Ticks are parasites that need blood to survive and reproduce. They feed off a range of hosts including mammals, reptiles, birds and amphibians. They may pose public health and biosecurity risks. This is because they can carry and spread human and animal diseases.

Health risks of ticks

We are not aware of any cases of people catching a disease from a tick bite in Aotearoa New Zealand. The main diseases of concern in some other countries are not currently present in Aotearoa. But there is the potential for this to change. For example, if disease carrying ticks arrive on travellers who have been in countries where they are present.

Diseases from ticks

The bite wound from the tick is not generally painful. But some people may have itching and redness around the area.

During the feeding process ticks extract the blood of their host. They regurgitate excess water from the blood back into the wound. This process allows diseases to be spread between a tick and its host.

In some countries ticks have spread diseases such as:

  • Theileriosis, caused by a protozoan pathogen.
  • Lyme disease, caused by Borrelia bacteria.
  • Spotted fever, caused by Ricketsia bacteria.
None of these diseases are present in Aotearoa New Zealand.  

The spread of disease does not happen straight away. Usually the infected tick does not begin to spread diseases until it has been attached and fed for 24 hours or more.

Treatment for tick bites

Treatments for tick bites vary. If the tick is still attached to a person’s skin, it should be removed immediately. The area where the tick has bitten should then be cleaned and disinfected. If you have any symptoms following a bite, such as flu-like symptoms or infection, you should contact your healthcare provider.

It is helpful to keep removed ticks for identification purposes. Different species spread different diseases.

How to prevent tick bites

You can do these things to prevent being bitten.

  • Cover up when you are not moving, particularly ankles and feet.
  • Apply an insect repellent regularly when outdoors. Repellents that have diethyl toluamide or dimethyl phthalate as the active ingredients are most effective
  • Avoid walking in dense vegetation — keep to tracks and cleared areas.

How ticks feed

Ticks are known for latching onto their hosts and feeding off them, which results in a wound.

Both sexes feed on blood. But only the female becomes greatly swollen during engorgement.

Often the larval stage, the nymph stage, and adults seek new hosts after they have molted on the ground.

Types of ticks

There are 2 types of ticks.

  • Hard ticks (Ixodids)
  • Soft ticks (Argasids). 

Hard ticks are easier to identify than soft ticks. They also spend more time attached to their hosts than soft ticks, who feed for a short period of time.

Aotearoa New Zealand has endemic ticks. This means they are found here, and nowhere else in the world. These species are host-specific and infest mainly birds.  Endemic ticks generally do not spread disease to people.  

There is also an introduced species of tick in New Zealand – the brown cattle tick. This tick can infest warm blooded mammals, such as cattle or humans. In some parts of the world the cattle tick is known as a carrier of of animal and human diseases, such as:

  • tick borne fever
  • Japanese (Oriental) spotted fever
  • Russian spring-summer encephalitis. 
These diseases are not present in Aotearoa.  

The ticks present in Aotearoa have shown the ability to spread pathogens, such as bacteria and viruses. This is rare and damage is mainly isolated to economic loss caused by heavy infestations.

Where ticks are found

Hard ticks prefer habitats with areas of vegetation, such as forests and fields, where females lay eggs on the ground. They may also be found in urban areas if there are unoccupied patches of grass.

Soft ticks generally prefer sheltered habitats and will hide in the nests of hosts.