Blood-sucking freaks

There’s an old saying in the Northern Rivers: If you’re out in the bush and you find yourself scratching the same place twice, you’ve probably got a tick.

Just because it’s winter, don’t think there are no ticks around. While scrub (aka paralysis aka shellback) ticks are abundant in the warmer months from September till March, like cyclones, they can hit any time.

The functionally named Ixodes holocyclus (literally ‘attaching disc’) occurs along Australia’s east coast, coincidentally where most of the population lives. Preferring moist, warm environments, ticks frequent humid coastal wet sclerophyll and temperate rainforests and are common in the northern rivers. They feed on birds, mammals and even reptiles, but their main hosts are bandicoots. Bandicoots and some other marsupials have a specially adapted double claw to remove ticks.

Spreading disease

Ticks are second only to mosquitoes in spreading human diseases and also cause potentially fatal allergies and paralysis. Over the past hundred years scrub ticks have killed at least twice as many Australians as funnel web spiders. 

Between 1914 and 1942, twenty people died in Australia from tick bites – and most were children. No human deaths have been recorded in the past 70 years since an antitoxin was developed by Commonwealth Serum Laboratories.

While scrub ticks can cause paralysis in livestock they mainly affect dogs, cats and humans. One tick can kill a large dog and every year in Australia at least 10,000 companion animals require veterinary treatment for tick bites, and 500 die.

Paralysis is caused by holocyclotoxin, a neurotoxin similar to scorpion venom found in the tick’s saliva. Holocyclotoxin allows a tick to feed on a host for days by concealing its presence from the host’s immune system while preventing blood clotting. The longer a tick remains attached, the more powerful the venom becomes, reaching peak toxicity after 4–5 days. 

Removing a scrub tick triggers a deterioration in the host’s condition, and symptoms often appear hours later. 

Lifecycle

Ticks live for two years and will bite as larvae, nymphs and adults. Adult ticks usually attach on the scalp behind the ears, armpits and groin, but may be found anywhere on your body.

Symptoms begin with lethargy, unsteady gait, loss of appetite, ascending symmetrical paralysis (aka ‘down in the back legs’), and rashes. Swollen glands and flu-like symptoms are followed by laboured breathing, brachycardia, and facial paralysis, then heart failure and death. 

Scrub ticks can transmit Q Fever and Spotted Fever (aka Qld Tick Typhus); both are potentially fatal bacterial infections that can be simply and effectively treated with antibiotics.

Lyme disease is a debilitating illness caused by the tick-borne bacteria Borrelia burgdorferi in Africa, Asia, and the Americas. Although Lyme disease bacteria have yet to be found in Australian scrub ticks, people in Australia do suffer Lyme-like symptoms from tick bites. 

It is highly likely that scrub ticks do carry as yet unidentified Lyme-like bacteria, and there are probably more Australian tick-borne infections to be identified. 

Meat allergy

Alpha Gal is a protein found in the blood of all mammals – except humans and apes. When a person is bitten by a tick that earlier fed on bandicoot’s blood, the alpha gal protein in the tick’s saliva enters the host’s bloodstream, causing mammalian meat allergy in susceptible people. 

Mammalian meat allergy causes nausea after eating red meat, gelatin and soft white cheeses. The only real solution is to stop eating red meat.

Removal: don’t touch – never squeeze

If you find a tick on a person or a pet, try not to touch or disturb it. Never squeeze a tick to pull it out – squeezing forces the saliva glands and stomach contents into your body, increasing the dose of venom and bacteria.

Never douse an embedded tick with methylated spirits, solvents or insect repellants; they cause the tick to produce more saliva, increasing the venom/bacterial dose. 

The safest way to remove a tick is to spray it with ether (found in Wart Off and Aerostart), or use cream containing permethrin (Lyclear). When the tick is dead, try to let it drop off naturally.

If you suffer rashes, fevers, blurred vision, a red bulls-eye pattern, a dark scab (eschar), or any other negative reaction to a tick bite, immediately seek medical help.

Pets

Always use tick collars on your pets. Avoid long grass after rain and wear pale clothing and spray with DEET when in the bush. To keep ticks out of your yard, remove undergrowth, mow, and encourage insectivorous birds. If necessary, fence to exclude bandicoots.

Scrub ticks can cause severe illness and death, but extreme reactions can be avoided by taking simple precautions and seeking early treatment if you are bitten. 

Although dangerous, scrub ticks are an integral part of the Northern Rivers ecosystem and unfortunately, we just have to learn to live with them – or consider moving elsewhere.