Worms in Cats & Transferring to Humans

Roundworms

• Roundworms are nematodes that infect a cat's intestine and digestive system. Roundworm infection is common and has few symptoms. In humans, infection occurs by exposure to roundworm eggs from an infected cat's fecal material. Ingestion must occur for these worms to spread, so infections are most commonly seen in children who play in kitty litter or sandboxes where a cat has defecated, then placed dirty hands in their mouths. Once ingested, the eggs hatch and the worms migrate to body tissues, but they rarely cause fatal reactions.

Hookworms

• Hookworms are nematodes that live in the cat's small intestine, and infection can cause anemia and damage to the intestinal walls, according to the Merck Veterinary Manual. Hookworm larvae are also present in infected cat fecal material, but ingestion is not necessary for infection. Usually hookworms directly penetrate the skin through bare feet. After burrowing below the skin, they cause cutaneous larval migrans, characterized by pain and swelling. Hookworms die after several weeks and the infection is not fatal, just annoying.

Tapeworms

• Tapeworms are spread from cats to humans via infected fleas. Tapeworm larvae are ingested by a cat either directly or through another infected animal, and they live in the intestine. Infection is characterized by weight loss and is fairly common in outdoor cats. To get a tapeworm infection from a cat, a human must ingest an infected flea, and it usually only occurs in young children. Tapeworms are easily cured with medication.

Ringworm

• Ringworm is a skin infection not caused by a worm but a fungus and is characterized by loss of fur, red rings on the skin's surface and itchy or irritated patches. Since ringworm is a fungus and not a parasite, humans are infected when they pet or touch a cat with ringworm. In humans, the infection results in a rash and is easily cured with oral and topical medication.

Heartworm

• Heartworm infection is rare in cats and occurs in both outdoor and indoor cats via a mosquito host carrying heartworm larvae. Infection in humans is extremely rare, and usually harmless. According to the American Heartworm Association, symptoms include loss of appetite, weight loss, lethargy, coughing or wheezing and difficulty breathing. Heartworms are easily avoided through monthly medication regiments and are treated with corticosteroids.

Lungworm

• Lungworm infection in cats occurs when a cat ingests an infected bird or rodent. Lungworms cannot be passed to humans. Symptoms are characterized by coughing or wheezing accompanied by weight loss and is difficult to diagnose. Treatment involves anti-parasitic drugs and must be tailored to the level of infection in each cat.