Hepatitis A was in Green Onions

The FDA has confirmed that the outbreak of hepatitis A that struck restaurant diners in the US earlier this fall was caused by green onions grown in Mexico. This modern epidemiological mystery is considered solved because the hepatitis A virus found in stricken residents of Tennessee, Georgia and Pennsylvania was virtually identical to the virus found in residents living along the US-Mexican border where the green onions were originally harvested and processed.

The FDA offers the following advice:: "Cook green onions thoroughly. This minimizes the risk of illness by reducing or eliminating the virus. Cook in a casserole or saut in a skillet. Check food purchased at restaurants and delicatessens and ask whether menu items contain raw or lightly cooked green onions. Consumers who wish to avoid food that contains raw or lightly cooked green onions should specifically request that raw or lightly cooked green onions not be added to their food. Foods such as freshly prepared salsa and green salads often contain raw green onions."

Comment: Just because the green onion harvest is over for this year, at least in this location, we should still remember that contaminated fruits and vegetables, no matter where they come from, can make us sick. Raw produce needs to be sufficiently washed, cooked or, in some cases, avoided altogether. And just because some produce may be labeled as "organic" or "tripled-washed" or "ready-to-eat" does not mean that it is safe to consume it right out of the package.

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Barbara K. Hecht, Ph.D.
Frederick Hecht, M.D.
Medical Editors, MedicineNet.com

FDA Update on Recent Hepatitis A Outbreaks Associated With Green Onions From Mexico

The Food and Drug Administration is reaffirming that several recent Hepatitis A virus outbreaks have been associated with eating raw or undercooked green onions (scallions). Investigations by state and local health departments, the Centers for Disease Control and FDA have determined that the outbreaks were caused by green onions traced to Mexico for the three outbreaks with completed traceback investigations. It is important to remember that Hepatitis A Virus is transmitted by fecal-oral route. Produce can become contaminated when a person who has Hepatitis A or whose hands are contaminated with Hepatitis A virus comes into contact with the product or by exposure of the product to water contaminated with Hepatitis A virus.

Hepatitis A outbreaks associated with raw or undercooked green onions served in restaurants occurred in Tennessee, North Carolina and Georgia in September and in Pennsylvania in late October through early November. The source of the green onions in the outbreaks has been traced to Mexico for the Tennessee, Georgia and Pennsylvania outbreaks. The source of the onions in the North Carolina outbreak is still being determined. The exact source of the contamination has not been established in any of these outbreaks. FDA is continuing to investigate in both the U.S. and Mexico and has been in consultation with Mexican authorities to obtain their assistance in assessing the situation.

A team of investigators from FDA and CDC spent the first week of December in Mexico working with Mexican officials to visit the four firms and associated facilities identified in the FDA traceback investigations. Preliminary findings from the FDA team include the following points:

  • The onions would have been harvested in July or early August for the Tennessee and Georgia outbreaks and September for the Pennsylvania outbreak.
  • At the point of the inspections in December 2003, none of the farms or packing sheds inspected were harvesting or handling green onions, or had field workers or packing shed workers present.
  • No one firm's onions are common to all of the outbreaks under investigation.
  • FDA, CDC and the states to date have found no evidence of contamination of implicated green onions occurring at firms operating in the U.S., but investigations relating to the source of green onions in the North Carolina outbreak are continuing.
  • There are no reliable methods currently available to find Hepatitis A virus in samples collected in the field, so FDA did not collect environmental or green onion samples for Hepatitis A analysis.
  • The investigation team identified issues of concern from interviews and observations at all four firms visited including items such as poor sanitation, inadequate hand washing facilities, questions about worker health and hygiene, the quality of water used in the fields, packing sheds, and the making of ice, any of which can have a role in the spread of infectious diseases such as Hepatitis A.
  • 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.