How to prevent pet parasites

Fleas, ticks, worms and other parasites are more than just an annoyance to your pet. They can cause health problems and serious illnesses.

Parasites thrive in warm and humid conditions. As daily temperatures reach 20°C – 30°C and humidity levels increase beyond 50%, fleas and ticks become more active.

That means pet parasites are more active in the warmer spring, summer and autumn months. But they can be a problem during winter, too.

Some adult parasites, larvae and eggs can survive in freezing temperatures for extended periods. Others will make themselves at home in your indoor spaces, where it’s cosier than the outdoors.

Preventing fleas, ticks, worms and other parasites in your pet cat or dog is a year-round responsibility. A vet-recommended treatment and a good cleaning routine are the best ways to prevent parasites from making your pet unwell.

Who are the pesky parasites?


Fleas are very small, wingless, brown-coloured parasites that bite skin and suck blood to survive. They’re a bit like tiny vampires with incredible jumping abilities. Adult fleas only account for 5% of the population. The other 95% are eggs, larvae or pupae, and they live in bedding, carpet, soft furniture and floorboards.

As well as itchy skin and fleabites, if left untreated, fleas can give your pet major diseases, such as anaemia or Bartonellosis, that could be fatal.


Ticks are tiny and wingless, with harpoon-like mouthparts. They can’t jump like fleas, but they can walk, climb and fall. An adult tick saws the host’s skin before inserting its hypostome. Then it sucks out blood and secretes glue-like saliva, which helps the tick to hang on to its host.

Ticks are most likely to be found under your pet’s collar, inside ears, between toes or along the gum line. Tick bites can cause illnesses, diseases, paralysis, and in extreme cases, can be fatal to cats and dogs.


There are four common types of parasitic worms common in cats and dogs in New Zealand. These worms cause a range of illnesses and symptoms like loss of appetite, coughing, breathing issues, a swollen tummy, anaemia, vomiting and diarrhoea. Like other parasites, if left untreated, worms can be fatal to your pet.

  • Roundworms are the most common type of worms in dogs and cats. They live in the intestines and can produce 250,000 eggs per day. The eggs are shed in cat and dog faeces and can live in the soil for years.
  • Hookworms can infect cats and dogs. They feed by sucking blood and can live up to two years inside your pet’s small intestine. Puppies can be infected through their mother’s milk.
  • Whipworms have a whip-like shape and typically infect puppies 4+ months old and adult dogs. They eat blood, fluid and tissue inside the intestines.
  • Lungworm can infect cats and dogs. Pets can become infected if they eat infected creatures like frogs, snails or slugs. Mature larvae can move around the body and eventually end up in and around the lungs, where mature lungworms lay their eggs. These eggs are coughed up, swallowed and will exit the body via the pet’s waste, which can infect other animals.
  • Tapeworm There are many different tapeworms, but flea tapeworms are the most common. Infections can happen when your cat or dog eats an infected flea. They’re unlikely to cause clinical disease but can cause diarrhoea and some discomfort. Tapeworms can grow to be 50cm long! Yuck!

How your cat or dog can be infected with fleas, worms or ticks

The most common causes of parasite infection in cats and dogs are:

  • Exposure to infected dirt or animal poo
  • Eating uncooked meat or offal
  • Exposure to an infected area – parasites can live in your carpets, soft furnishings and other cosy hide-outs!

5 tips to prevent flea, tick and other parasites from making your pet ill

Prevention is the best protection against fleas, ticks, worms and other parasites.

Start treatment immediately if your pets show signs of being an all-you-can-eat buffet for munching fleas or parasites. If your pet is scratching a lot, is vomiting and/or has diarrhoea or is generally unwell, it’s always best to talk to your veterinarian as soon as possible.

  • Spring clean. Hot wash your pet’s bed, blankets and soft toys to help kill parasite eggs. Clean their food and water bowls regularly. In average New Zealand conditions, it can take up to 3 months to rid your house of a flea population. If you’re still struggling to get on top of the problem after that time, you might want to contact an exterminator.
  • Go to town with the vacuuming to get rid of flea eggs. Get under the beds and furniture. Pay particular attention to low-traffic areas like skirting boards and inside wardrobes. That will get rid of most of the eggs and the vibrations will encourage flea eggs left behind to hatch (this is a good thing; adult fleas are easier to get rid of).
  • Don’t leave poo in outdoor areas. It’s best to put cat and dog poo into a landfill as soon as you can. Parasites and eggs can live outdoors for a long time. So, leaving pet poo in your garden or putting it in your home compost isn’t a good idea.
  • Be wary of what your pet eats. Faeces, slugs, snails, frogs, uncooked meats and sick prey animals could all be a source of parasite infection or other illnesses.
  • Preventative treatment. Talk to your veterinarian about what is right for your cat or dog. While there are plenty of preventative treatments on the market, not all products do the same job. Flea collars only repel the pests, while there are other treatments that are absorbed into your pet’s bloodstream. When a flea bites your pet, the flea dies rapidly. Once treated with an effective product, your pet becomes a furry vacuum, attracting fleas and quickly dealing with the problem.

Other common questions about pet parasites

Can pet fleas infect humans?

There are many kinds of fleas. The types you’re most likely to find on your cat or dog are attracted to your pet’s fur. Pet fur is a great place for these little parasites to hide, feed and breed. Fleas don’t live on humans because we don’t have fur – there’s nowhere for them to hide. (Human hair doesn’t feel cosy to a flea).

Nevertheless, fleas can bite humans. They often bite on the feet, ankles and legs in three rows. It’s jokingly referred to as ‘breakfast, lunch and dinner. Flea bites irritate your skin and can become infected, potentially causing a more serious health condition. If this happens, talk to your doctor or medical health professional.

Can cat and dog worms infect humans?

Humans can contract worms from cats and dogs.

Depending on the type of worm or parasite, humans can become infected when they accidentally eat a microscopic egg, larvae or worm-infected flea. Some worms, like hookworm, can burrow into our skin, causing irritation and itching.

Humans are most likely to ingest these tiny eggs, larvae and worm-inflected fleas if we’ve been gardening, playing in the dirt, or walking barefoot in an infected area. Thoroughly washing your (and your children’s) hands after contact with the soil is important. If your pet (or furry visitors like a neighbour’s cat) often poos in your garden, wear gloves when gardening, clean the area regularly and avoid walking around barefoot.


Companion Animal Parasite Council (CAPC), Resources and FAQs, (accessed August 2022),
Jason Drake & Tom Carey, Seasonality and changing prevalence of common canine gastrointestinal nematodes in the USA, Parasites & Vectors 12, 430 (2019), (accessed August 2022),
Matamata Veterinary Services, Worming for cats and dogs, (accessed August 2022),
Advantage Petcare Australia, Worms in dogs and cats: Myths vs. facts, (Accessed August 2022),

Though infection is more common in spring and summer, parasites can infect your pet anytime. It’s a good idea to talk to your veterinarian about year-round flea and tick control. And to avoid unexpected costs, make sure your pet is insured.