Zoonotic Diseases Passed From Animals to Humans

Mosquito bite

Ryan Lebel Photography / Getty Images

While we often think of contagious diseases as those that can be passed from person to person, a large number have made the leap from animals to human. Some, like malaria, are directly transmitted from animals, often as the primary route of infection. Others, like HIV, have evolved into a separate disease after being transferred from the animal source.

These types of infectious diseases, in their entirety, are referred to as being zoonotic.

How Zoonotic Diseases Cause Infection

Zoonotic diseases can involve viruses, bacteria, and parasites that are transmitted through blood-borne water-borne, food-borne, or air-borne infections. These include:

  • Animal bites that break the skin
  • Insect bites, including mosquitos and fleas
  • Drinking tainted water or dairy products
  • Eating infected meat
  • Inhaling pathogenic droplets or particles
  • Direct skin-to-skin contact
  • Direct or indirect contact with animal feces or urine

Animals can often transmit a disease that they are not affected. We often see this with bats. On the other hand, there are diseases, like rabies, that both humans and animals equally.

In some cases, we can reverse the route of transmission and inadvertently infected certain animals. This has certainly happened with primates which share physiological similarities to humans but have vastly different immune responses to different pathogens.

Types of Zoonotic Diseases

The range of zoonotic diseases is surprisingly diverse. Some are fast-acting causing serious illness in a short span of time. Others are slowly progressive and may or may not cause symptomatic illness.

The most familiar examples of zoonotic diseases include:

  • ​Anthrax which can be spread through animal contact or animal products
  • Bird flu transferred almost exclusively from birds to humans
  • Bubonic plaque which is spread through fleas
  • Ebola which is spread through contact with infected persons
  • E. coli bacteria spread largely through food
  • HIV which made the leap to human from the African green monkey
  • Leptospirosis which can be caused by contact with soil containing animal urine
  • Lyme's disease which you can get from a tick bite
  • Malaria which is predominately spread by mosquitos
  • Rabies which we associated with infected dogs and wild animals
  • Ringworm can be caused by direct contact with stray animals or farm animals
  • Salmonella spread largely by eating tainted eggs or dairy products
  • Toxoplasmosis often passed through contact with cat litter

While these diseases can affect anyone, they are more likely to cause serious illness in children under five, pregnant women, adults over 65, and persons with severely compromised immune systems.

15 Ways to Prevent Exposure

Since the route of infection varies by the type of disease involved, there is no one way to prevent zoonotic infection. There are, however some guidelines you should follow if you know you are at risk:

  • Washing your hands with soap and water when in contact with animals
  • Wearing gloves when cleaning the litter box or doing gardening
  • Having a hand sanitizer on-hand with a minimum 60 percent alcohol content
  • Using insect repellent to prevent mosquito, tick, or flea bites
  • Using mosquito netting in areas where mosquito-borne diseases are prevalent
  • Not going barefoot in soil or grass where farm animals live
  • Avoiding drinking water from rivers, streams, or lake
  • Avoiding drinking water in countries where water-borne diseases are common
  • Cooking meat well done in areas where foodborne pathogens are common
  • Cooking meat well done if it is from hunted wild game
  • Avoid playing with stray animals
  • Seeing a doctor if you are bitten by an animal, domesticated or wild
  • Avoid getting scratched by pets
  • Getting your pets vaccinated for rabies and other transmittable diseases
  • Getting updated travel and health advisories if planning a trip overseas
Was this page helpful?
Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  • Centers for Disease Control and Prevention (CDC). "Zoonotic Diseases." Atlanta, Georgia; updated October 25, 2016.