Skip to main content

Zoonotic Diseases & Horses

Zoonotic Diseases & Horses

A zoonotic disease is a disease that can be passed from animals to humans. These diseases can be caused by viruses, bacteria, parasites, and fungi. Humans can contract zoonotic or vector-borne diseases through contact with an animal, its bodily fluids, its infected waste or its living environment; by contact with water or soil contaminated by infected animal waste; by eating meat from infected animals or eating food such as fruits and vegetables that have been contaminated by infected animal waste; or through vectors—such from infected animals to humans via mosquitoes, fleas or ticks. Following are some related to equine:


Campylobacter is the most common bacterial cause of gastroenteritis worldwide and can be transmitted from horses to people via activities such as cleaning their stalls and grooming. Symptoms include diarrhea, abdominal pain, fever, headache, nausea, and/or vomiting lasting 3-6 days. You can also prevent Campylobacter infection by avoiding contact with horses and their manure, and if contact is necessary, thoroughly wash hands and clothing afterwards.


Cryptosporidosis is a parasitic disease that causes a mild to severe infection of the gastrointestinal system, including watery diarrhea, fever, abdominal cramps, nausea, and vomiting. Most people who get cryptosporidosis get it from contaminated food or water, but the parasite Cryptosporidium may be present in horse manure, so exhibit caution when visiting and caring for horses. If you develop symptoms, contact your physician.

Pigeon Fever

It is characterized by intramuscular abscesses, primarily in the pectoral area and ventral part of the abdomen, which gives the horse a puffed-out appearance similar to that of a pigeon. The infection is confirmed with a bacterial culture and by symptoms. Other symptoms are lethargy, stiffness and lameness from the pain and swelling. Horse should be checked daily; look closely at the underside and check for swelling. In some cases, the infection can spread to the horse’s legs, causing a syndrome called ulcerative lymphangitis, which more challenging to treat. Ruminants, such as sheep, goats and cattle, can also become infected by this bacteria. Horses contract the disease through an open wound or fly bite, with bacteria entering through these abrasions or wounds and, sometimes, mucous membranes. In 2008, an Oregon veterinarian who was treating horses with pigeon fever contracted the bacteria. This case highlights the importance of wearing gloves while caring for infected horses and following disinfection protocols. Gloves should be worn when handling infected horses. Read more about pigeon fever.


Salmonellosis is caused by the bacteria Salmonella. Typical symptoms include diarrhea, fever, and stomach pain that starts 1 to 3 days after infection. These symptoms usually go away after 1 week. In some cases, medical attention is required because the diarrhea is severe or the infection has affected other organs. Usually, people get salmonellosis by eating contaminated food, such as chicken or eggs. However, farm animals such as horses can carry Salmonella and pass it in their feces. If you have a compromised immune system, be extra cautious when visiting farms and animals at petting zoos.

West Nile Virus

West Nile is a viral infection that can affect humans, horses, and many types of birds. It is a vector-borne disease carried by mosquitoes, which become carriers by feeding on infected birds. Humans can only get the virus from the bite of an infected mosquito; the disease does not spread from other animals to humans, or from person to person. Most infections are mild, with fever and flu-like symptoms. About one in 150 develops severe illness, including coma, convulsions, paralysis and vision loss. The most severe cases, as well as most deaths, occur in those over 55 who have conditions such as diabetes or hypertension or chronic illness. In addition to vaccinating your horses, the best way to minimize the threat of West Nile for your and your horses is to control mosquito populations and prevent exposure to them. Read more about West Nile Virus.


  • Regular veterinary care is important for the health of every animal. Your veterinarian can recommend a parasite prevention and vaccination protocol for your horse to keep it safe from infectious zoonotic and vector-borne diseases.
  • Wash your hands thoroughly with soap and water directly after handling, feeding or caring for your horse and after cleaning up its waste. Adults should supervise hand washing for young children. If soap and water are not readily available, use hand sanitizer until you are able to wash your hands.
  • Manure management and parasite/insect control programs are important in equine and livestock settings. Humans can spread disease via boots, hands and tools. Proper disinfection protocols should be utilized to limit the risk.
  • If you have any questions about these diseases or concerns about your animal's health, please consult your veterinarian. If you have concerns about your health, please seek medical attention from your health care provider.

Updated: June 25, 2019