Chikungunya outbreak a growing risk
THE chances that Australia could suffer an outbreak of Chikungunya virus could be far greater than thought, following confirmation that native mosquitoes can be infected when exposed to the virus. The virus — closely related to the betterknown Ross River virus — can cause fever, vomiting, muscle pain, headache and rash. Its name is derived from an African word meaning something that curves — thought to refer to stooped postures caused by the arthritis with which the infection is also associated.
While sporadic outbreaks have been recorded in Africa and south and south-east Asia, there is no endemic virus in Australia.
It had been thought that in Australia, Chikungunya virus could only be spread by two species of mosquito, which were confined to far north Queensland — the Aedes aegypti mosquito, which also transmits dengue fever, and Aedes albopictus .
However, Andrew van den Hurk, from Queensland Health’s Forensic and Scientific Services, says testing has revealed the virus was is capable of being transmitted by other species that range far more widely. The two principal species identified as potential vectors, or carriers, are Aedes vigilax — distributed along most of Australia’s coast — and Aedesprocax , mainly along the coast from Brisbane to Sydney.
Van den Hurk says although the Chikungunya virus itself is not present in Australia, events around the world show this is no cause for complacency. Although not normally considered life-threatening, an outbreak on Reunion island, in the Indian Ocean east of Madagascar, in 2005 killed more than 200 people.
As global travel becomes more common, the risks increase that someone could be infected by the virus overseas, return to Australia and then pass the infection on to local mosquitos through being bitten after their return.
There was an outbreak of Chikungunya in Italy last year that was traced to an Indian man visiting from India,’’ van den Hurk said.
Professor John Mackenzie, deputy CEO of the Australian Biosecurity Centre, said the
current epidemic activities of Chikungunya virus show no signs of abating’’. Outbreaks in the region are increasing, with new outbreaks in Singapore, Malaysia and Indonesia. This greatly increases the chance of an outbreak in Australia and we simply can’t ignore the risk any more.’’
Although the fever and joint pain associated with the virus usually only last a few days, in some people the joint pain can persist for weeks.
Van den Hurk says a person can only pass infection to a mosquito during the period they were experiencing acute symptoms. He says people need to reduce mosquitos’ breeding areas — by emptying water from plant pot bases and other places, unblocking gutters, and ensuring water tanks are covered.