Federal health officials have added Massachusetts to a hepatitis A outbreak linked to imported frozen clams, and the case count has climbed to 37 people across four states. Thirty of them, or 81 percent, have been hospitalized. The CDC outbreak page was last reviewed on September 3, with figures current as of that date.
The other significant change is who is getting sick. The age range now runs from 6 to 40 years old, meaning a young child is among the people counted in an outbreak that federal and state investigators have been working on since May.
For families, that shifts the practical question. This is no longer only a matter of adults eating raw shellfish at restaurants. Young children can be exposed through food prepared at home or at a family gathering, and hepatitis A infection in children under six is often without symptoms, which means an infected child can pass the virus to household members before anyone realizes anything is wrong.
A Ceviche Link Comes Into Focus
The CDC has also published interview data that narrows the food question considerably. State and local officials asked patients what they ate in the 15 to 50 days before falling ill. Among those interviewed, 77 percent reported eating ceviche, 76 percent reported eating raw or undercooked shellfish, and 47 percent reported eating raw or undercooked conchas negras, also called black clams.
Those percentages were significantly higher than what the FoodNet Population Survey finds for the general public, which is the comparison investigators use to judge whether a food is genuinely overrepresented. The agency says the difference suggests people in this outbreak may have gotten sick from eating raw or undercooked clams.
Illness onset dates now stretch from July 30, 2025, to June 23, 2026, according to the CDC outbreak timeline. That is nearly eleven months of illnesses tied to one product category. No deaths have been reported.
The product at the center of the investigation is La Serranita brand concha negra fresh frozen shell meat from Ecuador, sold in 16-ounce plastic packages. An FDA safety alert first issued in April advised restaurants and retailers not to serve or sell it and told consumers not to eat it. Dealers in New York and New Jersey have recalled the product. Traceback work to identify the original source or sources is still underway.
Households Most Likely to Have the Product
Distribution and illness are not the same map, which is the detail most likely to catch a household off guard. The FDA says the shell meat went to restaurants and retailers in Connecticut, Massachusetts, New Jersey, New York, Ohio and Pennsylvania, and may have been distributed further. Confirmed illnesses, by contrast, have been identified in Massachusetts, Minnesota, New York and Pennsylvania.
That gap matters because freezing does not kill hepatitis A virus. A package bought a year ago and pushed to the back of a freezer is as much of a risk today as it was the week it was purchased. This is why the investigation has stayed open across two summers.
The highest risk falls on people who eat raw marinated shellfish, households that shop at markets serving Ecuadorian, Peruvian, and other Latin American communities in the Northeast and upper Midwest, and anyone who has never been vaccinated against hepatitis A. Older adults and people with chronic liver disease face the greatest chance of severe illness. Children under six may carry the infection without visible symptoms.
Connecticut's health department flagged the product for its own residents even though the state has no confirmed outbreak cases. Commissioner Manisha Juthani of the Connecticut Department of Public Health said a limited number of Connecticut retailers had received the same product and that state teams were working with local health officials "to ensure that the product is not served to consumers" at establishments in the state.
Steps Worth Taking Before the Next Update
Check the freezer for La Serranita brand concha negra shell meat and throw away or return any package that matches. Cooking is not a workaround for a product under a recall advisory, and the outbreak product is most often eaten raw in ceviche. Anyone who handled the product should also clean and sanitize surfaces and containers it touched.
Anyone who ate the recalled product raw or undercooked within the past 14 days and has not been vaccinated should contact a clinician or local health department promptly. A hepatitis A vaccine given soon after exposure can prevent illness, which is why the 14-day window is the deciding factor rather than whether symptoms have appeared.
Symptoms usually surface two to seven weeks after exposure and can include fatigue, fever, nausea, stomach pain, joint pain, loss of appetite, dark urine, pale or clay-colored stools, and yellowing of the skin or eyes. Jaundice, confusion, or worsening abdominal pain warrant prompt medical evaluation rather than waiting it out at home.
Several unknowns remain. Investigators have not identified the point of contamination in the supply chain. The CDC says the true case count is likely higher than reported, since some people recover without medical care and are never tested, and recent illnesses usually take weeks to be linked to an outbreak. The agency also says the outbreak may not be limited to the states with known illnesses.
MedicalDaily previously reported on the open investigation into the imported clams when the count stood at 30 cases in three states.
Key Questions Answered
How many people are sick and where? Thirty-seven people in Massachusetts, Minnesota, New York, and Pennsylvania, as of September 3. Thirty have been hospitalized, and no deaths have been reported.
What changed in this update? Massachusetts was added as a fourth state, cases rose from 30 to 37, and the youngest identified patient is now 6 years old.
Which product is involved? La Serranita brand concha negra fresh frozen shell meat from Ecuador, in 16-ounce packages, under an FDA safety alert and recalled by dealers in New York and New Jersey.
Does cooking or freezing make it safe? Freezing does not inactivate hepatitis A virus. The FDA advises discarding or returning the recalled product rather than attempting to cook it.
Who faces the greatest risk of serious illness? Older adults and people with chronic liver disease. Children under six often have no symptoms, which makes household spread easier to miss.
What should someone do after a recent exposure? Anyone who ate the product raw or undercooked in the past 14 days and is unvaccinated should contact a clinician or local health department about postexposure vaccination.
Is the reported count complete? No. The CDC says the true number is likely higher because mild infections often go untested and recent illnesses take weeks to be linked.
