Dec 10, 2003 (CIDRAP News) The Food and Drug Administration (FDA) yesterday reaffirmed its earlier findings that recent hepatitis outbreaks in Tennessee, Georgia, and Pennsylvania were caused by green onions (scallions) from Mexico.
The source of green onions blamed in one other recent outbreak, in North Carolina, is still under investigation, the FDA said. The Tennessee, Georgia, and North Carolina outbreaks occurred in September; the Pennsylvania one surfaced in late October and early November.
"The source of the green onions . . . has been traced to Mexico for the Tennessee, Georgia and Pennsylvania outbreaks," the FDA announcement states. "The source of the onions in the North Carolina outbreak is still being determined." Exactly how the green onions became contaminated has not been determined for any of the outbreaks, officials said.
Investigators from the FDA and the Centers for Disease Control and Prevention (CDC) spent the first week of December in Mexico visiting four firms that were identified in the FDA's investigations, the agency said. Mexican officials accompanied the US team.
The team determined that the onions would have been harvested in July or early August for the Tennessee and Georgia outbreaks and in September for the Pennsylvania outbreak. No one firm's onions were found to be involved in all of the outbreaks.
The investigators found possible problems at all four firms, the FDA said. These included poor sanitation, inadequate handwashing facilities, questions about worker health and hygiene, and questions about the quality of water used in the fields and packing sheds and to make ice.
The FDA "was pleased to see that some of the farms visited were making or had just completed improvements to their water systems and other physical facilities," the announcement says.
None of the farms or packing sheds were harvesting or handling green onions at the time of the inspections, the agency said. The FDA didn't collect environmental or green onion samples for analysis, because there is no reliable way to find hepatitis A virus in such samples.
Federal and state health investigators have found no evidence of contamination of green onions occurring at firms operating in the United States, officials said.
The FDA's statement came a day after Mexican officials disputed the connection between the Pennsylvania outbreak and green onions from Mexico. According to the Associated Press, Juan Pablo Hernandez Diaz, Mexico's secretary of agriculture in Baja California, said, "It is impossible to conclude that the outbreak can be traced to Mexican farms." He said the contamination could have occurred in the United States and that most of the scallions grown in northwestern Mexico are shipped to the western United States.
In a Nov 21 report, the CDC linked the Pennsylvania outbreak to green onions served at a Chi Chi's restaurant near Pittsburgh. More than 600 people became ill, and three died.