ARCHIVED - Outbreak of Trichinellosis in French Hunters Who Ate Canadian Black Bear Meat

1 May 2006

Volume 32

Number 09

CCDR 2006 Available on PubMed

This is to inform our readers that all issues of the Canada Communicable Disease Report (CCDR) since 1 January, 2006 are now available on PubMed.

Outbreak of trichinellosis in French hunters who ate Canadian black bear meat

On 27 September, 2005 Quebec public authorities received a ProMed alert informing them that several French hunters had contracted trichinellosis after consuming black bear meat in the course of a hunting trip to Northern Quebec.

We subsequently contacted the French authorities to learn more about the situation.

Epidemiological investigation in France

An epidemiological investigation conducted by a team in France1 uncovered the following facts: on 22 September 2005, the Institut de veille sanitaire in France was notified that five related patients had been hospitalized with fever, myalgia and hypereosinophilia. Fifteen days earlier, these five individuals had shared a meal that included bear meat brought back by one of the group following a hunting trip to Canada. The latter had been part of group of 10 hunters who ate bear meat in Canada; some members of the group also brought bear meat into France.

The epidemiological investigation carried out in France revealed that the hunters had eaten bear meat in the course of their hunting trip in Northern Quebec. All of the French subjects who were part of the hunting party that travelled to Quebec, as well as all subjects later exposed to Canadian bear meat in France, were identified. An alert was issued to the French network of 35 hospital parasitologists participating in the annual survey of the Centre National de Référence (CNR), as well as to the private laboratories (Biomerieux, Cerba, LCL) that also form part of this network. Subjects who had been exposed to the meat but had not yet become ill at the time of the investigation were referred to their attending physicians. The CNR urged all of them to undergo systematic biological testing and preventive treatment.

The complete epidemiological investigation revealed that different groups had been exposed to the black bear meat. The exposed population comprised 25 individuals who fell into three groups: the initial group of 10 hunters who returned from Canada; a second group of six guests in the Orléans region (Loiret) who (along with three of the hunters) ate a meal that included bear meat; and a third group of nine individuals in the Narbonne region (Aude) who (along with one of the hunters), ate meat from the same animal.

In October, 17 cases of trichinellosis were identified (in persons aged 31 to 67, including 13 men and four women). This corresponds to an overall disease rate of 68% (M: 86.7%,W: 40.0%). The cases manifested between 9 and 29 September, 2005. Incubation periods ranged between 7 and 24 days (mean: 18 days). Two muscle biopsies were performed on one of the hunters and one of the dinner guests. These biopsies revealed a parasite load of at least two larvae per gram of muscle. Eight of these individuals were hospitalized for an average of 10 days. No serious form of the disease was observed.

Analyses carried out on the Trichinella larvae revealed that the species in question was nativa, which is far more resistant to freezing than the T. spiralis species.

Treatment with Albendazole at doses ranging between 400 and 800 mg/day was commenced for all cases and for all exposed subjects 20 to 28 days after exposure. Among the Narbonne dinner guests, most of whom received preventive treatment, only one third presented symptoms.

The black bear in question was killed on 26 August, 2005, in Northern Quebec (57° North and 65° West), in a tundra area near the George River. The animal was skinned, eviscerated and cut up on site. The four legs, filets, trophy, skin and various edible viscera, including the tongue, were brought back to the hunting camp. The meat was hung under cover for 3 to 4 days. The hunters ate some of the meat on several occasions during the period of 28 and 30 August, 2005, sometimes as stew in the local style, other times as lightly done or rare steaks. Some in the group went so far as to taste the meat raw. The tongue was eaten well-done. The various members of the group, with the exception of the guide, returned to France on 2 September, 2005. Two of them brought back pieces of bear meat in their luggage, despite statutory prohibitions against this practice. One group of guests ate some of the meat on the evening of 2 September, upon the hunters' return, while the other group of guests consumed the meat on 6 September, after it had been frozen for 3 days. Both groups consumed the meat in the form of steaks at varying degrees of doneness, based on individual taste. Amounts consumed ranged from a single bite to approximately 100 g. All of the meat brought into France was consumed.

The Centre National de Recherche has had discussions with the Direction générale de la santé regarding an information notice that will be forwarded to all hunting federations, informing them of the hazards of consuming underdone bear meat and reminding them of the prohibitions against the importation of meats.

Quebec investigation conducted by investigators of the ministère de l'Agriculture, des pêcheries et de l'alimentation (MAPAQ)

MAPAQ investigators contacted the outfitter implicated in this matter, in order to determine whether he and his team of guides were well-informed about the risks of contracting trichinellosis from underdone bear meat. A representative for the outfitter explained that French tourists like to come to Quebec on the “European plan,” which commonly provides a Quebecois guide for every group of six to 12 hunters. The guide is responsible for ensuring the group's safety and maintaining the camp. However, the outings are based on the forest survival concept whereby participants must prepare their own food. This differs from the American plan, where there is a guide for every two clients and clients are accompanied at all times by their guide and a cook who prepares their meals.

The outfitter receives approximately 30 clients per year for bear hunting and three-quarters of these clients are usually nonresidents who come from different parts of the world. It would appear that French tourists show the keenest interest in bear hunting. While they primarily hunt caribou, they are also very partial to black bear hunting, unlike Americans who mostly hunt caribou. It would appear that hunters seldom bring back bear meat, preferring to eat it in the wild (if at all).

According to the representative for the outfitter, these are the first cases of trichinellosis the company has been associated with in 20 years. In 2005, 11 bears were killed during the outfitter's period of operation: three by French tourists, six by American tourists, two by Slovak tourists, and one by a Quebecois hunter. Based on information obtained from the outfitter, it would seem that the French are particularly fond of bear meat, although they are aware that the meat must be consumed well-done.

As for the group of hunters who contracted trichinellosis in September 2005, they hunted and consumed black bear in Northern Quebec. They were accompanied by a French guide and a Quebecois guide. The Quebecois guide accompanied the group for 3 days only. The French guide, who sells these trips in France, accompanied the participants throughout their stay in Quebec. It would seem that the guide was aware that the meat needed to be cooked thoroughly, although he himself ate meat that was underdone. The representative for the outfitter, who accompanied the group for 3 days, has stated that the group ate the food they caught hunting and fishing. They fished, hunted and liked to survive solely on what they hunted and fished. Since participants were responsible for cooking their own food, they were free to prepare the meat as they saw fit; in this instance, the meat was eaten rare. It is important to note, however, that no print information on trichinellosis is currently provided to outfitters, guides and hunters.

A box of the meat in question was shipped to Schefferville and then to Montreal, as a gift to an Aboriginal person, who gave some to two other people as gifts. On 12 October, this person was informed that the meat was infected. As the meat had not been consumed, it was sampled for analysis. The tests performed by the Laboratoire d'épidémiosurveillance animale du Québec revealed the presence of approximately 300 larvae per gram of meat. The larvae were sent to the International Trichinella Reference Centre (Laboratory of Parasitology, Istituto Superiore di Sanita viale Regina, Rome, Italy) for species identification by Polymerase Chain Reaction (PCR).

Discussion

Trichinella sp. is a parasite found in Quebec, primarily in predators such as polar bears, wolves, foxes, and, surprisingly, the seals of Hudson Bay and Hudson Straits. Black bears, which occasionally consume animal carcasses or act as predators, can also carry the infection. In Quebec, it is estimated that less than 1.5% of black bears south of the 50th parallel are infected ². No study of the prevalence of this parasite in black bears north of the 50th parallel has been conducted, although Butler and Khan³ have reported a prevalence rate of 1% in Labrador, which suggests that the prevalence of this parasite in black bears may be similar throughout Quebec.

Interventions in Quebec subsequent to the outbreak

Meetings were organized between Quebec outfitters and officials of the ministère des Ressources Naturelles et de la Faune (MRNF) and MAPAQ. Information on trichinellosis was passed on to participants.

MAPAQ is coordinating the production of a brochure that discusses the risk of contracting trichinellosis from underdone black bear meat and outlines a number of preventive measures. This brochure will be distributed by MRNF to outfitters, wildlife preserves and hunters in Quebec. The information will also be made available on the Internet sites of MRNF, MAPAQ and MSSS.

References

1. Ancelle T, De Bruyne AE, Dupouy-Camet J, Outbreak of trichinellosis due to consumption of bear meat from Canada, France, September 2005. Eurosurveillance Weekly, 2005:10(10).

2. Côté N, Villeneuve A, Bélanger, D. Trichinella spiralis chez l'ours noir (Ursus americanus) au sud du 50^e parallèle au Québec, Canada : intensité d'infection, génotypes, distribution et prévalence. Unpublished study.

3. Butler CE, Khan RA. Prevalence of Trichinella spiralisin black bears ( Ursus americanus ) from Newfoundland and Labrador, Canada. J Wildl Dis 1992;23(3):474-3.

Source : C Gaulin, MD, medical consultant, Ministère de la Santé et des services sociaux (MSSS); I Picard, DVM, N Côté, DVM, IPSAV, Ministère de l'Agriculture, des pêcheries et de l'alimentation du Québec (MAPAQ); M Huot, BSc, Ministère des Ressources naturelles et de la faune (MRNF); J-F Proulx, MD, Direction de la santé publique du Nunavik, Québec, Québec.