Malaria experts abuzz on global warming fears

OSLO – Malaria-carrying mosquitoes were once a scourge of Shakespeare’s chilly England and even Arctic regions of the Soviet Union.

With malaria’s history of surviving in the cold, experts are at odds about how far modern global warming may spread one of the planet’s most deadly diseases which kills a million people a year in poor countries. UN reports say rising temperatures linked to human burning of fossil fuels are likely to widen malaria’s range in the tropics because mosquitoes and the parasite they pass on when sucking human blood thrive best in hot, wet climates.But some insect experts swat those reports as simplistic.”Temperature is only one of many, many factors in malaria, and in many cases it’s totally irrelevant,” said Paul Reiter, professor of medical entomology at the Pasteur Institute in Paris.”Many climate scientists don’t know anything about the complexities of malaria,” he said, adding that the same applied to mosquito-borne diseases like dengue fever or West Nile virus.The dispute about mosquito lifestyles goes far beyond academic backstabbing — malaria kills an African child every 30 seconds, saps economic growth in developing countries and consumes 40 per cent of health budgets in some nations.And predictions of its future range will affect the lives of hundreds of millions of people.”In terms of malaria and many other (mosquito-borne) diseases… a changed climate will stress health care systems in some parts of the world,” said professor Alistair Woodward of the University of Auckland, New Zealand.Woodward was a co-author of a 2003 UN book that says climate change already kills 150 000 people a year and that the number could double by 2030.Malnutrition, diarrhoea, malaria and floods were the biggest threats in a warming world.Reiter admits mosquitoes and plasmodium parasites reproduce faster in hot, damp climates but says higher temperatures might trigger floods that wash away stagnant pools in which malaria larva breed or spread deserts and dry up the waters.”More rainfall sometimes means more malaria, it sometimes means less,” he said.All experts agree that there is scant risk that clouds of malaria-bearing mosquitoes will whine north to make the disease again endemic in nations from the United States to Russia.”Developed countries are likely to stay malaria-free,” said Professor Andrew Haines of the London School of Hygiene and Tropical Medicine.Any outbreaks would be scattered cases, like from insects unwittingly stowed away on airplanes.Countries most at risk are in the Third World or at the fringes where health care systems are weak.Some studies say malaria may gain to higher altitudes in mountain areas in developing countries.Reiter says UN reports ignore malaria’s history and a variety of factors that led to its defeat in developed countries.Shakespeare, who lived from 1564 to 1616, mentioned malaria – then called ‘ague’ — in plays like ‘The Tempest’.Horace and Tacitus also described malaria-like fevers in Imperial Rome.In 1923-25, 600 000 people died in the Soviet Union from a malaria epidemic that reached the Arctic port of Archangelsk.Reiter and eight colleagues including Harvard professor Andrew Spielman, author of the best-selling book ‘Mosquito’, wrote a letter to the British medical journal The Lancet in June urging more accuracy in linking malaria to climate change.Why, for instance, did malaria disappear from the French Riviera before northern Germany, they ask in the letter entitled ‘Global warming and malaria:a call for accuracy’.Woodward, one of the scientists criticised by name in the letter, stuck by his conclusions.He said that governments inevitably have to map out future risks like climate change based on imperfect models.Reiter’s desire for certainty, he said, would mean a wait-and-see attitude to urgent problems.UN experts reckon temperatures are likely to rise by 1,4-5,8 Celsius (3-11F) by 2100, largely because of emissions of carbon dioxide from the burning of oil in factories and cars.Reiter says climate had nothing to do with the defeat of malaria in developed countries.Drainage of marshes and the spread of farm land in Europe in the 19th century were big factors in destroying mosquito breeding grounds.Farmers built barns, drawing mosquitoes away from human homes to feed on cows and other livestock.Many people moved to towns, and built better houses, making it harder for mosquitoes to buzz in.Reiter says that dengue fever, for instance, was first described in Philadelphia in 1780 and has been kept at bay in the United States – as has malaria – largely by simple measures such as windows that seal homes.In 1999, when West Nile virus was first traced in New York, “it also broke out in Volgograd in Russia, formerly Stalingrad which is not known for high temperatures”, he said.- Nampa-ReutersUN reports say rising temperatures linked to human burning of fossil fuels are likely to widen malaria’s range in the tropics because mosquitoes and the parasite they pass on when sucking human blood thrive best in hot, wet climates.But some insect experts swat those reports as simplistic.”Temperature is only one of many, many factors in malaria, and in many cases it’s totally irrelevant,” said Paul Reiter, professor of medical entomology at the Pasteur Institute in Paris.”Many climate scientists don’t know anything about the complexities of malaria,” he said, adding that the same applied to mosquito-borne diseases like dengue fever or West Nile virus.The dispute about mosquito lifestyles goes far beyond academic backstabbing — malaria kills an African child every 30 seconds, saps economic growth in developing countries and consumes 40 per cent of health budgets in some nations.And predictions of its future range will affect the lives of hundreds of millions of people.”In terms of malaria and many other (mosquito-borne) diseases… a changed climate will stress health care systems in some parts of the world,” said professor Alistair Woodward of the University of Auckland, New Zealand.Woodward was a co-author of a 2003 UN book that says climate change already kills 150 000 people a year and that the number could double by 2030.Malnutrition, diarrhoea, malaria and floods were the biggest threats in a warming world.Reiter admits mosquitoes and plasmodium parasites reproduce faster in hot, damp climates but says higher temperatures might trigger floods that wash away stagnant pools in which malaria larva breed or spread deserts and dry up the waters.”More rainfall sometimes means more malaria, it sometimes means less,” he said.All experts agree that there is scant risk that clouds of malaria-bearing mosquitoes will whine north to make the disease again endemic in nations from the United States to Russia.”Developed countries are likely to stay malaria-free,” said Professor Andrew Haines of the London School of Hygiene and Tropical Medicine.Any outbreaks would be scattered cases, like from insects unwittingly stowed away on airplanes.Countries most at risk are in the Third World or at the fringes where health care systems are weak.Some studies say malaria may gain to higher altitudes in mountain areas in developing countries.Reiter says UN reports ignore malaria’s history and a variety of factors that led to its defeat in developed countries.Shakespeare, who lived from 1564 to 1616, mentioned malaria – then called ‘ague’ — in plays like ‘The Tempest’.Horace and Tacitus also described malaria-like fevers in Imperial Rome.In 1923-25, 600 000 people died in the Soviet Union from a malaria epidemic that reached the Arctic port of Archangelsk.Reiter and eight colleagues including Harvard professor Andrew Spielman, author of the best-selling book ‘Mosquito’, wrote a letter to the British medical journal The Lancet in June urging more accuracy in linking malaria to climate change.Why, for instance, did malaria disappear from the French Riviera before northern Germany, they ask in the letter entitled ‘Global warming and malaria:a call for accuracy’.Woodward, one of the scientists criticised by name in the letter, stuck by his conclusions.He said that governments inevitably have to map out future risks like climate change based on imperfect models.Reiter’s desire for certainty, he said, would mean a wait-and-see attitude to urgent problems.UN experts reckon temperatures are likely to rise by 1,4-5,8 Celsius (3-11F) by 2100, largely because of emissions of carbon dioxide from the burning of oil in factories and cars.Reiter says climate had nothing to do with the defeat of malaria in developed countries.Drainage of marshes and the spread of farm land in Europe in the 19th century were big factors in destroying mosquito breeding grounds.Farmers built barns, drawing mosquitoes away from human homes to feed on cows and other livestock.Many people moved to towns, and built better houses, making it harder for mosquitoes to buzz in.Reiter says that dengue fever, for instance, was first described in Philadelphia in 1780 and has been kept at bay in the United States – as has malaria – largely by simple measures such as windows that seal homes.In 1999, when West Nile virus was first traced in New York, “it also broke out in Volgograd in Russia, formerly Stalingrad which is not known for high temperatures”, he said.- Nampa-Reuters