Malaria down but not out (yet)

According to the World Health Organization's World Malaria Report 2010, an increase in malaria control programmes has resulted in over half a billion people being protected from malaria infection over the past few years.

However, malaria researchers warn that malaria is still a long way from being eradicated, and any lessening of effort to control it now could result in even more infections and deaths in the future.

The WHO report found that cases of malaria were down in virtually every country in the world, with 11 African countries showing a greater than 50 per cent reduction in confirmed cases or admissions and deaths over the past decade.

Much of this reduction has been fuelled by increased funding for controlling malaria, such as from the Bill & Melinda Gates Foundation, with total funding reaching a record US$1.5 billion in 2009, rising to US$1.8 billion in 2010.

However, the report notes that these funds still fall short of the roughly US$6 billion required for malaria control in 2010.

Professor Alan Cowman, malaria researcher at the Walter and Eliza Hall of Medical Research, says that the reductions in malaria cases are a positive sign, but that we mustn't become complacent.

"It's very good news. Anything less would be bad news," he told ALS. "But it comes with some warnings. This kind of an effort was tried in the 1950s and 1960s by the WHO, and it got good results, but then everyone took their foot off the pedal and things crashed."

Cowman's concern is that malaria, and the mosquitoes that carry the Plasmodium falciparum parasite, are a moving target, capable of adapting to our attempts to control them.

"If you take your foot off the pedal, it'll come back with a vengeance. Then more will die than if you hadn't started the control programme in the first place."

The primary driver of the reduction in malaria cases over the past several years has been the roll-out of insecticide-treated nets and indoor residual spraying. The nets are estimated to have protected more than 578 million people, and the spraying a further 75 million people, since 2008.

However, Cowman warns that unless pressure is kept up, the mosquitoes might adapt to the nets and the spraying and develop new behavioural patterns or resistance.

"The worry there is we might select for changes in mosquito behaviour with spraying and bed nets in houses," he said. "This means programmes need to be adaptable to get to the goal of eradicating malaria."

The risk is that signs that malaria is in retreat might be perceived as an indication that we can lessen our efforts at controlling malaria, thus allowing the newly resistant mosquitoes an opportunity to bounce back stronger than ever.

Cowman likens this control-only approach to the Greek myth of Sisyphus, who was condemned to an eternity of pushing a heavy boulder up a hill, only to have it roll down to the bottom each time.

Ultimately, Cowman believes that the end goal must be a malaria vaccine. He suggests that a working vaccine is close, but it'll still take many years yet before malaria can be eradicated.

"Eradication of malaria is still a long way off - I think it's possible, I really do - but we're talking 20-25 years."

The World Malaria Report report can be read on the World Health Organization website.