Ixodes Holocyclus - Early Scientific History

Early Scientific History

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 favourable 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 anchorlike 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).

In 1970 Roberts' work Australian Ticks gave the first comprehensive description of Australian ticks, including Ixodes holocyclus.

The first confirmed human death due to tick poisoning in Australia was reported by Cleland in 1912 when a large engorged tick caused flaccid paralysis in a child, progressing to asphyxiation. Headstones at the Cooktown cemetery apparently reveal how some human deaths were attributed to ticks.

In the first half of the 20th century at least 20 human deaths had been attributed to the paralysis tick. Eighty percent of the victims reported in NSW between 1904 and 1945 were children aged under four years. Many cases of 'infantile paralysis' (later known as poliomyelitis) may well have been misdiagnosed and actually been cases of tick paralysis.