Ticks

Distribution

Ticks are found throughout WA in bushland or long, grassy environments where they may climb up blades of grass or vegetation and wait for a host (animal or person) to pass by. They can also actively move toward a host, so care should be taken when resting in open natural environments, including nature reserves, designated clearings and camp grounds.

Activity

Peak tick season in WA runs from September to April. This coincides with the spring, summer and autumn months, when the weather is warmer.

Life cycle

A tick life cycle generally involves four stages: egg, larva, nymph and adult. It can take up to three years for a tick to complete its life cycle, but many die in process, seeking a host.

Ornate kangaroo tick (Amblyomma triguttatum)  

All female ticks need to take a blood meal before producing eggs. Once engorged, the female will drop from the host and lay a clutch of eggs. Larval ticks hatch and can survive for weeks without a bloodmeal. Larvae will then attach to a host and feed over several days, before dropping off to moult to the nymph stage. The cycle is then repeated, with the adult tick reaching maturation on its third host.

Larvae and nymphs require a blood meal to grow and moult from one stage to the next. Adult female ticks require a blood meal to produce eggs. Adult males feed very little on blood and tend to seek a host in order to find a female tick. Ticks range in size from smaller than a pin head (larva) to as large as a marble (engorged adult). Their colours also vary from shades of brown and reddish brown, to grey and black. Ticks can even appear a bluish-grey if they have taken a large blood meal.

During the feeding process, ticks cut the surface of the skin with their mouthparts, insert a feeding tube and secrete saliva containing anaesthetic properties so the host cannot feel the tick has attached itself. Unlike mosquitoes which feed for a matter of seconds, hard ticks can remain attached for several days. Once embedded in the skin, tick saliva creates a pool of lysed tissue and capillaries below the skin surface, allowing a constant supply of liquid nutrients.

Most ticks will feed on a new host at each stage of their life cycle. While ticks parasitise a range of animals including mammals, birds, reptiles, and amphibians, many tick species have a host preference. 

There are several tick-borne diseases of human and veterinary medical importance around the world, but few are known to be present in Australia. As feeding can take several days and the host may travel a long distance in this time, ticks are considered significant vectors of disease globally.

Tick bite reaction

In WA, the most common health impact associated with ticks is a localised reaction at the site of the bite.  Following tick removal, a small, itchy, bruise-like mark may persist for days or months. Proteins in the saliva can induce an allergic/anaphylactic reaction, although this is not common.

Mammalian meat allergy

Tick-induced mammalian meat allergy has become an emergent allergy world-wide. Whilst cases associated with Ixodes holocylus have emerged from the east coast of Australia, a single case of mammalian meat allergy was diagnosed in an individual located in the South West of WA. This case was not associated with the common tick species listed above, but Ixodes australiensis. It represents a unique case, being the first record of human infestation by the species and the only diagnosis of mammalian meat allergy to have occurred in WA (external site).

Rickettsial disease

Ticks can transmit Rickettsiae, a diverse group of rod-shaped, gram negative bacteria that can cause rickettsial disease. Infections of this nature are rare in WA. Severity of symptoms vary, and include:

• fever
• rash
• myalgia (muscle pain)
• headache
• fatigue
• eschar (dead tissue at the tick bite site)

Whilst there are a range of different rickettsial diseases distributed throughout Australia, Rickettsia gravesii (spotted fever group rickettsia) infections have been reported in WA. Murine typhus (Rickettsia typhi) and scrub typhus (Orientia tsutsugamushi) are known to occur in WA, but are not tick-borne. Antibiotics are used to treat rickettsial infections. There is no vaccine available.

Rickettsia is a notifiable infectious disease in WA. Practitioners involved in the diagnosis of a patient with rickettsial disease are legally required to notify the WA Department of Health.

Other tick-borne illness

With the exception of certain rickettsial diseases, tick-borne illnesses in Australia are less well understood than in many other countries. Amblyomma triguttatum has been implicated in the transmission of Coxiella burnetii, the causative agent of Q Fever, although there is limited evidence to support this. Knowledge of Australian tick-associated micro-organisms has increased in recent years, but more research is required to provide a greater understanding of them.

A parliamentary enquiry into tick-borne illness in Australia was recently undertaken, with the final report published online (external site).

The simplest way to prevent tick bites is to avoid infested areas. If this is not possible:

• wear light coloured clothing to make it easier to see ticks before they attach
• treat clothing with permethrin wash kit before entering tick infested area
• wear long sleeved shirts and pants 
• tuck shirt into pants, and pant legs into socks 
• apply repellent containing diethyltoluamide (DEET) or picaridin to all areas of exposed skin, according to the label instructions.

After exposure to tick habitats, all clothes should be removed and placed in a hot tumble dryer for 20 minutes to kill any that may be present. The entire body should be checked for tick presence, paying attention to the neck, behind head and ears, scalp, skin folds (including groin and underarm area) and underneath clothing. In the event that a tick is found, refer to tick removal options.

If an individual has a known tick allergy, they should seek medical assistance immediately. Removal should not be attempted without medical supervision. If an individual has a known hypersensitivity or is concerned for any reason, a medical professional should also be consulted prior to attempting tick removal.

Tick self-removal

In most other cases, self-removal of a tick is appropriate. The recommended method of tick self-removal is to apply permethrin-based creams or ether-based sprays. Preliminary research indicates that by killing ticks prior to removal, the risk of allergic/anaphylactic reactions may be lessened, as exposure to tick saliva is reduced.

Permethrin-based scabies creams can be applied to kill small larvae while still attached to the skin. This is most appropriate when the larvae are small and hard to target with an ether-based spray. Nymph (pepper tick) and adult ticks are best removed by freezing them with an ether-based spray. Several different sprays are now available at local pharmacies specifically for tick removal. 

If the tick has been frozen in situ yet does not fall off on its own, it can be removed with fine tipped forceps/tweezers. The tick should be grasped as close to the skin as possible. Avoid squeezing the body of the tick and gently but firmly pull directly upwards. Be sure not to twist or pull on an angle, as this may increase the likelihood of breaking the tick, leaving the mouthparts embedded in the skin.

Following tick removal, a first aid cream containing an antiseptic, anti-inflammatory, and possibly an anaesthetic, can be applied to the bite site.

In the eastern states where the paralysis tick is found, removal by tweezers is not appropriate. Folklore remedies such as kerosene, petroleum jelly, or burning to kill embedded ticks should never be used.

It is not possible to eliminate ticks from natural bush areas. On private property, tick infestations can be reduced by keeping grasses short and by pruning shrubs along pathways to avoid direct contact with foliage where ticks may live. In some circumstances, application of a residual insecticide treatment may also be appropriate, however it is best to seek the advice of a trained pest technician.