Zoonoses Associated with Small Ruminants and Camelids
This document provides information on various diseases that can be passed from sheep, goats, llamas, alpacas and camels to humans. Often these diseases do not make the animal appear sick but can cause serious illness in humans. Persons with specific medical conditions such as a chronic illness, immunodeficiency and pregnancy may be at higher risk of developing disease or complications from a zoonotic disease and should consult with their physician before working with animals. The diseases associated with small ruminant animals include rabies, orf, ringworm, Q fever, chlamydiosis, leptospirosis, campylobacterosis, salmonellosis, yersiniosis, listeriosis, pathogenic E. coli infections, cryptosporidiosis, giardiasis, anthrax, and MRSA. Additional information on zoonotic diseases can be found on the Center for Disease Control and Prevention Website, Healthy Pets, Healthy People.
Brucellosis and tuberculosis are potential bacterial zoonoses in ruminant animals but due to a federal eradication program for Mycobacterium bovis (bovine tuberculosis), Brucella abortus and Brucella melitensis, these diseases are rare in the United States except in a few areas where they persist in a wildlife reservoir. Brucella ovis, the primary cause of brucellosis in sheep, does not cause disease in people. Animals affected by Brucellosis usually do not present any signs of illness but are suspected of having the disease when reproductive problems are evidenced as infection in the reproductive organs, abortions and stillbirth, or weakened offspring. People can become infected after consumption of raw (unpasteurized) dairy products or direct contact with infected animals or animal tissues and fluids, such as blood. The bacteria can penetrate damaged skin and mucous membranes. Infected people typically have flu-like symptoms and the disease can affect the reproductive organs and cause miscarriages. Bovine tuberculosis, although much rarer in people than the disease caused by M. tuberculosis, is a concern as it can also cause severe illness and death. The most common way people become infected with M. bovis is by consumption of contaminated, unpasteurized dairy products. It is also possible to become infected via direct contact with animals including cattle, bison, and cervids (e.g., deer, elk) and their products (i.e., milk, meat, hides), or body fluids, such as blood, since the bacteria can penetrate abraded skin. Inhalation of this agent in contaminated air is also a possible way of contracting the disease. Signs of the illness in animals include weakness, loss of appetite and weight, fever, etc. Symptoms in people affected by bovine tuberculosis include fever and weight loss and can affect several organs depending on the route of infection.
Rabies is a fatal viral infection that can be transmitted by bites and mucus membrane exposure from an infected animal. Domestic animals can be infected from contact with wildlife such as bats, skunks, and raccoons. Infected animals often exhibit neurological symptoms and unusual behavior. Rabies is rare in the Pacific Northwest but if a person is bitten or has salivary mucus membrane contact from a suspect animal, the animal should be tested for the rabies virus. If exposed, persons should seek post-exposure rabies prophylaxis from a medical professional immediately.
Orf or contagious ecthyma is a viral infection that causes red raised skin lesions around the face and mouth of young animals and the udder on nursing females. Humans can be infected and develop similar pox-like lesions if they come into direct contact with an animal’s lesions. Dermatophytosis is a fungal skin infection commonly known as “ringworm” seen in both animals and people as scaly round areas of hair loss. Transmission of both ringworm and orf are by direct contact with an infected animal or from contaminated objects.
Q fever, Chlamydophila psittaci and Chlamydophila abortus are agents associated with abortion in pregnant sheep, goats and camelids but are often carried by normal animals. There is an especially high concentration of these agents at the time that the animals give birth, so particular care needs to be used in handling newborn animals, placental tissues, and birth fluids. These agents can be acquired by exposure to placental membranes and fetuses from infected animals and by aerosol and inhalation of dust particles contaminated with dried feces, urine, or other fluids from infected animals. In people, symptoms can include malaise, fever, chills or sweats, muscle aches and chest pain. Q fever and Chlamydophila infections in pregnant women are associated with infectious abortion or miscarriage. Persons who are pregnant, have valvular heart disease or other chronic disease conditions should consult their physician before working with pregnant or birthing sheep, goats or camelids.
Leptospirosis is a bacterial disease that causes reproductive problems, and liver and kidney failure in small ruminants. The bacteria are typically shed in the urine of infected animals. People acquire the infection by accidental ingestion and contact with contaminated urine, placenta, and fetal tissues. The organism can infect through abraded skin. In people, the disease causes fever, headache, abdominal and muscle pain, vomiting, diarrhea, jaundice, and rash. In more severe cases, it can cause hemorrhagic pneumonia, liver and kidney failure and can lead to death.
Salmonellosis, campylobacterosis, listeriosis, pathogenic E. coli infections, cryptosporidiosis and giardiasis are acquired by contact and accidental ingestion of fecal material from infected animals. Animals infected with these diseases typically have diarrhea, but some animals may show no symptoms of disease. Any animal with diarrhea should be suspect of having a zoonotic disease. Symptoms in people include abdominal pain, diarrhea, and fever. Yersiniosis is acquired through bites from infected fleas or from contact with body fluids from infected animals. Symptoms of yersiniosis in people can include high fever and chills, headache, malaise, and swollen lymph nodes.
Anthrax is caused by a bacterium (Bacillus anthracis) that is present in the environment and can infect animals, including livestock, through ingestion of contaminated water, soil, or plants. Although Anthrax is rare in the United States, it is still of concern. People can become infected and severely ill after contact with affected animals (live or dead) and their products (e.g., hide, wool, etc.) or by consuming food contaminated with bacterial spores. Infection can happen via accidental ingestion of spores or by penetration of bacteria through abraded skin. Infected animals can die quickly so owners do not always perceive any signs of illness. Signs in animals affected by this disease can include fever, depression, difficulty breathing, staggering, and seizures. Symptoms in people can include skin reactions in the case of cutaneous Anthrax, with formation of blisters followed by ulceration of skin, or in the case of infection via ingestion of spores, symptoms include stomach pain, diarrhea (that could be bloody), sore throat and difficulty swallowing, swelling of neck, fever, chills, and redness in the eyes and face.
Methicillin-resistant Staphylococcus aureus (MRSA) are bacteria that have acquired resistance to certain antibiotics. They can be found on the skin of healthy animals and people, where they can opportunistically cause infections. People can get infected after direct contact with animals carrying these bacteria. If left untreated, the infection can progress to septicemia and affect other organs including the lungs.
Individuals with exposure to animals and animal environments may develop allergic reactions to animal proteins (allergens). Approximately 20-30 percent of individuals working with laboratory animals will develop an allergic reaction to animal proteins and 5-10 percent of individuals will develop asthma. Personnel may be exposed to allergens through inhalation and contact with skin, eyes, and mucous membranes. Animal allergens may be present in animal dander, hair, wool, skin, urine, saliva, serum and any contaminated feed or bedding materials. Risk factors for developing an allergic reaction include history of previous allergies to animals. The signs and symptoms of an allergic reaction are nasal discharge and congestion, conjunctivitis, tearing and eye itching, skin redness, rash or hives and lower airway symptoms (coughing, wheezing and shortness of breath). Individuals with symptoms suggestive of an allergic reaction related to a workplace allergen should report their concerns to their supervisor and consult a physician.
Transmission of zoonotic diseases from animals is primarily by direct contact, contact with contaminated bedding or materials, ingestion or inhalation of aerosolized fluids. We can protect ourselves from most injuries and diseases by using the following procedures:
- Handle animals safely to avoid injury.
- Do not eat, drink, apply cosmetics or use tobacco products while handling animals or in animal housing areas.
- Wear gloves when handling ill animals, animal tissues, body fluids and waste and wash hands after contact.
- Wear dedicated protective clothing such as a lab coat or coveralls and shoe-covers or boots when handling animals. Launder the soiled clothing separate from your personal clothes and preferably at the animal facility.
- Wear respiratory protection when appropriate.
- Keep animal areas clean and disinfect equipment after using it on animals or in animal areas.
Most importantly, familiarize yourself about the animals that you will be working with and the potential zoonotic diseases associated with each species. If at any time, you suspect that you have acquired a zoonotic disease, inform your supervisor and seek medical care.
**Prepared by Office of the Campus Veterinarian and the Office of Research Assurances January 2021
- Centers for Disease Control and Prevention. Healthy Pets, Healthy People. (https://www.cdc.gov/healthypets/pets/farm-animals.html)
- Centers for Disease Control and Prevention. Mycobacterium bovis (Bovine Tuberculosis) in Humans (https://www.cdc.gov/tb/publications/factsheets/general/mbovis.pdf)
- World Organisation for Animal Health. Bovine Tuberculosis. (https://www.oie.int/en/animal-health-in-the-world/animal-diseases/bovine-tuberculosis/)