SYDNEY: Southeast Asia and South Pacific island nations face a growing threat from malaria and dengue fever as climate change spreads mosquitoes that carry the diseases and climate-change refugees start to migrate.

A new report titled "The Sting of Climate Change", said recent data suggested that since the 1970s climate change had contributed to 150,000 more deaths every year from disease, with over half of the deaths in Asia.

"Projections of the impact of climate change on malaria and dengue are truly eye-opening," said the Lowy Institute report released in Sydney on Thursday. According to the World Health Organisation, rising temperatures and higher rainfall caused by climate change will see the number of mosquitoes increasing in cooler areas where there is little resistance or knowledge of the diseases they carry. The Lowy report said early modeling predicted malaria prevalence could be 1.8 to 4.8 times greater in 2050 than 1990.

The share of the world's population living in malaria-endemic zones could also grow from 45% to 60% by the end of the century. By 2085, an estimated 52% of the world's population, or about 5.2bn people, will be living in areas at risk of dengue. It also said diseases will spread once climate change forces people to flee their homes, such as low-lying islands or coastal land swamped by rising sea levels.

For example, in the Pacific nation of Tuvalu, a ring of nine Polynesian islands, several thousand people have already left for New Zealand to restart their lives because of rising seas. "The number of environmental refugees as a whole may reach 50m by 2010, with small, low-lying island populations at the greatest risk. Displaced people from lowland areas could well provide the human reservoir for the spread of malaria and dengue," said the report.

"Global climate change will intensify the already significant malaria and dengue problems in maritime Southeast Asia and the Pacific Islands," said the report. "Those countries with the fewest resources and poor public health infrastructure are likely to feel the impact of increasing disease the most acutely," said the report. Up to half a billion new cases of malaria and as many as two million deaths, mostly children, are recorded each year. There are an estimated 50-100m cases of dengue fever annually and approximately 25,000 deaths.

Malaria is a major health problem for Indonesia, East Timor, the Philippines, Papua New Guinea, Solomon Islands and Vanuatu. Indonesia had an estimated 6m to 15m registered malaria cases in 2005 and it is estimated that almost half of its population of over 225m people will eventually be at risk from malaria due to climate change, said the Lowy report.

Australia, free of malaria and dengue fever, is also at risk because it is a "fringe country" to the expanding endemic zone of mosquito-borne diseases to its north, said the report. "Mosquitoes are very sensitive to changes in climate. Warmer conditions allow the mosquitoes and the malaria parasite itself to develop and grow more quickly, while wetter conditions let mosquitoes live longer and breed more prolifically," it said.

"The sting of climate change is an international public health crisis being felt on Australia's tropical doorstep. It may soon be pressing on Australia's northern shores as well."

Climate change also threatens to increase the spread of dengue fever. The South Pacific's scattered island nations of Samoa, Tonga, New Caledonia, Kiribati, New Caledonia and Palau are currently struggling with an endemic of dengue, with more than 2,000 cases so far recorded in 2008. Modelling showed that dengue fever could increase by 20 to 30% in Fiji due to climate, said the Lowy report.