SNAP Cats

Feline Parasites

Provided by the Cornell Feline Health Center, Cornell University

Gastrointestinal parasitism is a common problem in cats, with prevalence rates as high as 45 percent. The parasites can be wormlike (e.g., stomach worms, roundworms, hookworms, tapeworms) or one-celled (e.g., Isospora, Giardia, Toxoplasma) organisms. The signs associated with parasite infections are fairly nonspecific, such as a dull hair coat, coughing, vomiting, diarrhea, mucoid or bloody feces, loss of appetite, pale mucous membranes, or a pot-bellied appearance. The vomiting, diarrhea, anemia, and dehydration caused by intestinal parasites will weaken a cat, making it more susceptible to viral and bacterial infections and diseases; thus robbing your cat of good health. Furthermore, some parasites have the potential of infecting humans.

Wormlike Parasite

Roundworms
Roundworms (Toxascaris leonina and Toxocara cati) are the most common intestinal parasite of cats, with an estimated prevalence of 25% to 75%, and often higher in kittens. The adult roundworms are 3 to 5 inches long, cream-colored, and live in the cat’s intestine. The adult female worm produces fertile eggs that are passed in the infected cat’s feces. The eggs require several days to several weeks to develop into the infective larva stage.

Cats become infected with Toxocara cati by ingesting eggs or by eating rodents (transport hosts) that have larvae in their tissues. Kittens can become infected by larvae that are passed through an infected queen’s milk. In those cases, it is possible for kittens to become infected soon after birth. Cats become infected with Toxascaris leonina in a manner similar to Toxocara cati, but unlike Toxocara, the parasite is not transmitted through the milk.

Roundworm infections can potentially become life-threatening if the numbers are so great that intestinal blockage occurs. Usually, roundworm infections are relatively benign when compared to other intestinal parasites. However, infected kittens are in serious danger if left untreated. Diagnosis is confirmed by finding parasite eggs in the stool during microscopic examination. Many medications are effective, but reducing exposure to the feces of an infected cats and prohibiting hunting are the best means of prevention. Treatment of queens prior to breeding reduces the likelihood that the parasite will infect kittens.

Visceral larval migrans and ocular larval migrans are diseases caused by the migration of Toxocara larvae through the tissue of people, particularly children. Although these diseases are rare, they can be quite serious, especially when they occur in young children. They can be easily avoided by preventing ingestion of Toxocara eggs in contaminated soil or on the hands.

Hookworms
Hookworms (Ancylostoma and Uncinaria) are less than 1/2 inch long, slender, thread-like worms that as adults live in the cat’s intestine. Because of their small size, they usually are not visible in the feces of infected cats. Hookworms are long-lived and are capable of living as long as the cat. Less common than roundworm infections, the prevalence of hookworm infections in North America is estimated to be between 10% and 60%.

Adult cats usually become infected by larvae that penetrate their skin or that are ingested. Once the larvae gain entrance into the host, they migrate to the lungs and then to the intestines to develop into adult worms. It is uncertain whether cats can become infected by eating rodents containing larvae in their tissues, or ingesting queen’s milk that contain larvae.

Severe parasitism can cause anemia due to blood loss from the intestines where the worms attach themselves. The cat’s feces will appear black and tarry due to blood in the feces. If too much blood is lost, the cat can become anemic and may die if left untreated. Fortunately, like roundworms, these worms are easily diagnosed and treated. Good sanitation and daily cleaning of the litter box are keys to controlling hookworm infections.

Hookworm larvae can penetrate human skin. As they migrate under the skin, they cause a dermatitis called cutaneous larval migrans.

Tapeworms
Tapeworms (cestodes) have long flattened bodies that resemble a tape or ribbon. The body is comprised of a small head connected to a series of segments that are filled with eggs. The adult tapeworm lives in the small intestine with its head embedded in the mucosa. As the segments farthest from the head become fully mature, they break off and are passed in the feces. These segments can be observed near the cat’s tail and rectum, or in the feces. The segments are about one-quarter inch long, flat, and resemble grains of rice when fresh or sesame seeds when dry. When still alive they will usually move by increasing and decreasing in length. Microscopic examination of fecal samples may not always reveal the presence of tapeworms, because eggs are not passed singly, but as a group in the segments. Although the discovery of tapeworm segments can be quite alarming to cat owners, tapeworm infections only rarely cause significant disease in cats.

Cats usually become infected with tapeworms by ingesting infected fleas while grooming or by eating infected rodents. Fleas and rodents become infected by eating the tapeworm eggs that are in the environment. Modern medications are highly successful in treating tapeworm infections, but reinfection is common. Controlling the flea and rodent populations will reduce the risk of tapeworm infection in cats.

Some tapeworm species that infect cats can cause disease in humans if the eggs are accidentally ingested; but good hygiene virtually eliminates any risk of human infection.

Whipworms
Whipworms are an uncommon parasite of cats in the United States. Adult whipworms reside in the large intestine of infected cats but do not cause serious disease.

Stomach Worms
Ollanulus tricuspis and Physaloptera species are worms that can inhabit the feline stomach. Ollanulus infections occur only sporadically in the United States and are more common in free-roaming cats and those housed in multiple-cat facilities. Cats become infected by ingesting the parasite-laden vomitus of another cat. Chronic vomiting and loss of appetite, along with weight loss and malnutrition may be seen, although some infected cats show no signs of disease. Diagnosis of Ollanulus infection can be difficult, and depends upon detecting parasite larvae in the vomitus. The most effective treatment is not known; avoiding exposure to another cat’s vomitus is the most effective means of controlling infection.

Physaloptera infections are even more rare than Ollanulus infections. Adult female worms attached to the stomach lining pass eggs that are subsequently ingested by an appropriate intermediate host, usually a species of cockroach or cricket. After further development within the intermediate host, the parasite is capable of causing infection when a cat ingests the insect or another animal (a transport host), such as a mouse, that has eaten an infected insect. Cats infected with Physaloptera may experience vomiting and loss of appetite. Diagnosis relies upon microscopic detection of parasite eggs in the stool, or seeing the parasite in the vomitus. Effective treatment exists, and infection can be prevented by limiting exposure to intermediate and transport hosts.

Neither Ollanulus nor Physaloptera are capable of causing disease in humans.

Protozoan Parasites

Isospora
Isospora sp. (coccidia) are microscopic one-celled organisms causing the disease coccidiosis. Virtually all cats become infected with Isospora felis during their life. Cats become infected with this parasite by eating the cyst (thick-walled, egg-like stage) that has been passed in the feces and has matured in the soil. The cysts can be infective within six hours after being excreted in the feces.

Isospora infections usually cause no problems in adult cats, but evidence suggests that the parasite can cause significant disease in kittens. In infected kittens, the coccidia destroy the lining of the intestine and cause diarrhea with often contains mucous. Serious infections may develop in crowded environments. Good sanitation and hygiene will help control coccidia, but accurate diagnosis and effective treatment can only be achieved with your veterinarian’s assistance. Isospora of cats cannot cause disease in humans.

Giardia
Giardia are flagellated protozoa (one-celled organism) that parasitize the small intestine of cats. The prevalence of feline giardia infection (giardiasis) is estimated to be less than 5% but can be much higher in some environments. Cats become infected by ingesting giardia cysts present in the feces of another infected animal, usually a littermate or chronic carrier cat. Giardiasis is more common in multiple-cat households and catteries due to its mode of transmission. Also, the infection rate is greater in cats less than one year old.

The cysts are very resistant to freezing. Also chlorination of municipal water does not destroy the cysts. After ingesting of Giardia cysts, it takes 5 to 16 days before the cat will show signs of diarrhea. Acute or chronic, and continuous or intermittent diarrhea is the most common sign of infection, although the majority of Giardia-infected cats are free of disease. They do, however, remain a source of infection to other cats. The cat probably requires several exposures to the organism before infection actually occurs.

Diagnosis of giardiasis depends upon microscopic identification of cysts in the stool. For accurate diagnosis, several fecal samples may need to be evaluated since cysts are not continuously shed in the stool. Several effective medications are available, but resistance is common. Elimination of Giardia infections from households of cats may be difficult and depends on proper treatment and sanitation.

It is uncertain whether species of Giardia that infect cats are contagious to humans or vice versa. Careful hygiene will eliminate the risk of accidental ingestion of cysts.

Toxoplasma
Cats are the definitive host for the Toxoplasma organism. Infection with this protozoan parasite is fairly common, but actual disease caused by this parasite is relatively rare in cats. Cats can become infected by Toxoplasma by eating any of the three infective stages of the parasites. The most common route of infection is probably by ingestion of tissue cysts in infected prey or in other raw meat. Toxoplasma multiply in the small intestines and in approximately two to three weeks the oocysts are excreted in the infected cat’s feces. (For more detailed information on this parasite, see Toxoplasmosis.)

Treatment
Treatment may require administering one or more dosages of the medication prescribed by your veterinarian. Whenever using medications, be sure to carefully follow the directions provided by your veterinarian.

Parasite re-infections are very common, but can be prevented. Parasite control begins with good sanitation procedures. This includes daily removal of feces; washing the litter box with a disinfectant (e.g., diluted household bleach) on a regular basis; avoiding overcrowded conditions; avoiding diets with raw meats; and controlling intermediate hosts (fleas, ticks, and rodents). Good parasite control is the key to a healthier cat.

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.