Overview

Tick-transmitted Diseases in Australia

By Dr Bernie Hudson (Royal North Shore Hospital, Sydney) 2008

Unfortunately, ticks and illness related to their bite have not been well studied in Australia. This presents a problem for residents of tick-prone areas, particularly on the eastern seaboard of Australia. There is much confusion about what happens after a tickbite, how to remove ticks and even how to prevent tick bites. Persons have moved out of their homes sometimes for one reason only, ticks. They could not put up with constant tickbites to themselves or their children.

A rational approach to research and community awareness concerning ticks and tickbites can improve the lifestyle of residents in tick-prone areas. Information leaflets and posters have been disseminated to doctors, hospitals, fire brigades and other groups in the community to help improve community knowledge about ticks, so that ticks and tickbite can be dealt with in the correct fashion.

Some basic background information about the Tick Diseases Research Unit (TDRU), ticks, tickbites and potential illness related to tickbite is presented below.

What are Ticks?

Ticks are blood-sucking invertebrates (class Arachnida), more closely related to spiders, scorpions and mites than insects. They have several stages in their life cycle.

The earliest stage after hatching from the egg is the larva. Sometimes people suffer multiple bites from larval ticks, often called "grass ticks". They are just the first stage of the common Australian Paralysis Tick, Ixodes holocyclus. Larvae are pale in colour, almost invisible to the naked eye, and have 6 legs.

The next stage is the nymph which is slightly larger, but still difficult to see. The nymph has eight legs and is more likely to transmit Lyme disease as it can stay embedded in the skin for days before detection. It often just looks like a speck of dirt on the skin.

After feeding on a human or an animal, the nymph drops off onto the ground. It then develops into an adult. Adults are larger, with female adult ticks becoming the size of a watermelon seed when swollen with blood after feeding on a human or animal. 

Tickbites

Tickbites are common in Australia. Whilst most tickbites cause nothing more than local irritation at the bite, allergic reactions, paralysing toxicity and the transmission of infectious diseases are also possible complications.

Allergic Reactions

The most common medical problem is allergy to toxins and other substances that the tick injects into the skin. This is usually seen as swelling and redness of the skin, which may be quite extensive e.g. the whole face may swell up. This is more common in some persons and may be made worse by incorrect methods of removal. Recently (2006), TAGS has had several anecdotal reports of the development of red meat intolerance following tick bite. More >.

Toxicity

Children and animals may develop weakness of limbs or obvious paralysis following tickbite. This is more common in young children (e.g. under 5 years of age) especially if the tick has been attached for a number of days and not been noticed.

Infections

There are two bacterial infections that may be caused by tickbites. One is Spotted Fever. Another is Lyme Disease. Not every tickbite leads to these infections, but you should be aware that they could occur following a tickbite. Please read the descriptions below. If you have been bitten by a tick and develop an illness with a rash or fever, see your doctor. Sometimes you may have an illness but do not remember being bitten. Check with your doctor.

Spotted Fever

Spotted Fever is an illness caused by the bacteria Rickettsia australis. It is probably more common than Lyme Disease. Sometimes infection with Rickettsia australis occurs without a rash - there may just be a high fever. Usually there is an "eschar" or "black spot" at the site of the tickbite. This looks like a scab with redness and swelling around it. Often lymph glands nearby are enlarged and sore. Fever starts 1-14 days following the tickbite, followed within a few days by a rash. The rash can look like chicken pox as the spots may contain some fluid. Other symptoms include headache, stiff neck, aching muscles and joints. The illness may be more severe in adults and elderly persons. Spotted Fever is diagnosed by two blood tests taken 10 days apart. As antibiotic treatment is very effective, many persons feel so well that they do not return to have the second blood sample collected. This second blood test is important as it is the only way of proving the diagnosis of Spotted Fever. Spotted Fever never occurs more than once; the body becomes immune for life. More > 

Lyme Disease

Lyme Disease was first described in Europe in 1883, the 1970s in North America and 1982 in Australia. It is an illness caused by a spiral bacterium called a spirochaete. The most common name for this spirochaete is Borrelia burgdorferi, but many different Borrelia species cause Lyme Disease worldwide. An Australian spirochaete has not been found in humans yet, and may be quite different from Borrelia burgdorferi. Despite clinical case reports, it is still controversial as to whether Lyme disease can be contracted in Australia. Some doctors and health authorities believe it does, while others are adamant that it does not. Until the controversy is resolved, our advice is that patients with possible Lyme Disease should be treated with an appropriate course of antibiotics because early treatment of Lyme Disease invariably results in a complete cure.

Skin lesions of Lyme disease. Early symptoms in the first four weeks after a tickbite include a rash or red patch that gradually expands over several days. It may get quite large (up to 50 cm or more in diameter). This rash is called erythema migrans or EM. It can be difficult to tell fron an allergic reaction at the site of the bite. Allergic rashes usually occur within 48 hours of the bite, then fade. EM usually first appears after a delay of 48 hours following the tickbite and gets bigger over a few days or weeks. As it expands, EM rash often has a "target" appearance, clearing in the middle with a more obvious red edge. EM can persist for months or years, coming and going in that time. Sometimes many small EM rashes occur. EM may only occur in as few as 20% of persons with Lyme disease.

Other body systems affected by Lyme Disease. More common than EM are symptoms due to invasion by the spirochaete of the nervous system, heart, muscles and joints. These may start weeks or months after the tickbite. Initially, they may include flu-like illness, fever, headache, sore throat, fatigue, aching muscles and joints. More serious are meningitis, Bell's palsy (weakness of the face muscles), swelling of joints, and heart problems with palpitations and breathlessness. Lyme disease is difficult to distinguish from many other illnesses like Chronic Fatigue Sydrome (CFS) because the symptoms may be similar. If you have symptoms that could be Lyme disease, even if you do not remember a tickbite, see your doctor. Diagnosis is helped by a blood test called a Western Blot test, but your doctor will consider whether any other illness could be causing your symptoms and may do some other tests.

Treatment of Lyme Disease. Early treatment with antibiotics is important to prevent more serious problems. Pregnant women bitten by a tick should see their doctor. Some data suggests that Lyme Disease can affect the foetus, but two large studies in USA and Europe showed no increased risk of adverse effects on the foetus.

Prevention & Tick Removal

Prevention of Lyme Disease and Spotted Fever is achieved by avoiding tickbites and by removing ticks as soon as possible, by the correct method.

Tips for prevention of tickbite are:

  • Be aware where ticks occur, usually in bushy areas and gardens.
  • Dress appropriately to avoid tickbites. Wear a wide-brimmed floppy hat, long-sleeved shirt and long pants tucked into socks. Light coloured clothes are best as it is easier to see ticks crawling on them.
  • Use insect repellents. Repellents containing DEET (diethyl toluamide) work best, but be careful when using them on children (ask your doctor or pharmacist). A product containing the lemon eucalyptus extract citridiol claims effective tick repellency for up to 4 hours.
  • Brush off clothing and pets before entering the house.
  • Undress and check for ticks. Ticks may crawl around for several hours before biting.
  • Remove attached ticks with fine tweezers by grasping as close to the skin as possible and remove by pulling gently but firmly upwards.
  • Do not kill the tick before removal or apply alcohol, methylated spirits, nail polish remover or other substances to help removal as this causes the tick to inject more toxins and bacteria.
  • Save the tick in a sealed jar with a leaf or blade of grass. Label with the date removed and the locality where the tick was acquired. The tick can be identified later if you develop illness, especially in the following 4 weeks.


Subpages (1): Information for Doctors