fresh produce. People of all ages are at risk for infection, and travelers to developing countries can be at increased risk.