'Smoking gun' in outbreak will be hard to find
A team of four U.S. investigators will travel this weekend to investigate agricultural practices in the Mexican green onion industry, but a public health expert says locating precisely the sources of recent hepatitis A outbreaks won't be easy.
Fields that produced the green onions implicated in the outbreaks now lie fallow or are planted with other crops, said Dr. Tony Fiore, investigator for the Centers for Disease Control and Prevention.
Many of the workers who harvested the scallions have likely moved on, too, he said. And medical records won't show which viral strains were infecting people.
"It's not likely that you'll ever find that smoking gun," Fiore said. "I think FDA will find a lot of things that can really help with trying to make agricultural practices better, but we haven't gotten to that level of determining in the past, 'Here's what happened on Sept. 15.' "
Three investigators from the Food & Drug Administration and one from CDC will work in Mexico for up to two weeks, beginning Sunday, said Jack Guzewich, director of emergency coordination and response in FDA's Center for Food Safety and Applied Nutrition.
Contaminated green onions are the likely source of hepatitis A outbreaks that sickened more than 900 restaurant patrons this fall in Tennessee, Georgia, North Carolina and Beaver County, Pennsylvania.
FDA has traced scallions served in restaurants in Tennessee, Georgia and Beaver County to four companies in northwest Mexico.
When green onions were implicated in a hepatitis A outbreak in 1998 at an Ohio restaurant, investigators traced the scallions to two farms in Mexico and one in California. FDA is looking to see whether any of the companies involved in that or other outbreaks also are implicated in the current investigation, Guzewich said.
In developing countries, hepatitis A sweeps through communities periodically and infects a very large number of children, Fiore said. Many of those infected are under the age of 2 and don't have symptoms.
"It's possible that the harvest this year coincided with one of those sweeps through the community," he said. "But contaminated irrigation water wouldn't be any less of a possiblility."
The Mexican government this weekend closed four green onion exporters, but would not say if they were the same companies implicated by FDA.
However, Amada Velez, Mexico's director general for food safety, said in an interview yesterday that at least two of the closed firms are on the FDA list. Three of the closed companies are owned by Americans, Velez added, while one owner is Mexican.
Velez said she could not respond to comments published in the Post-Gazette on Wednesday from one exporter who said Mexican authorities had neither inspected his company nor shut it down. The exporter, Manuel Valladolid, owns Agro Industrias Vigor, which was listed as a scallion source by FDA.
The number of confirmed hepatitis A cases among patrons and workers at the Beaver Valley Mall Chi-Chi's in Center held at 615 yesterday.