Which combination of animal groups are commonly associated with reservoirs for zoonotic Type A influenza?

• A. Waterfowl
• B. Pigs
• C. Waterfowl and pigs
• D. Cats

Answer: (C)

The idea being tested is that influenza A viruses persist in animal populations that serve as reservoirs, with wild waterfowl acting as the natural reservoir and pigs providing a place where different influenza strains can mix. Waterfowl routinely carry a broad range of avian influenza subtypes and shed virus into the environment, often without severe disease, which keeps the virus circulating in nature. Pigs, on the other hand, can be infected by both avian and human influenza viruses because their respiratory tract receptors can bind multiple hemagglutinin types. When a pig is coinfected with different strains, the viruses can reassort their gene segments, creating new combinations that may infect people and potentially cause pandemics. This combination—waterfowl maintaining diverse influenza A viruses and pigs acting as mixing vessels—is why these two groups are commonly linked to reservoirs for zoonotic Type A influenza.

Cats can be susceptible to influenza A, but they are not the primary reservoir that maintains and perpetuates these viruses in nature, which is why they aren’t the best match for the question about reservoirs.