The outbreak in Pennsylvania of hepatitis A has affected over 500 people who ate at a Chi-Chi's restaurant last month, and three people have died. Almost 9,000 people have been given immune globulin shots to try to prevent the illness, but symptoms may not show up for as many as 50 days following exposure. The incident has raised questions about the safety of increasingly international foods, as health officials suspect that green onions from Mexico may be the source of the outbreak. Recent outbreaks of hepatitis A in Tennessee, Georgia, and North Carolina have been traced to uncooked or undercooked green onions, some of which were traced to Mexico, said the Food and Drug Administration's Bob Racket.