Q fever spike linked to rainfall
8 April 2011
Research has identified the first seasonal driver for Q fever, an influenza-like illness that people can catch from livestock such as sheep and cattle.
Although most people recover from Q fever over months, in a few people it can have chronic [long-term] effects.
A review of more than 3000 cases of suspected Q fever recorded in a Townsville Hospital laboratory database over 11 years revealed a link to rainfall, Queensland researchers say.
The infection was confirmed in almost 250 of these patients, and the researchers then plotted the residential location and date of around 90 of the most acute cases.
This revealed a higher case incidence in areas where suburbs had expanded over historic livestock grazing sites, and that most infections occurred in May.
The worst-affected suburbs had an incidence of notification of the infection 8 times that seen across Queensland.
"The wet season is January and February, and 3 months later we have this spike in Q fever – which no-one has ever described in Australia before", said Dr Katie Eales, from Pathology Queensland at Townsville Hospital.
"We’ve just speculated as to why that might be, and one of our theories ... is that the Q fever is in a lot of wildlife – wallabies and kangaroos – and they become more abundant after the wet season because there is lots of new growth."
Q fever is caused by the bacterium Coxiella burnetii, which is known to infect livestock and, additionally, local wildlife and tick populations.
An earlier study of Q fever infection in Townsville showed around one-half of those infected had "no clear history of animal or occupational exposure".
Abattoir workers, farmers, vets and stockyard workers are otherwise known to be at increased risk of contracting the infection.
Dr Eales said May was also a peak time for calving, and this may contribute to the spike.
The research was presented at the Australasian Society for Infectious Diseases conference, in Lorne, Victoria (30 Mar - 2 Apr 2011).
Last Reviewed: 08 April 2011
- 1. Australasian Society for Infectious Diseases [website]. http://www.asid.net.au/ (accessed Apr 2011).
