*Patient’s name has been changed.
Late last year, the U.S. began to see a tiny flurry of hepatitis A virus [HAV] infections linked to frozen, organic strawberries grown on farms in Baja, Mexico.
At the time of this writing, the imported berries have been linked to sickening nine people in Washington, Oregon, and California. No one has died, but three patients required hospitalization. In the meantime, stores in more than 30 states have already pulled possibly contaminated bags from their freezer-cases and new recalls have recently been issued. We can only hope that non-immune people who actually ate those products received timely post-exposure vaccines or GamaSTAN, the only hepatitis A-specific immune serum globulin currently on the market.
So, you may be wondering, why all the fuss about a minor flare of an age-old, fecal-oral foe? Well, for one thing, FDA-mandated recalls have hit major retail chains like Texas’s H-E-B supermarkets, Trader Joe’s, Aldi, Walmart, and Costco. Plus, for each patient who contracted HAV after purchasing the frozen fruit, who knows how many more have not yet fallen ill or been diagnosed, given HAV’s lengthy 15- to 50-day incubation period. Then there’s the future shock possibly awaiting those who bought and stored the frosty, tainted berries. Months to years from now, could they still eat them and fall ill?
In a word: yes.
Hepatitis A 101
In the late 1970s, when I was a resident in Chicago, it was not unusual to see hospitalized patients with acute hepatitis A, their sclerae lemon-yellow, their mentation clouded, their liver enzymes off the charts.
But today, the picture has changed. In the U.S., better food hygiene and HAV vaccines first approved in the 1990s have helped protect a growing number of people. On the other hand, in low- and middle-income countries, where hepatitis A was once a near-universal (and typically mild) childhood infection, better hygiene has also spelled greater vulnerability later in life. As a result, in some overseas settings, there are far more non-immune adults than ever before, including some with jobs as food or agricultural workers who can contract HAV and temporarily shed a whopping 106 to 108 infective virions per milligram of feces.
A few more HAV factoids rarely taught in medical school help us understand how infectious and resilient HAV truly is:
- A mere 1 to 10 viral particles can initiate infection
- Thanks to their sturdy protein capsids, infectious virions sometimes persist for months in food or on environmental surfaces
- HAV can also survive multiple freeze-thaw cycles
Of Freezing and Global Farm-to-Fork Chains
You might be surprised to learn that several foodborne microbes can withstand ice-cold conditions. Norovirus and HAV lead the pack, but Listeria and Salmonella can also survive in frozen food. Long story short: just because certain items are frozen as hard as a rock, it still isn’t safe to eat them without adequate cooking.
Moreover, due to demand by first-world consumers, freezing imported produce to prolong its shelf life is increasingly common. In one recent study, contaminated frozen berries led to 43% of all produce-linked outbreaks. Frozen food writ large also equals big money. Already a major food-industry sector, the market’s current growth exceeds 6% per year. By 2030, its global worth will likely top $500 billion.
Lastly, let’s zoom back to some of the myriad ways HAV can contaminate produce along global farm-to-fork chains. Sewage-polluted irrigation? Check. Soil fertilizers containing organic waste such as manure or fecal sludge? Check. Manipulation by human hands at multiple stages from harvest to consumption? Check. You get the picture.
So, aside from trying to reform the global food production system — an unrealistic task, to say the least — what’s the best way for modern health professionals to help modern patients from falling prey to hepatitis A?
Déjà Vu All Over Again
In 2013, the U.S. suffered a multi-state HAV outbreak traced to a frozen medley packed in Oregon that contained cherries, strawberries, raspberries, and pomegranate arils originally sourced from the U.S. and other countries. But well before the specific, tainted component was confirmed, I received a panicky call from two of my patients who adored smoothies.
For months, the married lawyers I’ll call Marilyn* and Clark* had made their daily quaff using almond milk, protein powder, a banana, and some frozen mangoes and blueberries. Sixty seconds in their blender and presto! They were drinking fruity goodness.
Then, one day while walking through their local Costco, the couple spied a new frozen product labeled “Townsend Farms Organic Antioxidant Blend” and began to salivate. And it’s organic! they thought.
“Of course, we didn’t read the fine print,” Marilyn later recalled, “but it probably wouldn’t have stopped us,” referring to the international origin of three of Townsend’s four ingredients.
The HAV thunderbolt hit 10 days later when people who had purchased the Townsend medley in several western states became sick; all told it was linked to infecting 165 people including 69 who were hospitalized with severe symptoms and one who required a liver transplant.
The good news? Based on viral typing performed by CDC techs, the pomegranate arils from Turkey were identified as the HAV-laced culprit. But even before then, Costco mined its internal data and notified a quarter-million at-risk consumers. Then, the giant chain provided post-exposure HAV vaccines in 200 of its own stores. Other people like Marilyn and Clark who had ingested the perilous arils received shots from their private providers.
A Simple Solution
Like it or not, we now live in a world in which food is a global commodity capable of carrying many different pathogens. Can some of us stick to locally grown, in-season produce and lessen our risk? Perhaps. But when it comes to hepatitis A, what could be easier than rolling up a sleeve and receiving a safe, effective vaccine?
The CDC currently recommends the hepatitis A vaccine for all children ages 12-23 months, unvaccinated children, adolescents ages 2-18 years, international travelers, men who have sex with men, people who use injection or non-injection drugs, people who have an occupational risk for infection, people who anticipate close contact with an international adoptee, people experiencing homelessness, people with HIV, people with chronic liver disease, and — last but not least — any person wishing to obtain immunity.
It’s a personal decision, of course, but encouraging vaccination is my best solution to declaring victory against a remarkably hardy virus that, for all I know, is happily ensconced in one or more colorful, healthful products in my own freezer. Or, for that matter, yours.
Claire Panosian Dunavan, MD, is a professor of medicine and infectious diseases at the David Geffen School of Medicine at UCLA and a past-president of the American Society of Tropical Medicine and Hygiene. You can read more of her writing in the “Of Parasites and Plagues” column.
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