Most animals are carriers of disease. The diseases that animals can transmit to humans are called zoonotic diseases or zoonoses.
It’s no secret that some of the deadliest diseases in history were transmitted to humans by animals. The bubonic plague, which wiped out one-third of Europe’s population, was carried to people by fleas living on black rats.
Smallpox began as a virus in animals and was transmitted to humans. And today, the Ebola virus outbreak in Africa continues to spread among people who have had contact with infected animals such as bats and monkeys.
The risk of infection does not just depend on the animal species and its way of life, but also on our behavior in relation to it. Some diseases are transmitted through direct contact with an animal, other diseases are transmitted indirectly by insects or other animals.
Some diseases transmitted to humans by animals can be prevented through vaccination or prophylaxis. Others do not have treatment available at present.
Diseases that animals can transmit to humans
Here are five diseases that animals can transmit to humans.
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Coccidioidomycosis
Coccidioidomycosis, also known as Valley Fever, is a fungal infection caused by the inhalation of the fungus Coccidioides. This fungus is found in soil and dust in the southwestern United States, Mexico, and some areas of Central and South America.
The fungus lives as a spore until it is inhaled by an animal or human. Once it enters the body, it grows into a mold that causes disease. Symptoms include fever, chills, headache, muscle aches, rash, and joint pain. Severe cases can result in pneumonia or meningitis.
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Leptospirosis
Leptospirosis is a bacterial infection caused by Leptospira bacteria. Infected animals shed the bacteria in urine and other body fluids, making contaminated water or soil dangerous to humans who come into contact with it. The bacteria can live for months in water and soil under certain conditions.
Humans become infected by coming into contact with infected urine or contaminated water or soil through breaks in their skin, eyes, or mouth; sometimes people become infected after swallowing contaminated water while swimming or rafting.
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Toxocariasis
This disease is caused by roundworm parasites commonly found in dogs and cats that shed eggs in their feces. People become infected when they accidentally ingest these eggs in soil or sand contaminated with the feces (for example, during outdoor play).
The larvae hatch and migrate through the body causing symptoms such as fever, cough, body aches, rash, eye pain, vision changes, and abdominal pain.
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Salmonellosis
Salmonellosis is an infection caused by the salmonella bacteria. The bacteria can infect several different species of animals including reptiles (such as lizards and turtles) and birds (like parrots and chickens).
People become infected when they ingest food or water contaminated with the bacteria from an infected animal’s feces. Symptoms include fever, diarrhea, abdominal cramps, and vomiting.
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Campylobacteriosis
Campylobacteriosis is an intestinal infection caused by contact with the feces of infected animals. Humans can become infected with Campylobacter bacteria and become ill with diarrhea, which may be bloody or watery.
This disease can be spread to humans by eating raw or undercooked meat or poultry contaminated with Campylobacter bacteria. The risk is highest during the summer months when visitors will be handling animals and eating raw or undercooked animal products.
Not sure how to take care of animals? Read our guide on 7 ways to take care of animals.