This is a press release from the Food and Drug Administration from November 15, 2003.

Consumers Advised That Recent Hepatitis A Outbreaks Have Been Associated With Green Onions
The Food and Drug Administration is advising the public that several recent hepatitis A outbreaks have been associated with eating raw or undercooked green onions (scallions). Hepatitis A is a liver disease that develops within 6 weeks of an exposure. Hepatitis A is usually mild and characterized by jaundice (yellow discoloration of the skin), fatigue, abdominal pain, loss of appetite, nausea, diarrhea, and fever. It can occasionally be severe, especially in people with liver disease.

Hepatitis A outbreaks associated with raw or undercooked green onions served in restaurants occurred in Tennessee, North Carolina and Georgia in September. Another outbreak of hepatitis A among patrons of a single restaurant occurred in Pennsylvania during late October and early November, although the source of the outbreak has not yet been determined. FDA, CDC, and the State of Pennsylvania have an investigation underway to determine if a specific food is associated with the Pennsylvania outbreak, and if so, the source. The source of the green onions in the Tennessee outbreak appears to be Mexico. FDA is continuing to investigate these outbreaks and has been in consultation with Mexican authorities to obtain their assistance in assessing the situation.

FDA offers the following advice to consumers concerned about the possibility of getting hepatitis A from green onions:

Cook green onions thoroughly. This minimizes the risk of illness by reducing or eliminating the virus. Cook in a casserole or saute 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. FDA, CDC and the States are actively investigating the outbreaks in an attempt to determine the source of the green onions associated with the outbreaks and how they became contaminated, so that corrective action can be taken.

While the investigations are ongoing, FDA will closely monitor the safety of green onions and will take further actions as necessary to protect consumers. Consumers who have recently eaten raw or lightly cooked green onions do not need to take any specific measures, but should monitor their health. Consumers who are experiencing symptoms that could be hepatitis A should consult their health care providers or the local health department.

More information:
FDA: Q&A Hepatitis Outbreak/ Green Onions