* Mosquito nets, proper diagnosis, treatment key to success
* Good progress in past decade but gains fragile, WHO says
* Annual funding at $1.8 billion, $6 billion needed
By Stephanie Nebehay
GENEVA, Dec 14 (Reuters) - The world could stop malaria deaths by 2015 if massive investment is made to ramp up control measures, including wider use of insecticide-treated mosquito nets, the World Health Organisation (WHO) said on Tuesday.
Progress has been made over the decade, with deaths estimated to have dropped to 781,000 last year from nearly 1 million in 2000, the WHO said in its World Malaria Report 2010.
The largest absolute decrease in mortality was recorded in sub-Saharan Africa, which still accounts for nine out of 10 deaths, mainly children, according to the U.N. agency. More countries are reporting that they have halved cases and deaths since 2000, 11 of them in Africa and 32 in other regions.
"By maintaining these essential gains, we can end malaria deaths by 2015," Ray Chambers, the U.N. secretary-general's special envoy for malaria, said in a statement with the report.
Robert Newman, director of the WHO's global malaria programme, said the target was ambitious. "It is a long way to go, so serious work has to be done. But this disease is entirely preventable and treatable, so it's the right aspirational goal," he told Reuters.
Experts are debating the next steps in the fight against malaria, with a new vaccine on the horizon from GlaxoSmithKline. But the goal of wiping out malaria altogether poses some tough economic questions.
There are now an estimated 225 million cases a year of malaria, which can damage the nervous system, kidneys and liver. Severe cases can lead quickly to death.
The WHO report said control measures are protecting more Africans against the disease, although three countries -- Rwanda, Sao Tome and Principe and Zambia -- reported resurgences in the number of cases, illustrating the fragility of gains.
In the past three years, enough insecticide-treated mosquito nets have been provided to protect 578 million people at risk of malaria in sub-Saharan Africa. A further 75 million are protected by indoor residual spraying, according to the WHO.
But funding, estimated at $1.8 billion a year, falls far short of the $6 billion needed to fully control malaria.
"After so many years of deterioration and stagnation in the malaria situation, countries and their development partners are now on the offensive," said WHO director-general Margaret Chan. "Current strategies work."
Some 42 percent of African households own at least one insecticide-treated mosquito net. The rate remains low in some of the largest countries including Nigeria and Democratic Republic of Congo, although more nets are on the way there, the report said.
About one-third of cases are confirmed with a diagnostic test, against just five percent at the start of the decade, but low rates persist in most African countries.
The WHO recommends that all suspected cases of malaria be confirmed by a quick and cheap diagnostic test before antimalarial drugs are taken -- rather than assuming any person with a fever has the mosquito-borne parasitic infection.
This cuts down the over-prescribing of artemisinin-based combination drugs and slows the spread of resistance to them.
The WHO said last month that a form of malaria resistant to the most powerful drugs available may have emerged along the Thai-Myanmar border and Vietnam. Artemisinin-resistant malaria first emerged along the Thai-Cambodia border. (Additional reporting by Kate Kelland in London, editing by Janet Lawrence)