CLIMATE change alone will not push dengue fever into metropolitan Australia, experts say.

[Sally Furniss]

Temperature won't increase spread of dengue fever: scientist
March 9th, 2009

CLIMATE change alone will not push dengue fever into metropolitan Australia, experts say.


Some scientists have warned of a future risk for major population centres to the south as projected hotter temperatures and a rollout of water tanks improve conditions for its carrier mosquitoes. A recent outbreak remains centred on Cairns, with more cases reported elsewhere.
The number of cases confirmed in northern Queensland since December last year rose on Monday to 609, with 532 of these in Cairns.
There are a further 70 cases in Townsville while infections have also been reported elsewhere.
But Peter Whelan, director of Medical Entomology at Darwin's Centre for Disease Control , says historic factors would continue to work against the spread of dengue.
"It's unlikely that temperature rise alone will increase the range of either the mosquito or the virus," he said.
"Although the disease is currently restricted to northern Queensland, the chief culprit ... the mosquito called Aedes aegypti actually inhabits an area larger than the disease transmission areas and is not restricted by temperature. It's unlikely that temperature rise alone will increase the range of either the mosquito or the virus."
Counting against dengue's spread were the same factors which had dramatically cut populations of Aedes aegypti across Australia since the 1940s, he said.
The species was last collected in NSW in 1948, in the NT it was 1956 and it was last spotted in WA in 1970.
Australia's existing climate was favourable for the mosquito in all states except Tasmania and highland areas, and yet it remained confined to northern Queensland.


http://www.ntnews.com.au/article/2009/03/09/38115_ntnews.html

 

[Sally Furniss]

Re: CLIMATE change alone will not push dengue fever into metropolitan Australia, experts say.

Danny Rose | 3rd March 2009



CLIMATE change alone will not push dengue fever into metropolitan Australia, experts say, as the outbreak in northern Queensland topped 600 people infected.
The outbreak remains centred on Cairns, but recent studies have warned of a future risk for major population centres to the south as projected hotter temperatures and a rollout of water tanks improve conditions for its carrier mosquitoes.
A study by the CSIRO in 2006 warned a two to three degree celsius rise in temperature could extend the dengue risk zone south to Brisbane, while a three to four degree rise could see it also reach Sydney.
Peter Whelan, Director of Medical Entomology at Darwin's Centre for Disease Control, rejects this saying historic factors would continue to work against the spread of dengue.
"Although the disease is currently restricted to northern Queensland, the chief culprit ... the mosquito called Aedes aegypti actually inhabits an area larger than the disease transmission areas and is not restricted by temperature," Mr Whelan said.
"It's unlikely that temperature rise alone will increase the range of either the mosquito or the virus."
Counting against dengue's spread were the same factors which had dramatically cut populations of Aedes aegypti across Australia since the 1940s, he said.
The species was last collected in NSW in 1948, in the NT it was 1956 and it was last spotted in WA in 1970.
Australia's existing climate was favourable for the mosquito in all states except Tasmania and highland areas, and yet it remained confined to northern Queensland.
It has also not been spotted in Brisbane since 1956, writes Mr Whelan with colleagues in the Medical Journal of Australia.
The fall in numbers of the Aedes aegypti was attributed to the roll-out of reticulated water supplies, competition from indigenous mosquitoes, the availability of household residual insecticides along with improved and targeted public health initiatives.
"Reports to the Australian scientific and general community continue to cite projections ... but none of these projections appear to fully consider the past and present distribution of the (mosquito) vector," Mr Whelan said.
"They all ignore the fact that, before the 1930s, dengue on the East Coast was recorded as far south as Gosford and as far inland as Bourke."
Factors which could lead to more cases of dengue include increasing trade with ports South East Asian and Pacific ports and the risk of another more virulent dengue-carrying mosquito (Aedes albopictus) becoming established in Australia, Mr Whelan said.
Dengue, also known as breakbone fever, is widespread in parts of Asia and Papua New Guinea and cases in Australia are blamed on an infected person travelling in from these areas where it is endemic.
It causes illness ranging from a mild fever to a severe, even fatal condition known as dengue haemorrhagic fever or dengue shock syndrome.
The number of cases confirmed in northern Queensland since the December last year rose on Monday to 609, with 532 of these in Cairns.
There are a further 70 cases in Townsville while infections have also been reported in Port Douglas, Innisfail and the aboriginal communities of Yarrabah and Injinoo.


http://www.themorningbulletin.com.au/story/2009/03/03/dengue-fever-victims-rise-to-609/

 

[Sally Furniss]

Re: CLIMATE change alone will not push dengue fever into metropolitan Australia, experts say.

Dengue and climate change in Australia: predictions for the future should incorporate knowledge from the past


Richard C Russell, Bart J Currie, Michael D Lindsay, John S Mackenzie, Scott A Ritchie and Peter I Whelan
MJA 2009; 190 (5): 265-268


Abstract

• Dengue transmission in Australia is currently restricted to Queensland, where the vector mosquito Aedes aegypti is established. Locally acquired infections have been reported only from urban areas in the north-east of the state, where the vector is most abundant.
• Considerable attention has been drawn to the potential impact of climate change on dengue distribution within Australia, with projections for substantial rises in incidence and distribution associated with increasing temperatures.
• However, historical data show that much of Australia has previously sustained both the vector mosquito and dengue viruses. Although current vector distribution is restricted to Queensland, the area inhabited by A. aegypti is larger than the disease-transmission areas, and is not restricted by temperature (or vector-control programs); thus, it is unlikely that rising temperatures alone will bring increased vector or virus distribution.
• Factors likely to be important to dengue and vector distribution in the future include increased dengue activity in Asian and Pacific nations that would raise rates of virus importation by travellers, importation of vectors via international ports to regions without A. aegypti, higher rates of domestic collection and storage of water that would provide habitat in urban areas, and growing human populations in northern Australia.
• Past and recent successful control initiatives in Australia lend support to the idea that well resourced and functioning surveillance programs, and effective public health intervention capabilities, are essential to counter threats from dengue and other mosquito-borne diseases.
• Models projecting future activity of dengue (or other vector-borne disease) with climate change should carefully consider the local historical and contemporary data on the ecology and distribution of the vector and local virus transmission.

http://www.mja.com.au/public/issues/190_05_020309/rus10887_fm.html

 

[LaMenchos]

Re: CLIMATE change alone will not push dengue fever into metropolitan Australia, experts say.

Dengue and climate change

Hoarding rainwater could ?dramatically? expand range of dengue-fever mosquito

http://uninews.unimelb.edu.au/view.php?articleID=5672

Media Release, Tuesday 27 January 2009
Ecologists have developed a new model to predict the impact of climate change on the dengue fever-carrying mosquito Aedes aegypti in Australia ? information that could help limit its spread.

"Our results highlight that dengue-vectoring mosquitoes can spread to areas where they are currently not found once suitable breeding sites, such as containers, become available. Our research can help target water hygiene education campaigns to areas most at risk of dengue mosquito establishment.?


http://www.videosnice.com/video/mMVZFk-C5Ao/Visions-Episode-44-Dengue-Fever-Mosquito.html

CreditsProducer: Nerissa HanninkVideo: Clive BanfieldEditing: Rob CrossStill photography courtesy of Les O'RourkeThanks to Kelly Richardson, mosquito wrangler, Dr Michael Kearney, Dr Ary Hoffmann and the British Ecological Society.? The University of Melbourne, 2009. All rights reserved.