Arctic Polar Bear Health Threatened by Rising Pathogen Exposure

In a world of constantly changing and warming climates, polar bears are facing an increasing number of challenges, primarily related to their diminishing winter habitats. Simultaneously, they may also be encountering a growing number of bacterial and parasitic infections.

Researchers from the US Geological Survey's Alaska Science Center recently reported in the scientific journal PLOS ONE that polar bears living near Alaska are now more frequently coming into contact with five different pathogens compared to decades ago.

Polar bears living in the Chukchi Sea region of the Arctic Ocean were the perfect subjects for this study. Researchers screened serum and fecal samples collected from 232 Chukchi bears between 2008 and 2017 to detect antibodies against a range of bacteria, viruses, and parasites. The presence of antibodies against specific pathogens in the samples indicated that the bears' immune systems had encountered the pathogens at some point. Subsequently, the team compared this analysis to a similar study conducted on 115 Chukchi bears between 1987 and 1994.

The researchers found that since the 1990s, the proportion of polar bears exposed to the parasite Toxoplasma gondii and bacteria causing brucellosis and tularemia has at least doubled. There are also more bears carrying antibodies against canine distemper virus, and the proportion of bears infected with Toxoplasma has increased sevenfold, from 2% to 14%.