Malaria is a disease caused by a parasite (Plasmodium) transmitted through the bite of an infected mosquito (female Anopheles). Through the bloodstream, the parasites reach the liver, where they produce another form of the parasite that infects red blood cells. As they do so, they multiply within these cells, rupture them, and continue to infect others. As a result, an immune response to the infection occurs, with symptoms such as fluctuating fever, chills, and fatigue. Additionally, anemia develops due to the destruction of red blood cells, and kidney damage occurs from the circulating free hemoglobin. Without treatment, other organs can be affected, including the central nervous system, potentially leading to death.
In the past, significant efforts were made that did not eradicate the disease but did eliminate it in many countries. However, malaria remains a public health threat for the poorest, especially in sub-Saharan Africa. The use of new tools and strategies for its elimination will only achieve their objectives if there is a global commitment to support them. This requires taking measures related to climate change. Additionally, combating malaria must be addressed in humanitarian contexts with high transmission of the parasite, resulting from political instability, conflicts, mass forced displacement of people, and deteriorated health systems.
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The efforts of the 20th century did not eradicate malaria
Malaria has accompanied mankind through the centuries.
We have been living with malaria since the Neolithic revolution, the time when populations shifted from hunting and gathering to agriculture and animal husbandry. In fact, it is believed that this disease may have been the cause of the death of Alexander the Great in 323 BC and of Alaric I, the first "barbarian" king to besiege and sack Rome. It was also the cause of Attila abandoning his conquest of Italy in 452 or the death of a third of the Christian soldiers during the Third Crusade (1188-1192).
Malaria is even attributed to the end of Genghis Khan's military campaign in Eastern Europe in 1241, as well as facilitating the entry of European invaders into the Americas in the 16th century. It was also malaria that defeated more than half of the British and French troops during the Haitian Slave Insurrection of 1791, which ultimately led to Haiti's independence. For example, it is estimated that malaria accounted for 66% of deaths during the American Civil War (1861-1865).
We also know, despite the scarcity of records, that throughout this time, of course, malaria has been and continues to be endemic in Africa.
In the 20th century, mankind thought that malaria could be eradicated in a few years
The mechanism of malaria transmission was discovered in 1897. This led to the development of new techniques in the early 20th century. These included, for example, rapid and massive vector control campaigns, the use of new medications such as chloroquine, and improvements in sanitation and environmental conditions.
Years later, the goal shifted from isolated actions to a global program aimed at achieving sustainable change. This was motivated by the desire to minimize the negative impact of malaria on the economy. Additionally, there was great optimism stemming from the success of the first residual insecticide, DDT, in interrupting the transmission of the disease. As a result of all this, the WHO launched the Global Malaria Eradication Programme (GMEP) in 1955.
The "eradication" attempt was based on the rapid and massive application of the residual insecticide DDT
When launching the GMEP, some believed that talking about eradication was unrealistic. After all, despite the existence of DDT, addressing the problem in Africa could be extremely challenging. There were hard-to-reach areas and very weak, or even nonexistent, health systems. Additionally, it was estimated that the cost of this program could be very high. At the same time, however, some advocated for the urgent need to act. The reason was the fear that the potential danger of developing insecticide resistance in mosquitoes could become a reality. Such resistances had been known since 1951.
Finally, it was decided that there was already sufficient technical and scientific knowledge to implement vector elimination actions using residual DDT insecticide. It was expected to eliminate malaria transmission in just over a year and to eradicate the Plasmodium reservoir in another 4-6 years. Eradication and its consolidation were to be achieved in less than 7 years. It was also considered necessary to avoid indefinite-duration epidemiological control approaches and that potential cultural and social barriers were not significant. On the other hand, although resistance of the parasite to chloroquine had already emerged by 1950, it was believed that this would not be a problem. After all, once transmission was interrupted, treatment would be needed only minimally.
There was still no awareness of the risks of failure associated with this approach or the ridiculousness of this overconfidence. Nor was it appreciated how unjust and irresponsible it was to overlook the particularities of different contexts and the needs of the African continent. In fact, this program neglected the region of the planet with the highest malaria burden. In sub-Saharan Africa, the program barely managed to be implemented.
After a failed and exclusive eradication effort, malaria surged back more strongly than before
Numerous efforts were made under the framework of this program, especially in countries with the capacity to mobilize resources for it. However, reality and inequality quickly asserted themselves in the poorest and most vulnerable countries.
Attack actions failed to reach the most remote and hard-to-access areas. Furthermore, during this period, little progress was made in accessing new malaria medications. The only notable efforts in this regard were the attempts by the United States to protect its soldiers in Vietnam. Ultimately, the massive use of DDT against malaria, especially in agriculture, spread resistance of mosquitoes to the insecticide, diminishing its effectiveness. As a result, transmission was only interrupted in many areas for a time. However, after this temporary suppression, malaria resurfaced with tremendous strength. The parasite wreaked havoc on populations that now had reduced immune capacity, while epidemiological surveillance systems were unprepared for it.
In 1969, it was assumed that the eradication strategy should be replaced by a longer-term control strategy, and the program was halted. Just as it was never a real attempt at eradication, but rather elimination, it would be unfair to speak only of failure. A significant number of countries did eliminate the risk of disease for millions of people thanks to this international effort. However, these were countries with higher socioeconomic levels, better health systems, and less intense malaria transmission. Meanwhile, in countries with higher endemic malaria transmission, there were no advances. Furthermore, the opportunity to strategically leverage the tools that existed at the time in the fight against malaria where they were most needed was virtually lost.
Subsequent efforts to control malaria were also unsuccessful
The failure to eradicate malaria served as a stimulus for new strategies and approaches. The study of this failure allowed for learning from mistakes. Thus, there was now more emphasis on community health and strengthening health systems, including the movement for primary health care. However, it took several decades for the world to regain the capacity to vigorously confront the fight against this disease again.
It was not until 1998 that another major global initiative, the Roll Back Malaria Partnership, aimed to reverse the trend of malaria. However, by 2004, this initiative had not achieved greater funding for the fight against malaria. Moreover, it had also failed to reverse the trends in malaria deaths, which had been rising since 1980. It was evident that the goal of halving malaria deaths was not being met. Additionally, according to some sources, in 2004, there were a peak of 1,817,000 malaria deaths. This was nearly double the figures from 1980, and even triple when considering only children under 5 years old in Africa.
A change in trend in the 21st century was hindered by the COVID-19 pandemic
It was only between 2005 and 2015 that the trend changed and global malaria cases and deaths declined. This was, in part, the result of new global and international initiatives. These included the creation of the Global Fund to Fight AIDS, tuberculosis, and malaria in 2002, and the launch of the United States President’s Malaria Initiative in 2005. Additionally, the Global Malaria Action Plan was published in 2008, and a Global Technical Strategy for Malaria in 2015.
The High Burden to High Impact approach was also launched in 2018 to prioritize countries with the highest disease burden. However, later, in 2020, the situation worsened again, coinciding with the COVID-19 pandemic.
Today, efforts to eliminate malaria continue
Since 2005, there has been a sustained decline in malaria cases, only interrupted by the COVID-19 pandemic in 2020. Still, currently, approximately 250 million cases and 600,000 deaths from malaria occur in 85 endemic countries and areas each year. Many countries have declared malaria elimination in their territories in recent years. However, the world is still far from achieving the targets set for 2030.
The current malaria elimination strategy proposes a series of progressive steps
Today, malaria elimination efforts are guided by a technical strategy, published in 2015 and updated in 2021. This strategy proposes a path to malaria elimination, adapted to each context. To this end, it proposes that three consecutive priorities be addressed as progress is made in reducing transmission of the disease:
The first priority focuses on reducing morbidity and mortality by decreasing transmission. To achieve this, a strategic pillar aligned with universal health coverage is proposed. It involves ensuring access to prevention through vector control and chemoprevention, as well as to diagnosis and treatment.
Once transmission is lower, the elimination of malaria must be pursued. This requires an emphasis on epidemiological surveillance of clinical cases, with active case finding. At this stage, it is also essential to understand the determinants of residual transmission. Eliminating the last remnant of local transmission may require innovative interventions to eliminate reservoirs or to address any insecticide resistance that arises. Furthermore, community mobilization is necessary for all of this.
Finally, when the goal of elimination is within reach, it is necessary to consolidate achievements. To do this, it is essential to transform and strengthen the surveillance strategy. This involves ensuring the detection, treatment, mandatory reporting, and investigation of any suspected infection cases that still arise. The objective of this phase is to prevent the resurgence of malaria once local transmission has been eliminated.
The first strategic pillar seeks to reduce transmission: to do so, prevention must be expanded
The two main malaria prevention tools are vector control and chemoprevention.
For vector control, it is recommended to select the appropriate intervention depending on the context. The two available interventions to choose from are the use of insecticide-treated bed nets or indoor residual spraying. It is not recommended to use both simultaneously. In addition to this, mosquito resistance to insecticides should be monitored, and the impact of the selected intervention should be assessed. Besides these key interventions, there are other actions that can be complementary, depending on their effectiveness in the local context and their cost. An example of this is the use of larvicides. Other interventions, such as the use of insecticide-treated clothing or topical repellents, are not recommended at the population level.
Chemoprevention involves administering treatment against malaria preventively to individuals at higher risk in areas of moderate to high transmission. It can also be done during specific times of the year in areas with high seasonal transmission, regardless of whether these individuals are infected or not. For example, it is recommended for pregnant women, with intermittent treatment involving multiple doses during prenatal visits. It is also recommended for children in high-risk groups during peak transmission times. For individuals without immunity migrating to an endemic area and for local individuals with some risk of severe malaria, chemoprophylaxis is recommended. This consists of administering doses of treatment that are lower than therapeutic levels but sufficient to prevent infection.
Since 2023, malaria is also a vaccine-preventable disease
There are already two recommended vaccines against malaria: the RTS,S/AS01 vaccine and the R21/Matrix-M vaccine. Both can be used in children over 5 months of age. They require the administration of 3 doses spaced one month apart, followed by a fourth dose at least one year later. They have been shown to reduce the number of malaria cases by half during the first year after vaccination with three doses. This is especially important because it is the period when children are the smallest and most vulnerable. Additionally, administering the fourth dose, although it provides reduced protection, extends the duration of immunity somewhat longer. When used in areas of high transmission coinciding with the seasonal peak, they can prevent up to 75% of malaria episodes.
The implementation program for the RTS,S/AS01 vaccine was developed in Ghana, Kenya, and Malawi and concluded in 2023. It not only succeeded in reducing transmission but also reduced mortality from all causes excluding injuries by 13% in the eligible child population for vaccination. This was the case despite more than 25% not being vaccinated and less than half having received the fourth dose. Although they have not been compared in specific studies, both appear to have similar efficacy. However, the R21/Matrix-M is more cost-effective. They are not expected to replace other preventive measures, but vaccination against malaria is now an additional option to consider.
To reduce malaria transmission, diagnosis and treatment must also be expanded
The correct diagnosis of malaria is essential. All patients suspected of having malaria should receive a diagnostic confirmation. This can be done through parasite detection via microscopy or a rapid diagnostic test. An appropriate diagnosis helps to avoid the overuse of first-line treatments and minimizes the risk of resistance. Additionally, it aids in improving the approach to other possible pathologies that present with fever, for which differential diagnoses are often not made.
Diagnosis is the gateway to treatment. Likewise, universal access to the recommended treatment is what prevents the progression of the infection to severe malaria and death. This recommended treatment consists of artemisinin-based combination therapies, which have a local efficacy of over 95%. However, in many endemic countries, there is a widespread circulation of counterfeit or low-quality medicines. This occurs when regulatory authorities lack the capacity to prevent smuggling, counterfeiting, or the circulation of outdated medications. As a result, patients may use these products or other therapeutic regimens that are no longer recommended, such as artemisinin monotherapies. This puts those who use them at risk, but also increases the global threat of resistance to combination therapies. Therefore, it is essential to maintain good surveillance of treatment failure.
Both for diagnosis and treatment, community health workers can play a key role. Programs that employ them offer rapid diagnostic testing and immediate treatment in the community. This helps overcome access barriers and increases coverage in the fight against malaria.
The second strategic pillar begins once the transmission has already been lowered
Once morbidity and mortality from malaria have been reduced and transmission is lower, it is necessary to accelerate its elimination where it still persists. To achieve this, actions from the previous strategic pillar must be adapted to the new objective while simultaneously initiating other new actions.
It is a priority to identify and prioritize the most hard-to-reach areas, where the most disadvantaged people live. In these communities, malaria may still persist strongly. Therefore, prevention, diagnosis, and treatment should be intensified in these areas. On the other hand, in regions with few cases, other interventions can be studied. One of these is the use of certain special therapies. These prevent mosquitoes from becoming infected when they bite the infected and undergoing treatment person. Here, it may also be appropriate to adapt strategies to halt the transmission of Plasmodium vivax, not just falciparum. Finally, it is important to provide preventive information and chemoprophylaxis to individuals traveling to areas where malaria is still endemic.
Epidemiological and entomological surveillance (of mosquitoes) must be present at all stages, but adapted to the local risk of transmission. In areas of high transmission, aggregated data should be used to monitor trends in mortality. The coverage of actions, population behaviors, and operational aspects of programs, such as available resources, are also monitored. However, as transmission decreases, the focus should be adjusted. This is the time to intensify surveillance in higher-risk groups. To do this, it is necessary to increase the frequency of reports, allowing for the early identification of a potential outbreak. Additionally, when transmission is low, data from each case that appears should be analyzed rather than relying on mere aggregated information.
The third strategic pillar aims at the complete elimination of the transmission
The third stage prioritizes, once elimination is well underway, achieving complete elimination. Additionally, it aims to reduce the risk of the local transmission of malaria reappearing.
In these final stages, surveillance becomes more complicated. There may be no cases, but even so, it is important to remain alert to increases in the risk of importation or transmission. Genomic surveillance may be necessary. This can be done, for example, by collecting blood samples from pregnant women during their prenatal consultations. This type of surveillance allows for monitoring how parasites mutate and evolve.
For these final steps, it is essential to have well-adapted national strategic plans. However, this is not enough. It is also necessary to work on actions for strengthening the health system and its information system.
Eradicating malaria remains the goal, with a target date set for 2050
The ultimate goal of eradication remains on the horizon. After all, there are no absolute barriers preventing it. Furthermore, today there is a more coherent strategy than that of 1955 for combating malaria. This strategy aims for the elimination of the disease in each country through priorities for action tailored to their levels of transmission and morbidity and mortality.
The world has also changed significantly since the (unsatisfactory) end of global eradication programs in 1969. Today, there are better tools, more scientific knowledge, and, seemingly, a renewed global commitment to this goal. Moreover, some even wish to set a date for it: 2050.
However, eradication will only be possible if the world is prepared to address the challenges in the places where it will be most difficult to eliminate malaria. These places are the countries where transmission levels remain extremely high. They also include countries affected by conflict and humanitarian crises, where the risk of failure of the recommended approaches is highest.
Malaria in humanitarian crises and conflicts
The risk of malaria transmission increases in complex humanitarian emergencies
Malaria has been closely linked to conflicts and humanitarian crises throughout history. This relationship persists today. In 2022, 89% of people in need of humanitarian assistance lived in countries where malaria is endemic. Furthermore, of the ten African countries with the highest current malaria disease burden, seven had a Humanitarian Response Plan in 2024. These are Nigeria, the Democratic Republic of the Congo, Mozambique, Burkina Faso, Niger, Cameroon, and Mali. The other three were included in Refugee Response Plans: Uganda (with 1.7 million refugees), Tanzania (with 242,000), and Ghana (with 11,000).
The causes of the high risk of malaria transmission in complex humanitarian crises are well known. They often include displacement of people with low immunity to malaria to endemic areas. This also occurs when people with subclinical infections are displaced to urban environments. Malaria is also associated with poor conditions of water, sanitation, hygiene, and habitability. When housing is precarious, it provides little protection against mosquitoes. Another significant risk factor is the interruption and overload of essential health services. In these cases, there is poor access to diagnosis and treatment. Additionally, malaria increases alongside other concurrent health issues, such as malnutrition.
For all these reasons, it is essential that in the fight against malaria, there is a rapid coordination of many different actors to carry out multisectoral actions.
Reducing malaria transmission in these contexts remains a challenge
Clearly, having a logical and coherent strategy against malaria does not eliminate the challenges of implementing it.
On one hand, there are recommended actions in stable contexts that are less effective in complex humanitarian crises. An example of this is the distribution of insecticide-treated bed nets. Despite being a well-studied effective intervention, there are many barriers to its success in these contexts. These barriers include the difficulty of use in the new living conditions or the need to sell the nets to acquire other goods. It is also known that other actions, such as indoor residual spraying, are not entirely feasible in acute emergencies.
Similarly, there are essential actions, such as epidemiological surveillance, that can pose a real challenge in a complex crisis. In many of these cases, it is not even possible to ensure access to malaria diagnosis and treatment. The problem escalates if the population is on the move. Even in cases where it is possible to ensure minimal epidemiological surveillance, it may be impossible to establish good vector surveillance or monitor the therapeutic efficacy of antimalarials.
Infectious diseases
External links
- WHO, 2024. WHO Guidelines for Malaria.
- WHO, 2024. Global Malaria Programme operational strategy 2024-2030.
- WHO, 2024. Malaria vaccine: WHO position paper.
- WHO, 2024. Guiding principles for prioritizing malaria interventions in resource-constrained country contexts to achieve maximum impact.
- Mertens, 2024. A history of malaria and conflict.
- WHO, 2023. World Malaria Report 2023.
- Messenger, 2023. Vector control for malaria prevention during humanitarian emergencies: a systematic review and meta-analysis.
- WHO, 2021. Global technical strategy for malaria 2016–2030, 2021 update.
- WHO, 2020. Malaria eradication: benefits, future scenarios & feasibility.
- WHO, 2018. Malaria surveillance, monitoring and evaluation: a reference manual.
- Feachem, 2019. Malaria eradication within a generation: ambitious, achievable, and necessary.
- WHO, 2013. Malaria control in humanitarian emergencies: an inter-agency field handbook, 2nd edition.
- Murray, 2012. Global malaria mortality between 1980 and 2010: a systematic analysis.
- Najera, 2011. Some Lessons for the Future from the Global Malaria Eradication Programme (1955–1969).
- The Lancet, 2005. Reversing the failures of Roll Back Malaria.
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