BABESIA GIBSONI: A TICK-BORNE PARASITE AFFECTING DOGS

The exotic (from overseas) red blood cell parasite Babesia gibsoni has been found in 3 dogs in Christchurch. Find out about this parasite, what we’re doing about it, and how you can help us.

Babesia gibsoni is a parasite that primarily affects dogs and can lead to the disease babesiosis which can cause anaemia, lethargy and other symptoms.

It was found in a dog in Christchurch at the end of March 2024 and investigations since have revealed 2 further affected dogs from the same connected group.

We’re working to find out how the dogs became infected with this parasite not previously found in New Zealand and determine if there are other cases.

We still consider the risk of this disease being widespread is low but as the parasite can be spread by tick bites, we recommend dog owners ensure their animals’ flea and tick treatments are up-to-date.

Vets should contact us if they come across any suspected cases on freephone 0800 80 99 66.

What is Babesia gibsoni?

Babesia gibsoni is a parasite that mainly affects dogs. It is widespread around the rest of the world, including Australia. Infection with the parasite can cause the disease babesiosis, which is mostly mild and without symptoms, but in some cases can be severe.

How is it spread?

Babesia gibsoni is blood-borne and spreads where there is transfer of blood between dogs. It can be transmitted by ticks from dog-to-dog through bites from the New Zealand cattle tick (Haemaphysalis longicornis). Ticks that are exotic to New Zealand, such as the brown dog tick (Rhipicephalus sanguineus) also spread this parasite.

Along with ticks, Babesia gibsoni can also be spread through dog bites, blood transfusion, and through the placenta from an infected mother to her pups.

In countries where Babesia gibsoni is widespread, the focus is on preventing infection by treating dogs with tick treatments (similar to flea treatments) and limiting fighting behaviour.

There are veterinary treatments available for infected dogs that reduce the risk of transmission.

What should dog owners do?

Dog owners should not be concerned. Most dogs with this disease will only experience mild symptoms, if any, and there are treatments to manage it.

It is important dog owners ensure their animals’ flea and tick treatments are up-to-date. A range of tick treatments or combined flea and tick products are available over the counter in New Zealand. Owners should ask their vets about the best product for their particular circumstances.

Babesia gibsoni can also be spread through dog bites, so we recommend limiting any fighting between dogs. If you have any concerns about your dog’s health, talk to your veterinarian.

What is Biosecurity New Zealand doing about the parasite?

Our investigation is focused on how the dogs in Christchurch became infected and understanding if there are any other cases in the country.

We have traced and tested contacts from the first known case (which was severely affected and was euthanised at the owners’ request) and the 2 further dogs that have tested positive. These 2 other dogs are not showing any signs of illness.

We know that the second dog we located through our tracing and testing, was imported to New Zealand 2 years ago. It met all importing requirements, including tests for Babesia gibsoni, which were negative.

The owners of this dog and the other positive dog have been issued with legal directions to take measures to manage any risk of spread.

Currently, we believe the risk of babesia being widespread in Christchurch’s dog population is low. We have tested a number of dogs who are close contacts of the original affected dog and subsequent affected dogs and have found no further positives.

We are asking vets and anyone else who works with dogs to help our investigation. Contact us if you have any suspected cases of Babesia gibsoni – freephone 0800 80 99 66.

How did B. gibsoni get into New Zealand and is it widespread?

Biosecurity New Zealand has robust measures in place designed to prevent Babesia gibsoni coming into New Zealand. All imported dogs must comply with import health standards (IHS) requirements, including veterinary inspections and treatments for external parasites, and serological or molecular testing for parasites.

In the Christchurch cases, one of the infected dogs had been imported, but met all the import requirements, including tests for Babesia gibsoni, which were negative. We are further investigating this.

What disease does B. gibsoni cause?

Many dogs do not develop symptoms of disease, but remain infected by the parasite. When disease does occur, it is referred to as babesiosis. The disease is often chronic and mild, but in some cases, it can be acute and severe. Chronic babesiosis often presents as intermittent fever, lethargy, and weight loss. Acute babesiosis is characterised by fever, lethargy, and anaemia.

Subclinical and recovered dogs often reach a balance where their immune system suppresses the parasite, preventing disease, but does not eliminate it. This means they may still spread the parasite and may develop disease in times of immune suppression.

What species are affected by B. gibsoni?

Dogs are the most affected species. Pit bull terriers, Staffordshire bull terriers, and greyhounds are the most commonly affected breeds.