While humans were busy worrying about the spread of COVID in 2020, another disease had quietly started to spread through dogs in northern and western Australia.
Ehrlichiosis [er-lick-ee-oh-sis] is a disease spread through the bite of an infected brown dog tick and has been detected in more than 300 dogs in the Kimberley region of Western Australia and in Katherine in the Northern Territory since May 2020.
In January 2021, Australia’s chief veterinary officer reported that brown ticks infected with ehrlichiosis had been discovered in South Australia.
What is Ehrlichiosis?
Ehrlichia canis is a bacteria carried by brown dog ticks that infects dogs causing a disease known as canine monocytic ehrlichiosis (CME), or as it is more commonly known, ehrlichiosis. This bacteria is found throughout tropical and subtropical regions of the world and is endemic in Southeast Asia.
The E canis bacteria was originally discovered in Algeria in 1935 and later caused huge problems for the US and their allies during the Vietnam War (1955-1975) when large numbers of military dogs became infected and subsequently died.
Where Are Brown Dog Ticks Found in Australia?
Brown dog ticks can be found across a large part of Australia including the northern and coastal parts of Western Australia, the vast majority of the Northern Territory, the vast majority of Queensland and part of northern New South Wales. Some maps, such as the one below, indicate that brown dog ticks have been found as far south as Sydney and Melbourne. More regular warmer weather will mean that the distribution of the brown dog tick will continue to spread south.
The red area shows where brown dog ticks have been found in Australia
Three Phases of Ehrlichiosis Infection
The acute phase of ehrlichiosis infection occurs 1-3 weeks after a dog has been bitten by an infected tick. Dogs will display mild symptoms that last between 2-4 weeks such as lethargy, weight loss, loss of appetite, fever, swollen lymph nodes, swelling of the chest or legs, or unusual bruising or bleeding.
The subclinical phase of infection occurs after the acute phase and dogs may appear to have recovered as they show only mild or no symptoms. This phase can last anywhere between a few months up to a few years. Some dogs will progress to the third, chronic stage of infection, and some will recover and eliminate the bacteria.
The chronic form of ehrlichiosis has similar symptoms to the acute phase of the disease, but they are more severe. As well as the symptoms listed under the acute phase, dogs may also develop pale gums, difficulty breathing, eye or neurological abnormalities, runny eyes or a runny nose, weakness, and may also suffer from bleeding from the nose. Dog’s in the chronic stage of infection are also very susceptible to other infections. The chronic stage of ehrlichiosis can be fatal.
Diagnosis & Treatment
Ehrlichiosis is diagnosed with a blood test as it has very similar symptoms to other tick-borne diseases such as babesiosis and anaplasmosis. It is treated with a long course of antibiotics and severely unwell dogs may require hospitalisation and further supportive care such as blood transfusions.
If a dog is found to be infected with ehrlichiosis, it must be reported to the national Emergency Animal Disease Watch hotline. If you dog has been seen by a veterinarian and diagnosed with ehrlichiosis, your veterinarian will usually make this report on your behalf.
Protect Your Dog
There are several things you can do to protect your dog from ehrlichiosis. If you are able to, avoid travelling to regions where infected ticks have been reported. So far, the disease has been confirmed in dogs in Halls Creek, Kununurra, Broome, Derby, South Hedland and Port Hedland in Western Australia and Katherine and a remote community west of Alice Springs in the Northern Territory.
Check your dog daily for ticks, especially if you live in a region where brown dog ticks or other ticks are known to live. Run your fingers all over your dog and through their coat feeling for lumps or bumps. Brown dog ticks like to attach to the areas of the head, neck, inside ears, chest, armpits, belly and between the toes and around the gums and mouths of dogs.
If your house or yard has a tick infestation, it needs to be treated by a pest controller. Brown dog ticks love to live in cracks and crevices around the house and can hide in kennels, door and window frames and skirting boards. Ticks are brought into houses and yards from the bush, and can survive for months between feedings. If your yard is adjacent to bushland areas, consider creating an empty corridor between the two at least 1 metre wide to prevent ticks from venturing into your yard.
Choose protection that kills the tick before it can bite your dog and infect it. Tick collars and certain spot-on preventatives kill ticks on contact and don’t require the tick to bite your dog before the active ingredient starts to work. If you are using a chewable preventative for your dog, and you live in a region where ticks are prevalent, a tick collar would be an ideal choice to ensure your dog has the lowest possible chance of picking up a tick.