Australian paralysis ticks are a tiny parasite that feeds on dogs, cats, livestock, and even humans. Their name comes from the toxin they inject while feeding, which can cause paralysis in the host in sufficient quantities. Although there are more than 75 species of tick within Australia (with 16 of those known to feed on humans), more than 95% of human tick bites along the eastern coast of Australia come from this species.
So exactly what are paralysis ticks? Are they a danger to humans, and do they cause life threatening emergencies if you or someone you know gets bitten by one? Let’s take a moment to find out some details about this relatively common – and arguably quite icky – species.
What Is A Paralysis Tick?
Paralysis ticks (officially known as Ixodes holocyclus) are a species of parasitic arachnid that feeds off the blood of mammals. Although they’re sometimes called bugs, they’re actually more closely related to spiders than to insects. They feed by cutting a tiny slice into their host’s skin, jamming their head down into the hole (latching on with a special barbed feeding tube), and then drinking the blood that leaks into the opening. An adult tick can drink hundreds of times its body weight in blood, and their bodies swell to many times their original size in the process. Once a tick is done feeding and ready to drop off, it is known as being engorged.
Paralysis ticks also inject a variety of substances into the host as the feeds, including chemicals to block the body’s natural healing processes (so it can continue drinking for days at a time). They also injects a venom that can potentially partly paralyse the host creature to make feeding easier – hence the name.
The traditional prey of Paralysis ticks are native Australian animals such as bandicoots, echidnas and possums, which have mostly adapted to be immune to the paralysis toxin. However, Paralysis ticks aren’t picky, and frequently feed on pets and livestock – which their toxin is far more effective on. They are also quite willing to feed on humans.
Contrary to common belief, paralysis ticks don’t jump large distances to catch a host. Instead, they tend to climb out onto the farthest tip of leaves or branches, latch on with their back legs, and hold out their front limbs – waiting for a large mammal to brush past so the tick can catch on. They’ve also been known to drop onto animals passing below them. And because they’re so small, they’re often latched on and feeding long before the host creature knows it’s there.
Paralysis ticks live almost exclusively along the eastern coast of Australia, where they’re relatively common – normally within 20km of the coastline. This also happens to be Australia’s most densely populated region.
What Does A Paralysis Tick Look Like?
Paralysis ticks actually have three distinct life phases once they hatch from the egg, each of which is vastly different in size – although their general appearance does stay roughly similar despite the size changes. The ticks have flatish, seed shaped bodies with legs protruding from the narrow end. They generally have brownish legs, with a body that’s a pale grey, yellowish, or brown in colour.
When they first hatch from eggs, the ticks are referred to as Larva. They’re only around the size of a pinprick – around half a millimetre across and often almost invisible to the naked eye. At this point, they only have six legs, but you’d probably need a magnifying glass or something similar to count them. Once they’ve fed on a host animal, they’ll swell to many times their original size – their bodies becoming round and oval-shaped – before unlatching and dropping off.
Once they’ve fed off a host and dropped off again, they’re then able to grow to become a nymph – the “teenage” phase of the tick lifecycle. Nymphs have bodies approximately the size and shape of a sesame seed, and they’ve now grown an extra set of legs – bringing them up to their official total of eight (they are arachnids, after all). And once again, they’ll swell many times larger when feeding.
After their second feeding cycle, the tick will grow into an adult – at which point their body will be about the size of a watermelon seed. At this size, you can often see that their front and back legs are darker brown, while their middle pairs are paler.
And you thought they were gross before they started feeding!
Once they’re an adult, you only really need to worry about the females, as they need to feed on a host one more time before they can reproduce (the males will feed from the female). While feeding, an adult Paralysis tick will swell massively, growing from watermelon seed size to something more like a red kidney bean with tiny legs on one end.
Overall, this lifecycle takes around a year to complete – from newly hatched larvae in Autumn through to fully grown adults laying their eggs at the start of summer.
Bush Tick VS Paralysis Tick
Paralysis ticks are often known by a range of other names – such as scrub ticks, bush ticks, dog ticks, wattle ticks, common hardback ticks, bottle ticks, blue bottle ticks, and shell-back ticks. The larvae are also known as grass ticks, seed ticks, shower ticks, and scrub-itch ticks. Some of these names are also used for other species of tick (such as bush ticks and dog ticks), so it’s possible some of those alternate names may have originally been a matter of mistaken identity.
The most distinctive feature of the paralysis tick that sets it apart from other ticks is probably the front and back legs being darker than the middle two pairs. But as a rule, if you’re suffering from a tick bite within 20km of the eastern Australian coastline, it’s most likely a paralysis tick.
How Dangerous Are Paralysis Ticks?
There are two primary risks to humans from a paralysis tick. Although the paralysis toxin is rarely dangerous to humans, some people are particularly susceptible to it. It can be particularly dangerous if a person has been bitten by multiple ticks, or is very young.
The first confirmed Australian death due to paralysis ticks occurred in 1912, in a child – who suffered paralysis and eventually asphyxiation (they literally stopped breathing due to the toxin). In the first half of the 20th century, around 20 deaths were reported – eighty percent of which were children under four. It’s also suspected that more tick-related deaths may have occurred, but people assumed the cause was Polio, or other health conditions.
Fortunately, ticks are better understood now, and such deaths are far less common.
The other danger of Tick bites is the risk of anaphylaxis – the most significant form of allergic reaction, which can often be caused by insect and spider bites and stings. The particular danger here is that if the victim isn’t aware of the tick, they could be suffering an anaphylactic reaction without knowing the cause or being able to address it.
A secondary issue with ticks is that they are a common transmitter of diseases due to their feeding habits. The best-known example of this is Lyme disease, although this is not generally encountered in Australia. There are many other tick borne diseases that are found in paralysis ticks, of course, such as Rickettsial Spotted Fever.
Paralysis Tick Symptoms
Paralysis tick bites often have the most dramatic effects on animals, such as dogs, cats and livestock. Paralysis tick venom can cause symptoms such as heavy breathing and salivation, coughing, vomiting, having wobbly back legs, or even collapsing and lying still. These symptoms can strongly indicate your animal has a tick attached somewhere (this can be incredibly hard to locate amongst the fur), and certainly says you should get them to a vet ASAP. Deaths in animals due to paralysis tick bites are far more common than in humans.
Paralysis Tick Symptoms In Humans
Humans are normally more resistant to Paralysis tick bites than animals, but they can still suffer negative effects. This is particularly true if they’ve gone unnoticed and have been feeding for some time – Paralysis ticks feed for many days before they finally become engorged and drop off. The most common symptom is inflammation and redness around the bite zone. Other common symptoms include rashes, headaches, fever, and other flu-like symptoms, as well as tender lymph nodes, being unsteady on their feet, light sensitivity, and in some cases even partial facial paralysis.
More significant paralysis is quite rare and normally only seen in children.
There is also the potential for an anaphylactic reaction. If the person starts to show symptoms of anaphylaxis – such as tightness or swelling in the throat, difficulty breathing, or a swollen tongue – you should call 000 as soon as possible.
Paralysis Tick Symptoms After Removal
Once a tick has been removed or has dropped off naturally, there should be few ongoing symptoms other than some potential irritation and redness around the bite region. If you experience significant ongoing symptoms after a tick has been removed, you should see a doctor as soon as possible – you may have contracted a secondary tick-bourne disease.
Paralysis Tick Treatment
If you or someone near you discovers a tick on their body, the ultimate goal is to remove the tick as promptly as possible – although some care is needed to do so. Under no circumstances should the tick be crushed or popped, as this greatly increases the chance of disease and infection and can leave parts of the tick still embedded in the skin. Nor should the tick be “encouraged to leave” through the use of heat or chemicals – as one might do with salt or a lit cigarette on a leech. The goal here is to kill them or carefully but forcibly remove them.
To kill them, apply bicarbonate of soda moistened with water, or spray them with a pyrethrin-based insect repellant. Apply the remedy of choice at least twice within a minute to ensure the tick is killed. It should then drop off naturally within 24 hours.
The other alternative is to use fine-tipped tweezers. Grab the tick as close as possible to the head, and then with strong, steady force, pull the tick back out of the wound – straight back along the line it went in. Don’t twist the tick or grab it by the body, or you may break off the mouthparts and leave them in the wound, potentially causing infection. However, if the head or parts of the mouth do get left in the wound, it’s probably best to either leave it alone and let your body deal with it naturally, or go to a doctor. You may find it incredibly difficult to remove the leftover bits yourself. Either way, it’s best to treat the wound with antiseptic once the tick has been extracted.
While many paralysis tick bites are relatively harmless, the risk of infections and anaphylactic reactions is a real one. One of the best ways to be prepared for such a situation – and a variety of other medical emergencies – is by investing a day in professional first aid training. Don’t be the one desperately googling symptoms when a friend or loved one is in danger – be ready when the time comes!