parasites in cats

The three major groups of parasites which are a constant threat to our cats are worms, fleas and ticks. We will deal with fleas and tapeworms first as they are linked.


Fleas cannot be under estimated as a problem for cat owners. You do not want your cat to get fleas because:

  • They can cause severe irritation and skin disease in your cat.
  • Fleas can cause general illness, loss of weight and, in young cats, failure to thrive as a result of chronic blood loss.
  • They can transmit tapeworms to your cat.
  • They can lead to an infestation in your home which can take at least 3 months to clear.
  • Fleas can bite you and cause nasty skin disease in humans.
  • Fleas can harbour the Bartonella infection (also known as cat scratch disease) which can also be transmitted to humans by a scratch from an infected cat.

The flea life cycle

  • Dog or cat fleas jump onto an unprotected cat.
  • They feed on your cats’ blood.
  • Female fleas lay on average 20 eggs per day which fall off into the environment.
  • These hatch and the larvae crawl away infecting your home!
  • These larvae pupate and eventually hatch into adults but this may take up to 6 months.
  • An adult flea needs a daily blood meal to survive, but if living on a cat which has not been protected, the fleas can live for 160 days - that is potentially 3,200 new fleas! (although the average flea probably lays a maximum of about 500 eggs in a lifetime)

You can see how easy it is for a flea infestation to take hold in your home.


Once a cat has fleas, it is almost inevitable that it will end up with tapeworms. Cats can get tapeworms by grooming themselves and ingesting the fleas which are intermediate hosts for the tapeworm species Dypilidium caninum. They can also get Taenia species of tapeworm from hunting and eating intermediate hosts such as mice and voles. These tapeworms are long flat worms with many segments. The segments break off and are passed out in the faeces, or crawl out of the anus. These are then eaten by the intermediate hosts and the life cycle continues.


Toxacara cati are large worms measuring as much as 10 cm. They resemble small spaghetti and adults live in the intestine. It is the worm that commonly affects all kittens as it is passed down via the mother’s milk. Kittens with large worm burdens can be severely affected. Like dogs, adult cats tend to have fewer worms but there is no absolute prevention in adults, so we should bear this in mind even when dealing with house cats. This especially applies to hygiene when dealing with litter trays. Humans can be infected by ingesting infective eggs, and zoonotic disease (a disease which can be transmitted from animal to human) can result. This is the worm responsible for causing blindness in rare cases in humans.


As with dogs, ticks follow the same life cycle. Immature ticks (nymphs) climb up grasses, find a host passing by and change by moulting into an adult tick. The adult tick eventually finds its final host and will attach itself to the unsuspecting moggy. As cats are likely to put their faces into everything including small furry animals acting as hosts to ticks, they very easily pick up ticks on their face and neck. Ticks can transmit disease by infected saliva and heavy infestations can lead to anaemia through blood loss.

Find out how you can check your cat for parasites in our next blog >