Paralytic shellfish poisoning in Alaska: a 20-year retrospective analysis.

Outbreaks of paralytic shellfish poisoning have occurred worldwide. The authors reviewed records at the Alaska Division of Public Health to determine the epidemiologic characteristics of this disease. To assess risk factors for illness, the authors conducted a case-control study. A case was defined as illness compatible with paralytic shellfish poisoning within 12 hours of the consumption of shellfish, and a control was defined as a non-ill participant at a meal in which at least one case occurred. The authors documented 54 outbreaks of paralytic shellfish poisoning involving 117 ill persons from 1973 to 1992. One person died, four (3%) required intubation, and 29 (25%) required an emergency flight to a hospital. Outbreaks occurred with multiple shellfish species, during all four seasons, and at many locations. During the case-control study, illness was not associated with the shellfish toxin level, method of preparation, dose, race, sex, or age; alcohol consumption was associated with a reduced risk of illness (odds ratio = 0.05; p = 0.03). Although paralytic shellfish poisoning causes significant illness, the authors could not identify risk factors with clear implications for prevention strategies. This suggests that shellfish from uncertified beaches should not be eaten. Alcohol may protect against the adverse effects of paralytic shellfish poison.