Ticks and what you need to know!

The Australian Paralysis Tick Advisory Panel recommends the year-round use of isoxazoline based acaricides for all dogs and cats that are living in, or travelling to known paralysis tick regions.   Please ask us about what is the bes product for your pet (range include Nexgard, spectra, and Bravecto)

1. Eastern Paralysis Tick

The eastern paralysis tick (Ixodes holocyclus) is the cause of most cases of tick paralysis in domestic animals, wildlife and humans in Australia.

It is very closely related and morphologically similar to the southern paralysis tick (Ixodes cornuatus). The two species are genetically distinct and may be distinguished morphologically – in I. holocyclus the first and fourth pairs of legs are darker in general colour (brown) compared to the second and third pairs of legs (beige).

Lifecycle and hosts

Ixodes holocyclus has a broad host range, being reported from a range of mammalian and avian hosts, however native bandicoots (primarily the northern brown bandicoot and the long-nosed bandicoot), kangaroos and wallabies are considered the primary hosts.

It has a typical three-host tick lifecycle and there is a single generation of ticks per year. As a result there is marked seasonality to the prevalence of different life stages.

 

Figure 1. Life-cycle of Ixodes holocyclus. Adapted from Ticks of AustraliaThe species that infests domestic animals and humans (p 106), by S.C. Barker and A.R. Walker, 2014, Auckland, NZ: Magnolia Press. Copyright 2014 by Magnolia Press. Adapted with permission.

Clinical significance

Tick paralysis

  • Clinical signs include hind limb incoordination and paresis (often progressing to paralysis), dyspnoea, change in voice, coughing, gagging and vomiting.
  • It usually takes 3 to 5 days after attachment/feeding for clinical signs to appear.
  • Clinical signs can be seen with feeding nymphs/larvae, but most commonly with feeding adult females. Males do not cause tick paralysis.
  • Greatest risk is associated with high numbers of adult ticks in the environment in spring and summer, but disease can be seen throughout the year.
  • It is estimated that tick paralysis affects tens of thousands of dogs and cats each year in Australia, with many animals dying.

Other

  • I. holocyclus is a vector for Rickettsia australis (Queensland tick typhus) and Coxiella burnetii (Q fever)
  • Feeding of I. holocyclus may trigger the development of mammalian meat allergy in humans by stimulating an immune response against a carbohydrate, galactose-α-1,3-galactose (α-Gal), found in mammalian meat.2 This condition is not seen in dogs and cats, as unlike humans, α-Gal is expressed as a self-antigen and subject to immunological tolerance.

2.  Southern Paralysis Tick

The southern paralysis tick (Ixodes cornuatus) is very closely related and morphologically similar to the eastern paralysis tick (Ixodes holocyclus). The two species are genetically distinct and may be distinguished morphologically – the legs of I. cornuatus are all the same brown colour whereas I. holocyclus has the feature of the first and fourth pairs of legs being darker in colour (brown) compared to the second and third pairs of legs (beige).

I. cornuatus has been reported in Tasmania, southern Victoria and southern New South Wales, although recent data indicates that its range has been pushed south.

I. cornuatus has been reported in Tasmania, southern Victoria and southern New South Wales, although recent data indicates that its range has been pushed south.

3. Bush tick (Haemaphysalis longicornis)

Bush ticks were introduced to Australia from Asia. Cattle are the preferred host of bush ticks in Australia but dogs, horses, and some species of marsupials and birds may also become infested.

The spur on coxa 1 (circled in red) distinguishes this female from female I. holocyclusI. hirstiI. tasmaniI. cornuatus and R. sanguineus.

Distribution

Haemaphysalis longicornis is found along parts of the east coast and west coast of Australia. In Queensland and New South Wales it is abundant in high rainfall areas such as Tamborine, Buderim and Maleny (Queensland), and Taree and Wauchope (New South Wales).

Clinical significance

Haemaphysalis longicornis can cause skin irritation. They are also a known vector of babesiosis in dogs. Babesia parasites are transmitted to dogs in the saliva of the tick. They invade the red blood cells causing anaemia which can be fatal. Babesiosis has a reported prevalence of 5% in client owned dogs in northern Australia.2

4. Brown dog tick (Rhipicephalus sanguineus)

Brown dog ticks (Rhipicephalus sanguineus) are specialised parasites of domestic dogs. Immature stages of this tick may attempt to attach to humans.

The presence of large eyes (circled in red) distinguishes this female from the other five common species of tick affecting dogs and cats in Australia (Hirst’s marsupial tick, common marsupial tick, eastern paralysis tick, southern paralysis tick and bush tick).

Distribution

Rhipicephalus sanguineus is the most widespread tick in the tropics and sub-tropics. It is found across much of mainland Australia and as far south as Melbourne.

Clinical significance

Rhipicephalus sanguineus can cause skin irritation and in heavy infestations dogs may become anaemic from excessive blood loss.

They are also an important vector of disease in dogs:

  • Babesiosis: Babesia parasites are transmitted to dogs in the saliva of the tick. They invade the red blood cells causing anaemia which can be fatal. Babesiosis has a reported prevalence of 5% in client owned dogs in northern Australia.2
  • Ehrlichiosis: a potentially fatal bacterial infection transmitted by R. sanguineus which was confirmed in Australian dogs for the first time in 2020.3



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