U.S. officials have linked four Mexican green onion producers to the outbreak at a Chi-Chi's restaurant at the Beaver Valley Mall that has sickened at least 635 and killed three. But Mexican officials disputed that during a briefing Monday.
"It is impossible to conclude that the outbreak can be traced to Mexican farms," Juan Pablo Hernandez Diaz, Mexico's secretary of agriculture in Baja California, told the Pittsburgh Tribune-Review after the briefing. "The evidence we have doesn't necessarily tell us that the problem originated here."
Green onion farmers in Mexico were pleased with the announcement.
"This is great news, but the FDA has the final word," said Fernando Beltran Quijada, owner of Tecno Agro in the town of San Luis Rio Colorado.
On Nov. 21, the Centers for Disease Control and Prevention said green onions were likely the cause of the Pennsylvania outbreak. The FDA stopped all green onion shipments from the Mexican firms whose raw green onions were linked to restaurant outbreaks in Pennsylvania, Tennessee and Georgia. The onion growers were inspected and the FDA was still trying to determine how they were being contaminated.
Georgia health officials reported 259 hepatitis A cases in September and October and were clustered around metro Atlanta and Macon. There were no Georgia deaths from the liver infection.
Officials with the CDC said the contamination could have occurred in many ways, including poor hygiene by infected workers at any stage of the onions' transit from field to the restaurant.
Hernandez Diaz said the contamination could have happened in the United States. He said most of the green onions grown in northwestern Mexican are shipped to the western United States and not in Pennsylvania.
"You have some boxes of green onions that are re-iced in the U.S.," he said. "How do they know they weren't contaminated at that point?"
Last week, Javier Trujillo, undersecretary for food safety and quality in Mexico's Ministry of Agriculture, said Dos M Sales de Mexico - a company located near the border city of Mexicali, in Baja California state - was washing its scallions with water from a nearby reservoir, rather than with purified drinking water as required. However, it's still not known if that caused the contamination.