Outbreaks of a bacterial infection caused by Pasteurella multocida sporadically occur in staging areas where millions of waterfowl congregate during migration. During these periods where the density of the birds is very high, transmission of the bacteria can easily occur through close contact, splashing of bacteria laden water, and other mechanisms. Some outbreaks have resulted in deaths of thousands of ducks and geese. Some species are more sensitive to infection than others. For example in 1979, over 100,000 snow geese died near Hudson Bay due to avian cholera infection.
Beavers have gotten a bad rap for hosting and shedding in their feces a protozoan pathogen known as Giardia lamblia. Acquiring this gastrointestinal infection is associated with drinking untreated or unfiltered water from lakes and rivers even in remote areas such as the Boundary Waters Canoe Area in Minnesota. Although beavers get blamed for releasing this protozoan pathogen into the water, it is far from clear and certainly more complex; likely involving other wildlife species as well as domestic animals such as dogs. Even humans may have contributed to the prevalence of this pathogen in many pristine areas.