By Stan Deresinski, MD, FACP, FIDSA, Clinical Professor of Medicine, Stanford University, Hospital Epidemiologist, Sequoia Hospital, Redwood City, CA, is Editor for Infectious Disease Alert.
Source: World Malaria Report 2012. Summary and Key Points. World Health Organization. http://ow.ly/hIj0n
It is estimated that there were approximately 219 million cases of malaria in the world in 2010 and 680,000 or these cases were fatal. The majority of deaths occur in children, most in Africa — with one dying every minute. Fourteen countries are estimated to account for 80% of deaths, with the Democratic Republic of the Congo and Nigeria accounting for 40% of total global malaria deaths. These startling statistics exist despite elimination efforts of this preventable disease by WHO and other organizations which have been associated with a reduction in malaria mortality rates which have diminished since 2000 by >25% worldwide and by 33% in the WHO African Region. Those efforts appear, however, to be leveling off, despite great continued need. Worldwide disbursements for malaria control increased from less than US$ 100 million in 2011 to US$ 1.66 billion in 2011 and US$ 1.84 billion in 2012. This amount appears to be plateauing and falls well short of the US$ 5.1 billion judged to be necessary to achieve universal implementation of malaria interventions.
Among the supported preventive measures is the use of insecticide-treated nets (ITN) for use while sleeping. It is estimated that the proportion of households in sub-Saharan Africa owning at least one ITN increased from 3% in 2000 to 53% in 2011, but with no change in the following year. Survey data indicates that 9 of 10 ITNs are actually used. The proportion of the population sleeping under an ITN increased from 2% in 2000 to 33% in both 2011 and 2012. Another important control measure is mosquito control. In the African Region, the percentage of households protected by indoor residual spraying (IRS) rose from <5% in 2005 to 11% (77 million individuals) in 2010 with no further increase in 2011. Globally, 153 million people were protected by IRS. However, resistance of mosquitoes to at least one pesticide has been detected in 64 countries. As of 2011, 77 countries had a policy for monitoring of insecticide resistance.
Many studies have found a lack of accuracy of microscopic diagnosis in many endemic regions as well as the frequent empiric administration of antimalarials in febrile individuals without diagnostic testing. In 2005, 68% of suspected cases globally received a parasitological test, a proportion that increased to 77% in 2011, an increase of only 1% from 2010. In the public sector in the African region, this value increased from 20% in 2005 to 47% in 2011, with most of the increase due to the use of rapid diagnostic tests.
Artemesinin combination therapy (ACT) is the recommended therapy for infections due to Plasmodium falciparum, as well as for Plasmodium vivax infections acquired in regions where this parasite is resistant to chloroquine. In 2011 the total number of tests performed was less than half the number of ACT distributed, indicating that they are given to many patients in the absence of confirmatory testing. It is estimated, however, that, despite their inappropriate use without a laboratory diagnosis, only 52% of patients managed in the public sector in the African Region received ACT in 2011. Because of a concern about the development of resistance, WHO has officially recommended since 2007 that oral artemesinin monotherapies be progressively removed from the market and replaced by ACTs. The number of countries that continue to allow single agent artemesinin oral products decreased from 55 in 2008 to 16 in 2012, with 8 of the 16 being in the African Region. Unfortunately, resistance to artemisinins has been detected in 4 countries of the South-East Asia Region — Cambodia, Thailand, Myanmar, and Viet Nam. ACT is still often effective as long as the parasite is susceptible to the partner drug. However, resistance to both components of multiple ACTs is present in the Palin province in western Cambodia near the border with Thailand.
Another important measure is the following: “Intermittent preventive treatment (IPT) is recommended for population groups in areas of high transmission who are particularly vulnerable to Plasmodium infection and its consequences, particularly pregnant women and infants.” With IPT, a curative dose of an effective antimalarial drug is administered to all pregnant women at each routine antenatal care visit beginning in the second trimester whether or not they are Plasmodium-infected. Thirty-six of 45 countries of sub-Saharan Africa, where 32 million pregnant women and a large proportion of the estimated 28 million infants born each year could benefit, had adopted this policy by 2011. Primarily due to low coverage in Nigeria and the Republic of Congo, only an average of 22% of pregnant women had received 2 doses of IPT (the recommendation at the time) in the 16 African countries for which household survey data was available.
Seasonal malaria chemoprevention, recently recommended by WHO, could benefit 25 million children in the region.
In assessing these statistics, it must be realized that only 58 of 99 countries with ongoing malaria transmission reported adequate data to WHO in 2011. The countries that did report accounted for only 15% of the estimated worldwide burden of malaria.
An important concern is the leveling off of international financial support and, consequently, of control and treatment activities. An example is the procurement of ITNs, 66 million of which were obtained in 2012 represents a decrease from the 145 million in 2010 and 92 million in 2010. Given the estimated mean useful life of ITNs of 2-3 years, ITN coverage appears to be headed for a decline in the absence of a massive increase in procurement in 2013. While there has been progress, there is a long distance to go and it is no time to slow down in efforts to control malaria.