There are three parasites that commonly affect pets – fleas, ticks and worms:

Fleas are small, just a few millimetres long, and are usually brown – pet owners may be able to see them in their pet’s fur. Fleas can’t fly, but they do move quickly and can jump from animal to animal or to surrounding areas. Fleas feed on a pet’s blood, can transmit diseases such as ‘cat scratch disease’ (bartonellosis), and they can be infected with tapeworm.

Ticks are members of the spider family. They attach to the pet and cut vessels under the skin to feed on blood. They are around 2.5mm long, but their size can increase to around 10mm when they feed. They can carry and transmit organisms that cause infections, such as Lyme disease, which can also affect humans.

Worms are parasites that live inside an animal. Pets can pick up the eggs from soil, carcasses, faeces or infected meat. A female animal that is infected with roundworm may also pass the infection on to her young. The most common worms are the intestinal roundworms and tapeworms, but there are many others such as whipworm, hookworm, lungworm and heartworm. Some worms can also infect humans. The rare illness toxocariasis is caused by roundworm parasites.