Zoonotic diseases

Diseases common to animals and humans


A zoonosis is a disease common to animals and humans. Zoonotic diseases are more common and serious in third world countries or in tropical climates. Still, pet owners should be aware of the potential risk of the zoonoses found in our area. In many of these zoonotic diseases, humans may not "catch" the disease directly from the pet. Instead, the animal patient serves as a barometer, signaling the presence of infectious agents in the environment.


Anyone who saw the movie "Old Yeller" knows that rabies is a zoonotic disease. Rabies is caused by a virus transmitted through animal saliva. Signs of rabies include personality and behavioral changes, incoordination, difficulty swallowing, seizures, and death. Rabies is fatal -- there is no cure in man or animals.

Protect yourself by not handling wild or stray animals and by having all your dogs and cats vaccinated against rabies to serve as a buffer between you and the wild animal reservoir. Rabies is very rare in the Cincinnati, Ohio Tri-state area.

[More on Rabies]


Ticks can transmit diseases to animals and people. In our area, common "wood ticks" can carry Rocky Mountain Spotted Fever. To date, no established population of deer ticks, which carries Lyme disease, has been found in Ohio. Both diseases are caused by tiny organisms that are transmitted to people or animals from tick bites, and cause fevers, rashes, and joint pain. Neither disease is transmitted directly from pets to people; you must be bitten by the tick to get RMSF or Lyme disease. Clermont County is one of three hot beds in Ohio for RMSF; Lyme disease, which receives more notice from the press, is extremely rare.

Protect yourself by wearing long sleeves and long pants tucked into boots when walking in woods or fields where ticks live, cutting back weeds and brush near your home, using tick repellent on yourself and your pets, and by looking for and removing ticks regularly.

[More on ticks]


Toxoplasmosis is caused by a protozoan, a one-celled parasite. Hunting cats often contract this parasite by eating small rodents, then shed the cysts in their stool. The parasite is also found in raw meat. Most cats and people show no signs of the disease, or have only mild flu-like symptoms. Those who have a weakened immune system may develop a much more serious infection. Fetal infection, especially during the first three months of pregnancy, can result in blindness, so pregnant women must take special precautions to avoid contacting toxoplasmosis cysts.

Protect yourself by not letting your cat hunt and not feeding it raw meat. Pregnant women and persons with AIDS should wear gloves when gardening, wash thoroughly after handling raw meat, cook meat to 160 F for 15 to 30 minutes, and should not change litterboxes.


Nearly every puppy is born with roundworms contracted from its mother. These worms can be transmitted to people, especially children. Most infections in people are so mild as to cause no signs at all, but the potential for severe illness exists. Migrating worms may damage the liver, eyes or brain. Because the eggs are transmitted in the puppy's stool, sanitation is essential; feces should be removed and disposed of daily and everyone who handles the puppy should wash their hands frequently. This is especially important in young children, who often put their fingers in their mouths.

Protect yourself by having your veterinarian test several stool samples from your new puppy, and do yearly tests on adult dogs. Some veterinarians prescribed regular dewormings even in the face of negative stool tests because of these risks.

[More on worms]


Ringworm is not a worm at all, but a fungal infection of the skin. It can be difficult to diagnose in animals, as the lesions do not look the same from case to case. Some animals, especially cats, can carry the fungus in their hair coat without showing signs of itching, scaly skin, and hair loss. In people, the classic lesion is a raised, reddened, and itchy "ring."

Sarcoptic mange or scabies

Another zoonotic skin condition in dogs is sarcoptic mange or scabies. This mite burrows under the skin, and causes severe itching, scabs, and hair loss. In extreme cases, the dog may even have a generalized illness. Skin scrapings to find and identify the mite are often negative. In humans, a pinpoint red rash is often found on the chest and abdomen. Treatment in dogs includes multiple dips to kill the mites, and medications for itching and secondary infections. A new injectable drug, ivermectin, can be used to treat mange, although it is not yet approved for this use, and should not be used in Collie dogs.

Protect yourself by having suspect skin lesions examined and treated by your veterinarian. Fungal cultures may be the only way to confirm a case of ringworm. Skin scraping tests should be done when mange is suspected, even though the results may be false. Suspected cases of ringworm or mange should be treated even if unconfirmed to prevent the spread of these diseases.

{More on sarcoptic mange]

Pet owners should be informed about the risks of zoonotic diseases. Consult your veterinarian and your personal physician whenever you suspect one of these diseases, but do not panic. Early diagnosis and veterinary care, as well as simple precautions, can protect you and your family from most of these diseases, and keep your pets healthier, too.

Kathleen R. Hutton, DVM

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