A study, published in the British medical journal Lancet, found that the number of deaths caused by mosquito-borne diseases, like malaria, are twice as high as estimated in 2010 by the World Health Organization (WHO).
In 2010, the WHO estimated that malaria was responsible for about 655,000 deaths globally. However, this new study, led by Dr Christopher Murray from the University of Washington in Seattle, found that nearly 1.24 million people lost their lives to mosquito-borne diseases in 2010. More specifically, they reported that more than 78,000 children, between the ages of five and 14-years-old, died from malaria, and more than 445,000 people, 15-years-old and older died from malaria in 2010. This shows that 42 percent of malaria death occur in older children and adults, which is contrary to what is believed.
In addition, more than 90 percent of these deaths occurred in Africa.
This study was supported by funding from the Bill and Melinda Gates Foundation. The researchers were able to use new data and computer modeling software to construct this database of malaria statistics from 1980 to 2010.
As a result, they found that in 1980, there were 995,000 deaths from malaria. From then, the number of deaths increased and peaked in 2004 at 1.82 million deaths. Since 2004, the number of deaths has decreased to 1.24 million in 2010.
Although, the number of deaths has decreased recently, the number of deaths is significantly above the WHO estimates.
Between 1980 to 2004, the number of death increased, potentially due to a growing population at-risk for being infected by infected mosquitoes. However, with help from sources, like the Global Fund to Fight Aids, Tuberculosis and Malaria, more people were able to access malaria prevention and treatment programs and supplies. Thus the number of death dramatically decreased.
These malaria prevention and treatment programs have enabled 230 million people access to bednets, indoor spraying, and antimalarial drug treatments. These actions have dramatically decreased the number of malaria infections.
According to the WHO estimates, children under the age of five-years-old are most at risk for malaria. However, researchers from this study found that older children and adults are still affected. This conclusion challenges the well-established belief that young children develop immunity to malaria, after multiple infections. This is referred to as adaptive immunity. However, since more older children are dying from malaria, it suggests adaptive immunity may not play a significant role in preventing severe cases of malaria and death.
In addition, the researchers reported that malaria eradication will unlikely in the short-term. According to their model, if the number of malaria infections decrease at the same rate, the number of death, caused by malaria will be less than 100,000 deaths after 2020.
There are many reasons why the number of death caused by malaria are higher than expected. First, in some regions, the reporting system is ineffective at classifying cause of deaths because many people who die from malaria may never reach a hospital setting or surveying mechanism. Second, rapid diagnostic tests for malaria have enabled accurate diagnoses of malaria, where before these malaria cases might be diagnosed ad treated as for a different condition.
These readjustments have increased the number of reported malaria death by 21%.
In the end, this study highlights the importance of increased funding toward combating malaria, both in preventive and treatment care.
Malaria is a global issue with over 3.3 billion people at risk with about 500 million reported cases annually. Malaria remains endemic in Sub-Saharan Africa, Southeast Asia and parts of South America, burdening the countries’ healthcare systems and economies. There are five species of the plasmodium parasite affecting humans, Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, and Plasmodium knowlesi, with Plasmodium falciparum responsible for virtually all mortality cases.
Malaria is particularly devastating in children and pregnant women. It also affects people with HIV/AIDS and travelers. In pregnant women, malaria causes high rates of miscarriages, estimating 200,000 fetal deaths during pregnancy. HIV/AIDS positive individuals and travelers have dampened or unexposed immune systems that increase their vulnerability to the parasite. Additionally, malaria can have profound economic effects since it weakens countries’ workforces, and can decrease GDP by as much as 1.3% in countries with high incidences of disease. Over time, these setbacks accumulate into substantial differences in GDP between countries with and countries without malaria. The health costs of preventing and treating malaria can total up to 40% of public health expenditures, 30-50% of inpatient hospital admissions, and up to 60% of outpatient health clinic visits for countries struggling with high malaria transmission. Poorer people are disproportionately affected by malaria because they cannot afford treatment or have limited access to healthcare. Thus families and communities can be sent down the poverty spiral. Although there are preventative measures for these people to use to reduce their risk, a vaccine would be the ideal solution to reduce the disease burden and could contribute to eliminating malaria in some regions.
Preventive methods include bed nets and indoor spraying, and treatment medications include cholorquine and artemisinin-based combination therapies, or ACTs. However, there have been cases of drug resistant strains of malaria from these antimalarial treatments. There is no vaccine for malaria, yet; however, Glaxosmithkline has a contending vaccine in phase III clinical trial.
