parasites

Scientists believe that it evolved to protect human beings from invisible contaminants such as pathogens and parasites.

After all, parasites like hematophages are the bedrock of the tree of life, outnumbering free living species by about 3 to 2.

“The vertebrate's natural body defenses against blood loss and invasion include blood clotting, platelet aggregation, vasoconstriction and immune defenses. Most if not all blood feeding parasites secrete a form of saliva into the feeding site that contains many different proteins and even chemicals that target host defenses.”

As the Arctic warms, polar bears face a growing risk of contracting viruses, bacteria and parasites that they were less likely to encounter just 30 years ago, research has revealed.

The researchers tested for six different pathogens in total - viruses, bacteria or parasites that are primarily associated with land-based animals but have been recorded before in marine animals, including species that polar bears hunt.