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Common Intestinal Parasites of the Cat
Gastrointestinal parasites are fairly common in cats, with prevalence rates as high as 45% depending on where you live. The parasites can be worm-like, such as roundworms, hookworms, stomach worms and tapeworms; or they can be single-celled microscopic organisms such as Isospora, Giardia and Toxoplasma. The signs that a cat may have parasites can include a dull haircoat, coughing, vomiting, diarrhea, anemia, dehydration, appetite, pale mucous membranes, or a pot-bellied appearance. The vomiting, diarrhea, anemia, and dehydration that the parasites can cause your cat makes them more susceptible to viruses and bacterial infections. Some of these parasites are zoonotic, which means they transmittable to humans.
Roundworms: (Toxocara cati, and Toxascaris leonina) are the most common intestinal parasite of cats, with an estimated prevalence of 25% to 75%. This percentage is often higher in kittens. Adult roundworms are three to five inches long, cream-colored, and live in the cat's intestines (think spaghetti). They survive by eating food ingested by the host without attaching to the wall of the intestine. The adult female will produce eggs that will be shed in cats stool. It takes several days to weeks for the eggs to develop into larva. Cats become infected by roundworms by ingesting eggs or by eating rodents that have the larva in their tissue. Kittens can become infected by larva that pass through the mother's milk and this can happen soon after birth. In kittens, the symptoms of these worms can be deadly if the infection is not treated. Roundworms are zoonotic to humans. Most of roundworm infection in humans causes visceral larval migrans and ocular larval migrans. These are human diseases caused by the migration of larvae through the tissue. Roundworm infection in humans are rare, but they are serious, especially in children. It is important when working outside in the garden to wear gloves and shoes. Make sure to keep a cover on kids sand box and always wash your hands.
Hookworms: (Ancylostoma and Uncinaria) these worms are a slender, thread-like worm, that are less than 1/2 inch long. They live attached to the lining of the wall of the intestines, and feed on the host's blood. Hookworms are small in size, so they aren't visible in feces like roundworms. Hookworms are capable of living a long time in the intestinal system of most cats. However, they are less common in cats: 10% to 60% depending on where you live. Cats become infected by hookworms by either larvae that penetrate their skin or ingestion by a cat grooming themselves. Once the larvae gain entrance to the cat, they migrate to the lungs and then to the intestines, where they will develop into adult worms. Mild infection can cause diarrhea and weight loss in cats. A severe infection can cause anemia due to blood loss from the parasite. If your cat is suffering from severe hookworm infections, their stools will appear black and tarry due digested blood in the feces. Hookworms are zoonotic to humans- this occurs when hookworm larvae (Ancylostoma) penetrate human skin when people come in close contact with contaminated soil. As the hookworm migrates under the skin this can cause a skin infection called cutaneous larval migrans; this causes itchiness, irritation and a development of long linear lesions under the skin.
Tapeworms: (Taenia and Dipylidium caninum)- Tapeworms are a type of worm called Cestodes. They have long flattened bodies that resemble a tape or ribbon. The body is comprised of a small head connected to a series of segments called proglottids that are filled with eggs. The adult tapeworms lives in the small intestine. Its head is embedded in the mucous lining, and survives by absorbing nutrients from the host. As the segments at the end of the tapeworm fully mature, they break off into the cats feces. The segments can be found near the cat's tail and rectum. The segments resemble grains or rice when fresh and if the segments become dry they resemble sesame seeds. In a microscopic exam of stool you may not find evidence of tapeworms, since the eggs are not singly shed but as a group of segments. Rodents and fleas become infected by eating tapeworm segments in the environment, then cats usually become infected when ingesting rodents or eating an infected flea while grooming.
Protozoan Parasites: Types of these kind of parasites that are common in cats are Isospora, Giardia, and Toxoplasma. Protozoans are single celled organisms. Isospora causes the disease coccidiosis. Virtually all cats become infected with Isospora felis at some point in their lives. Cats usually become infected with this parasite by eating the cyst that has been passed in the feces and has matured in the soil. They can also become infected by eating either flies or cockroaches that carry infective Isospora cysts. Isospora usually does not cause harm in adult cats, but the parasite in kittens can make them extremely sick. Kittens infected with coccidia may experience destruction of the lining of the intestine which causes diarrhea with mucous. Giardia parasitize the small intestine of cats. The prevalence of Giardia infection in cats is about 5%, but can be higher depending on where they live. Cats become infected by ingesting Giardia cysts present in feces of another infected animal, usually a littermate. Giardia is more common in multiple cat households and catteries due to mode of transmission, and infection rate is greater in cats less than one years old. After ingesting the cysts, it takes about 5-16 days before a cat will show signs of diarrhea. Diagnosis of Giardia and Isospora takes a microscopic exam of the stool to find the cyst. It can take multiple stool samples to find Giardia since cysts are not constantly shed in the stool. Infection of Toxoplasma is fairly common in cats, but the actual disease caused by the parasite is rare in cats. Cats can become infected by Toxoplasma by eating cysts in infected prey or other raw meat. The organism multiples in the small intestine and in about two to three weeks the spores (called oocysts) are excreted in the infected cats feces. The oocysts take about 1-5 days to become capable of infecting another host after being shed in the feces. Toxoplasma is zoonotic can transmit to humans; it is most dangerous to immunocomprised and pregnant women, and pregnant women contracting Toxoplasma can cause severe birth defects in their unborn child.
Keeping your cat free of intestinal parasites is not very complicated. For outdoor cats, it involves a quarterly deworming. Kittens should have a series of dewormings done and two fecal checks where there are no parasite eggs seen. Every cat should have a yearly fecal check to make sure they are continuing to be parasite free. Parasites can burrow into tissues of your cat and lie dormant for years. Once triggered, such as illness, stress, or pregnancy, these dormant parasites come out. It is important to eliminate your cats contact with intermediate hosts (birds, fleas, ticks, rodents and earthworms). Children, immuncomprised and pregnant women are most at risk for contracting intestinal parasites. Good hygiene is keep in prevention of parasites in humans. Pregnant women should avoid cleaning the litter box when pregnant. Keeping a cover on children's sandboxes gives greater protection since parasites thrive in these locations. Make sure to teach young children good hygiene when handling your kitty and to always wash hands after outside activities.