If you’re strolling through grasslands in Australia, South Africa and the US Rocky Mountains in spring and early summer it’s important to check that you haven’t picked up an unwelcome and dangerous hitchhiker.
The paralysis tick is a blood-sucking insect, the adult female of which has a nasty added extra – a powerful neurotoxin in her saliva that she injects into any animal she lands on to feed.
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To access her meal, she cuts the skin and buries a barbed drinking tube into the underlying flesh. The point of the potent poison, therefore, is to disrupt the victim’s nervous system so it doesn’t notice the invader.
This prevents any attempt to remove the tick before it has drunk its fill of blood, which can take several days. The longer the tick stays latched on to the skin, the more toxin it pumps in until the host’s legs start to give way and their face and breathing muscles begin to freeze. Male paralysis ticks may feed a little on the site of a female bite but they are more engaged with mating than sucking blood.
Finding this killer tick on the body is not as easy as might be imagined. The animal is picked up from grass stems as the blood donor – human, dog, cat or farm animal – brushes by them. Once on board the tick heads for warm, moist, hairy places. In people this could be the scalp, armpits, chest hair or around the genitals. A thorough check for ticks after a walk should also include between the fingers and toes, the belly button, inside the ears, behind the knees and around the waist.
In dogs hidden ticks are obviously much harder to find until they start to fill with blood. But by that time they will have released a lot of toxin so it’s the symptoms of a tick bite that have to be watched for.
There are 40 types of paralysis ticks, each associated with a different area of the world. The symptoms they inflict on the animals they bite vary depending on the type of tick but in dogs these generally include hind leg weakness, drooling and a husky bark.
In humans the first sign is usually numbness, tingling and possibly pain in the legs, followed by fatigue and irritability. The next stage is a slow paralysis of the feet that moves gradually upwards. If there is sufficient toxin in the body it will then start to affect the muscles of the chest and head, bringing breathlessness and, in the extreme cases, incapacity of the lungs and death.
The good news is, whichever the species of paralysis tick, the solution to its paralysing effects are the same – prompt removal of the tick. This means the entire insect – body and buried feeding tube – the latter being tricky to pull out because of the barbs. If this can be achieved the symptoms subside in two or three days; gone as quickly as they arose.
