Approximately 1.2 million humans die each year from malaria, a much higher figure than the previously estimated 600,000, researchers from the Institute for Health Metrics and Evaluation, University of Washington, Seattle, USA, reported in The Lancet this week. The authors added that the majority of deaths occur in children under the age of 5 years, while 42% occur in adults and older children.
However, the huge international anti-malaria effort that has taken place over the last ten years is paying off. Malaria mortality has significantly dropped. The study was paid for by a grant awarded by the Bill & Melinda Gates Foundation.
Professor Christopher Murray and team gathered malaria mortality data over a thirty-year period, ending in 2010. They have revealed that the death figure reported in the World Malaria Report 2011 was an underestimate – there are significantly more deaths occurring in several parts of the world, especially in Africa.
The number of people who died annually from malaria between 1980 and 2010 rose from 1 million to 1.8 million in 2004, the authors wrote. The increase was caused by two factors:
- A rise in malaria death rates in the early 1980s and early 1990s
- A rise in populations in high malaria-risk areas
The death figure dropped by 32% (from 2004) to 1.2 million by 2010.
In 1980, approximately 377,000 children under 5 years of age in sub-Saharan Africa died of the disease – rising to over 1 million in 2004. In 2010 about 56% of all malaria deaths worldwide occurred in African children under 5; in that year 700,000 children in that age group in Africa died, a drop of about 350,000 compared to 2004.
The researchers inform that in 2010, malaria death rates are highest in sub-Saharan Africa – especially central sub-Saharan Africa.
Even though most deaths occur among young children and babies, the authors explain that the death toll among adults is still very high.
Below is a breakdown of malaria deaths globally in 2010:
- People aged 15-49 years – 20% of all deaths
- People aged 50-69 years – 9% of all deaths
- People aged 70+ years – 6% of all deaths
- In other words – adults (people aged 15+) account for over one third of all deaths
In the majority of cases, except for sub-Saharan Africa where malaria transmission is particularly high, adults accounted for about the same proportions of total deaths from malaria.
The figures below illustrate how much higher the new malaria death estimates are in comparison to before with the World Malaria Report 2011:
- Among children/babies under 5 years in Africa – 1.3 times higher
- Among children aged 5+ years in Africa – 8.1 times higher
- Among all age groups outside Africa – 1.8 times higher
The researchers report that 24% of all childhood deaths in Africa in 2008 were directly linked to malaria, a much higher figure than the 16% reported in a previous study, which had gathered data from the World Malaria Report. In order to be able to reduce mortality by two-thirds among under 5s between 1990 and 2015 – a Millennium Development Goal 4 – combating malaria mortality needs to become a central strategy, the authors emphasized.
“That malaria is a previously unrecognised driver of adult mortality also means that the benefits and cost-effectiveness of malaria control, elimination, and eradication are likely to have been underestimated.”
The previous report had estimated total global malaria deaths among people aged 5+ years at 91,000 in 2010, compared to 524,000 in this latest report – a difference of 433,000.
Dr. Christopher Murray said:
“You learn in medical school that people exposed to malaria as children develop immunity and rarely die from malaria as adults. What we have found in hospital records, death records, surveys and other sources shows that just is not the case.”
The team wrote:
“Since the global peak in 2004, there has been a substantial decrease in malaria deaths that is attributable to the rapid, although variable, scale-up of control activities in sub-Saharan Africa. This scale-up has been driven in part by an expansion in health aid targeted towards malaria and suggests that the investments made by major funders such as the Global Fund to Fight AIDS, Tuberculosis and Malaria have rapidly decreased the burden of malaria.”
The researchers believe that the target of zero malaria deaths by 2015 is probably unrealistic – they say these new figures mean that short-term goals will need to be re-assessed.
Dr. Murray and team wrote:
“We estimated that if decreases from the peak year of 2004 continue, malaria mortality will decrease to less than 100 000 deaths only after 2020.”
The announcement by the Global Fund that round 11 of funding would be cancelled raises enormous doubts as to whether the gains in malaria mortality reduction can be built on or even sustained. From 2003 to 2008, the Global Fund provided 40% of development assistance for health targeted towards malaria. This reduction in resources for malaria control is a real and imminent threat to population health in endemic countries.”
The following quote comes from a conclusion in a linked Lancet Editorial:
“What should happen now? WHO’s new independent advisory body, the Malaria Policy Advisory Committee (MPAC), held its first meeting this week. But MPAC only has 15 members.
We believe urgent technical and policy analyses must be initiated by WHO – involving a broader group of experts (eg, including those in child survival) and country representatives – to review these new data and their implications for malaria control programmes. This opportunity needs to be grasped with urgency and optimism.”
Malaria means bad air, from the 18th century Italian words mala, aria. Medical historians say the term was first used by Dr. Francisco Torti, an Italian phyisician – at that time people believed the disease was caused by the foul air that existed in marshes.
In 1880, scientists found out that malaria was caused by a parasite, and described it as a parasitic disease, transmitted by the anopheles mosquito. It infects the host with a (one-cell) parasite, known as plasmodium. A few years later they discovered that it was the female mosquito that transmitted the parasite to humans through its bite.
- The female anopheles mosquito takes a blood meal from a human, infecting him/her.
- Initially, sporozoites get into the bloodstream and make their way to the liver.
- Sporozoites infect liver cells (hepatocytes). There they multiply, and become merozoites.
- The merozoites rupture the liver cells and find their way into the bloodstream.
- The merozoites infect the red blood cells. They develop into ring forms – schizonts and trophozoites – these produce even more merozoites.
- Gametocytes (sexual forms) are also produced. If a mosquito bites a human with gametocytes, the mosquito will become infected and can potentially spread the disease on to other humans it bites, where the parasite continues its life cycle.
The illustration below explains the signs and symptoms of malaria.
Written by Christian Nordqvist