A multi-state outbreak of a dangerous liver disease is being investigated by officials after more than three dozen people have been sickened.
The CDC is investigating an outbreak of hepatitis A across four states. Thirty-seven people have been sickened and 30 have been hospitalized. No deaths have been reported.
Cases have been documented in Massachusetts, Minnesota, New York and Pennsylvania.
The hepatitis A outbreak has potentially been linked to frozen clams, the CDC stated.
Hepatitis A is a highly infectious liver disease spread via the fecal-oral route, close person-to-person contact and by eating and drinking contaminated food and beverages.
Unlike other strains of hepatitis, such as B and C, it does not become chronic, and most people recover completely, but in rare severe cases – particularly in older adults or people with underlying liver disease – it can lead to acute liver failure, which can be deadly.
According to the CDC investigation, state and local health officials interviewed people about the foods they ate in the 15 to 50 days before they got sick. Of the people interviewed, 77 percent reported eating ceviche – raw fish marinated in citrus – 76 percent reported eating raw or undercooked shellfish and 47 percent reported eating raw or undercooked black clams.
The CDC found that people sickened in the outbreak were significantly more likely than the general population to have eaten ceviche, raw seafood or undercooked seafood or shellfish, suggesting contaminated clams may be behind the illnesses, the agency said.
The CDC began investigating the outbreak in May 2026, but said illness onset dates range from July 30, 2025 to June 23, 2026.
Officials also said: ‘The true number of sick people in this outbreak is likely higher than the number reported, and this outbreak may not be limited to the states with known illnesses.
‘This is because some people may recover without medical care and are not tested for hepatitis A virus. In addition, recent illnesses may not yet be reported as it usually takes weeks to determine if a sick person is part of an outbreak.’
Patients range in age from six to 40 years old.
Epidemiological data showed that imported frozen clams may have been contaminated with the hepatitis A virus that made people sick in this outbreak.
Traceback investigations are ongoing to identify the source of the frozen clams.
However, the CDC did list an FDA safety alert in its investigation. The alert was for La Serranita-branded concha negra (black shell) shell meat products.
In April 2026, the FDA issued a safety alert for hepatitis A in connection to the La Serranita-branded products from Ecuador.
The shell meat was distributed to restaurants and retailers in Connecticut, Massachusetts, New Jersey, New York, Ohio and Pennsylvania, but the FDA alert warned it may have been further distributed.
The FDA safety alert advised Americans to not eat, serve or sell the product.
In a May 2026 update, the FDA reiterated that the shell meat should not be consumed because it may be contaminated with hepatitis A virus and that the products were recalled in New York and New Jersey.
Hepatitis A symptoms typically appear about two to seven weeks after exposure and a person can transmit the virus before realizing they are sick.
Symptoms include fatigue, fever, loss of appetite, nausea, vomiting, abdominal pain, diarrhea, joint pain, dark urine, pale or clay-colored stools and jaundice – the yellowing of the skin and whites of the eyes.
These symptoms can be dependent on the age of the patient; about 70 percent of infections among children younger than 6 cause no symptoms, but older children and adults typically develop symptoms, most commonly jaundice.
Symptoms typically last less than two months, but in ten to 15 percent of symptomatic patients, symptoms can be prolonged or relapse for up to six months.
For most healthy people, the body’s immune system clears a hepatitis A infection on its own, but in rare cases, a complication called fulminant hepatitis can occur – or acute liver failure.
This is a rapid loss of liver function that can be fatal.
The World Health Organization estimates that 35,570 people died from hepatitis A globally in 2023, the latest data available.
In the US, the CDC reported 1,648 hepatitis A cases in 2023, the latest data available, but the agency estimates there may have been up to 3,300 infections after accounting for underdiagnosis and underreporting.
There were 85 hepatitis A-related deaths reported that year.
To treat hepatitis A, there is no specific cure or medication. Treatment consists of rest, hydration and getting proper nutrition.
And to prevent hepatitis, a vaccine can be given beginning at age one. It is a routine childhood vaccine given in two doses between the ages of 12 and 23 months, separated by at least six months.
Adults who never received the vaccine in childhood can get it at any age and it is recommended for people at increased risk of infection, such as people traveling to a country where the virus is more common, men who have sex with men, people who use drugs, the unhoused, people with chronic liver disease and people with HIV.
An unvaccinated person can also receive the vaccine as a post-exposure prophylaxis. It should be administered as soon as possible following exposure and within two weeks.
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