Ticks

The most economically important tick affecting livestock in Australia is the cattle tick (Rhipicephalus australis – previously known as Boophilus microplus).

An MLA research project estimated in 2015 that the annual on-farm cost of ticks (production losses plus control costs) to the Australian cattle industry was approximately $146m. Additional costs are incurred maintaining the 'tick line' inspection points between New South Wales and Queensland and the tick line within Queensland.

Young cattle and goats in the coastal areas of eastern Australia may also be affected by the paralysis tick (Ixodes holocyclus). Information on paralysis ticks is available in the NSW Department of Industry & Investment publication Paralysis ticks.

Cattle of all ages in the coastal areas of eastern Australia may also be infested by the bush tick (Haemaphysalis longicornis) and the wallaby tick (Haemaphysalis bancrofti). Both these ticks are known to transmit the blood parasite Theileria (Theileria orientalis).

Cattle tick

The cattle tick (Rhipicephalus australis) is primarily a parasite of cattle in northern Australia, with European breeds of cattle most susceptible. Cattle ticks can also survive on other animals e.g. sheep, goats and horses. It is a single-host tick and once the hatched tick larvae are picked up by the host they spend all three parasitic life stages (larvae, nymphs and adults) on the same animal for about 21 days, when engorged female ticks drop off.

Cattle ticks are a vector (carrier) for tick fever, a disease caused by the blood parasites Anaplasma marginale, Babesia bovis and Babesia bigemina.

Conditions where cattle tick is likely to occur

• Infestation with cattle tick usually occurs within the endemic regions of Queensland, the Northern Territory and Western Australia.
• In endemic regions, highest numbers of ticks occur in late spring and summer but ticks lay viable eggs all year round in northern Queensland.

Sporadic infestations with cattle tick can occur outside the tick endemic regions. Any cattle ticks found in Queensland outside the cattle tick infested zone must be reported to Biosecurity Queensland. Cattle moved from the QLD cattle tick infested zone to the cattle tick free zone (across the QLD Tick Line) must be tick free and accompanied by a biosecurity certificate.

Management and eradication on infected properties outside the tick endemic regions is prescribed and regulated by the appropriate statutory authority.

Identification and diagnosis

Clinical signs that would lead producers to suspect an infestation of cattle tick include the following:

• nngorged female ticks (pea to blueberry size) are visible, particularly around the neck, brisket, flanks and between the hind legs
• licking and rubbing at the bite sites (‘tick worry’)
• tick sores and ulceration
• pale gums and membranes around the eyes due to anaemia
• lack of energy, loss of condition and even death.

Prevention

An integrated approach to tick control should consider the following:

• Increasing Bos indicus content is associated with higher resistance to tick attachment.
• Producers are encouraged to seek genetics from tick resistant cattle. It has been estimated that selection of the right genetics could reduce the effect of ticks on live weight production by 60%.
• Using a combination of chemical treatments, pasture spelling and tick-safe pastures can help control cattle ticks.

Paralysis tick

The paralysis tick (Ixodes holocyclus) secretes a toxin in its saliva that can cause paralysis. Small animals (calves, sheep, goats and dogs) are more vulnerable than fully grown cattle.

The paralysis tick occurs in the coastal areas of eastern Australia. It is a three-host tick, meaning that after engorgement in each of the three parasitic phases (larvae, nymphs, and adults) the tick drops off the host to moult, and then has to find a new host. It is in the adult stage that the female tick can cause paralysis.

Conditions where paralysis tick is likely to occur

• east coast of Australia
• habitats for native animals such as bandicoots, wallabies and possums as they are the natural hosts for the tick and are usually immune due to frequent exposure
• adult ticks can most commonly be seen from July through to December.

Identification and diagnosis

The paralysis toxin affects the nervous system of the host animal resulting in loss of coordination in the hindquarters which spreads to the rest of the body. Breathing becomes affected when the paralysis reaches the lungs. Untreated, the result is death.

Prevention

An integrated approach to paralysis tick control should consider the following:

• preventing access to areas where native hosts are likely to inhabit, especially for high risk stock
• treating stock with ticks prior to moving to low risk paddocks
• clearing of scrubby, overgrown country where possible
• managing calving times to ensure calves are stronger and heavier by the time the ticks are active
• chemical treatment before the toxin can be injected

Controlling the paralysis tick can be challenging, however, as they only stay attached to the host for a short period each time. They can also survive for as long as nine months on the ground during the non-parasitic phases or attach to native animals who cannot be treated with tickicides.

Bush and wallaby ticks

Bush and wallaby ticks (Haemaphysalis species) have been shown to transmit the blood parasite Theileria (Theileria orientalis) in cattle. Like the paralysis tick Haemaphysalis ticks need a different host for each of the three parasitic phases (larvae, nymphs, and adults). They are primarily a cattle parasite but can infest many warm blooded animals.

Conditions where bush and wallaby ticks are likely to occur

• east coast of Australia
• habitats for native animals such as bandicoots, wallabies and possums as they are the natural hosts for the tick.

Identification and diagnosis

Wallaby ticks are dark brown in colour as adults and roughly the size of a pea when fully engorged.

These ticks seldom occur in the same large numbers as cattle ticks, but clinical signs that would lead producers to suspect an infestation of bush or wallaby ticks include the following:

• reduced growth rates
• licking and rubbing at the bite sites (‘tick worry’)
• pale gums and membranes around the eyes due to anaemia
• lack of energy, loss of condition and even death in younger, more susceptible livestock.

Prevention

An integrated approach to Haemaphysalis tick control should consider the following:

• preventing access to areas where native hosts are likely to inhabit, especially for high risk stock
• treating stock with ticks prior to moving to low risk paddocks
• clearing of scrubby, overgrown country where possible
• managing calving times to ensure calves are stronger and heavier by the time the ticks are active
• chemical treatment before the toxin can be injected.

Controlling the Haemaphysalis ticks can be challenging, however, as they only stay attached to the host for a short period each time. They can also survive for as long as nine months on the ground during the non-parasitic phases or attach to native animals who cannot be treated with tickicides.