If the past few years have taught us anything, it’s that our well-being is intimately linked to the health of animals.

The current Ebola epidemic probably got its start when someone came into contact with an infected animal, perhaps a monkey or a fruit bat. The virus causing Middle East respiratory syndrome appears to spread from camels to humans.

Yet animal pathogens remain a scientific terra incognita. Researchers have begun cornering animals in far-flung parts of the world to learn more about what infects them.

Recently, a team of pathogen hunters at Columbia University went on an expedition closer to home. They conducted a survey of the viruses and bacteria in Manhattan’s rats, the first attempt to use DNA to catalog pathogens in any animal species in New York City.