The most common parasites that will affect your cat are worms (roundworm, tapeworm, ringworm), fleas, ticks, and ear mites.  Below is a description of each.  You should speak to your vet if you suspect your cat develops any of the symptoms, and all kittens should be given preventative medication for worms. 

Roundworm
Most kittens are born with roundworms, which are long, white, and string-like in appearance. A cat may also get these worms if they happen to hunt and eat a rodent, bird, or insect that has already ingested worms. The worms will appear whole in the cat's feces, and most of the time they will still be alive. Symptoms of ringworm include a dull coat, diarrhea, vomiting, coughing, and a pot-bellied appearance. 

Tapeworm
Most common in adult cats, this worm has a long body that is made up a flat segments that look like rice grains.  It has a flat head that fastens onto the intestinal walls of the cats.  The segments that make up its body break off and are passed in the cat's feces and eggs are released.  Tapeworms may be spread by an intermediate host, such as a flea, small rodent, or a bird.  If the cat eats the infected prey, most commonly a flea, the worm larvae hatches in the cat's gut and develops into an adult worm, starting the cycle described above.  Symptoms of tapeworm may be weight loss, digestive upsets, anal irritation, and segments are sometimes found in the hair around the anus.

Ringworm
Ringworm is a contagious skin condition caused by fungus.  Other cats, rats, mice, or hedgehogs may pass this onto your cat, or he can catch the fungus from objects harboring the spores.  The most commonly infected areas are the head, ears, forelegs and paws, where small circular scaly bald patches will be present. However, sometimes there are no symptoms at all.  If your cat exhibits these symptoms, take him to the vet immediately where he can be treated with shampoo or tablets.  Ringworm is contagious to other animals as well as humans, children being more at risk than adults due to their delicate skin.  Circular red patches on the skin, mainly around the hands or arms, are signs of ringworm and you need to see your doctor as soon as possible.

Fleas
Fleas can be present on indoor pets as well as outdoor pets, and they are generally at their worst about five to six weeks after the weather starts to get hot.  To try to keep fleas to a minimum, sprays can be bought and furniture (especially around the skirting boards) and bedding should be washed and vacuumed on a regular basis.  Adult fleas can live for 7-14 days, feeding and reproducing on your cat, and females can lay several eggs a day, many which fall off of your cat.  Within two to five days the eggs hatch and tiny larvae hide in carpets, furniture, or other dark places.  This larvae then develops into pupae, which can live for months without being noticed, until a suitable host comes along.  The flea then emerges from its cocoon and climbs onto its host, starting the cycle all over again.  If your cat scratches a lot, he probably has fleas.  You should regularly check his fur by combing through it with a flea comb. You will either pull out fleas with the fur, or you will see lots of black specs, called flea dirt. Fleas feed on your cat's blood and what you are seeing is the flea's feces. 

If you should happen to pull out fleas on the comb, pull the hair out and deposit them in a bowl of hot water, submerging the flea to kill it.  You need to speak to your vet about obtaining flea medication, which is thick liquid administered monthly on the back of your cat's neck (if he accidentally licks it, he will foam from the mouth - don't worry, he won't be harmed).  You should never buy flea medication from any place other than your vet - you cannot be certain what is in generics and this might result in the medication not working or your cat could get sick.  The flea medication should be put on and allowed to dry before your cat lays in any favorite areas or on bedding.  Before putting on the medication it is recommended that you give your cat a bath using dishwashing liquid (our favorite is Ivory), starting at the neck (where fleas commonly are found) and moving down his body.  The foam from this soap suffocate fleas and make them fall off of your cat, giving you a better base to start off with.  Make sure you completely rinse the soap off of your cat, as this soap can dry out his skin.  A day or so after you put the flea medication on your cat, you should start to flea comb him regularly to pull off any fleas that might be running around on him.

There are a few health problems that your cat can develop when it has fleas.  They can have a reaction to flea saliva and develop Flea Allergy Dermatitis (FAD), which will cause severe itching, scabs, and bumps.  Anemia can occur in young, old, and sick pets and can be life threatening.  If your cat ingests fleas, tapeworms may hatch in his belly (your vet can give you medication to kill them).  Your cat can also develop Rickettsiosis, which can be passed onto humans.

Ticks
Ticks, which are blue-gray in color and resemble a small bean, are most commonly found in rural areas where there is dense vegetation, hedgehogs being the main carriers of them in towns and cities.  They attach to your cat's skin and feed off of its blood.  These parasites can grow to be half an inch long and are sometimes mistaken as cysts or tumors.  If you find a tick on your cat, never pull it off, which can cause its head to be left inside your cat and could lead to an abscess.  The most popular way to remove a tick is to use a flea/tick spray, such as Frontline.  You can also dab the tick with surgical spirits or coat with Vaseline, which will cause it to suffocate and fall off. 

Ear Mites
Scientific name: Otedectes Cynotis. Ear mites are common external parasites of cats.  They are tiny crab-like parasites that can be found living inside the ear canal, a place that is hard for the cat to groom.  Ear mites can also be found on other places of the body, such as on the skin of the cat's neck, face, and feet.  They feed on tissue debris and tissue fluids rather than blood.  Ear mites are very contagious, and they can be passed between species (i.e. between a cat and a dog).  Humans can also be used as transient carriers to other animals.  Most cats will encounter ear mites at some point in their life, kittens and younger cats mostly because they have less of an immunity. Young cats sometimes pick up the mites from their mothers.  Severe infestations cause irritation and an excessive production of brown wax, causing concrete-like encrustations in the ear.  The cat will then scratch or shake his ears, causing inflammation or possibly haematoma (ruptured blood vessels which lead to swelling causing permanent crinkling of the ear). 

If you suspect your cat has ear mites, you need to have a vet examine him.  Ear mites are only visible by using a magnifying otoscope - the warmth from the light draws the mites out from the wax and makes them visible to the vet.  The vet will then clean out your cat's ears and prescribe medication, usually in the form of eardrops.  These will kill the adult mites but not their eggs, so it is essential to continue treatment for at least one month to cover the 21 day cycle of the ear mite.  If your cat's skin is affected you will have to apply topical clean, and because ear mites are so contagious all animals in the house will need to be treated even if they don't show symptoms.  Ear mites should never be left untreated; failure to treat them could lead to secondary infections or loss of hearing.  You should clean your cat's ears once a month to prevent parasite problems.