After three people fell ill from eating salmonella-tainted cantaloupe at a church dinner in Oregon in February, the state’s epidemiologist alerted Del Monte Fresh Produce.

Evidence that the company’s cantaloupe was the source of contamination was “overwhelming,” William E. Keene wrote in an e-mail to the company on March 19. “I think we need to move ahead with the common understanding that your cantaloupes caused this outbreak,” he added.

Keene included in the e-mail an epidemiological analysis of cantaloupe consumption in the United States and how it relates to the U.S. share of cantaloupe from a farm in Guatemala that supplies Del Monte Fresh Produce. He used this analysis to explain the high probability that the contaminated cantaloupe originated from the farm, located in AsuncionMita.

“In our world, these numbers are considered pretty good evidence, however circumstantial,” he wrote.

The Oregon cases were the first confirmed victims of an outbreak involving a rare strain of salmonella that eventually reached 10 states — from California and Nevada to Pennsylvania and Maryland — and was linked to 20 illnesses this spring. The cases are unrelated to the current listeria outbreak linked to cantaloupes from a Colorado farm that have killed eight people, including one in Maryland.

In a series of e-mail exchanges with Keene, obtained through public records requests, Del Monte Fresh Produce defended practices at its farm. “I cannot imagine how [salmonella] could be coming from our Mita operation, but I am available to assist you in your investigation,” Thomas Young, Del Monte Fresh Produce’s vice president of research and agricultural services, wrote in one e-mail.

But under pressure from the Food and Drug Administration, the company issued a limited, voluntary recall of nearly 60,000 imported cantaloupes on March 22.

Now, in an action that could have a significant impact on how authorities investigate and try to contain foodborne illnesses, the company is challenging the decisions and conclusions of the FDA, the Oregon public health department and its senior epidemiologist.

In court actions against the FDA and Oregon, Del Monte Fresh Produce contends its cantaloupes never tested positive for salmonella and, as a result, federal and state investigators did not have proof of the contamination. The company said the FDA did not exhaust other possibilities of contamination, including when the product was in the hands of retailers or during transit.

“In a way, epidemiology is on trial,” said David Acheson, former FDA associate commissioner of foods.

It’s rare for scientists investigating foodborne illness outbreaks to test the exact food suspected of carrying pathogens, said Kirk Smith, epidemiology supervisor for the Minnesota Department of Health. By the time symptoms occur and a foodborne illness is reported and confirmed, the product in question has likely been consumed or has exceeded its shelf-life and been thrown away.

Instead, scientists, like detectives, interview victims, collect data, analyze patterns and match food “fingerprints” to determine the likely source of an outbreak.

“The majority of outbreaks, we don’t have the food to test,” Smith said. “Laboratory confirmation of the food should never be a requisite to implicating a food item as the vehicle of an outbreak. Epidemiology is actually a much faster and more powerful tool than is laboratory confirmation.”

On July 15, several months after the outbreak, the FDA issued an import alert, effectively banning future melon imports from Asuncion Mita.

In an Aug. 22 complaint filed in U.S. District Court for the District of Maryland, Del Monte Fresh Produce contested the recall and import alert, saying the FDA has no evidence that the cantaloupe from Asuncion Mita was the source of the salmonella outbreak. The company said the government actions were based on “erroneous speculation, unsupported by scientific evidence.”

In another unusual move, Del Monte Fresh Produce filed notice to sue the Oregon Health Authority’s Public Health Division as well as Keene, its senior epidemiologist, for “misleading allegations regarding Del Monte Fresh’s imported cantaloupe.”

In court documents, the company said the FDA demanded that it either go along with the recall “or suffer the consequences of an FDA consumer advisory questioning the wholesomeness of Del Monte cantaloupes.”

The suit says that with the winter cantaloupe season approaching, the company will face “irreparable harm” if the alert is not immediately lifted. Del Monte Fresh Produce, the largest importer of cantaloupe to the United States, gets roughly 27 percent of its cantaloupe from Asuncion Mita, according to data in the court filings.

“The lawsuit against the epidemiologist in Oregon is very troubling to me because they seem to be singling out an individual official,” said Tony Corbo, a senior lobbyist on food-related legislation for Food and Water Watch, a food safety advocacy group. “This lawsuit could have a chilling effect on public health agencies recommending that recalls be taken based on epidemiological information.”

“Although Dr. Keene is mentioned in our filings, our intent was not to single out any particular state official,” Del Monte Fresh Produce said. “Rather, we reluctantly took these actions to draw attention to weaknesses in the current system that appear to have influenced this recall.”

Young, the company’s vice president, argued in the e-mail exchange with Oregon’s epidemiologist that none of Del Monte Fresh Produce cantaloupes tested positive for Salmonella Panama. Keene responded that a positive test “is a pretty tough standard to meet,” given the fact that the implicated cantaloupe had already been consumed and whatever remained had likely been thrown away.

In court documents, Del Monte Fresh Produce contends that the contamination could have occurred when the cantaloupes were in the hands of retailers. The company also contends that the FDA never tested cantaloupes from the site and that its own tests showed they were safe.

FDA officials declined comment because the case is in litigation.

— News21

This article was produced as part of the Knight-Carnegie News21 program, a national university reporting project headquartered at the Walter Cronkite School of Journalism and Mass Communication at Arizona State University.