Tracking sources of Clostridium botulinum type E contamination in seal meat

Abstract

Botulism in Nunavik, Quebec is associated with the consumption of aged marine mammal meat and fat. The objective was to identify meat handling practices presenting a risk of contamination of seal meat with C. botulinum. Potential sources of contamination were assessed through interviews with igunaq producers from five communities of Nunavik. These sources were verified by detection and isolation of C. botulinum from igunaq prepared in the field from seal carcasses. Interviews indicated practices presenting a risk for contamination included: placing meat or fat on coastal rocks, using seawater for rinsing, and ageing meat in inverted seal skin pouches. Although the presence of C. botulinum type E spores was detected in only two of 32 (6.3%) meat or fat samples collected during the butchering process, two of four igunaq preparations from these samples contained type E botulinum toxin. Analysis of C. botulinum type E isolates recovered from these preparations indicated that shoreline soil may be a source of contamination. Seal meat and fat may be contaminated with C. botulinum type E during the butchering process. Measures can be adopted to reduce the risks of contamination in the field and possibly decrease the incidence of type E botulism in Nunavik.

Keywords: Arctic; Clostridium botulinum; environment; marine mammal; meat handling; spore.

Figure 1.

Dendrogram of PFGE analysis showing the relationship between C. botulinum type E isolates recovered from harvested seals and related igunaq preparations and those from the proximate coastal environments. SmaI was also used on all strains (data not shown). SmaI analyses generated 14 different PFGE profiles, whereas XhoI generated 20 profiles and was deemed more discriminatory. The sample types igunaq and misiraq correspond to the aged meat and oil components of the igunaq preparation, respectively. The similarity (%) among strains was determined using the Dice Coefficient and the clustering was performed by unweighted pair group method with arithmetic mean (UPGMA).