In an alarming projection, the Intergovernmental Panel on Climate Change (IPCC) has warned that a population of 1.5 billion to 3.5 billion people could face the risk of being afflicted by dengue by 2080 as a result of global warming. Besides, worldwide it is estimated that an additional 220 to 400 million people could be exposed to malaria.
The United Nations Human Development Report 2007-08, released in November and based on the IPCC projection, points out that dengue fever is already in evidence at higher elevations in previously dengue-free areas of Latin America. Likewise, in Indonesia warmer temperatures have led to the mutation of the dengue virus, leading to an increase in fatalities in the rainy season. "While there is no proven evidence that climate change is implicated, in the late 1990s El Nino an La Nina events in the country were associated with severe outbreaks of both dengue and malaria, with malaria spreading to high elevations in the highlands of Irian Jaya," the report said.
In the Asian context, the report pointed out that during 2005, Bangladesh, India and Pakistan faced temperatures 5 to 6 degree Celsius above the regional average. As a result of this, 400 deaths were reported in India alone.
The report also warns: "Summer heat-related mortality could increase 55 per cent by the 2020s, more than double by the 2050s and more than triple by the 2080s. Climate change could also contribute indirectly to at least three cases of wider health problems - incidence of vector-borne diseases such as West Nile Virus, Lyme disease and malaria may rise; water-borne disease organisms may become more prevalent; and photochemical air pollution may increase."
As for the threat of malaria epidemic, the report observed that increased rain, even in short downpours, warmer temperatures and humidity create a 'perfect storm' for the spread of the Plasmodium parasite that causes malaria. "Rising temperatures can extend the range and elevation of mosquito populations, as well as halving incubation periods," it said.
More disconcerting still, the seasonal transmission period may also increase, effectively increasing average per capita exposure to malarial infection by 16-28 per cent. Currently, malaria claims around one million lives annually, of which over 90 per cent of them are in Africa. Besides, worldwide some 800,000 die as a result of malaria each year, making it the third largest killer of children.
Beyond these figures, the report notes, malaria causes immense suffering, robs people of opportunities in education, employment and production, and forces people to spend their limited resources on palliative treatment.
On a broader perspective, it says that climate change is likely to have major implications for human health in the 21st
century. "Many of the emerging risks for public health will be concentrated in developing countries where poor health is already a major source of human suffering and poverty - and where public health systems lack the resources (human and financial) to manage new threats. An obvious danger is that climate change under these conditions will exacerbate already extreme global inequalities in public health," it has warned.
The report also gives a wake up call to public health administrators globally. Calling upon Governments in the development world to respond to the public health threats posed by climate change, it puts the onus on advanced nations saying: "The starting point of action is the recognition that rich countries themselves carry much of the historic responsibility for the threats now facing the developing world."