A new disease has emerged in Australia, with Ehrlichiosis detected in Western Australia and the Northern Territory in 2020, and in January 2021, ticks infected with the bacteria were found in South Australia’s far north. So far in WA it has been detected at Halls Creek, Kununurra, the Kimberley regions of Broome and Derby, and in the Pilbara regions of South Hedland and Port Hedland. In the Northern Territory, reports have been made in both Katherine and west of Alice Springs. With many of our hunters loving a road trip and itching to get away after lockdown, we thought it important you should all be aware of the emergence and risks if you are travelling north with your 4-legged furry mates.
E. canis (ehrlichiosis) occurs throughout the world, mainly in tropical and subtropical regions. Infection with E. canis (ehrlichiosis) however, was only confirmed for the first time in Australian dogs in 2020. It is spread via tick bites, usually the brown dog tick (Rhipicephalus sanguineus). When the tick feeds on a blood meal from the dog, along with the saliva injected by the tick, if the tick is infected with E.canis it can be transmitted to your dog. Infected dogs do not directly transmit the disease to other dogs; transmission only occurs through infected ticks which are widespread in mainland Australia and Tasmania. Thankfully, the bacteria is not commonly found in cooler areas, however it is not impossible and dog movements are being restricted in numerous areas up north to try to reduce the risk of spread. Many of these areas where affected dogs have been detected also have travel restrictions in place, so if you are considering a hunting trip check with the local vets or Dept of Agriculture for information on permitted travel. A number of the state governments are also running surveillance programs in areas where ticks carrying Ehrlichia have been detected.
Signs of ehrlichiosis
Ehrlichiosis has three possible phases of disease: an ‘acute’ phase or early signs of disease, a ‘subclinical phase’ where there are no obvious signs of disease, and a ‘chronic’ or long-term stage with severity of the disease varies considerably.
Acute or early phase
Initial signs of infection are non-specific and may last 2-4 weeks. The dog may have inappetence (disinterest in food), fever, lethargy (reduced activity or tired), swollen lymph nodes, weight loss or unusual bleeding or bruising. Just “being a bit off” is what is commonly noticed by the owner. Several other diseases like Babesia and Anaplasmosis (which we already have in Australia), rodenticide/rat bait toxicity, immune mediated bleeding disorders and more can present with similar signs. Letting your vet know if you have travelled through at-risk areas is essential to assist us in diagnosing this issue in your dog, after all it is new to us too.
Acute disease develops about 1–3 weeks after the tick bite, but the chronic form of ehrlichiosis may not appear until months or years later.
Some dogs that recover from the acute phase no longer look sick, showing mild or even no obvious early signs. The subclinical phase can last for months to years. These dogs may recover, remain infected without visible disease signs, or advance to the chronic form of the disease.
Only some infected dogs will go on to relapse and develop the “chronic” form of ehrlichiosis. Chronic disease signs are similar to those in the acute phase but are usually more severe. They can include intermittent fever, weakness, weight loss, unusual bleeding or bruising, including blood from nose, pale gums, runny eyes and nose. As you can imagine, these are not specific signs and so may be quite confusing for vets to work through to obtain a diagnosis if they do not know you have travelled to at-risk areas, even if it has been years before. Appropriate history makes all the difference in getting a speedy diagnosis and specific treatment. Infected dogs may be more likely to develop other infections at the same time as they are run down and this can also confuse things further. The chronic form of the disease can be fatal.
Diagnosis, treatment and prevention
Infection with E. canis (ehrlichiosis) is a notifiable disease in Australia. This means if you think a dog has ehrlichiosis, you must call your private vet, DPIRD vet or the Emergency Animal Disease hotline on 1800 675 888.
Your vet will take blood samples for testing to confirm a diagnosis of ehrlichiosis. Blood tests are needed as the disease can look like other tick-borne diseases in dogs.
Ehrlichiosis is treated with antibiotics, supportive care and may require hospitalisation depending on the severity of the infection. Early treatment by your vet will provide the best opportunity for recovery.
To help prevent your dog contracting ehrlichiosis, if you need to travel to these areas, treat your dogs for ticks before you go and regularly while away according to the manufacturer’s directions.
Talk to your vet about the tick treatment that is right for your dog – some products are longer lasting and/or quicker acting, and there are choices from chews, spot-ons and collars. We do not generally recommend rinses as if the dogs get wet, the benefit will wash away.
If you have a long-hair breed of dog, consider a haircut before you go to make finding ticks easier. Check your dogs for ticks regularly (especially around the neck, head, ears, armpits and belly) and carefully remove any ticks. This is important as tick treatments may not always kill the tick fast enough to stop the dog becoming infected.
Your vet can advise on the best methods of tick removal but carrying a set of tick-tweezers in your first-aid kit is cheap and easy.
Humans can also be at risk! While infected dogs do not directly spread Ehrlichia to people, in rare cases, infected ticks may transmit E. canis to people. See the WA Department of Health website for information on human health implications associated with ticks, as well as prevention, removal and first aid advice.
Below are sites where you can access ehrlichiosis information provided by your state or territory biosecurity authority.