Horse & Human Crossover Diseases

Diseases that are transmitted from horses to humans are called zoonotic diseases. Sometimes the transmission is directly from the horse, and other times it is indirectly transmitted from the pathogen causing the disease in the horse. There are many diseases that a horse owner or caretaker needs to be aware of, for possible infection from handling a sick horse. Some of the more common zoonotic diseases from horses are presented in this article.

It is a general understanding that coming in contact with a sick horse poses the risk of possible human infection. Humans can also be infected by the vector, or disease carrier. Vectors can be insects, rodents, opossums, raccoons, or other disease-carrying animals. Certain health conditions put people at a higher risk of catching a zoonotic disease from a horse. Avoid caring for a horse if any of the following conditions apply: Babies and small children should avoid loose contact with a horse, and have no contact when sick. Elderly people with impaired or compromised immune systems Pregnant women Sick people taking antibiotics Immunocompromised people, such as cancer patients Animal caretakers or health-care professionals are at higher risk because of the frequent contact with animals. Prevent infection by wearing protective clothing. Use gloves---a pair per horse. Properly wash and disinfect all of the sick horse's items, and just as a rule, do not become too comfortable with sharing items from one horse to another. Always contact the veterinarian at the first sign of disease, and contact your doctor if you feel sick, as well, to rule out a zoonotic disease.

Encephalitis is another zoonotic disease that a person can contract from a sick horse. Encephalitis is considered a mosquito-borne arbovirus because it is contracted through a mosquito bite. There are several types of encephalitis infections: West Nile virus, Venezuelan encephalitis, western encephalitis, and eastern encephalitis. Handling the blood or cerebrospinal fluid of an infected horse can cause transmission of the disease to humans. Vaccinations against encephalitis are a recommended preventive measure.

Contracting rabies from horse is fairly uncommon, but if rabies is caught, it is a fatal disease. It is difficult to diagnose rabies as the cause of a sick horse's symptoms. There may not be a visible bite, and the symptoms could easily be misunderstood. As a precaution, veterinarians work to rule out rabies at the first sign of a neurologic problem in a horse. Rabies can be transmitted through the horse's saliva. If a person has an open wound that comes in contact with the infected saliva, then this will lead to a rabies infection in the person.

There are several zoonotic diseases that cause diarrhea in horses. People can contract these from handling the horse waste, and other horses can become infected as well. People and horses who are receiving antibiotics are especially vulnerable to contracting these diseases. Hygienic practices will help prevent infection from these diseases, in both humans and other horses. Salmonellosis is caused by the salmonella bacteria. It is a gastrointestinal infection that causes sudden diarrhea. Clostridium difficile is a bacterial infection that causes both colitis and diarrhea in people and horses. Crytosporidiosis is caused by an infection with the Crytosporidium parvum protozoan. This pathogen also causes diarrhea, and is very commonly found in younger horses. Giardiasis is caused by the Giardia intestinalis parasite. This gastrointestinal disease is spread through the Giardia cysts that is spread through the diarrhea it causes.

There are several skin diseases that can be transmitted between horse and human. Dermatophytosis, or ringworm, is a fungal disease that can be contracted from a horse or its grooming supplies. Brucellosis is a skin disease caused by the Brucella abortus bacteria. Contact with an infected horse's skin abrasion is the main way this skin disease is transmitted to humans. Dermatophilosis, or rain rot, is transmitted when people come in direct contact with its lesions. This commonly occurs when the horse is in wet environmental conditions.

Leptospirosis is caused by the Leptospira interrogans bacteria. Leptospirosis causes renal disease, abortion, and stillborn foals in horses. Leptospirosis can be transmitted to humans through contact with the horse's fluids.

Horses can also transmit the anthrax disease to humans. Bacillus anthracis is a spore-forming bacteria that is highly contagious. Anthrax causes sudden death in horses---death before there is any time for treatment. The anthrax spores are spread to humans through the air. When a horse dies from anthrax, its body is cremated and all items surrounding the horse's care is also burned. This is to avoid the airborne transmission of the disease.