Zoonotic Diseases & Farm Animals

A zoonotic disease is a disease that can be passed from animals to humans. Following are some related to farm animals, including cows, pigs, goats, and sheep.

Bovine Spongiform Encephalopathy (Mad Cow Disease)

Bovine spongiform encephalopathy (BSE), also known as Mad Cow Disease, is a chronic, fatal disease that affects the central nervous system of cattle. Caused by the formation of abnormally shaped proteins called prions, the disease’s incubation period is long, ranging from 3 to 6 years or perhaps longer. Humans may contract variant Creutzfeldt-Jakob disease if they consume tissues from cattle which contain the disease-causing prions, specifically the brain or spinal cord. There is no cure for this disease, which has been responsible for over 150 human deaths in Europe. While the discovery of BSE in the US has increased public concern about the safety of meat, the USDA has stated that the food supply is safe. Milk and dairy products are considered universally safe; the transmission of BSE or its disease-causing prions through these products has never been demonstrated.


Campylobacter is the most common bacterial cause of gastroenteritis worldwide and is prevalent in food animals such as cattle, pigs, and sheep. Symptoms include diarrhea, abdominal pain, fever, headache, nausea, and/or vomiting lasting 3-6 days. Transmission is food-borne via undercooked meats and meat products, as well as raw or contaminated milk. Ingestion of contaminated water or ice is also a source of infection. The only effective methods of eliminating Campylobacter from contaminated foods are through cooking, pasteurization, or irradiation. You can also prevent infection by avoiding contact with farm animals and their manure.

E. coli

Each year, Escherichia coli (E. coli) causes an estimated 73,000 cases of infection and 61 deaths in the United States. Infection often leads to bloody diarrhea, fever, abdominal cramps, nausea, and vomiting. Young children are more likely to have severe symptoms, including kidney failure. While most illness has been associated with eating undercooked and contaminated ground beef, it also can be passed in the manure of young calves and other cattle. Animals do not have to be ill to transmit E. coli to humans. The organism can be found on a small number of cattle farms and can live in the intestines of healthy cattle. Meat can become contaminated during slaughter, and organisms can be mixed into beef when it is ground. You can prevent E. coli infection by avoiding contact with cattle or their manure, by thoroughly cooking ground beef, avoiding unpasteurized milk, and washing hands carefully.


Salmonellosis is a bacterial disease. 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 undercooked chicken or eggs. However, farm animals such as cattle, sheep, pigs and goats 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.

To reduce infection risks, you should:

  • Wash hands after contact with pets, pet food and pet bowls. Wash with soap and running water for at least 20 seconds, then rinse and dry your hands with a paper towel.
  • Routinely clean pet food bowls and feeding areas.
  • Keep children younger than age 5 away from pet food and feeding areas.
  • Clean pets' food and water dishes in a separate sink or tub, not in the kitchen or bathtub.
  • Avoiding bathing infants in the kitchen sink.


It is important to remember that the best way to protect yourself from many of these zoonotic diseases is to practice good hygiene after handling animals or their waste. Wash your hands thoroughly with hot, soapy water after any contact. Always throughly cook any meat you intend to consume.

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.