Parasitic worms are an extremely common parasite in cats. There are several types of worm that commonly affect cats which include:
What is toxoplasmosis?
Toxoplasmosis is an infection caused by the intracellular parasite Toxoplasma gondii. It infects multiple warm-blooded animals including humans, livestock, and birds (all of whom act as intermediate hosts). Cats are the only definitive hosts to T. gondii, which means that the parasite is only able to sexually reproduce in felines (both wild and domesticated).
What are threadworms?
Also known as pinworms, threadworms (Strongyloides) are small worms which live in the small intestine, they are around 1/8 to 1/5 of an inch long.  There are several dozen species of threadworms, cats are most commonly affected by Strongyloides stercoralis. Threadworm is a rare infection in cats, and humans are believed to be a major source of infection for cats with S. stercoralis. 
Tapeworms at a glance
What are tapeworms?
Tapeworms are flat, segmented worms with hooks that anchor the worm to the wall of the small intestine, where it feeds on nutrients the cat ingests.
What is notoedric mange?
Also known as feline scabies, notoedric mange is a highly contagious and intensely itchy skin disease caused by the mite ‘Notoedres cati‘. These mites are closely related to the Sarcoptic mange mite, which causes mange in dogs.
What are lungworms?
Lungworms are slim, hair-like worms that are approximately 1 cm in length. There are several species of lungworm; however, the most common to affect cats are:
- Aelurostrongylus abstrusus – Feline lungworm.
- Capillaria aerophila (Eucoleus aerophilus) – Feline and canine bronchial capillarid.
Cat worms at a glance
- About: Parasitic worms can infect cats, the most common are tapeworm, hookworm, roundworm and heartworm.
- Transmission: This varies from worm to worm but can include fleas, hunting and contaminated environment.
- Diagnosis: Most worms can be diagnosed by the presence of eggs in the feces. A blood test is used to detect heartworm larvae in the blood.
- Treatment: Anti-worming medications are used to treat most worms. Heartworm treatment can be dangerous, and in most cases, supportive care is given.
Giardia at a glance
- About: Giardia is a parasitic protozoan infection of the small intestine affecting many mammals.
At a glance
About: Flea allergy dermatitis is a hypersensitive reaction to proteins in flea saliva which it injects into the skin when it feeds.