Thoroughly ticked off
Eyeless, miniscule, unable to fly or jump and a carrier of the grim Lyme disease, the common sheep tick is a most unattractive and objectionable creature, concludes David Profumo
David Profumo finds the tick to be unattractive and objectionable
Widespread in high summer, and a vector of several serious diseases, the common sheep tick is an ectoparasitic blood-sucking mite that must qualify as one of the almighty’s more rebarbative creations. an arthropod belonging to a heterogeneous order of spider-like animals (Acarina), there are more than 20 species of tick in Britain, including one confined to tortoises. several bite humans—although they are said to shun redheads—and the chief culprit is
Ixodes ricinus, also known as the castorbean tick.
eyeless, miniscule, unable to fly or jump, the mature adults have four pairs of legs (they’re not insects), a hard exoskeleton protected by a scale-like shield and a reddish abdomen that swells up and turns greyish when engorged after a blood meal—thus the expression ‘as tight as a tick’. The larger female can then measure more than half an inch long and resembles a repulsive miniature haggis.
Tykes, keds and taids have long been known as livestock pests—pliny called them ‘the foulest and nastiest of creatures’. They cause animal diseases such as sheep-trembling ill, redwater fever in cattle and louping ill that’s fatal to red-grouse chicks. From Tudor times, the word—like ‘louse’—has been a term of verminous belittlement (one of evelyn Waugh’s detractors liked to refer to him as ‘that awful little tick’), but there have been few vernacular sobriquets for it. How about Beelzebub’s beauty spot?
With a particular liking for bracken, moorland and bilberry, ricinus infests woodland and moors from the New Forest to urban parks, wherever it’s damp and humid. The immature tick lurks on vegetation awaiting the proximity of a potential host, sensorily detected by its Haller’s organ, which responds to changes in carbon dioxide. it then latches hooked limbs onto a convenient feather or hair. The very thought of them, blind and questing in the undergrowth, gives me a psychogenic itch.
Their three-host lifecycle lasts several years and begins when the larvae hatch and search for small mammals, bats or birds. These ‘pepper ticks’ are the size of a Country Life full stop. after a moult, they metamorphose into nymphs of poppy-seed dimensions, which are responsible for the majority of human bites. Finally, the adult seeks out a large herbivore—deer, sheep, boar—mates for a week in its fur, then drops to the ground where eggs are laid. Our overly large population of various deer species seems to correlate with the modern abundance of ticks in Britain.
Not all ticks are infected, but many pass on various zoonitic diseases to humans, including the encephalitis virus. Most notable is the spirochetal bacterium Borrelia burg
dorferi, which is carried in its salivary glands and causes Lyme disease. Usually biting soft, damp areas of the body by night, the parasite burrows its soft rostrum into your flesh and injects an anticoagulant saliva along with histamine binders (most victims don’t even realise they’ve been bitten).
The longer a tick is in place, the higher the chances of infection. remove it by grasping with pointed tweezers as close as feasible to the skin or use a wire loop; never twist or squeeze, as this may prompt the tick to release bodily fluids, as can the folk remedies of burning or applying petroleum jelly. if you break off the mouth parts or spurs, they may cause further irritation. One of the more delicate manoeuvres of my life was removing a tick embedded in the antihelix of my baby grandson’s pale outer ear.
Tick fever has featured in medical writings for centuries, but Lyme disease was only named in 1975, following diagnosis in the Connecticut township of Old Lyme. The first recorded case in Britain was in 1977, although analysis of tick specimens in the Natural History Museum indicates the bacterium was present in Victorian times.
in many (but not all) cases, the initial telltale symptom is Erythema migrans—a red, bull’s-eye rash followed by fatigue, joint pain, nausea or other flu-like symptoms. Undiagnosed, it can attack the nervous system and prove fatal, although prompt treatment with antibiotics is usually successful. it’s officially estimated that 2,000 to 3,000 new cases may occur here annually. There is currently no vaccine for Lyme disease.
in the 1990s, an animated american cartoon series called The Tick lampooned superheroes such as spider-man and there will be a live-action TV series this summer. in 1993, a grotesque tick-flick—variously entitled Ticks or Infested—involved a group of Californian misfits confronting mutant bugs (the result of steroids from a local marijuana farm) and, although some of the special effects were rudimentary (model arthropods being pulled along on fishing nylon), it was a spectacular gorefest that some enterprising distributor ought to reissue on dvd. ‘it’s not nice to mess with Mother Nature,’ concluded the trailer. No doubt pliny would have agreed.
‘One of Evelyn Waugh’s detractors referred to him as ‘that awful little tick’
Not very romantic: in the UK, the sheep tick (Ixodes ricinus) is the principal agent in the spread of Lyme disease, which can cause skin lesions, cardiac abnormalities and arthritis