Number of annual malaria cases worldwide decreases

Sep 22 2008

There were about 247 million malaria cases worldwide in 2006, according to the World Malaria Report 2008, which was released by the World Health Organization on Thursday, Reuters reports (MacInnis, Reuters, 9/18). According to the report, 3.3 billion people worldwide were at risk for malaria in 2006, and the disease remains a major burden among children younger than age five and in many African countries (AFP/Google.com, 9/18).

The report included reduced estimates of the global malaria burden that were calculated with new surveillance measures for non-African countries. The estimate of 247 million malaria cases is lower than the estimated 350 million to 500 million annual malaria cases reported in WHO's World Malaria Report 2005. The new report estimated there were 881,000 malaria deaths in 2006, down from the previous estimate of one million deaths. The reduced figures are the result of new calculation methods, and it is unknown whether malaria cases and deaths actually declined from 2004 to 2006, WHO said (Reuters, 9/18). Although malaria control efforts have helped reduce the global malaria burden, most malaria-endemic countries are not meeting WHO targets for malaria control, the report said, noting that there is "no evidence yet to show that malaria elimination can be achieved and maintained in areas that currently have high transmission" (Bennett/Doherty, Bloomberg, 9/18).

WHO attributed the revised malaria estimates to new assessment measures in Asia, where data used for the 2005 report had not been updated for 40 years. According to Mac Otten -- coordinator of surveillance, monitoring and evaluation at WHO's Global Malaria Program -- factors such as deforestation, urbanization and malaria control efforts have affected malaria estimates in Asia (Blue, Time, 9/17). Cambodia, Laos, the Philippines, Thailand and Vietnam all reported a decline in malaria deaths in 2006 (Bloomberg, 9/18).

WHO's surveillance methods in Africa, which estimate malaria prevalence by using climate data and sample surveys, have remained the same since the 2005 report, the report said (Reuters, 9/18). According to the report, 45 of the 109 malaria-endemic countries worldwide are in Africa, and more than half of the continent's malaria cases in 2006 occurred in the Democratic Republic of Congo, Ethiopia, Kenya, Nigeria and Tanzania (AFP/Google.com, 9/18). The report noted that malaria interventions have helped reduce malaria cases and deaths by more than 50% in Eritrea, Rwanda, Sao Tome and Principe, and the Tanzanian island of Zanzibar (Time, 9/17). The report found that about 40% of people at risk for malaria in Africa had access to insecticide-treated nets last year, compared with 3% in 2001 (Bloomberg, 9/18). The report also found that the number of ITNs distributed to national malaria control programs was enough to cover 26% of people in 37 African countries but that most African countries did not meet WHO's target of 80% coverage for the four main malaria treatments: ITNs, artemisinin-based combination therapies, indoor-insecticide spraying programs and treatment for pregnant women (AFP/Google.com, 9/18).

According to the report, children in Africa accounted for eight of 10 malaria deaths worldwide, but only 3% of African children younger than age five had access to malaria drugs in 2006. According to Bloomberg, it is likely that more children received treatment last year because supplies of ACTs increased to 49 million doses in 2006, up from six million doses in 2005. WHO said the discrepancy between drug supplies and availability could be because of delays on orders placed in 2006 (Bloomberg, 9/18).

Reaction

According to WHO Director-General Margaret Chan, the new estimates provide more accurate information for assessing malaria control efforts. "With dramatic increases in funding and intense momentum towards reducing the malaria burden in recent years, we have a greater need for reliable information and analysis," she said in a statement (Reuters, 9/18).

Bernard Nahlen, deputy coordinator of the President's Malaria Initiative, added that although the estimated number of malaria cases worldwide has been reduced, the disease still is a burden. "Whether it's 200 million or 500 million [malaria cases per year], that's a lot of infection with a big health burden and a big economic burden," he said, adding, "It's sometimes hard to know what these numbers actually mean" (Time, 9/17). Ray Chambers, the United Nations special envoy for malaria, added, "We know that malaria control interventions work and that we can make rapid progress towards ending malaria deaths. Now is the time to expand these results to all of Africa and the rest of the world" (WHO release, 9/18).

The report is available online.