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Prevent the spread of diseases between horses and humans through proactive protection. Equine fetal loss/abortions pose a risk to human health in the form of zoonotic diseases, or zoonoses. Zoonoses are infectious diseases that can affect animals and humans. They are caused by bacteria, viruses, parasites or pathogenic agents known as prions.

Bacterial and viral diseases are major causes of reproductive loss in horses, either through abortions, stillbirth or the death of newborn foals.

How do zoonoses spread?

Zoonoses spread between animals and humans through several exposure pathways, including air, insect vectors (e.g. ticks and mosquitos), direct contact with infected animals or animal excreta (e.g. saliva, blood, urine, manure, faecal matter) and food (e.g. consuming food from infected animals). The risk of infection occurs at three levels: Horse to horse — infection can spread between horses via direct horse-to-horse contact; Human to horse to human — infection can spread from horses to humans and humans to horses; Human to human – people can transmit zoonoses to other people.

What are the key risks during pregnancy?

Research funded through the AgriFutures Thoroughbred Horse Program has highlighted two key zoonotic risks that occur in Australia that thoroughbred stud managers and their staff need to manage when handling pregnant mares and aborted fetal material (i.e. fetal membranes and fetuses):

Chlamydia — caused by infection with Chlamydia psittaci bacteria, which typically infects birds, but can infect other species, including horses and people. Chlamydia can cause abortions in horses and disease in humans. Symptoms in humans include fever, headache, aches, chills and dry cough.

Q fever — caused by infection with Coxiella burnetii bacteria. It has been shown to lead to abortions in horses in some countries and premature delivery, low birthweight, and stillbirths in infected women. Flu-like symptoms also experienced in humans may become chronic causing prolonged illness.

There are other equine diseases that present zoonotic risk but have not been identified to occur in Australia, such as Leptospirosis. There are also new and emerging causes of abortion such Mycobacterium avium complex that present a zoonotic risk.