More than half a billion people — nearly double previous estimates — were infected by the deadliest form of malaria in 2002, scientists reveal in a report out on Thursday.
They calculate that one in three in the world — a total of 2,2-billion people — is at risk from the mosquito-borne parasite Plasmodium falciparum.
The discovery that malaria is far more prevalent than anyone had realised is a jolt to public health chiefs the world over. The disease claims one million lives a year in sub-Saharan Africa alone, most of them children under five.
Of the four malaria parasites, Plasmodium falciparum is by far the most dangerous, especially to the undernourished, weak or very young. It is prevalent throughout the tropics, and has developed resistance to successive drugs.
Health experts said the new figures were alarming. ”There is much more malaria than has previously been estimated in Asia, than we recognised before,” said Joe Lines of London’s School of Hygiene and Tropical Medicine.
In 1998 the World Health Organisation put the global incidence of malaria at 273-million cases. But that was an estimate, with no reliable data available.
New research published in Nature from Bob Snow, of the Kenya Medical Research Institute in Nairobi, and the Centre for Tropical Medicine at the University of Oxford, calculates that in 2002 there were around 515-million cases worldwide. In Africa in that year, there were 365-million cases: 1-million new infections every day.
”This is Plasmodium falciparum, the most deadly of the malaria parasites,” Snow said. ”We have worked very hard to get the credible estimate for deaths from malaria in Africa that is largely used by the WHO: it is about a million people each year. Outside Africa, we know surprisingly little.”
Control depends on safe water, efficient public health measures, education, supplies of up-to-date drugs and bednets to protect against the parasite-carrying mosquito.
There is hope: geneticists have unravelled the DNA of both mosquito and parasite, and have begun to look for weak spots that could lead to weapons.
A new vaccine tested on more than 2 000 children in Mozambique last year offered at least partial protection against the disease, and confirmed that an effective vaccine is at least feasible. In January, the British government, the United States billionaire Bill Gates and the Norwegian government promised more than $2,89-milion for new vaccines against childhood diseases, including malaria.
But malaria is both a disease of poverty and a cause of poverty. Sick people cannot work. Africa is already hit by a high incidence of HIV infection and tuberculosis, and malaria alone is estimated to cost the economy of the continent $12-billion a year. But that too could be an underestimate. – Guardian Unlimited Â