(Adds WHO official interview, details)
Dec 11 (Reuters) - Global efforts to curb malaria have saved the lives of 3.3 million people since 2000, cutting global death rates from the mosquito-borne disease by 45 percent and by half in children under 5, the World Health Organization said on Wednesday.
WHO said in its World Malaria Report 2013 that expanded prevention and control measures helped produce declines in malaria deaths and illness. Of the 3.3 million lives saved, most were in the 10 countries with the highest malaria burden and among children under age 5, the group most afflicted by the disease.
"Investments in malaria control, mostly since 2007, have paid off tremendously," said Ray Chambers, the United Nations secretary-general's special envoy for malaria.
According to the WHO report, child deaths fell to fewer than 500,000 in 2012.
Overall, there were an estimated 207 million cases of malaria in 2012, which caused some 627,000 deaths, according to the report, which includes information from 102 countries with malaria transmission.
The estimated number of malaria cases per 1,000 at-risk individuals - a figure that takes population growth into account - shows a 29 percent drop globally between 2000 and 2012, and a 31 percent drop in Africa.
During the same period, death rates per 1,000 at-risk individuals fell by 45 percent globally and 51 percent in children under age 5.
"This remarkable progress is no cause for complacency: absolute numbers of malaria cases and deaths are not going down as fast as they could," WHO Director-General Dr Margaret Chan said in a statement accompanying the release of the report.
"The fact that so many people are infected and dying from mosquito bites is one of the greatest tragedies of the 21st century."
Malaria is endemic in more than 100 countries worldwide but can be prevented by the use of bed nets and indoor spraying to keep the mosquitoes that carry the disease at bay. The mosquito-borne parasitic disease kills hundreds of thousands of people a year, mainly babies in the poorest parts of sub-Saharan Africa.
An estimated 3.4 billion people continue to be at risk for malaria, mostly in Southeast Asia and in Africa where around 80 percent of cases occur.
Chambers said progress against malaria has been threatened by funding cuts in 2011-2012, which translated into a flattening in the curve of the decline. The WHO noted significant drops in delivery of insecticide-treated bed nets in its 2013 report.
But that could begin to ease. Last month, the Global Fund to Fight AIDS, Tuberculosis and Malaria, UNICEF, the UK's Department for International Development and the U.S. President's Malaria Initiative agreed to provide over 200 million nets in the next 12 to 18 months, which will replace 120 million existing bed nets and provide 80 million new ones.
WHO also continues to track emerging parasite resistance to artemisinin, the core component of malaria drugs known as artemisinin-based combination therapies, or ACTs, and mosquito resistance to insecticides.
Four countries in Southeast Asia reported artemisinin resistance in 2013, and 64 countries found evidence of insecticide resistance, suggesting recent gains against malaria are still "fragile," Dr Robert Newman, director of the WHO Global Malaria Programme, said in a telephone interview.
"The greatest threat to the future isn't biological, but financial. It's not having enough money to stay a step ahead," Newman said.
(Reporting by Julie Steenhuysen in Chicago; Editing by Kenneth Barry and Eric Beech)