Strawberries linked to hepatitis A: Here's how the virus might've contaminated the fruit

Public health officials are investigating an outbreak of hepatitis A potentially linked to organic strawberries. But how could the virus have gotten into the fruit in the first place?

The source of any hepatitis A food contamination is human, said Francisco Diez, director of the Center for Food Safety at the University of Georgia. 

"There are different possibilities how the virus gets to the strawberries," Diez said. "One of them could be because the water used for irrigating the strawberries could have been contaminated with sewage, because the virus is specific for humans." 

The berries could have also been contaminated after being handled by an infected person who did not follow proper hand washing hygiene, Diez said.

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Hepatitis A is a highly-contagious and vaccine-preventable liver infection caused by a virus. The hepatitis A virus is found in the stool and blood, and is spread by ingestion. Food can be contaminated with the virus at any point, from growing to harvesting to processing, according to the Centers for Disease Control and Prevention.

"Hepatitis A itself is a very hardy virus and so it can really survive in the environment for a while," said Ellen Shumaker, director of outreach for Safe Plates at North Carolina State University. "It's very stable in the environment. It survives in water." 

Hepatitis A outbreak: FDA investigating outbreak of Hepatitis A potentially linked to organic strawberries

The current hepatitis A outbreak is not the first that has been linked to strawberries. 

In 2016, an outbreak of hepatitis A was associated to frozen strawberries imported from Egypt. The outbreak resulted in 143 cases across nine states. Fifty-six people were hospitalized, but no deaths were reported, according to the CDC.

"From past experience with this type of outbreaks, it's always something went wrong during the growing, harvesting and post harvest packaging and handling of the product," said Pratik Banerjee, an associate professor of food safety at the University of Illinois at Urbana-Champaign.

Good hygienic practices are 'critical'

Several factors contribute to berries being at risk of carrying the virus, including the uneven and rough surface of the fruit and that they're picked by hand, Banerjee said.

Though "we are seeing more and more outbreaks associated with hepatitis A, we should not consider them as, perhaps, the only type of fruits that could have this virus," Banerjee said. "There are other fruits that could also get the virus."

The berries linked to the current outbreak were fresh and organic, according to the Food and Drug Administration. But whether the berries are organic or conventional, fresh or frozen, doesn't make a difference in terms of its risk of carrying a harmful pathogen, experts said.

"Organic practices do not allow the use of sewage as fertilizer," Diez said. "That goes against good agricultural practices if something like that happened, so it doesn't matter whether they're organic or conventional."

The strawberries branded FreshKampo and HEB potentially linked to the outbreak are currently past shelf life and were purchased between March 5 and April 25, the FDA said. The agency encouraged consumers who bought and froze the berries to dispose of them. 

The virus could survive freezing, and strawberries typically aren't cooked, which kills the virus. Rinsing fresh fruits and vegetables before consumption helps reduce contamination, but won't eliminate all microorganisms, Diez said. 

"What is really critical is the farms that produce the fruits and the strawberries that they enforce good hygienic practices on the field," Diez said, "with the workers and with  making sure that the source of water hasn't been contaminated with sewage or human fecal matter."

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The FDA said it has identified 17 cases of hepatitis A linked to the strawberries – 15 in California, one in Minnesota and one in North Dakota. Twelve people have been hospitalized, according to the agency. 

Hepatitis A symptoms usually appear two to seven weeks after infection and usually last less than two months, according to the CDC. Not everyone develops symptoms, though, and some people can be ill for as long as six months. 

Symptoms may include jaundice, loss of appetite, upset stomach, vomiting, fever and dark urine or light-colored stools.

The FDA urged consumers who suspect they have hepatitis A symptoms after eating the strawberries or who believe they ate the berries in the last two weeks to contact their health care providers.

Follow reporter Amanda Pérez Pintado on Twitter: @aperezpintado.