IOWA CITY —
Which animals are the most likely to harbor zoonotic pathogens?
For reasons that are not currently understood, bats are able to be infected with a huge variety of viruses. They pass these viruses to other animal species via bites or guano. The classic bat-origin virus is rabies, but bats have also been implicated as possible reservoir species for the Ebola and Marburg viruses, Nipah, Hendra and others. Even influenza has recently been found in bats. Bats also appear to be the reservoir for the SARS coronavirus, which surfaced in 2002 in Asia. SARS eventually infected more than 8,000 individuals around the world and killed almost 800 of them between November 2002 and July 2003, spreading to at least 37 countries. A new SARS-related virus has recently surfaced in Saudi Arabia, and speculation is that it's also from bats.
Other Wild Animals
While bats appear to be responsible for a disproportionate amount of novel pathogens, every animal species carries its own unique microbiota — the collection of microbes that live on and in an animal's body. Some of those can also spread to humans. As mentioned above, birds can spread many different types of influenza viruses. In fact, wild waterfowl serve as the ultimate reservoir for all known types of influenza viruses. Birds also can transmit a number of encephalitis viruses, such as West Nile. Because many migrate long distances, birds may be particularly efficient at introducing pathogens into new areas.
Primates also harbor a number of pathogens that have crossed over into human populations, often an easy jump since we are so closely related. HIV is the result of multiple species jumps from nonhuman primates into human populations, likely due to butchering of infected animals. Research carried out by Nathan Wolfe and others has shown that bushmeat hunters in Africa are still being infected with viruses from our primate relatives.