Federal health officials are investigating 37 hepatitis A illnesses across four states, including 30 hospitalizations, after epidemiological evidence pointed to imported frozen clams consumed raw or undercooked as a possible source.
By yourNEWS Media Newsroom.
Federal health officials are investigating a multistate hepatitis A outbreak that has sickened at least 37 people and hospitalized 30, with imported frozen clams emerging as a possible source of the infections.
Cases have been identified in Massachusetts, Minnesota, New York and Pennsylvania, according to the Centers for Disease Control and Prevention’s outbreak investigation.
As of the CDC’s latest outbreak update, 27 cases had been reported in New York, four in Pennsylvania and three each in Massachusetts and Minnesota. Patients ranged from 6 to 40 years old, and no deaths had been reported. Illness onset dates ranged from July 30, 2025, through June 23, 2026.
The investigation began after health officials noticed a striking pattern in what patients reported eating during the 15 to 50 days before becoming ill.
Among those interviewed, 76% said they had consumed raw or undercooked shellfish, while 47% specifically reported eating raw or undercooked conchas negras, also known as black clams. Seventy-seven percent said they had eaten ceviche, a preparation in which raw fish or shellfish is marinated in citrus juice.
Those percentages were significantly higher than the consumption rates reported in the FoodNet Population Survey, which public health officials use to estimate how frequently Americans eat foods associated with gastrointestinal illnesses.
The difference led investigators to focus on raw or undercooked clams as a possible source.
“During the outbreak, epidemiologic data showed that imported frozen clams may have been contaminated with hepatitis A virus and made people sick in this outbreak,” the CDC said. “Traceback investigations are ongoing to identify the source or sources of frozen clams that were consumed raw or undercooked by people who are ill.”
Investigators have not yet identified a single source accounting for every outbreak-associated illness.
The CDC also cautioned that the actual number of infections is probably higher than the 37 identified cases and that additional states could be affected.
Some people with hepatitis A recover without seeking medical attention and therefore are never tested, while several weeks can pass before a newly diagnosed illness is determined to be part of an outbreak.
One product has already been recalled during the investigation.
La Serranita-brand concha negra, or black shell, fresh frozen shell meat from Ecuador was recalled by dealers in New York and New Jersey after hepatitis A illnesses were associated with the product.
The Food and Drug Administration said the 16-ounce packages were distributed to restaurants and retailers in Connecticut, Massachusetts, New Jersey, New York, Ohio and Pennsylvania and could have been redistributed elsewhere.
Federal officials have advised consumers, restaurants and retailers not to eat, sell or serve the affected La Serranita product. Potentially contaminated packages should be discarded or returned through the distributor, and surfaces or containers that contacted the shellfish should be thoroughly cleaned and sanitized.
The CDC recommends that anyone who ate recalled La Serranita black shell meat raw or undercooked within the previous 14 days and has not been vaccinated against hepatitis A contact a health care provider or local health department to discuss post-exposure treatment.
Hepatitis A is a contagious liver infection caused by the hepatitis A virus.
Transmission can occur when a person consumes contaminated food or water or through close personal contact with someone carrying the virus. Unlike hepatitis B and hepatitis C, hepatitis A does not normally develop into a chronic liver infection.
Symptoms do not always occur, particularly in young children.
When illness develops, symptoms typically appear two to seven weeks after exposure and may include fatigue, fever, nausea, vomiting, abdominal pain, loss of appetite, diarrhea, joint pain, dark urine, pale or clay-colored stool and jaundice, or yellowing of the skin and eyes.
Most patients recover completely, although symptoms can persist for weeks or several months.
In rare cases, hepatitis A can lead to acute liver failure and death. Severe disease is more common among older adults and people with underlying medical conditions, particularly chronic liver disease.
The World Health Organization estimates that 35,569 people died from hepatitis A worldwide in 2023, representing about 2.6% of deaths from viral hepatitis. The organization says hepatitis A can appear sporadically or in epidemics and that the virus can survive in the environment and withstand some food-production processes used to control bacterial pathogens.
The current U.S. investigation remains active as federal, state and local health agencies work to trace the frozen clams consumed by patients and determine whether additional products or suppliers contributed to the outbreak.
For consumers, the CDC’s immediate advice is to avoid recalled black clam products, contact a health care provider after a recent exposure if unvaccinated and seek medical attention if symptoms consistent with hepatitis A develop.
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