Federal health investigators have determined that a deadly outbreak of hepatitis A among restaurant diners in Tennessee, Georgia and Pennsylvania was caused by green onions produced in Mexico, the U.S. Food and Drug Administration said on Tuesday. More than 500 people were infected in the outbreak and three died.
The Hepatitis A virus is transmitted in raw or undercooked food that has been contaminated with the feces of a person with the disease. Its symptoms include jaundice, fatigue, nausea, diarrhea and fever, and the virus can be fatal to those with a chronic liver disease.
FDA investigators pinpointed a link between the three outbreaks and green onions from Mexico after visiting four Mexican companies last week. They found poor sanitation and inadequate hand washing facilities and also had concerns about the quality of water used in the fields, packing sheds, and the making of ice, which can help spread the disease.
A fourth outbreak of hepatitis A occurred at a North Carolina restaurant, but health department workers have not finished their investigation. All of the outbreaks occurred between September and early November, the FDA said.
The investigation has been difficult because no reliable methods exist to find the virus in green onion samples collected in the field. Instead, health workers analyzed the hepatitis A viruses in infected consumers and found they were virtually identical to those found in residents who live along the U.S.-Mexican border.
Mexico has stepped up inspections and controls for green onions and is working with the FDA to ensure the safety of produce shipped across the border.
The FDA investigation showed that the green onions linked to the restaurant outbreaks in Tennessee and Georgia were harvested in July or early August, the agency said. Green onions blamed in the Pennsylvania outbreak were picked in September.
The green onion harvest was no longer under way at the farms and companies inspected last week in Mexico, the agency said.