Other than rabies, zoonotic diseases don't usually make the news. But anyone who has livestock should understand the significance of zoonotic diseases, or zoonoses, which are infectious diseases that can be transmitted from animals to humans.
Birth fluids from ewes or does can contaminate pasture and soil. If ewes or does are experiencing late-term abortions, work with your veterinarian to develop a plan to sanitize contaminated areas.
Photos by Sally Colby.
Organisms that cause abortion are among the most commonly recognized zoonotic agents. Most people have heard that pregnant women shouldn't handle cat litter boxes, and the reason is that cats can be carriers of toxoplasmosis. Toxoplasma gondii, the causative organism for toxoplasmosis, is a coccidial protozoan common to cats, but is also found in sheep and goats. Cats are the definitive host - the animal in which the organism reaches maturity - for T. gondii.
Cats acquire coccidial protozoan oocysts by ingesting contaminated feces. The oocysts develop further in the cat's digestive system, are excreted in feces and sporulate (reproduce) in the environment. When a sheep or goat ingests excreted oocysts, such as through feces, contaminated feed, hay or water, the result is a systemic infection in the new host. The T. gondii organism enters the bloodstream and spreads to the body's organs. In pregnant animals, T. gondii can enter the placenta and multiply there. The result is often late-term abortion, fetal mummification, full-term but stillborn kids or lambs, or weak newborns. Because T. gondii is present in placental tissue and birth fluids of infected animals and can be transmitted to humans, pregnant women should not handle aborted lambs or fluids and tissue from newborns.
Chlamydiosis, also known as enzootic abortion of ewes (EAE), is another zoonotic disease that can affect sheep and goats. The causative organism is the bacteria Chlamydophila abortus, which the animal can harbor without becoming ill. Animals become contaminated with the bacteria by ingesting or inhaling contaminated birth fluids on bedding or pasture.
Pregnant animals infected with C. abortus give birth to dead, weak or small lambs or kids in the final weeks of pregnancy. The placentas from affected animals are visibly infected and appear thick and often reddish-brown. In addition, the ewe or doe may have a reddish-brown vaginal discharge that can last from several days to a week. Chlamydiosis that is transmitted to humans from infected ewes or does can cause abortion in pregnant women.
Another infective, zoonotic, abortive disease is listeriosis, which is caused by the bacteria Listeria monocytogenes. This bacteria is most often found in improperly ensiled or spoiled silage or spoiled hay, and is also found in soil and fecal matter. The organism enters the body through ingestion, inhalation, conjunctiva (eyes) and wounds. Listeriosis can cause encephalitis, fever, lack of appetite, uncoordinated circling and abortion. The L. monocytogenes organism can be shed in milk, which may become a source of infection for both animals and humans.
Bedding, whether it's in a barn or the result of hay waste outside, can harbor organisms that cause abortion.
To ensure human safety, pregnant ewes and does should be carefully monitored during late pregnancy for signs of abortion, especially if new animals have been added to the flock or herd. If animals are aborting in late pregnancy, it's important to take action immediately to determine the cause of abortion and, when possible, prevent further abortions.
In the case of abortions, especially late-term, in sheep or goats, consult your veterinarian immediately for specific information on how to handle animals that have aborted, as well as aborted tissue and fluids. The veterinarian may recommend antibiotic treatment for all animals in the flock or herd to prevent further abortions. It's also important to recognize and consider other causes of abortion, including poisonous plants and the use of certain dewormers during pregnancy.
Animals that abort should be isolated immediately, and all tissue and fluids associated with the abortion should be removed from the birthing area. Use disposable gloves when handling infected tissue, fluids or newborns that survive. All clothing, especially shoes and boots, should be disinfected with an appropriate product such as a quaternary ammonium compound. Limit the number of people who have access to the area in which abortions occurred, and limit contact with infected animals. Refrigerate aborted fetuses and/or placentas if you plan to submit samples to a diagnostic laboratory.
Pregnant women can safely handle feeding and other routine work with healthy sheep and goats, but should avoid duties such as assisting at birth, handling newborns that are still wet, and handling afterbirth and birthing fluids. If animals start to abort, pregnant women should immediately stop contact of any kind with the flock or herd until the causative agent is identified and a veterinarian has reviewed the health status of the animals.
The author is a frequent contributor and freelance writer who farms and raises Great Pyrenees in south-central Pennsylvania. Comment or question? Visit www.farmingforumsite.com and join in the discussions.