Which type of shellfish is most likely to cause illness?

Oysters are particularly notorious for causing illnesses because they are filter feeders that can concentrate pathogens and toxins present in their surrounding waters. When water is contaminated with harmful bacteria, viruses, or harmful algal blooms, oysters can accumulate these microorganisms in their tissues.

Consumption of raw or undercooked oysters is a common route of human illness, as they may harbor pathogens such as Vibrio vulnificus, norovirus, and others that can lead to severe gastrointestinal issues or more serious health consequences, especially in individuals with compromised immune systems.

While clams, scallops, and mussels can also pose health risks, oysters have a higher associated risk due to their feeding mechanism and the environments they are harvested from, which can frequently be affected by coastal pollution and water quality issues. This characteristic makes oysters the shellfish type with the highest likelihood of causing illness.