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Life-threatening reactions prompt tick alert

Common ticks cause life-threatening reactions in dozens of patients every year, the largest ever study of Australian tick bites has found.

Researchers from three Sydney hospitals – Hornsby, Concord and Mona Vale – found that 34 patients suffered anaphylaxis – an acute life-threatening allergic reaction – after being bitten by ticks, most commonly the paralysis tick Ixodes holocyclus, which is endemic along the nation’s eastern seaboard.

The findings were based on an examination of emergency presentations of patients with tick bite at Mona Vale Hospital between January 2007 and December 2008.

The study, led by Dr Tristan Rappo of Hornsby Hospital, identified more than 500 cases of tick bite cases at Mona Vale Hospital over the two-year period, 6 per cent of which involved anaphylaxis.

Dr Rappo said tick bite anaphylaxis has been rarely reported in Australia, and the first formal notification was not made until the 1960s.

Of those found in the study to be suffering anaphylaxis, the vast majority (94 per cent) showed symptoms on their skin, and more than a third (13 out of 34 cases) had a history of allergies or previous anaphylaxis.

The most common sites of tick bites were the head and neck (57 per cent) and trunk (20 per cent).

Dr Rappo said ticks were common in Australia – there are about 70 species – meaning health workers needed to be aware of the symptoms they could cause.

“The variations in the presenting symptoms and signs, as well as in management, highlights the need for increased awareness and guidelines for tick bite management in tick-endemic areas,” he said.

The study was published in Emergency Medicine Australasia.

Adrian Rollins

 

Image by John Tann on Flickr, used under Creative Commons licence

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