Serosurvey of selected zoonotic agents in polar bears (Ursus maritimus)

Abstract

Between 1982 and 1999 blood samples were collected from 500 polar bears (Ursus maritimus) captured in the Beaufort and Chukchi seas, to determine the seroprevalence of Brucella species, Toxoplasma gondii, and Trichinella species infections. The bears were classified into four age groups, cubs, yearlings, subadults and adults. Brucella and Toxoplasma antibodies were detected by agglutination (a buffered acidified card antigen and rapid automated presumptive test for brucellosis and a commercial latex agglutination test for toxoplasmosis); an ELISA was used to detect Trichinella antibodies. The overall seroprevalence of Brucella species was 5 per cent, and subadults and yearlings were 2-62 times (95 per cent confidence interval 1.02 to 6.82) more likely to be seropositive for Brucella species than adults and their cubs. The antibody prevalence for Toxoplasma gondii was 6 per cent, and for Trichinella species 55.6 per cent. The prevalence of antibodies to Trichinella species increased with age (P<0.001).

A circumpolar monitoring framework for polar bears

“…Polar bears from East Greenland, Svalbard, and the Barents Sea screened for antibodies to the protozoan parasite Toxoplasma gondii were 21.4% seropositive (Oksanen et al 2009). This was much higher than an earlier study from the Beaufort and Chukchi Seas and the Russian Arctic (6%; Rah et al 2005), although a subsample from the Russian Arctic showed a prevalence of 23% (7 of 30). More recently, Jensen et al (2010) documented an increase in the prevalence of T. gondii in Svalbard polar bears and speculated this might be due to warming ocean waters enabling higher survival of oocysts.…”

Morbillivirus and Toxoplasma Exposure and Association with Hematological Parameters for Southern Beaufort Sea Polar Bears: Potential Response to Infectious Agents in a Sentinel Species

“…Although incidence of clinical toxoplasmosis among marine mammals appears low, antibodies to the parasite have been detected in numerous species across the Arctic (Tryland, 2000). Seroprevalence for Alaskan polar bears was 6% (Rah et al, 2005), and in Svalbard and Greenland, polar bears ranged from 3.6% to 28.7% depending upon age, sex, and location (Oksanen et al, 2009). Antibodies to T. gondii occur in several species sharing habitat with polar bears in Alaska including: walrus (Obobenus rosmarus), bearded seals (Erignathus barbatus), spotted seals (Phoca largha), and ringed seals (Dubey et al, 2003); grizzly bears (Zarnke et al, 2000); wolves, and caribou (Rangifer tarandus) (Zarnke et al, 1997); and in Canada: hooded (Cystophora cristata) and gray seals (Halichoerus grypus) (Measures et al, 2004).…”

“…Antibodies to morbillivirus and Toxoplasma gondii have been previously documented in polar bears throughout the Arctic (Garner et al, 2000;Tryland, 2000;Tryland et al, 2005;Cattet et al, 2004;Zarnke et al, 2004;Rah et al, 2005;Oksanen et al, 2009;Jensen et al, 2010). Transmission dynamics of morbilliviruses and Toxoplasma in the Arctic may be affected as climate changes impact vectors and the health, behavior, movement, and population dynamics of reservoir populations of marine (e.g., pinniped) and terrestrial hosts (e.g., domestic and wild canids).…”

Demographic Characteristics and Infectious Diseases of a Population of American Black Bears in Humboldt County, California

“…Through vectors, scavenging, and occasional predation, black bears may be exposed to pathogens, including agents of anaplasmosis, borreliosis, toxoplasmosis, trichinosis, plague, tularemia, brucellosis, bartonellosis, and rickettsiosis (Anderson and May 1979, Hill and Dubey 2002, Rah et al 2005. Thus, bears may be a source of human disease, especially trichinosis and toxoplasmosis, through hunting and consumption of undercooked meat (Nutter et al 1998).…”