What Is Malaria?
Malaria is a life-threatening disease that is caused by Plasmodium parasites, which are transmitted to people through the bites of infected female Anopheles mosquitoes.
Malaria symptoms include fever, headache, and chills. If not diagnosed and treated within 24 hours, malaria can progress to severe illness or death. In 2019, malaria accounted for 409,000 deaths (WHO report) worldwide, the majority of which occurred in sub-Saharan Africa. Pregnant women and children under five years of age are the most vulnerable groups.
Along with its toll on human health, malaria imposes a heavy social and economic burden in low-and middle-income countries. Malaria elimination – and ultimately, malaria eradication of Plasmodium falciparum (P. falciparum) and Plasmodium vivax (P. vivax) – is the unifying goal for global malaria partners.
What Causes Malaria?
In order to eliminate malaria, we need to break its transmission cycle. Malaria is caused by Plasmodium parasites, which are spread to people through the bites of infected female Anopheles mosquitoes. There are five species of Plasmodium parasites that cause malaria in humans. Of these, P. falciparum and P. vivax are the most harmful. P. falciparum causes the most deaths worldwide. P. vivax is typically not fatal, but it is the most widespread malaria species and can hide out in the liver to cause recurrence of the disease even after many years.
The infected mosquitoes, or vectors, typically bite between dusk and dawn. Each species of Anopheles mosquito has its own preferred habitat: some, for example, prefer shallow collections of fresh water, which are often abundant during the rainy season in tropical climates.
Malaria has a very long history that goes back to the Palaeogene period. The first evidence of malaria parasite was found in mosquitoes preserved in amber that are approximately 30 million years old. The first link between the parasite and the disease was established in 1880, by Charles Laveran. The name malaria was given by ancient Romans and is derived from “mal” “aria”, which means bad air, stemming from the belief that the disease resulted from the bad fumes of the swamps.
Malaria is one of the oldest surviving diseases to plague humankind, with clay tablets from the Mesopotamia period describing deadly periodic fevers that likely suggest malaria. It likely arrived in Europe in the first century AD and spread across the continent with travelers and nomadic settlers, eventually making its way to the Americas. The malaria parasite was discovered in 1880, and the first synthetic anti-malarial drugs were developed in the 1930s.
Malaria prevention, diagnosis and treatment
Malaria is preventable and treatable with an array of complementary tools that make the elimination of malaria possible within a generation.
Malaria is preventable with vector control, which refers to ways of reducing mosquito bites to reduce or break transmission of the malaria parasite. Primary vector control interventions include insecticide-treated mosquito nets, indoor residual sprays, and various types of environmental management to reduce mosquito breeding sites. In some situations, larviciding can play a role.
Research suggests use of genetically modified mosquitoes could also be a powerful and cost-effective approach to supplement existing interventions. In May 2021, new guidance from the World Health Organization set essential standards to inform future research and development on genetically modified mosquitoes, particularly addressing issues relating to ethics, safety, affordability and effectiveness. Gene drive technologies have the potential to quickly eliminate local populations of malaria-causing mosquitoes.
Malaria is also preventable via chemoprevention: in malaria endemic areas or in areas with moderate to high transmission in Africa, women, and children at risk of malaria can receive intermittent preventive treatment (IPT) of malaria with a preventive drug for pregnant women or infants. Children can receive seasonal malaria chemoprevention.
The newly recommended RTS,S malaria vaccine is the latest addition to the malaria arsenal, and a significant milestone in the history of malaria innovation. Not only is it the world’s first malaria vaccine shown to provide partial protection against malaria in children under five, it is also the first-ever vaccine against a human parasite recommended for use by WHO. The RTS,S vaccine is a complementary pediatric malaria prevention and control intervention that must be paired with other core malaria interventions, such as effective insecticide-treated mosquito nets (ITNs) or indoor residual spraying (IRS). It shows even great results when paired with chemoprevention.
Malaria researchers have more innovations in the development pipeline. A highly effective, all-ages malaria vaccine is still needed, and the R21 vaccine — which uses the same antigen platform as RTS,S — is showing strong potential in pilot trials. New malaria vaccines are also being developed on mRNA platforms, and monoclonal antibodies are another promising tool for malaria prevention.
Patients with suspected malaria should have parasitological confirmation of diagnosis, either by microscopy or rapid diagnostic test (RDT), before antimalarial treatment is started.
P. vivax can be difficult to diagnose, as RDTs are less sensitive than the test for P. falciparum. New RDTs with higher sensitivity to enable improved diagnosis are becoming available. Malaria surveillance systems also serve a critical early-warning antennae for the emergence of new disease pathogens that threaten global health security.
If diagnosed promptly and correctly, malaria is treatable and curable. The best available malaria treatment is artemisinin-based combination therapy (ACT). Use of artemisinin in monotherapies is a contributing factor for the spread of drug resistance to these essential front-line anti-malarials – and poses a major risk for malaria resurgence. For P. vivax, a new single-dose drug, tafenoquine, was approved in 2019. It can be taken as a single dose to achieve radical cure. Used in combination with newly sensitive diagnostics, it has the potential to be transformative for P. vivax malaria elimination.
In line with the movement to ‘decolonize’ health, there is growing recognition that malaria-endemic countries and communities must lead the charge to the last mile of malaria elimination. The exigencies of the COVID19 pandemic have made it clear that front-line community health workers, who often work on an unpaid basis, should be treated as essential workers. Housing, sanitation, access to health care and education are all closely interlinked with malaria outcomes and increasingly, countries are beginning to regard malaria as a social problem requiring social interventions.
Community engagement can improve treatment-seeking and malaria prevention behavior, ensure communication activities and health education methods are socially and culturally attuned, and build into a grassroots movement. For instance, communities that understand and own vector control mechanisms can destroy breeding sites in their environment — and hold political leaders to account for malaria outcomes.
Malaria has been eliminated progressively from many parts of the world over the last century, but major challenges remain: the constant evolution of the malaria parasite against interventions means constant innovation is necessary to counter drug and insecticide resistance. Against this backdrop, one of the biggest challenges to achieving malaria elimination is sustaining political will and funding when malaria cases drop. This is especially true in recent years, with the disruptions of the COVID-19 pandemic.
Sustained investment in the malaria fight is essential to end this preventable disease, and and represents one of the best investments in global health and foreign aid. A substantial increase in international financing for malaria two decades ago drove significant reductions in malaria mortality and morbidity by 2015 — but in the last decade, as international financing for the disease levelled off, malaria elimination results have hit a plateau. History has shown in every setting that when malaria campaigns stop short of elimination, resurgence of the disease is swift and relentless.
Working towards malaria elimination – and ultimately, malaria eradication
Malaria places a huge strain on half the world’s health systems, exposes gaps in basic health services, undermines economies and devastates families and communities. To ensure we continue to save lives and accelerate progress toward global malaria elimination goals, we need to stay a step ahead of an ever-adapting parasite and mosquito. This will only be possible through ongoing innovation in developing and scaling up a suite of tools that can deliver the greatest impact.
Malaria elimination will spur economic development and alleviate the poverty and inequality burdening the poorest and the most vulnerable communities. Because of the complexity of malaria biology, resurgence is a constant threat and ultimately, malaria eradication is the only sustainable approach. Our unifying global ambition is to achieve worldwide malaria eradication within a generation.