F998
Zoonotic Diseases


fungal | viral | bacterial | parasites | cat bites


Introduction: Zoonotic diseases are illnesses that can be shared between a pet and a human. There is only a very slim chance of contracting an illness from a cat. Most people get contagious diseases from other people, not their pets. Disease transmission may be more of a problem for people that are very young, very old, or have illnesses that suppress their immune system. Many of these diseases are not transmitted from the cat to the person, but spread because the cat and person share the same activities and environment, putting them both at risk from the organisms involved.

Transmission: Zoonotic diseases are spread from cats to people via several routes. Contact with the cat and sharing the catís environment are the two most common means of exposure to potential disease. Infectious agents can be in the catís saliva, feces, and urine and on the catís skin and hair coat.

Treatment: Most zoonotic diseases can be treated with specific therapy appropriate for each individual disease. Some are not treatable.

Prevention: Common sense and good hygiene can prevent most disease transmission between cats and people. Cat bites should be thoroughly washed with soap and water and seen by a physician. Cat feces should be disposed of daily. Illnesses in the cat should be treated immediately. Cats should be kept free of internal and external parasites. Hands should be washed after handling the cat or cleaning up its urine or feces. Children should be taught to keep their hands out of their mouths and to wash their hands before eating.

The following zoonotic diseases are broken down into five major categories: fungal, viral, bacterial, internal or external parasites, and other. Specific diseases and organisms are discussed under each major category.

Fungal Infections

  1. Ringworm:
    Disease Description/Causative Agent:
    The term dermatophytosis refers to infections of the hair, claws, and skin caused by unique fungi that have adapted to living on animals. In humans, the infection is commonly known as ringworm, due to the typically raised and circular shape of the lesion on the skin. There is no worm involved. Ringworm is caused by several species of fungal organisms. The most common species in cats are in the genera Microsporum and Trichophyton.

    Signs in Cats: Signs in cats can vary tremendously. Some animals show no disease signs, while others have patches of hair loss and scaling. Few animals show the classic ring with central healing and peripheral crusting. Cats may or may not suffer from itching. Some cats develop secondary bacterial skin infections.

    Signs in People: People tend to develop skin lesions in distinct, raised circular patterns. The periphery of the circle may have redness, crusting, and scaling. The ring gets larger as the disease progresses. The number of rings can vary.

    Transmission:
    Cats contact the ringworm organisms in several ways. They can get the fungi directly from the soil or from other animals, including other cats, dogs, and rodents. Humans can even spread the infection to their pets. Cats can also be exposed to the infectious agents found on environmental surfaces, such as brushes and bedding. Similarly, ringworm in people is transmitted by contact with fungi found in the soil or by exposure to ringworm infected animals and contaminated objects such as hair, skin flakes, bedding, brushes, and cages.

    Diagnosis:
    An exact diagnosis in cats and people is made by skin scrapings and fungal cultures.

    Treatment:
    There are a variety of anti-fungal creams, lotions, shampoos, and oral medications available for both cats and people.

    Prevention:
    Keep the catís skin healthy. Do not allow the catís skin to remain damp and dirty because these conditions encourage fungal growth. Routine brushing will help identify skin lesions early. Follow a veterinarianís instructions when treating ringworm. If ringworm is identified on the cat, all bedding, combs, brushes, and cages must be thoroughly cleaned and disinfected using a mixture of 1 part bleach to 10 parts water. The fungal spores remain viable for up to 18 months, so remove as many as possible by vacuuming floors, walls, all surfaces, and vents. Steam cleaning carpets may help. (See F770 for more details on fungal infections in cats.)

    Human Health Risk and Zoonotic Importance:
    Most zoonotic transmission to humans is from cats. Humans that contract ringworm from a cat will typically find the lesions on points of the body that contact the animal. This means that the forearms and chest are often involved.

  2. Systemic Fungi:
    Disease Description:
    There are thousands of species of fungi in the environment. A few of these can cause disease in man and animals. These diseases are called mycoses. Ringworm, a superficial fungal infection, is discussed previously. Systemic mycoses are those fungal infections that can invade internal organs and potentially cause serious illness. These types of infections are usually not contagious from cats to people. They occur in both species because both people and cats share the same environment and are exposed to the fungi living in the soil or vegetation. If a cat becomes sick with systemic fungi, people are also at risk of infection from the organism in the environment.

    Causative Agent:
    The four major systemic mycotic agents are Blastomyces dermatitidis, Coccidioides immitis, Histoplasma capsulatum, and Cryptococcus neoformans. These organisms can live in the soil or decaying vegetation and are typically found in areas of the country that fit the needs of the specific organism. Coccidioides is found primarily in the sandy, dry areas of the southwestern United States. Blastomyces thrives in sandy soil near water and is found the Mid-Atlantic States in an area that includes the Mississippi, Missouri, Ohio, and St. Lawrence River Valleys. Histoplasma likes moist, humid areas and is found in soil rich with nitrogen from bat and bird droppings. It is usually found in the center of the country throughout the Ohio, Missouri, and Mississippi River Valleys. Cryptococcus can be found throughout the country and is frequently associated with the droppings in pigeon roosts.


    Signs in Cats:
    Systemic mycoses are rare, even in areas where the fungi are concentrated in the soil and organic debris. Many animals carry the organisms without signs of disease. Cats that are exposed to large numbers of infective organisms or have a suppressed immune system may become ill. Those that get blastomycosis, coccidiomycosis, or histoplasmosis may show loss of appetite, weight loss, fever, coughing, difficulty breathing, eye problems, lameness, and skin disease. Cryptococcosis usually causes disease of the nasal cavity, sinuses, nervous system, eyes, and skin in cats.

    Signs in People:
    The systemic mycoses produce similar signs in people as in cats. The signs can be limited to the respiratory tract and include coughing, difficulty breathing, and fever. These mycotic agents can spread to other organs and cause a loss of appetite and weight loss. Cryptococcosis in humans is also associated with nervous system disease, including encephalitis and meningitis.

    Transmission:
    Cats and people usually contract these mycoses by inhaling infectious particles from the environment.

    Diagnosis:
    Diagnosis in both cats and humans is based on a history that includes exposure to fungal contaminated areas. Diagnosis in cats is usually made by finding the organisms in a tissue sample. This can be done by biopsy or by examination of fluid or cells microscopically. Blood tests are often used in humans to make the diagnosis but are used less frequently in veterinary medicine.

    Treatment:
    Both cats and humans are treated with antifungal medications. Treatment can take months.

    Prevention:
    The only way to prevent mycoses is to avoid exposure to the fungi that cause disease. This can only be accomplished by avoiding places that contain large numbers of organisms. Certain activities, including farming, gardening, recreational hobbies involving water, cave exploring, and cleaning out bird/bat roosting areas, increase exposure to these fungi.


    Zoonotic Importance and Human Health Risk:
    Most people that are exposed to these mycotic organisms do not get ill. The human health risk is greatest in those that have suppression of the immune system. In addition, laboratory and hospital workers have greater exposure and greater risk than the general public. Cat to person transmission is almost nonexistent, except for veterinary personnel exposed to contaminated wounds and the few reported cases of transmission by bite. The most important human health consideration is the knowledge that cats and humans share environmental exposure to these disease-causing organisms. If a cat contracts a systemic mycosis, it is a warning to those that share its environment.

  3. Sporotrichosis (Sporothrix schenckii): See F770.

Viral Diseases

Rabies:
Disease
Description: Rabies is the most important viral disease that is shared by humans and cats. Ninety percent of all rabies cases are found in wild mammals, including foxes, raccoons, skunks, and bats. Feral cats and dogs are also potential carriers, although there have been very few reported cases. If an unvaccinated cat contracts rabies from a wild or feral animal, the cat can potentially spread the disease to human beings.

Causative Agent: Rabies is caused by a virus that can infect all warm-blooded animals.

Signs in Cats: Rabies virus attacks the nervous system, resulting in inflammation of the spinal cord and brain. Affected animals may show no signs for several weeks after the infection. Sick animals show varying degrees of dementia, and signs can vary from extreme depression and quietness to "furious" behavior. The signs can include hiding, loss of appetite, unprovoked aggression, and biting at both living and inanimate objects. As the disease progresses, the animals become paralyzed, lose the ability to swallow, and may have seizures. The animals die within several days of the onset of these symptoms.

Signs in People: The symptoms vary depending on where the virus enters the body but involve abnormalities of the nervous system. Once the virus enters the spinal cord, the victim suffers from paralysis, which ultimately leads to death by preventing respiration.

Transmission: The primary means of transmission is through a bite from an infected animal. The saliva of an infected animal carries large numbers of the viral agent. Other less common means of transmission include infected saliva coming in contact with an open wound or abrasion. There have been a few cases of disease being spread by the inhalation of aerosolized virus. The most common way for the zoonotic transmission of rabies from cats to humans is through a bite from an infected cat.

Diagnosis: The only 100% accurate method for diagnosing rabies is to have a diagnostic laboratory perform tests on the brain of a suspected animal. There is no perfect diagnostic test for identifying rabies in humans. If a cat bites a person, the decision to treat the person for rabies is made by examining the circumstances surrounding the bite and the rabies vaccination history of the biting cat.

Treatment: There is no specific treatment for rabies once disease signs are evident. Most cases in animals and people are fatal once the virus replicates and enters the nervous system. Treatment in people is aimed at vaccinating exposed people before the virus replicates and before symptoms begin. All circumstances surrounding a cat bite must be examined to decide on a proper course of treatment and vaccinations. In general, if there is any possibility that the biting cat may carry rabies, the person involved must undergo a series of preventive injections. If the cat has a current rabies vaccination and can be found and quarantined, the injections may be avoided. If the cat is a stray, has no record of current vaccination, or cannot be found, the vaccines are given.

Prevention: Avoid contact with wild animals. Maintain current rabies vaccination for all pets in the family. See page A905 for specific vaccination recommendations. Keep cats away from wild and feral animals. Avoid cat bites and stray or loose animals. If an owned, vaccinated cat is bitten by another animal, wear gloves when washing the wound and seek veterinary care for the cat. The cat may need a rabies booster and to be quarantined. Unvaccinated animals exposed to rabies may need to be euthanized. Decisions regarding the handling of potentially exposed cats are usually made by local and state authorities.

Zoonotic Importance and Human Health Risk: Although most cases of rabies are found in wild animals, wild animals do interact with pet cats, which in turn interact with people. Behavioral changes in rabid wild-life actually increase their interactions with pet cats. Sick, inactive, wild animals are easy prey to cats and aggressive, rabid, wild animals lose their normal behavioral inhibitions and may attack cats. If these cats are not vaccinated, they can then contract rabies and expose their owners to infection. Vaccinating all pet cats maintains a protective barrier between people and wildlife and helps reduce the possibility of a pet spreading rabies if it is bitten. For additional information on rabies in cats, refer to page F702.

There are very few cases of rabies in people in the United States, but the disease carries a high human health risk because it is invariably fatal once it enters the nervous system.

Bacterial Infections

Cat Scratch Fever:
Disease Description/Causative Agent:
This uncommon problem is caused by the bacterium Bartonella henselae that infects human skin after a cat scratch or bite. It is most common in youth under the age of 17.

Signs in Cats: The cats that carry this disease usually do not act sick and do not have any signs of disease. If signs do occur, the cat may have a fever, anemia, and neurological problems. Once infected, cats may carry the bacteria in their blood for many months.

Signs in People: Most often, a small skin lesion that looks like an insect bite develops at the site of a cat scratch or a bite. A few weeks later, swollen and sometimes painful lymph nodes occur, and the person may have a fever. The problems usually resolve on their own, and treatment is not usually required unless the person has a compromised immune system (people with AIDS or receiving chemotherapy). The lymph nodes may take months, however, before they return to normal. In more complicated cases, the person may feel like they have the flu and experience nausea, chills, weakness, loss of appetite, a headache, and occasionally pneumonia. Reports indicate that severe inflammation of the liver, brain, and tonsils can occur in some isolated cases.

Transmission: Cats can pick up B. henselae from flea bites. Fleas have been shown to transmit B. henselae from cat to cat. Humans usually become infected through a scratch or bite wound. There is also some evidence that the bacteria are present in the environment and can be spread to humans without the cat bite or scratch.

Diagnosis: Currently, there is no reliable test to determine if a cat is infected with B. henselae. Many studies also show that the infection in the cat may come and go. Because of these reasons, it is not recommended that a cat associated with the disease be euthanized.

Treatment: Treatment for B. henselae infection is often not necessary or beneficial in both cats and humans. If treatment is justified, antibiotics are commonly used.

Prevention: Cat bites should be avoided by taking measures to prevent the interactions that lead to bites. If a bite or scratch does occur, it should be vigorously cleaned with copious amounts of water and soap and then rinsed thoroughly. A physician should see all bite victims. The wound should be irrigated to flush out contaminants. Any cat suspected of carrying B. henselae should be isolated from any sick or immunocompromised individuals.

Human Health Risk and Zoonotic Importance: Most transmission to humans is from cat bites or scratches; however, some people have been infected without a history of being exposed to cats.

Internal and External Parasites (Toxoplasmosis, Giardia, worms, ticks, fleas, and mites)

  1. Toxoplasmosis:
    Disease Description:
    Because toxoplasmosis is transmissible to humans, anyone who has contact with cats or cat feces should wear rubber gloves and take caution to not contaminate benches, tables, or countertops. Humans become infected with toxoplasmosis when they eat undercooked meat or accidentally ingest cat feces contaminated with parasite eggs. A human can be infected with toxoplasmosis for a period of time and not show any symptoms. Women who are considering pregnancy and think they may have come in contact with toxoplasmosis in the past, should see their physician before becoming pregnant. This disease can cause miscarriage, stillbirth, and serious birth defects in a human fetus. Pregnant women should avoid handling any cat feces or cat litter. All litter boxes should be changed on a daily basis. See page F836 for additional details on this disease in cats.

  2. Giardia:
    Disease Description:
    Giardiasis is the most common intestinal parasitic disease in humans in the United States. The organisms live in the intestinal tract of many different species of wild and domestic animals.

    Causative Agent:
    The protozoa Giardia lamblia causes Giardiasis. Protozoans are one-celled organisms. Most are free-living; only a few types of protozoa live in the bodies of mammals and can cause disease.

    Signs in Cats:
    Many cats infected with Giardia show no signs of illness. Others may have diarrhea. The diarrhea is characterized as pale, soft, voluminous, and especially rancid in odor. The diarrhea may be acute and short-lived, intermittent, or chronic. Animals may lose weight despite a good appetite.

    Signs in People:
    As in cats, Giardia infection in humans may cause no signs, intermittent signs, or severe disease. Diarrhea, stomach pain, nausea, gas, lethargy, and weight loss have been observed in symptomatic people.

    Transmission:
    Waterborne transmission is the most common. The parasite forms infective cysts that are passed in feces and make their way into fresh water supplies. Aquatic rodents may be responsible for fecal contamination of surface water sources. If water treatment and filtration is inadequate, the organism can enter the drinking water and be spread to thousands of people. Contamination of fresh water sources is also a problem for campers, hikers, and others that use water for recreational purposes.

    Direct oral-fecal contamination is a much less common means of transmission. Cysts passed in the feces can contaminate foods and be inadvertently swallowed.

    Diagnosis:
    This infection can be diagnosed in both humans and cats by performing specific laboratory tests on feces or finding the parasites during microscopic examination of the feces. Other diagnostic procedures include intestinal endoscopy accompanied by aspiration and biopsy.

    Treatment:
    There are no medications specifically approved and licensed to kill Giardia. The medications that are used in both cats and humans include specific anthelmintics and antibiotics. Treatments may not be 100% successful and often need to be repeated.

    Prevention:
    Proper filtration of human water sources is the most important tool for prevention. Avoid drinking water directly from lakes, ponds, and streams. Adults and children should be taught to wash their hands before eating. Cats with giardiasis should be rapidly diagnosed and treated to decrease the shedding of cysts. Proper sanitation should be practiced. Feces should be removed on a continual basis and hands should be washed after handling cats or cat feces.

    Zoonotic Importance and Human Health Risk:
    Giardiasis is the most common intestinal disease in the United States. It is estimated that 7% of the worldís population carry Giardia. Although both cats and humans can have giardiasis, cats are not at this time considered a source of infection for people. Instead, cats are a signal that Giardia can be found in the environment. Cats and humans often share water sources, and this water may be contaminated with Giardia. So, if a cat has giardiasis, people may also be at risk.

  3. Roundworms:
    Disease
    Description: Intestinal worms mature and reproduce in cats. The adult female worms lay millions of eggs that are passed in the animalís feces and contaminate the environment. If a person accidentally ingests the eggs, they will hatch in the small intestine and then migrate throughout the body, causing damage to the organs they pass through. This syndrome is called larva migrans.

    Causative Agents:
    Although other worms can cause this illness, the most common cause of larva migrans from cats is ascarids, commonly called roundworms.

    Signs in Cats:
    Signs of intestinal worms in cats can vary depending on the age and severity of infestation. Cats may have diarrhea, vomiting, a bloated belly, and appear unthrifty. Adult worms may be passed in vomitus or feces. Many adult cats have no symptoms. All kittens should be assumed to have roundworms even if the mother has been previously de-wormed and no signs of illness are present.

    Signs in People:
    The signs in people vary depending on the location of the migrating worm. Visceral larva migrans occurs when the larvae enter body organs and is characterized by fever, high white blood cell counts, and wheezing. Ocular larva migrans occurs when the larvae enter the eye and can result in inflammation of the eye and loss of vision.

    Transmission:
    There is no direct animal to person spread of this illness. The worms and eggs are not transferred by touching and petting cats. Transmission occurs when people accidentally swallow eggs. Mature worms in the cat lay millions of eggs that are passed in the feces and contaminate the environment. Humans touching the ground or soil that contains these eggs can then touch their mouths and swallow the eggs. This occurs primarily in children that pick up and eat contaminated dirt. Most cases occur in children because of eating dirt and lack of personal hygiene. Adults and children that handle the catís litter and bedding can also accidentally ingest the eggs. Cats usually become infected when they consume the tissues of animals (rodents) that are infected with roundworm larvae or when they ingest the infective eggs directly.

    Diagnosis:
    The diagnosis of roundworms in cats is made by checking the feces of the cat for roundworm eggs. Diagnosis in people is made by blood sample testing.

    Treatment:
    Roundworms in cats can be treated with proper use of medication that kills the worms. See page A622 for more information on internal parasite control. Humans are also treated with appropriate medication.

    Prevention:
    Proper hygiene and veterinary care are the keys to preventing worm infestations in both humans and cats. Clean up cat feces on a daily basis to prevent egg contamination of the ground. Avoid allowing the cat to defecate in playgrounds and school yards. If this occurs, clean up the feces immediately. Keep children away from areas that may be heavily contaminated with eggs, such as cat litter. Adults and children should wash their hands with soap and water after handling cats and before eating. Adult cats should be routinely tested and treated for intestinal worms. All newborn animals should be assumed to have roundworms and treated following the veterinarianís guidelines.

    Human Health Risk and Zoonotic Importance:
    There are several thousand suspected cases of larva migrans each year. The risk is greatest in young children. Unrecognized or treated incorrectly, larva migrans can lead to severe illnesses and even blindness.

  4. Hookworms:
    Disease Description:
    Hookworms are another intestinal parasite of cats that can cause disease in humans if larvae are accidentally ingested or stepped on in the soil. The larva can penetrate the skin and cause a disease known as cutaneous larva migrans. If the larvae penetrate deeper tissues, a visceral larva migrans syndrome can result.

    Causative Agent:
    Ancylostoma is the common intestinal hookworm in cats. It lives in the digestive tract and its eggs are shed in the catís feces.

    Signs in Cats:
    Cats with hookworm disease can have intestinal symptoms of diarrhea and suffer from anemia. The disease can vary in severity from asymptomatic infection to rapid death due to blood loss, depending on the number of worms and age or condition of the cat. Kittens usually show the most severe symptoms.

    Signs in People:
    Cutaneous larva migrans is also called creeping eruption because it is characterized by a progressive, linear, intensely itchy eruption of the skin. The migrating hookworm larvae create the linear path. If the larvae migrate deeper and penetrate body organs, signs of intestinal problems and other organ disease can occur.


    Transmission:
    Most people contact the hookworm larva when working or walking in areas of heavy hookworm egg concentration. The larvae directly penetrate the skin. Many cases have been traced to the soft, wet sand at beaches and under buildings. Cats usually become infected when they consume the larvae directly or when the larvae penetrate the skin.

    Diagnosis:
    Hookworm infestation in cats can be identified by examination of fecal samples by a veterinarian. Disease symptoms and laboratory tests can identify infection in humans.


    Treatment/Prevention:
    Control hookworm infestation in cats with routine testing and anthelmintic use. (See page A622 for information on internal parasite control.) Remove cat feces on a daily basis. Wash hands after handling cats and cleaning up their feces. Teach children to keep their hands out of their mouths and to wash their hands before eating. Wear shoes in areas contaminated by hookworm eggs. Keep children away from areas potentially contaminated with eggs, such as any cat litter. People are also treated with medication that kills the parasite.

    Human Health Risk and Zoonotic Importance:
    This syndrome is not reported to health authorities in the United States, so the number of annual cases is not known. However, the cutaneous larva migrans syndrome is most often diagnosed in the southeastern and Gulf states. Plumbers and workers that crawl beneath raised buildings, people that frequent the beach, and children are most commonly infected.

  5. Fleas:
    Disease Description:
    Fleas can cause disease by several mechanisms in cats. A severe flea infestation can lead to anemia from blood loss. Cats that are allergic to flea saliva can also suffer from fleabite hypersensitivity and allergic dermatitis. Fleas can carry the bacteria (Yersinia pestis) responsible for the plague and are intermediate hosts for tapeworms, which are spread to the host animal when an infected flea is swallowed.

    Causative Agent:
    Fleas are wingless insects that feed on the blood of animals, including cats and people. Adult fleas stay on the host.

    Signs in Cats:
    Biting fleas can cause a wide range of signs in cats. Some cats with only a few fleas show no symptoms. Most cats infested with fleas show intense itching. Affected cats may lick, scratch, chew and bite at their skin. Fleas are often concentrated along the back, above the tail and down the back of the rear legs, so biting may be confined to these areas. Discoloration of the hair coat and loss of hair may accompany intense biting and licking. Cats with fleabite hypersensitivity can be extremely itchy all over their body for many days after exposure to fleas. Cats may also show excess grooming behavior.

    Signs in People:
    People that are bitten by fleas usually have red, irritated, itchy, bumpy lesions on the ankles, and lower legs. The wrists and arms may also be involved. People that are allergic to flea saliva may have intense itchy reactions that can last for days.

    Transmission:
    Adult fleas tend to stay on the host animal unless the flea population on the cat exceeds several hundred, in which case the adult may leave if it finds another host with a lower population. Most flea infestations occur when newly hatched fleas leave the environment for a host that walks or sits near them. Adult fleas can survive for weeks waiting for a mammalian host. Fleas that bite animals prefer animals to people. Humans are usually bitten only when the flea burden on the pet becomes overwhelming or when the pet is absent. Many bites occur when people leave a house unattended for several weeks. When they return, the hungry fleas that had been left behind bite everyone.

    Diagnosis:
    When examining cats, the history and location of the skin lesions are considered important in a presumptive diagnosis of flea infestation. Identification of tapeworm segments also supports the diagnosis. An exact diagnosis is based on observation of the flea eggs, feces, or adult parasites. Diagnosis in people is based on the type and location of lesions, evidence of fleas on the pet or in the house, and resolution of lesions following removal of the biting insects.

    Treatment:
    There are a myriad of flea control medications designed to rid the cat and the environment of biting fleas, eggs, and larvae. (See F770 for specific details on treating fleas in pets.)

    Treatment in humans typically includes removal of fleas from the environment and topical anti-inflammatory drugs to control itching as the bites heal.

    Prevention: Flea control in the environment and on the cat and other pets is paramount. Flea control can be modified to meet the needs of the cat owner and can include a variety of topical and environmental treatments. Monthly spot-on solutions that kill fleas meet the needs of most cat owners. Cats with tapeworm infestations should be treated with the appropriate anthelmintics as well as being examined and treated for fleas.

    Zoonotic Importance and Human Health Risk:
    In most situations, fleas do not bite humans unless the flea population is too high for the pet to adequately support. Most fleabites on humans heal in several days and the bites will stop once the flea population is adequately controlled. Fleas do carry the bacteria responsible for the plague, and cats can be infected with the bacteria from fleabites or by eating infected rodents. These cats can then pass the illness to their owners through scratches/bites or, more commonly, by bringing the fleas carrying plague into contact with their owners. It is also theoretically possible, though very uncommon, for a person to swallow a flea and develop tapeworm infection. Human health risk from exposure to fleas from cats is primarily that of fleabites. (See F770 for specific details on flea infestation in cats.)

  6. Mites (Cheyletiellosis and Notoedric mange):
    Disease Description:
    Cheyletiellosis is a disease caused by mites commonly found on cats. Cheyletiellosis can also affect dogs, rabbits, and humans. Notoedric mange is another disease caused by a mite that can be found on cats, dogs, rabbits, and humans. Both cheyletiellosis and notoedric mange are very contagious.

    Causative Agents:
    Cheyletiella blakei is responsible for cheyletiellosis. Cheyletiella blakei is a rather large mite that lives its lifespan on the surface of the animal it has infected, without burrowing into the skin like other species of mites tend to do. Notoedres cati is the mite that causes notoedric mange in cats. Notoedres cati is a sarcoptic mite causing a skin disease in cats similar to sarcoptic mange in dogs.

    Signs in Cats:
    Cheyletiella blakei tends to cause flaking and dandruff on the back of cats. As the mites move, the large flakes of dandruff will move around as well. Because this movement is visible to the naked eye, the term "walking dandruff" is used. Itching can be severe to completely absent. Scaling (dandruff) is very common in cats with cheyletiellosis. Notoedric mange usually starts with itchiness and scratching at the head, ears, and neck, with crust formation. Later, the disease may spread to other areas of the body, especially the legs and the groin area. Secondary damage to the skin from the catís own scratching often leads to secondary bacterial or fungal infections. Lymph nodes may be swollen and tender.

    Signs in People:
    Both Cheyletiella blakei and Notoedric cati can cause intense itchiness in the people that become infected secondarily. Most commonly, the human infection is self-limiting and goes away on its own after several days. However, treatment may be sought through a physician because of the temporary intense itching suffered by some people. Allergic reactions to the mite bites may also occur in people.

    Transmission:
    Cats become infected with the mites when they come in contact with the parasite in the environment (carpets, rugs, bedding, etc.) or when they are in direct contact with other infected animals. People usually become infected when they directly contact an infected cat. Continual transmission may occur from the infected cat to a person if the cat is not properly treated. In such situations, the secondary infection in a person may never go away on its own until the cat receives appropriate treatment.

    Diagnosis:
    Diagnosis of cheyletiellosis is made by directly observing the mites and/or their eggs. Mites and eggs may be collected from an infected individual by skin scrapings, tape preparations, combings, vacuum techniques, or analysis of the feces. Diagnosis of notoedric mange is also made with skin scrapings, biopsy, and histopathology.

    Treatment:
    Treatment of cheyletiellosis may include weekly lime sulfur dips for 3-6 weeks, oral ivermectin treatments weekly for 4-6 weeks, or subcutaneously injected ivermectin every 2 weeks for 3 treatments. Many medications used to control fleas may also be successful at treating Cheyletiella blakei infections. Because this mite can live off of the host for a longer period than most mites, maintaining a clean environment is very important in successful management of this type of mange. Frequent vacuuming of carpets and rugs, washing of the bedding, and treatment of all dogs and cats in contact with an infected pet are all important in helping to prevent re-infection of treated animals. Treatment of notoedric mange in cats begins with clipping and cleaning of the affected areas. Lime sulfur dips given once weekly until the skin is back to normal can be used to cure this infection. Two or three ivermectin injections can also be used to treat this infection. Revolution is labeled for use in dogs to treat sarcoptic mange and may be used in cats as well; however, it is not specifically labeled for use in treating notoedric mange in cats and its use would be considered extra-label. Treatment of all cats on the same premises is critical in preventing this disease from recurring. A variety of antiparasitic, anti-inflammatory, and antibiotic creams, ointments, and oral medications may be used to treat both types of mite infections in people.

    Prevention:
    Maintaining good skin health in pet cats is the best prevention available. Restricting outside access where the cat may come into contact with stray or feral cats or other animals is also beneficial.

    Human Health Risk and Zoonotic Importance:
    Cheyletiellosis and notoedric mange in people are sporadic and uncommon. They are usually not considered dangerous or life-threatening in people. However, they are important in light of the potential irritation and annoyance they may cause for cat owners. (For additional details on mites in pets, see F770.)

Cat Bites:
Disease Description:
There are thousands of cat bites per year in the United States. Most bites are not severe, but depending on the location of the bite and the severity of the wound, bites can result in infection, loss of use of a limb, disfigurement, damage to bones and soft tissues, and death. Cat bites and scratches can also spread Yersinia pestis the bacterium that causes plague.

Causative Agent: The damage inflicted by cat bites is a function of both the physical trauma associated with the wound and the bacteria that spread from the catís mouth into the wound. Catsí mouths contain many species of bacteria; several of these bacteria can cause disease if inoculated into a wound. One common isolate of infected cat bites is Pasteurella multocida, a bacteria that can cause infection.

Signs in People: Most bites from familiar cats occur on the arms, hands, and possibly the legs. Most facial bites are inflicted on children. The majority of cat bites result in small wounds with minimal bruising, bleeding, and tissue damage. However, severe injury can result depending on the location and type of wounds inflicted. Physical damage results from injury to the soft tissue and bony structures involved in the bite. Additional signs will result if infection occurs secondary to transmission of bacteria from the catís mouth. Signs of infection can include pain, swelling, redness, and drainage from the wound. Septic arthritis, abscesses, and even fatal systemic infections can occur if treatment is not begun promptly.

Transmission: Cat bites are not a traditional zoonotic disease. There is no passive spread of a contagious agent from cat to person. Instead, disease spread is the result of an improper physical interaction between a person and a cat. Aside from people that handle cats routinely, such as veterinarians, most bites occur in children under the age of 12.

Diagnosis: Diagnosis is based on the report of the victim and observation of the wounds.

Treatment: All bites should be vigorously cleaned with copious amounts of water and soap and then rinsed thoroughly. A physician should see all bite victims. Irrigation should be performed to flush out contaminants. Removing severely damaged or contaminated tissue (debridement), suturing, and/or referral to a specialist may be needed. Many people are treated with antibiotics to prevent infection. Surgery may be required depending on the severity of the wound.

Prevention: Cat bites can be avoided by taking measures to prevent the interactions that lead to bites. The vast majority of bites are inflicted by family pets or animals that are known to the victims. Education and owner responsibility are the keys to the prevention of bites. Owners should learn proper methods for handling cats and behavior modification techniques. Children should be taught to avoid loose animals, how to properly handle and interact with all cats, and the necessary safety tips to avoid bites. Young children should always be supervised when playing with animals; no child should ever be alone with a dog or cat. Aggressive behaviors in a family pet should be identified and modified with appropriate therapy and training.

Zoonotic Importance and Human Health Risk: Every year there are thousands of dog and cat bites in the United States and 10 to 20 fatalities. Most bites involve children. Bite victims can suffer from long term negative physical and emotional effects.