A single package of frozen clams from Ecuador, processed months earlier and thousands of miles away, sat in a restaurant freezer waiting to be thawed and served. This is the reality of the global food supply chain, and in 2025 and 2026, it led to a hepatitis A outbreak that sickened people across multiple states over a period of at least eight months.
In April 2026, the U.S. Food and Drug Administration (FDA) issued a safety alert advising restaurants, retailers, and consumers not to eat, serve, or sell La Serranita‑brand concha negra (black shell) fresh frozen shell meat from Ecuador. The product was distributed to restaurants and retailers in Connecticut, Massachusetts, New Jersey, New York, Ohio, and Pennsylvania, and may have been further distributed. The New York City Department of Health and Mental Hygiene was investigating a cluster of hepatitis A illnesses in New York linked to this imported shell meat, and related cases had been reported in additional states.
The timeline of the outbreak is striking. The outbreak‑associated hepatitis A cases had onset dates from July 2025 through February 2026. Because the product was frozen, it could still be in home freezers or on retail shelves, posing a continued risk even though the most recent known illness occurred in February 2026. The Connecticut Department of Public Health noted that a limited number of Connecticut retailers had received the same product, and local health officials worked to ensure the product was not served to consumers at Connecticut establishments. Restaurants that had received the clams were urged to dispose of them immediately and to carefully clean and sanitize any surfaces or containers that had touched the product.
The first illness related to the clams was reported in July 2025, with the most recent case reported in February 2026. The threat is ongoing because of the long shelf life of the frozen black shell shell meat. The implicated clam meat was shipped to a New York dealer from a New Jersey dealer or importer and distributed within New York state, but the product may have been further distributed. Consumers could use label information to identify the product: La Serranita brand, Concha Negra, fresh frozen, shell meat, net weight 16 ounces (454 grams).
Understanding Hepatitis A
Hepatitis A is a highly contagious vaccine‑preventable liver infection caused by the hepatitis A virus (HAV). People become infected through the fecal‑oral route, usually by consuming contaminated food or water, through contaminated hands or objects, or through close personal contact with an infected person. The virus is remarkably resilient: it can survive on surfaces for weeks and is not killed by freezing. The Connecticut Department of Public Health noted that hepatitis A is a contagious liver infection that can be transmitted by consuming contaminated food or water, with symptoms including fatigue, nausea, stomach pain, and jaundice.
The illness typically occurs within 15 to 50 days after exposure, with an average incubation period of about 28 days. This long incubation period complicates outbreak investigations because patients may not connect their illness to a specific meal or product. Symptoms of hepatitis A include fatigue, nausea, vomiting, abdominal pain, jaundice (yellowing of the skin and eyes), dark urine, and pale stool. In some instances, particularly in children under six years of age, infection may be asymptomatic. But the virus can still be transmitted to others, making containment efforts difficult. People are infectious from two weeks before symptom onset until one week after the onset of jaundice or dark urine, meaning they may spread the infection before knowing they are infected.
For most people, hepatitis A is a self‑limiting illness lasting one to three weeks. However, it can lead to hospitalization and severe illness, particularly in older adults and those with chronic liver disease. Young children who are infected usually have few or no symptoms but can still transmit infection to others.
Shell Meat and Its Unique Risks
Concha negra, also known as black shell or black clam, is a type of saltwater clam found along the Pacific coast of the Americas, ranging from Baja California to Peru. It is a traditional delicacy in several Latin American cuisines, often served as a cocktail or added to ceviches. The “shell meat” refers to the edible flesh that has been shucked from the shell. Because the clams are frequently harvested from estuaries and mangroves, they are exposed to runoff and other contaminants that can carry human sewage.
Bivalve mollusks such as clams, oysters, and mussels pose a unique food safety risk because they feed by filtering large volumes of water. If the water is contaminated with hepatitis A virus, the clams can concentrate the virus in their tissues. The product recalled in this outbreak was sold frozen in 16‑ounce plastic packages. Freezing does not kill the virus, so the contamination can persist for the entire frozen shelf life. Because the shell meat is often eaten raw or lightly cooked, the virus is not inactivated before consumption. This makes such imported frozen shellfish a potential vehicle for hepatitis A transmission even months after harvest.
The Connecticut Department of Public Health’s statement on the investigation reminded residents that Connecticut has a robust, year‑round shellfish safety and sanitation program, with regular water quality, biotoxin, and pathogen testing. However, the warning noted that shellfish served in restaurants may be sourced from other states, other countries, or multiple suppliers, and not all of them operate under the same rigorous standards Connecticut has in place.
A Pattern of Recent Large Hepatitis A Outbreaks
The 2026 concha negra outbreak is part of a broader pattern of hepatitis A incidents linked to imported foods. In Europe, a hepatitis A outbreak traced to frozen strawberries and raspberries expanded to 11 cases in Sweden between September 2025 and March 2026. From mid‑September to the end of 2025, seven people were infected with a hepatitis A virus of genotype IA; all had eaten frozen imported strawberries and raspberries that had not been heated before consumption. In February and March 2026, four more people fell ill after eating the same products. The 11 patients were six men and five women aged between 17 and 64 years old and lived in different parts of the country.
In the Netherlands, an outbreak in late 2024 and early 2025 involved frozen blueberries sold by Albert Heijn, the country’s largest supermarket chain. Between November 2024 and February 2025, at least 24 people were infected, with eight hospitalizations. Lab testing results received in January 2025 confirmed the presence of hepatitis A virus in the berries.
In Italy, health authorities reported more than 130 hepatitis A cases in early 2026, largely linked to contaminated bivalve mollusks such as mussels and clams. The Italian outbreak prompted a ban on the serving of raw seafood in public establishments in Naples.
In January 2025, the FDA released a summary of a new strategy to prevent the contamination of fresh and frozen berries with enteric viruses, acknowledging that while no enteric virus outbreaks associated with domestically grown berries have been reported in 35 years, there have been repeated outbreaks linked to imported fresh and frozen berries. The strategy focuses on hygienic practices for field workers, sanitary facilities, cross‑contamination prevention, viral carriage monitoring of workers, and improved detection methods.
Analysis and Next Steps
What is new about the 2026 concha negra outbreak is that it involved an imported frozen product that had a shelf life long enough to cause illnesses over an eight‑month period, with cases continuing even after the initial alerts. The FDA’s safety alert, issued in April 2026 and updated in May 2026, came after the first illness was already recorded in July 2025 and the most recent known illness in February 2026. This timeline highlights the difficulty of quickly identifying a source when the vehicle is an imported frozen commodity and the incubation period of hepatitis A can stretch up to 50 days. The involvement of multiple state health departments and the FDA underscores the need for coordinated surveillance and rapid alert systems for imported foods that are often consumed without a kill step.
Why this matters is that hepatitis A can cause severe, prolonged illness, particularly in older adults and those with pre‑existing liver conditions, and the infection is entirely preventable through vaccination. Consumers may not realize that frozen products, which they perceive as safe because they are stored at low temperatures, can still harbor the virus. The outbreak also underscores that the global supply chain for seafood can introduce pathogens from regions where sanitation standards differ from those in the United States. Without robust monitoring of imported shellfish and a reliable way to detect the virus, similar outbreaks are likely to recur.
Who is affected includes not only the individuals who became ill, whose onset dates spanned months, and also their close contacts, who may have been exposed through person‑to‑person transmission. Restaurants and retailers that received the product faced the burden of tracing and disposing of inventory, and some may have unknowingly served contaminated product to customers. The broader public is also affected because the outbreak erodes confidence in imported seafood and highlights gaps in preventive controls.
What to do now is clear. Consumers who may have purchased La Serranita‑brand concha negra should check their freezers and discard any such product immediately. The FDA recommends that any surfaces or containers that touched the product be carefully cleaned and sanitized, as the virus can survive on surfaces for weeks. Anyone who consumed the product and has not been vaccinated should consult a healthcare provider about post‑exposure prophylaxis, which can be effective if given within two weeks of exposure. For the general public, the most effective long‑term protection is the hepatitis A vaccine, which is widely available and recommended for all children and for adults at increased risk. Food service operators should always source shellfish from licensed, certified dealers, maintain proper cold chain, and ensure that any imported shellfish is accompanied by documentation of origin and safety controls. Finally, public health agencies should continue to enhance the surveillance of imported frozen seafood and produce, using whole genome sequencing and traceback technology to shorten the time between the first illness and the identification of the contaminated source. By combining vaccination, thorough cleaning, and improved supply chain oversight, the risk of future hepatitis A outbreaks linked to imported shellfish can be substantially reduced.
