The global community has made significant strides since 2000 to eradicate malaria. These were largely triggered by the adoption by the UN of the Millennium Development Goals and a subsequent large increase in funds. The international financing available for malaria control has increased about 20 times, reaching US$2.7 billion in 2015.
These funds have been used mainly to finance standard malaria control measures:
- distribution of insecticide-treated bednets (ITNs)
- indoor residual insecticide spraying (IRS)
- prompt treatment of clinical malaria cases with artemisinin-based combination therapy (ACT)
Progress, however, has been uneven and still faces serious obstacles in some countries. Below is an insight into what has been achieved and what is next.
Results so far
In 2000 the number of cases of malaria was estimated to be 262 million with estimated deaths up to 1.1 million. By 2015 the malaria cases were estimated to have shrunk to 214 million and deaths to 429,000 globally.
Around 90% of cases and 92% of deaths occur in the sub-Saharan region. Taking into account population increases, the incidence rate decreased by 37% and the death rate by 60%.
The control measures implemented were:
- 214 million bed nets delivered in 2014
- 123 million people protected by IRS (but only 7% of children in sub-Saharan Africa were protected)
- 392 million ACTs procured in endemic countries in 2013 (but only 13% with fever in sub-Saharan Africa received therapy)
- 319 million diagnostic tests and 197 microscopic blood examinations (but most children with suspected malaria did not have a diagnostic test)
It is estimated that measures taken since 2000 have averted about 660 million clinical cases of malaria in sub-Saharan Africa alone.
In 2015, 91 countries had ongoing malaria transmission, putting 3.2 billion people at risk. These numbers, however, hide the reductions achieved in many countries since 2000. Between 1987 and 2007 malaria was not eliminated in any country, but following increased efforts after 2000:
- from 2007 to 2015 five countries were declared free of malaria by WHO (requires three consecutive years with no indigenous cases): Armenia, Maldives, Morocco, Turkmenistan, UAE
- in 2014, 13 countries reported no cases of malaria for that year: Argentina, Azerbaijan, Costa Rica, Georgia, Iraq, Kyrgyzstan, Oman, Paraguay, Sri Lanka, Syrian Arab Republic, Tajikistan, Turkey and Uzbekistan
In 2016 Sri Lanka and Kyrgyzstan were certified free of malaria by the WHO. These two countries had different journeys in achieving malaria eradication, but both show we need to learn lessons from the past and maintain the malaria control infrastructure.
In 1963 only 17 cases of malaria were reported in Sri Lanka, so the government moved funds elsewhere and reduced surveillance. Malaria cases surged and by the late 1960s, there were 500,000 cases. Anti-malaria activities were stepped up, but with little effect until the 1990s when more emphasis was put on parasite control, rather than vector control, and the use of treated bednets.
From 2000 on there was a large reduction in cases, even during the years of war up to 2009. Sri Lanka’s high literacy rates, good road infrastructure and the health system were seen as key factors in its success. The status is maintained by continued effective surveillance, rapid diagnosis and effective treatment.
Continued surveillance and treatment targets travellers, migrants and peacekeepers who are at risk of contracting malaria elsewhere and bringing it back — in 2014, 32 cases were detected in migrants returning from West Africa after failed attempts to smuggle them to other countries.
The country was first free of malaria in 1961 and remained free for 25 years. After independence from the Soviet Union in the 1990s borders were opened up, which allowed in visitors from malaria endemic countries. This was compounded by a financial crisis that led to cuts in health care and shortages of drugs and insecticides.
In addition, there was a major malaria epidemic in 2002 after a large number of people returned from working in neighbouring countries where malaria was endemic. Rapid intervention by WHO, USAID and several NGOs quickly contained the epidemic and strengthened the healthcare system. By 2011 there were no indigenous malaria cases in the country.
Why we should support global malaria eradication
Everyone can understand the humanitarian reasons for combatting malaria, but with political pressure in several countries to cut back on international aid it is important to stress that there are also hard economic reasons to eradicate this disease. Malaria and other tropical diseases are a major economic burden on the poorest countries and the poorest people in those countries.
According to the WHO draft report for the 70th World Health Assembly:
- malaria is associated with slower economic development: from 1965 to 1990, the economies of countries with malaria grew 0.25–1.3% less per capita per year than countries without malaria
- over a period of 25 years, growth in gross domestic product per capita in countries with a heavy malaria burden was less than a fifth of those countries without malaria
- according to a report on the economic impact of malaria on UK trade, commissioned by Malaria No More, between 2000 and 2015 a total of £96-524bn global economic output could have been lost due to the impact of malaria
With 91 countries affected by malaria, this single disease has a significant effect on global trade. Investment in malaria control is an investment in the global economy.
The importance of vector control
Vector control targets the mosquito species that carry the malaria parasite and are the foundation of malaria elimination. It has achieved major successes going back to the beginning of the last century and up to the present day. Examples of malaria vector control include:
- Malaysia 1900: environmental management by draining larval habitats and forest clearing — greatly reduced malaria.
- Panama, 1904: Integrated vector management by screening living quarters, draining or filling standing water, installing drains, spraying larvicides in breeding sites. These actions eliminated yellow fever and greatly reduced malaria
- Brazil, 1942: spraying larvicides in breeding sites and house spraying using short-acting pyrethroids eliminated the imported Anopheles gambiae mosquito that was the local vector for malaria
- Global, 1955-67: the Global Malaria Eradication Programme was based mainly on indoor residual spraying with DDT and other residual insecticides, larval control and provision of antimalarial medicines. This eliminated malaria from large parts of the world, especially outside the tropics
- Tropics, 2000-2015 (and continuing): issuing long-lasting insecticidal nets, indoor residual spraying and prompt treatment of patients — 50% reduction in malaria cases and 40% reduction in mortality.
According to the WHO, 53% of the population at risk in sub-Saharan Africa slept under insecticide-treated bednets in 2015, up from 5% in 2005. The distribution of nets is estimated to have contributed to about 70% of the 660 million malaria cases averted by vector control activities since 2000.
The early successes and the subsequent resurgence of malaria in many parts of the world show that there is a need for continued efforts in malaria control and constant vigilance to detect and halt new outbreaks. Many countries still do not have the ability to do these on their own.
Malaria control is complicated by the many variables that affect the transmission of the disease to humans. Each area, even within a country, has to be assessed and managed according to local conditions.
There may be differences in transmission from one area to another due to ecological and geographical characteristics, such as altitude, temperature and humidity, rainfall patterns, proximity to water bodies, land use, mosquito species distribution, socio-demographic characteristics, access to anti-malarial treatment and implementation of vector control.
There are 30-40 Anopheles mosquito species that are important malaria vectors. Multiple species can exist in one area and each has its own feeding and resting behaviour and preferred human or animal host. They may, therefore, have different susceptibilities to control methods and require different strategies. Mosquito populations can also adapt to control methods due to the elimination of those with certain behaviours and, for example, change their feeding behaviour.
Two types of resistance are a threat to the global programme to eradicate malaria:
- insecticide resistance in the vector mosquito populations
- drug resistance by the Plasmodium parasite that causes malaria
Vector control for malaria is greatly dependent on the use of several types of insecticide for bed nets and indoor residual spraying (IRS). Four classes of insecticide are used in malaria control: organochlorines, organophosphates, carbamates and pyrethroids.
Pyrethroid-based insecticides are the only class of insecticide recommended by WHO for treating Long Lasting Insecticidal Nets (LLINs) because they are safer, so if resistance builds up the choice is limited. For the moment, LLINs are still effective, however, but the use of two types of insecticide on nets is recommended in areas where mosquitoes show resistance.
Indoor residual spraying (IRS) involves spraying walls and ceilings with an insecticide that stays active for about 6 months. All four classes are used for IRS. Indoor spraying is effective because the malaria vector mosquitoes tend to rest indoors and it takes several days for them to become infective after biting an infected person. The mosquitoes go through several feeding, resting and egg-laying phases before they can pass on the parasites to another human. During this period the mosquitoes are likely to rest on a treated wall or ceiling and pick up a lethal dose of insecticide.
There are 73 malaria endemic countries that have provided WHO with insecticide resistance data since 2010. Of these, 60 have reported resistance to at least one class of insecticide, and 50 to two or more. Some countries, mainly in sub-Saharan Africa and India, have reported resistance to all four classes of insecticide. WHO recommends rotating different classes of insecticides for spraying to deter resistance .
The growing threat of resistance shows that there is a need to continue to fund research into new products. Luckily several are under development, both vaccines and new treatments, but there is still a long way to go to even prove their effectiveness.
Antimalarial medicine resistance
The Plasmodium parasites that the mosquitoes carry are also showing resistance to antimalarial medicines in some areas. The most effective treatment for malaria currently is artemisinin-based combination therapy (ACT), but resistance has occurred in the Greater Mekong subregion of South East Asia, which includes: Cambodia, Lao People’s Democratic Republic, Myanmar, Thailand and Viet Nam.
In 2013 WHO launched an emergency response to artemisinin resistance in the region. Then in 2015 the governments endorsed a strategy specifically to deal with this threat: the Strategy for Malaria Elimination in the Greater Mekong Subregion (2015–2030). Ongoing efforts in these countries are already showing great success: over three years (2012-15) the six countries reduced malaria cases by 54% and deaths by 84%. There is still a long way to go to achieve eradication, however, and new means of treatment are urgently needed.
What are the next goals for malaria?
The next major targets for the Global Technical Strategy for Malaria 2016-2030 are by 2020 to:
- reduce malaria mortality rates globally by at least 40% compared to 2015
- reduce malaria infection rates globally by at least 40% compared to 2015
- eliminate malaria from at least 10 countries that had it in 2015
- prevent the re-establishment of malaria in those countries that are free of malaria
The total international funding available in 2015 was US$2.7 billion, but to achieve the goal of a malaria-free world, the Roll Back Malaria Partnership estimates that funding will have to increase to US$6.4 billion per year by 2020 and US$8.7bn by 2030.
In 2016 a report published on World Malaria Day, Eliminating Malaria, WHO identified 21 countries that could achieve “zero indigenous cases of malaria” by 2020 (by WHO region):
- African Region: Algeria, Botswana, Cabo Verde, Comoros, South Africa, Swaziland
- Region of the Americas: Belize, Costa Rica, Ecuador, El Salvador, Mexico, Paraguay, Suriname
- Eastern Mediterranean Region: Iran (Islamic Republic of), Saudi Arabia
- South-East Asia Region: Bhutan, Nepal, Timor-Leste
- Western Pacific Region: China, Malaysia, Republic of Korea
In March this year representatives from the malaria control programmes in these countries attended a global forum in Geneva on “Getting to zero”. The forum established the “E-2020 initiative” and all 21 countries committed to achieving the target — this gave them just 45 months to achieve the elimination of malaria. Paraguay and Algeria already reported that they had been free of malaria for several years and were expected to be granted certification soon.
WHO has developed an updated Framework for malaria elimination to guide malaria control agencies and will convene an annual meeting to report on progress.
It is important that the international community increases support both for the malaria control programmes and research and development of new medicines and insecticides. This is vital for maintaining the momentum to achieve the goal of global malaria eradication.