How Do Diseases Spread From Animals To Humans?

From cats to birds to bats, animals can transmit zoonotic diseases, which kill millions of people every year.

- Lori Cuthbert

A deer tick climbs a blade of tall grass in the woods. It stretches its front legs as far as it can, waiting for a passerby. When a hiker brushes past, the tick clings on. It finds a prime position, cuts into the skin, and inserts its feeding tube. If the tick carries the bacteria that causes Lyme disease, that virulent microbe passes into the tick’s human host, and the person now has a zoonotic disease.

Also called zoonoses, zoonotic diseases are the many kinds of illnesses that pass from animals to humans. Almost 16 percent of all deaths worldwide can be attributed to infectious diseases, and zoonoses account for 60 percent of known infectious diseases and 75 percent of emerging infectious diseases, according to the National Institutes of Health.