Submitted to: Veterinary Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/18/2004
Publication Date: 2/6/2005
Citation: Hill, D.E., Gamble, H.R., Zarlenga, D.S., Coss, C.A., Finnigan, J. 2005.Trichinhella nativa (t2) in a black bear from Plymouth, New Hampshire. Veterinary Parasitology. 132; 143-146. Interpretive Summary: Sylvatic isolates of the genus Trichinella are widespread in the environment due to an expansive host range and worldwide geographic distribution. Though T. spiralis (T1) is virtually absent from the U.S. pig population (NAHMS, 2002), sylvatic isolates pose a risk for zoonotic transmission when wildlife has access to pig barns or non-confinement raised swine. In addition, game animals serve as hosts for Trichinella species that cause human disease if meats are not properly prepared.
Technical Abstract: A suspected case of trichinellosis was identified in a single patient by the New Hampshire Public Health Laboratories in Concord, New Hampshire. The patient was thought to have become infected by consumption of muscle larvae (ml) in undercooked meat from a black bear which was harvested in Plymouth, New Hampshire in October, 2003. Meat from the bear was frozen at -20oC in October, 2003; approximately 1.5 kg of frozen meat was sent to the Animal Parasitic Diseases Laboratory in December, 2003 and stored frozen at -20oC until January 2004. In January 2004, a 600g sample of the meat was thawed at 4oC, digested in hydrochloric acid and pepsin, and larvae were collected by sedimentation. Intact, coiled, and motile ml were recovered (366 larvae per gram of tissue (lpg)), which were passed into mice and in pigs. Multiplex PCR analysis of the recovered ml revealed a single 127 bp amplicon, indicative of Trichinella nativa (T2). The Reproductive Capacity Index (RCI) for the T. nativa-Plymouth isolate in mice was 24.3. Worm burdens in diaphragm tissue of two 3-month-old pigs given 2500 ml were 0.05 and 0.2 lpg by 35 days postinoculation, while 2.2 and 0.75 lpg were recovered from two 3-month-old pigs given 10,000 ml; no larvae were recovered from four 1-year-old pigs given 2500 ml (n=2) or 10,000 ml (n=2). Viable muscle larvae were also recovered from frozen black bear meat harvested at two additional locations, one in southern Ontario, Canada, and one in upstate New York, USA. Multiplex PCR using DNA from these ml demonstrated that both of these isolates were Trichinella nativa (T2). This is the first report of freeze resistant T. nativa (T2) within the continental United States.