Green onions were the likely source of a hepatitis A outbreak at a Mexican restaurant that has killed three people and sickened at least 575, but the origin of those onions and how they were tainted remains unclear, state health officials said Friday.
The outbreak, centered around a western Pennsylvania outlet of the Chi-Chi's chain of Mexican-American restaurants, is the largest single-source hepatitis A outbreak in U.S. history.
Shortly after it was confirmed Nov. 3, the Food and Drug Administration issued a national advisory that purchased green onions should be cooked and not eaten raw to ensure safety.
It is not known whether the green onions behind the Pennsylvania outbreak are linked to those already known to have caused smaller outbreaks of hepatitis A in Tennessee and Georgia in September.
The FDA announced Thursday that it has traced green onions in those outbreaks to three Mexican suppliers and is inspecting all green onion shipments from them.
The agency is still trying to trace the source of the onions in the Pennsylvania outbreak and another in North Carolina in September.
Health officials have said the strain of hepatitis found in Pennsylvania is very similar to the one in the Tennessee and Georgia cases.
The number of victims announced Friday by Dr. Calvin Johnson, the state Health Secretary, included 35 additional cases.
Officials still can't explain why the Pennsylvania outbreak was so much more extensive than the others. More than 250 people got hepatitis A at more than a dozen Georgia restaurants in September, and 80 were infected at one restaurant near Knoxville, Tenn., about the same time, officials in those states said.
At least eight people were sickened after eating green onions at a single restaurant in North Carolina in September, according to the Centers for Disease Control and Prevention. The FDA is also still trying to trace the source of those onions, CDC officials said Friday.
The large number of Pennsylvania cases may simply be because the Chi-Chi's restaurant at the Beaver Valley Mall, about 25 miles northwest of Pittsburgh, served so many meals — 11,000 in October, the month when nearly all those sickened ate there, state health officials said.
Even before the FDA issued its green onion advisory on Nov. 15, Chi-Chi's had pulled green onions from 99 other restaurants in 17 states from Minnesota to the Mid-Atlantic. Taco Bell has pulled scallions from some 6,000 American outlets, though there have been no reports of hepatitis A at those stores.
Chi-Chi's filed for Chapter 11 bankruptcy protection on Oct. 8 in a move unrelated to the outbreak. The chain on Thursday asked a bankruptcy judge for permission to spend $500,000 on an insurance deductible to free up as much as $51 million in liability insurance. The restaurant hopes to use the money to settle out-of-court claims for medical bills, lost wages and other expenses brought by those sickened in Pennsylvania.
A bankruptcy judge could rule on that request as early as Friday.
Up to 35,000 cases of hepatitis A are reported annually in the United States. According to the Centers for Disease Control and Prevention, one third of Americans have evidence of past infection to the disease, meaning they are immune. In 2000, 106 people Americans died from hepatitis A.