Ehrlichiosis in WA
Infection with ehrlichiosis was confirmed for the first time in Australian dogs in May 2020 in the Kimberley region of WA.
The disease has also been confirmed in dogs from the Pilbara, Gascoyne and northern Goldfields of WA, northern South Australia and Queensland.
Ehrlichiosis is a serious tick-transmitted disease of dogs that was considered exotic to Australia until recently. Ehrlichiosis disease of dogs occurs when a brown dog tick (Rhipicephalus sangineus) infected with the bacteria, Ehrlichia canis, bites a dog. Dogs do not directly transmit the disease to each other. The disease is maintained by a cycle of transmission between ticks and dogs.
Ehrlichiosis occurs around the world, particularly in tropical and subtropical regions, and is known to be active in northern WA.
There is no vaccine against ehrlichiosis. Prevention of ehrlichiosis in endemic areas requires dogs to be on an effective tick control program, using products that repel and kills ticks before they attach.
Ehrlichiosis is treated with antibiotics, supportive care and may require hospitalisation depending on the severity of infection. Early treatment by your veterinarian during the acute phase of the disease provides the best chance of recovery. However, a dog who is diagnosed with acute or subclinical ehrlichiosis is considered potentially subclinically infected for life, even after treatment.
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. The severity of the disease varies considerably with the phase.
Acute phase
The acute phase of the disease develops about 1-3 weeks after the tick bite and typically lasts for 2-4 weeks. Initial signs of infection are non-specific and may last 2-4 weeks.
The dog may have:
- fever
- lethargy
- swollen lymph nodes
- loss of appetite
- weight loss
- discharge from nose and eyes
- unusual bleeding or bruising.
Subclinical phase
Some dogs appear to fully recover from the acute phase and no longer look sick but are actually in the subclinical phase of the disease, as the bacteria can remain in the spleen or bone marrow for years. The dog may test negative to blood tests as the bacteria is not in the bloodstream in this phase. Dogs may stay in this phase or progress to the chronic form of the disease.
Chronic phase
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 more severe, and often untreatable. They can include:
- fever
- weakness
- weight loss
- unusual bleeding or bruising, including blood from nose
- pale gums
- discharge from nose and eyes.
Chronically infected dogs may be more likely to develop other infections at the same time such as dental infections or wounds that fail to heal. The chronic form of the disease carries a poor to grave prognosis and is often fatal.
Other tick-borne endemic diseases such as anaplasmosis and babesiosis can also present similarly to ehrlichiosis, as well as certain cancers (lymphoma, multiple myeloma) and the bleeding disorder immune-mediated thrombocytopaenia.
E. canis is no longer classified as a notifiable disease under the Biosecurity and Agriculture Management Act 2007.
Diagnostic testing on a fee for service basis can be arranged through the department’s Diagnostic Laboratory Services or Vetnostics.
Private veterinarians are requested to submit the animal pathology general fee for service submission form to DDLS when submitting samples for Erhlichia canis testing.
Laboratory fee exemptions do not apply.
While infected dogs do not directly transmit ehrlichiosis to people, in rare cases, infected ticks may transmit ehrlichiosis to people. See the Western Australian Department of Health website for information on human health implications associated with ticks as well as prevention, removal and first aid advice.
Ehrlichiosis is no longer regulated in WA and there are no interstate and intrastate movement conditions of dogs.
Dogs develop ehrlichiosis after being bitten by a brown dog tick (Rhipicephalus sanguineus) infected with the bacteria, Ehrlichia canis. The brown dog tick is widely distributed worldwide and is present across the centre and northern parts of Australia.
Dogs do not directly transmit the disease to each other. The disease is maintained by a cycle of transmission between ticks and dogs.
How can I help prevent ehrlichiosis?
To help prevent ehrlichiosis occurring:
- Where possible, avoid taking your dogs into brown dog tick-infested areas.
- If living in or travelling to areas where the brown dog tick is present, such as northern WA, ensure your dog is on an effective tick preventative. Your veterinarian can provide advice on the most suitable tick prevention and control products for your situation.
- Tick collars and spot-on treatments that repel and kill brown dog ticks are the best primary protection, as they can help prevent the tick attaching to the dog. This is important as once the tick has attached; it may only take 3 hours to infect the dog.
- Tablets and chews registered for brown dog tick control provide an additional layer of protection but are not sufficient to prevent infection without an effective repellent.
- Inspect your dog daily for ticks, especially if they have been in a tick-infested area. Run your fingers through your dog’s coat over their skin and feel for abnormal bumps. Pay particular attention to the head and neck, inside their ears, on their chest, between their toes and around their mouths and gums.
- If you find ticks on your dog, ask your veterinarian for advice on the best way to remove them. Also treat the places where the dogs sleep in your house and yard for ticks to prevent the dogs being reinfested.
- If you are travelling with your dogs to northern WA, try to prevent them entering tick-infested environments and having contact with other dogs which may be carrying ticks. This includes places where you may stop, like fuel stations and caravan parks.
- To prevent transmission to other dogs, dogs with suspected or confirmed ehrlichiosis who live in an area where brown dog ticks are likely to exist need lifelong treatment with registered systemic tick control products, even where there are no ticks visible on the dog’s body. This will reduce the risk of disease in other dogs.
Dog adoption and rehoming
When adopting a dog from an area where Ehrlichia canis is or may be active, ensure you are aware of:
- the dog’s health history including illnesses, treatments and tick preventatives
- the signs of ehrlichiosis
- diagnosis, treatment and prevention of ehrlichiosis.