Paralysis tick

Ixodes holocyclus, commonly known as the Australian paralysis tick, is one of about 75 species of Australian tick fauna and is considered the most medically important. It can cause paralysis by injecting neurotoxins into its host. It is usually found in a 20-kilometre wide band following the eastern coastline of Australia. Within this range Ixodes holocyclus is the tick most frequently encountered by humans and their pets. As this area also contains the majority of Australia's most densely populated regions, incidents of bites on people, pets and livestock are relatively common. Paralysis ticks are found in many types of habitat particularly areas of high rainfall such as wet sclerophyll forest and temperate rainforest. The natural hosts for the paralysis tick include koalas, bandicoots, possums and kangaroos. The use of common names has led to many colloquial expressions for Ixodes holocyclus. The most generally accepted name used within Australia is Australian paralysis tick or simply paralysis tick. The following table gives some of the other names used to describe various stages of Ixodes holocyclus.Many of these common names, such as dog tick or bush tick, are best not used for Ixodes holocyclus because they are also used for some of the other ticks found in Australia. One of the earliest Australian references to ticks as a problem in human disease is found in the journal kept by Capt William Hilton Howell for his 1824-1825 journey from Lake George to Port Phillip. In this he remarked on 'the small insect called the tick, which buries itself in the flesh, and would in the end destroy either man or beast if not removed in time' James Backhouse, a well-travelled Quaker of the early colonial period, gives the following account: 'At Colongatta, in Shoal Haven...district, which, like that of Illawarra, is much more favorable for the grazing of horned cattle than for sheep. Among the enemies of the latter in these rich, coast lands, is the Wattle Tick, a hard flat insect of a dark colour, about the tenth of an inch in diameter, and nearly circular, in the body; it insinuates itself beneath the skin, and destroys, not only sheep, but sometimes foals and calves. Paralysis of the hind quarters often precedes death in these cases. Sometimes it occasions painful swellings, when forcibly removed from the human body, after having fixed its anchor-like head and appendages in the skin. To prevent this inconvenience, we several times, made them let go their hold, by smearing them over with oil, or with wet tobacco ashes.' Whilst pioneering settlers knew that ticks posed a threat to their dogs and perhaps to themselves, the paralysis tick was not scientifically identified until 1899 (by Neumann). It was further studied by Nuttal and Warburton (1911). By 1921 Dodd had established a definitive link between Ixodes holocyclus and clinical disease in three dogs. His findings were that it took 5 to 6 days from time of attachment for clinical signs to develop, with motor paralysis being the major neurological deficit. The life cycle was studied chiefly by Clunies-Ross (1924). Ian Clunies Ross also demonstrated that a toxin produced by the tick was responsible for the paralysis and not some infective agent carried by the ticks. The lifecycle was further studied by Oxer and Ricardo (1942) and later summarised by Seddon (1968).