Can foodborne illnesses be transmitted through seafood?

Can Foodborne Illnesses Be Transmitted Through Seafood?

Yes, seafood is a significant source of foodborne illnesses and should never be consumed raw or undercooked, as it can transmit multiple bacterial, viral, and parasitic infections that cause substantial morbidity and mortality.

Risk Magnitude

• Seafood accounts for 10-19% of all foodborne illnesses in the United States, ranking third among food products causing foodborne disease 1, 2
• While viruses cause approximately half of seafood-related infections, bacterial agents are responsible for most hospitalizations and deaths 3
• Vibrio vulnificus infection from seafood consumption is the leading cause of death related to seafood in the United States, with case-fatality rates exceeding 50% for primary septicemia 4

Specific Pathogens Transmitted Through Seafood

Bacterial Infections

• At least 10 genera of bacterial pathogens cause seafood-borne diseases, with naturally-occurring bacteria (particularly Vibrio species) accounting for 20% of shellfish-related illnesses and 99% of deaths 2
• Vibrio species (including V. vulnificus, V. parahaemolyticus, and V. cholerae), Salmonella, and Campylobacter are commonly transmitted through contaminated seafood 5, 4
• Listeria can be transmitted through ready-to-eat seafood products 5

Viral Infections

• Viruses are the most common cause of shellfish-associated disease, with Norwalk virus and small round structured viruses responsible for the majority of outbreaks 2
• Hepatitis A virus transmission through shellfish has been documented 2
• Viral gastroenteritis from Vibrio species and Cryptosporidium parvum can be transmitted through raw or undercooked seafood 5

Parasitic Infections

• Multiple parasites including nematodes, trematodes, cestodes, and protozoa are readily transmitted through seafood consumption 6

High-Risk Populations

Immunocompromised individuals face dramatically elevated risk and must exercise extreme caution:

• HIV-infected persons, particularly those with severe immunosuppression, should avoid all raw or undercooked seafood 5
• Patients with liver disease are more susceptible to severe infections, particularly Vibrio vulnificus septicemia with mortality rates exceeding 50% 4, 3
• Hematopoietic stem cell transplant recipients must avoid raw or undercooked seafood to prevent viral gastroenteritis and Vibrio species infections 5

Prevention Guidelines

Cooking Requirements

• All seafood must be cooked until well done with no pink remaining in the middle (internal temperature >165°F or 73.8°C) 5
• This cooking temperature is critical for killing bacterial, viral, and parasitic pathogens 3, 6

Cross-Contamination Prevention

• Uncooked seafood must never contact other foods 5
• Hands, cutting boards, counters, knives, and all utensils must be washed thoroughly after contact with uncooked seafood 5

Travel Considerations

• When traveling to developing countries, avoid raw or undercooked seafood entirely, as the risk for foodborne infections is magnified in these settings 5
• Safe alternatives include steaming-hot foods, bottled beverages, and water boiled for 1 minute 5, 7

Common Pitfalls to Avoid

• Do not assume that fresh or high-quality seafood is safe to consume raw—naturally-occurring pathogens like Vibrio species are not related to fecal contamination and cannot be predicted by standard food safety indicators 2
• Avoid oysters and clams entirely if immunocompromised, as these filter-feeding shellfish concentrate pathogens and are particularly high-risk 5
• Temperature abuse is a major cause of scombroid poisoning from tuna, mahi-mahi, and related species, so proper refrigeration is essential 2
• Freezing does not eliminate all parasites, and adequate cooking remains the safest prevention method 6