Zoonotic disease: What is a zoonotic disease?

A zoonotic disease is a disease that can be transferred from an animal to man. Diseases such as Mad Cow Disease, Anthrax, Plague, and Rabies are examples of diseases in this category. Zoonotic diseases can be viral, bacterial, fungal, or parasitic. Zoonotic diseases can be spread by:

• Air contact, such as inhalation. Diseases can disseminate or spread through the air as dust particles or in tiny water droplets. Once inhaled, they can infect the lung or immune system. Some examples of these diseases are from birds such as tuberculosis and psittacosis. Hanta Virus is a fatal lung disease from ingestion of aerosolized infected mice and rat feces.
• Ingestion: Ingestion of a zoonotic disease can be from ingestion of tainted meat, ingestion of contaminated water, or fecal-oral contact (yuck). There are many diseases, which can be spread by this route. Leptospirosis, Giardia, certain worms from eating cattle, pork, or sheep that is poorly cooked, E. Coli, Salmonella, and Campylobacter are zoonotic diseases which can be spread by ingestion of undercooked meat or fecal-oral contact. Roundworm larvae can spread via fecal-oral contact.
• Direct contact: These diseases are generally skin diseases such as scabies, which is caused by a mite or ringworm, which is a soil fungus. Lice are not zoonotic; they affect only one species for each type of louse.
• Penetrating wounds: such as bite wounds can spread disease. Of these, Rabies is the most serious. Other diseases, such as cat scratch fever comes from infection by a bacterium called Bartonella that lives on the cat.
• Vector: A vector is anything, which brings the zoonotic agent in contact with the person. Mosquitoes, Sandflies, Fleas, and Ticks are the most common vectors, which can spread diseases like Lyme Disease, West Nile Virus, Plague, and many other diseases. It is important to note that the vector is REQUIRED to spread the disease, that these diseases can not be transmitted directly from the animal to the person.

Hopefully after reading this you are more knowledgeable but not terrified. People actually catching diseases from their pets are actually quite rare. But proper diligence is necessary.

Who is at risk for getting a zoonotic disease? Anyone can catch a zoonotic disease, but it is those who are immune-suppressed who are at the highest risk. This includes:

• AIDS patients
• people undergoing chemotherapy
• People who have received organ transplants
• Pregnant women
• Elderly or debilitated people
• Children
• Those people who work in high risk areas with increased exposure such as: ranching, cooking, pet stores, veterinary hospitals, and zoos
• People who live in areas with a high population of vectors such as fleas, ticks, and mosquitoes
  

What steps can be taken to prevent spread of a zoonotic disease?

• Ingestion: Cook meat thoroughly and disinfect cooking surfaces. Wash your hands before eating. If camping, use chlorine tablets and/or boil water before drinking. Check signs on beaches, lakes, and ponds before swimming to check for notices of high bacterial levels. Make sure that you practice good husbandry with your personal pets, make sure they are checked annually for parasites and their area is kept cleaned. Both Heartguard and ProHeart help to prevent infection by certain internal parasites in addition to their prevention of Heartworms.
• Penetration: Don't get bitten or scratched. Stay away from dangerous animals. Make sure your own pets are current on their Rabies vaccine. If you do get bit, see your doctor right away, as dog and cat bites are frequently infected. Clean the area well with water and an antiseptic soap.
• Inhalation: If cleaning areas that are dry and dusty with rats or mice, wear protective covering over your face. Even better is to have the area cleaned by a professional with professional grade air filters. Birds can be tested for tuberculosis and psittacosis. If positive, the results do have to be reported to health authorities.
• Vectors: Avoid areas with a high vector load. Use good flea and tick prevention on your pets. Stay away from wildlife that may carry these vectors.
  

As individual diseases are discussed, more specific recommendations can be offered.

Now that you understand the basics of zoonotic diseases, you know that proper hygiene and husbandry can dramatically reduce the risk of contracting disease from our animal friends. If you have specific concerns about a specific disease or if you have a high risk of infection, you should speak with both your veterinarian and your physician. There is no reason why we can't enjoy the companionship of our pets without compromising safety.

Zoonotic disease: Toxoplasmosis

Toxoplasmosis is a disease caused by a microscopic single-celled parasite called Toxoplasma gondii. Cats are the direct host of this organism, which means that cats are the only species in which the organism can complete its entire life cycle. All mammals though can be indirect hosts, which means they can become infected and spread the disease.

Cats which are indirectly infected no longer spread the disease in their feces, but can suffer a multitude of symptoms ranging from none to fever, anorexia, lethargy, central nervous signs (blindness, seizuring, dizziness), liver disease, coughing, or eye changes. In an ill cat, a test for Toxoplasmosis is frequently performed.

Humans do not frequently get Toxoplasmosis from cats. The two most common means of exposure are eating undercooked meat and not washing hands after gardening. Gardening is a problem because of feral or outdoor cat leave feces in the yard. Those at highest risk, as most zoonotic diseases, are the immune compromised. Humans affected by the disease get flu-like symptoms. It is estimated that 33% of people in the US have been exposed at some point during their lives.

What should you do if your obstetrician tells you to get rid of your cats or tells you to get a titer test for your cat?

To prevent human infection, especially in people who are immune-suppressed and pregnant, the following is recommended:

• Keep your cat indoors, to prevent eating of mice, birds, or feces contaminated water. Feed them commercial cat food only, as undercooked meat can lead to infection.
• Have someone else clean the litter box, as infected cysts maybe present, even with feces scooped daily. If you must clean the box, wear latex gloves and wash well. No matter who does the cleaning, it should be done daily to reduce risk.
• Do not garden, as you have no idea of what cat may have left a deposit sometime in the past. Also, keep sandboxes covered, as it could put your children at risk.
• Your meat should be ordered well done. Toxoplasmosis can be in beef, pork, or other meats. Undercooked meat is the number one mode of transmission.

With proper precautions in place, Toxoplasmosis should be a minimal risk. There is no reason to give up your cat or subject it to numerous tests. If you have further questions, please ask your veterinarian and physician.