J.-F. Duchesne
M. Rhainds
É. Dewailly

Unité de recherche en santé publique
Centre hospitalier universitaire de Québec (CHUL)
2400, ave. d'Estimauville
Beauport (Québec)
G1E 7G9

17 avril 2002

To obtain this report:
quebec.slv2000@ec.gc.ca

The Human Health component of the St. Lawrence Vision 2000 (SLV 2000) Program presents the results of the "Surveillance Program on Shellfish-Related Illnesses," whose main objectives were to estimate the prevalence of illnesses caused by shellfish consumption in Eastern Quebec. (2002-04-17)

Surveillance Program on Shellfish-Related Illnesses
Phase I (1999) and phase II (2000) Results

Shellfish harvesters Photo by: Magdalen Islands ZIP Committee

Duchesne, J.-F., M. Rhainds and É. Dewailly 2002. Programme de surveillance des maladies causées par les mollusques. Résultats PHASE I (1999) et PHASE II (2000). CHUL-Centre de recherche du CHUQ, Unité de recherche en santé publique, 90 p. ISBN : 2-89496-200-2.

Abstract

This document presents the results of the "Surveillance Program on Shellfish-Related Illnesses," whose main objectives were to estimate the prevalence of illnesses caused by shellfish consumption in eastern Quebec (Charlevoix, North Shore, Lower St. Lawrence, Gaspé-Magdalen Islands) and to characterize food poisoning cases related to the ingestion of toxic shellfish. This surveillance program required the involvement of clinical staff from various healthcare establishments in the study area (for case reporting), as well as healthcare professionals from regional public health departments (to conduct epidemiological investigations).

From spring 1999 to winter 2001, 48 poisoning episodes involving 66 people were reported under the program. We performed a comprehensive analysis of information available on each reported case (report form, epidemiological investigations, stool and blood samples, MAPAQ and CFIA investigation reports) to determine the link between the illness and shellfish consumption. The reported episodes were classified as follows: 3, "confirmed"; 30, "potential"; 11, "unlikely"; and 4, "rejected." One "confirmed" episode involved marine toxins. In this episode, nine people developed paralytic shellfish poisoning (PSP) after ingesting mussels harvested in an experimental culture zone. The other two "confirmed" episodes involved the presence of pathogenic bacteria (Bacillus cereus and Clostridium perfringens). Available information on "potential" cases was insufficient to positively identify the causal agent. It appears highly likely, however, that all reported illnesses were caused by some form of pathogenic micro-organism (bacterium, parasite, virus). Mussels were most often implicated in the "confirmed" and "potential" cases. The mussels in question came primarily from a food retail establishment (restaurant, grocery store or fish market).

The study was not able to shed light on the issue of whether marine toxin poisonings are being underreported, particularly PSP. The results obtained, however, do suggest that the microbiological contamination of shellfish continues to be a problem.