SNAP Cats

Zoonotic Diseases

Provided by the Cornell Feline Health Center, Cornell University

What is a zoonotic disease?
While most feline infectious diseases affect only cats, and most human infectious diseases affect only humans, it is important to be aware that some of these diseases-called zoonotic diseases-can be transmitted between cats and people. You are much more likely to contract ailments from other humans than you are from your cat. However, simple precautions, common sense, and good hygiene, including careful handling of litter boxes and treating cats with fleas and other parasites, can further reduce the risk of zoonotic disease.

How are zoonotic diseases transmitted?
Transmission of a zoonotic disease can potentially occur when a person comes into direct contact with secretions or excretions-such as saliva or feces-from an infected cat. Additionally, a disease may be contracted through contact with water or food that has been contaminated by an infected cat. Many zoonotic diseases can be transmitted from fleas or ticks (called vectors) to a person or a cat from another animal.

Who is at risk?
Most zoonotic diseases pose minimal threat; however, some humans are particularly at risk. Those with immature or weakened immune systems, such as infants, individuals with acquired immunodeficiency syndrome (AIDS), the elderly, and people undergoing cancer therapy, are more susceptible to zoonotic infections than others.

What are some common zoonotic diseases?
Bacterial Infections
Cat-scratch disease, also called bartonellosis, is by far the most common zoonotic disease associated with cats. Approximately 25,000 people are diagnosed every year in the United States. Cat-scratch disease can occur when a person is bitten or scratched by an infected cat. Fleas may also play a role in the transmission of infection. People with cat-scratch disease usually have swollen lymph nodes, especially around the head, neck, and upper limbs. They may also experience fever, headache, sore muscles and joints, fatigue, and poor appetite. Healthy adults generally recover with no lasting effects, but it may take several months for the disease to go away completely. People with compromised immune systems may suffer more severe, even fatal, consequences.

Some healthy cats are continuously or intermittently infected with cat-scratch disease bacteria, but antibiotics do not reliably cure infection in these cats and are not currently recommended. However, avoiding scratches and bites (for example, by not allowing children to play roughly with cats), controlling fleas, and keeping cats indoors all reduce the risk of cat-scratch disease. Because most cases of cat-scratch disease result from contact with kittens, immunosuppressed people should avoid such contact.

Salmonellosis, another common bacterial disease, can cause diarrhea, fever, and stomach pain beginning one to three days after infection. Salmonellosis usually resolves on its own. However, some people require medical attention because the diarrhea is severe or the infection is affecting other organs. People usually get salmonellosis by eating contaminated food, such as undercooked chicken or eggs. However, cats and other animals-even those that appear healthy-can carry and pass salmonella bacteria in their stool. Salmonella bacteria are more commonly harbored by cats that feed on raw meat or wild birds and animals. Feline infection can be prevented by keeping cats indoors and feeding them cooked or commercially processed food. Human infection can be prevented by wearing gloves and washing hands thoroughly after cleaning litter boxes (especially if used by a cat with diarrhea).

Parasitic Infections
Fleas are the most common external parasite of cats. While fleas cannot thrive on humans, their bites can cause itching and inflammation. Fleas may also serve as vectors for cat-scratch and other zoonotic diseases. Flea-infested cats may become infected with tapeworms from fleas ingested while grooming. Children, albeit rarely, can also become infected with tapeworms from inadvertently ingesting fleas.

Some feline intestinal parasites, including roundworms and hookworms, can also cause disease in people. Children are particularly at risk due to their higher likelihood of contact with contaminated soil. Visceral larva migrans, a potentially serious disease that can affect the eyes and other organs, results from inadvertent consumption of roundworm eggs (e.g. when soiled fingers are placed in the mouth). Cutaneous larva migrans, an itchy skin disease, is caused by contact with hookworm-contaminated soil. Proper hygiene, including washing hands before meals, cleaning soil from vegetables, and reducing exposure to cat feces (e.g., by covering children’s sandboxes when not in use) can prevent infection. Anti-parasite medications for kittens and annual fecal exams for adult cats can reduce environmental contamination and the risk of human infection.

Fungal Infections
Ringworm is not caused by a worm at all; it is a skin infection caused by a group of fungi. Infected cats most often come from environments housing large numbers of animals. In cats, ringworm appears as a dry, gray, scaly patch on the skin. In humans, ringworm often appears as a round, red, itchy lesion with a ring of scale around the edge. Ringworm is transmitted by contact with an infected animal’s skin or fur, either directly or from a contaminated environment. Infected cats continuously drop fungal spores from their skin and fur; these spores, which remain capable of causing infection for many months, are difficult to eradicate from a household. Children are particularly at risk of infection. To reduce environmental contamination, confine infected cats to one room until they are free of infection; then thoroughly clean and disinfect the household.

Protozoal Infections
Protozoans are single-celled organisms. The three most common protozoal diseases in cats and humans are cryptosporidiosis, giardiasis, and toxoplasmosis. Cryptosporidiosis and giardiasis can cause diarrhea in both cats and people, who usually become infected by a common source-for example, contaminated water-not by each other. To prevent the spread of infection, schedule annual fecal examinations for your cats, and medicate infected cats as directed by your veterinarian. Other preventive measures include wearing gloves while handling feces-contaminated material, washing hands afterwards, and boiling or filtering any surface water used for drinking.

Toxoplasmosis is caused by the parasitic protozoan Toxolasma gondii. People with weakened immune systems, or infants whose mothers are infected during pregnancy, can develop severe illness. People commonly become infected by eating undercooked or raw meat, or by inadvertently consuming contaminated soil on unwashed or undercooked vegetables. Unfortunately, pregnant women or immunosuppressed individuals are often mistakenly advised to remove cats from the household to reduce the risk of toxoplasmosis. However, people are highly unlikely to become infected from direct contact with their cats.

Cats can become infected by eating infected rodents, birds, or anything contaminated with feces from another infected cat. An infected cat can shed the parasite in its feces for up to two weeks. The parasite must then mature for one to five days before it becomes capable of causing infection. However, it can persist in the environment for many months and continue to contaminate soil, water, gardens, sandboxes, or any place where an infected cat has defecated.

Basic hygiene can prevent toxoplasmosis. Wear gloves when handling potentially contaminated material (for example, when gardening or handling raw meat), and be sure to wash your hands afterwards. Avoid eating undercooked meat, and thoroughly wash fruit and vegetables before eating. Surface water should be boiled or filtered prior to drinking, and children’s sandboxes should be covered when not in use to prevent wandering cats from defecating in them. Scoop litter boxes daily while wearing gloves, and wash your hands afterwards. Pregnant women or immunosuppressed individuals are safest when other household members clean the litter box.

Viral Infections
Most viruses infect only their natural host species. Human viruses, like those that cause the common cold, infect only humans, while feline immunodeficiency virus, feline infectious peritonitis virus, and feline leukemia virus infect only cats. However, one virus that can be passed from cats to humans is rabies, a viral disease resulting from the bite of an infected animal. Cats are highly susceptible to rabies, which attacks the central nervous system, causing a variety of signs. Rabies is almost always fatal. In people, rabies infections usually occur when an infected animal bites a person. In order to protect human health, rabies vaccination of cats is required by law in many areas. Even if your cat is kept indoors, it is important to keep rabies vaccines current because cats occasionally escape outdoors, and because rabid animals such as bats and raccoons occasionally enter houses. To further reduce your risk of rabies, avoid contact with wildlife and stray animals. See a doctor immediately if you have been bitten by an animal.

What can I do to protect my cat and myself?
Common sense and good hygiene will go a long way toward keeping you, your family, and your cat free of zoonotic diseases. Here are a few simple precautions:

Wash hands before eating and after handling cats.

Schedule annual checkups and fecal exams for your cat.

Seek veterinary care for sick cats.

Keep rabies vaccinations current.

Maintain appropriate flea and tick control.

Avoid letting your cat lick your face, food utensils, or plate.

Consider keeping cats indoors.

Seek medical attention for cat bites.

Feed cats cooked or commercially processed food.

Scoop litter boxes to remove fecal material daily.

Periodically clean litter boxes with scalding water and detergent.

Wear gloves when gardening or handling raw meat; wash hands afterwards.

Cover children’s sandboxes when not in use.

Wash fruits and vegetables before eating.

Filter or boil surface water before consuming.

Cook meat to 160°F or 80°C (medium-well-done).

Ringworms

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Ringworm

Ringworm (dermatophytosis) is a fungal infection that can affect the hair, skin or nails of cats, dogs and humans. It is the most common contagious skin infection in cats. In humans, the infection often causes classic ring-like lesions, but these are seen less commonly in cats and dogs. In most patients, ringworm is self-limiting; that is, it will self cure over time. However, because this infection can be transmitted from cats and dogs to other animals and also to people, every pet owner should be aware of the symptoms, transmission and treatment of ringworm.

Where is the fungus found?
Several different fungi found throughout the world can cause ringworm, however, the vast majority of cases in cats and dogs are caused by Microsporum canis, Microsporum gypseum, or Trichophyton species. The fungus is most commonly found either on an infected animal or in the living quarters of infected animals. Spores from infected animals can be shed into the environment and live for up to 24 months. Humid, warm environments encourage growth of the fungus. Spores can be on brushes, bedding, furniture, or anything that has been in contact with an infected animal or the animal’s hair. Cats can be asymptomatic carriers and harbor and shed the organism without showing signs of infection. Animals thought to be chronic carriers can be routinely cultured to determine if they are actual carriers.

How is ringworm transmitted?
Ringworm can be transmitted by direct contact with fungal spores. These spores can be found on a infected animal, on infected grooming equipment or brushes, in a contaminated boarding facility or cattery, or in the environment where an infected animal has visited. Because ringworm spores can survive for long periods in the environment your cat can contract ringworm from just about anywhere other dogs or cats have been. Fortunately, most healthy adult cats have some natural resistance to ringworm and never develop symptoms from the fungus. Young cats under a year old are most often infected. Cats with a suppressed immune system from diseases or overuse of steroids are also more susceptible to contracting the disease. Senior cats, free-roaming cats, and those who are under stress, malnourished or have other diseases such as parasites or viral infections also appear to be at increased risk. In addition, genetic factors may play a role, as Persians appear to be more susceptible to ringworm.

What are the signs of ringworm?
Cats with ringworm may have skin lesions which can appear different depending on where they occur and how long they have been present. The classic symptom is a small round lesion that is devoid of hair. The lesion will often have scaly skin in the center. Small are often found in the lesion. The lesion may start as a small spot and continue to grow in size. The lesion may or may not be irritated and itchy. Lesions are most common on the head, ears, and tail. In some infections, the fungus will not be in a circle and can spread across the face, lips, chin, or nose and look like an autoimmune disease or other generalized skin disease. Occasionally, the infection will occur over the entire body and create a generalized scaly or greasy skin condition. Hair loss may be mild or severe. In some cases the first sign may be excessive shedding, and hairballs may occur when large parts of the body are affected. Scratching at the ears is also common. Ringworm can also occur in the nails, often causing them to grow malformed.

How is ringworm diagnosed?
Ringworm cannot be diagnosed by simply looking at a lesion, but at least one of several testing methods must be used. One method is through the use of a specialized black light called a Wood’s lamp. Several species of the ringworm fungus will glow a fluorescent color when exposed to a Wood’s lamp. However, it is estimated that up to half of the most common species of M. canis do not fluoresce under a Wood’s lamp, and T. mentagrophytes does not fluoresce. Other substances may fluoresce and cause a false positive reading. In addition, a healthy animal may have spores on his coat but may not have an active infection. So, this is not the most accurate method.

Another method for identifying ringworm is to pluck hairs from the periphery of the lesion and examine them under the microscope. Between 40% and 70% of the infections can be diagnosed this way.

The most reliable way to identify a ringworm infection is by collecting scales and crust from the skin and coat and performing a fungalculture. Your veterinarian will commonly use a toothbrush to collect the sample of hair and scales from the cat to culture. There are special culture mediums designed specifically for identifying ringworm infections. Your local veterinarian can easily perform this routine culture.

Cats with ringworm should always be evaluated for underlying disease(s) that may have made them more at risk for this fungal infection.

How is ringworm treated?
In healthy shorthaired kittens and cats with small isolated lesions, the lesion is often treated with a topical cream containing an antifungal such as miconazole or thiabendazole. In addition, it is important to treat any underlying conditions, provide good nutrition, and prevent the spread to other animals and humans.

In more severe cases, a combination of oral and topical treatments is generally used. Often the lesions are clipped so the topical treatment can reach the skin. Many veterinary dermatologists feel that all longhaired cats must be shaved completely to achieve any success with ringworm treatment. Care should be taken not to irritate the skin when clipping, as this may cause the infection to spread. Also, realize that the clipped hair, clippers, and any grooming instruments that come into contact with an infected animal will harbor the spores and must be heat or chemically sterilized before being used on any other animal. The recommended topical treatment is lime sulfur dips. These dips have a bad odor and can temporarily turn the coat a yellowish color, but they are extremely effective and should be used if recommended by your veterinarian.

Alternatives to lime sulfur dips include miconazole shampoos and rinses, and enilconazole (available in some countries). Oral antifungal agents are generally recommended for any cat with severe generalized lesions, for longhaired cats, and in cases where the nails are infected. Oral antifungal agents may also be recommended when there is no response to topical therapy after 2-4 weeks of treatment. Itraconazole is the preferred drug of choice, and terbafine may also be used. Griseofulvin is another alternative, but has a higher risk of adverse effects.

Treatment is generally continued until there have been two negative cultures a week apart.

Some veterinarians have recommended using Program® (the once-a-month flea pill) at a higher dose to treat ringworm in cats, but it has been shown to be ineffective against ringworm.

How can ringworm be controlled in the environment?
Because the ringworm fungus can survive for such long periods in the environment, it is critical that an effective cleaning plan be used in all infections. Spores are very light and are carried in the air, so wherever there is dust and hair, there may be spores. Whenever cleaning, avoid sweeping and other types of cleaning that may actually spread spores through the air. Vacuuming, damp mopping and using a Swifter-type mop are generally recommended. Carpets should be steam cleaned and disinfected. Heating and cooling ducts and furnaces should be professionally vacuumed and filters replaced if a culture from the ducts comes back positive. Furniture and drapes should be vacuumed and the vacuum cleaner bags should be disposed of promptly. Housing units that contain wood or rusty metal should be re-painted. After vacuuming or mopping, clean with water and a detergent solution. Then, use bleach diluted to 1:10 with water and left on for at least 10 minutes to kill most of the organisms. All grooming tools, bedding, kennels, cat carriers, and cages should be thoroughly cleaned and disinfected with bleach, as well.

How can ringworm be controlled in catteries?
Some of the most difficult cases of ringworm come from catteries or small breeders, particularly those with Persian or Himalayans. Eliminating ringworm from these units can take months to years of diligent treatment. Remember that it will take a complete commitment to properly eliminate ringworm from a cattery. The owner must be willing to devote a large amount of time and make some difficult decisions if success in treatment is to be achieved.

There are several different approaches to controlling and eliminating ringworm in a cattery. The first approach includes total depopulation of the cattery, decontamination of the facility, and repopulating with only animals that test negative on three consecutive cultures performed at two-week intervals. The second approach is to treat the entire colony and facilities with appropriate topical medications, systemic therapy, and environmental cleanup. The colony is isolated and breeding and showing are interrupted. The third option would be to treat only infected kittens. This third option is only suitable for a breeder that produces kittens for the pet cat market and usually is not recommended for most breeders. Breeders will need to work very closely with their veterinarian to develop the best program for their facility.

Cultures should be performed on new cats coming into the cattery or returning from a show or a breeding. They should be quarantined and dipped once with lime sulfur. Since dogs and humans can carry ringworm into a cattery, both human and canine visitors should be kept at a minimum.

How is ringworm prevented?
Ringworm is a disease where an ounce of prevention is truly worth more than a pound of cure. If you have cats in your home, be very careful about bringing a new kitten into your household. Cat shows, kennels, and grooming facilities can also be a source of infection and caution should be used when exposing your cat to these places. Breeders of Persians and Himalayans need to be especially cautious about bringing any new animal that has not been cultured into their facility. If any sign of ringworm is seen, make sure you isolate the infected cat and seek prompt veterinary attention.

Is ringworm transmissible to people?
Yes. Ringworm can be transmitted between cats and people. Persons with suppressed immune systems, such as those with HIV infections or AIDS, and those undergoing chemotherapy may be especially vulnerable. Persons should wear gloves when handling affected animals and wash hands well afterwards. If you contract ringworm, treat with an OTC anti-fungal, such as Lotrimin.