Malaria

Malaria summary¹

Pathogenic agent

Plasmodium species (four to six Plasmodium species known to cause malaria; of these,
P. falciparum and P. vivax pose the greatest threat)

Location

Sub-Saharan Africa (over 90% cases), Southeast Asia, Eastern Mediterranean, Western Pacific, Americas (ie, warmer regions of the world)

Transmission

Bites of female Anopheles mosquitoes

Epidemiology

There were an estimated 229 million cases of malaria in 2019
These resulted in 409,000 malaria deaths
Children aged under 5 years are the most vulnerable group affected by malaria, accounting for two-thirds of all malaria deaths worldwide
Total funding for malaria control and elimination reached an estimated $3 billion in 2019

Malaria is a life-threatening disease caused by Plasmodium parasites that are transmitted to people through the bites of female Anopheles mosquitoes.¹ Six species of Plasmodium parasites are known to cause malaria across different geographical areas.² Nearly all (94%) malaria cases arise in Africa. Other regions where infections are found include Southeast Asia, Eastern Mediterranean, Western Pacific, and the Americas.¹

Malaria is highly prevalent; it affects everyone from indigenous people to migrants and travelers, and almost half the world's population is at risk of the disease.^1,3

In 2019, there were 229 million cases of malaria worldwide and over 400,000 malaria deaths, including 274,000 (67%) deaths in children under the age of 5 years.¹ Total global funding for malaria control and elimination reached an estimated $3 billion in 2019.¹

What characterizes malaria?

Malaria initially presents as a fever, headache, and chills, and, if left untreated, it quickly progresses to multi-organ failure and death.¹ Malaria parasites can enter the brain and cause cerebral malaria, which is characterized by convulsions and coma, and in pregnant women it can pass through the placenta, leading to birth complications.^4,5 It is thought that the malaria parasite infects red blood cells, causing them to get stuck (cytoadhere) in small blood vessels, blocking essential blood flow and resulting in organ dysfunction.⁴

Though serious, malaria is both preventable and treatable.^4,6 The mosquitoes that carry the malaria-causing parasite thrive in hot, tropical areas with high rainfall and humidity and lay their eggs in water.¹ The study of mosquito biology and ecosystems has contributed greatly to anti-malaria efforts.⁶ Mosquito control using insecticides and malaria nets is the most effective means to help prevent and reduce malaria transmission.¹ Early diagnosis is essential and fluid management remains standard of care in severe malaria cases.^1,4 Apart from these measures, anti-malaria medicines (eg, intravenous artesunate or oral artemisinin-based combination therapy) can be used to prevent the disease, and anti-malaria vaccination using the RTS,S vaccine is useful for pregnant women and young children.^1,7

Despite this progress, the malaria parasite is becoming increasingly resistant to antimicrobial treatments, though rotating between different anti-malarial drugs may reduce this unwanted trend.⁴ Moreover, the RTS,S vaccine is not fully effective,¹ and new tools are needed to combat this threat.

Vaccines for a malaria-free world

Today, new malaria vaccines are in development.⁸ Working toward the goal of a malaria-free world, the WHO Global Technical Strategy for Malaria 2016−2030 provides a comprehensive framework with the aim of reducing malaria incidence and mortality by 90% and eliminating malaria from at least 35 countries by 2030.⁹

World Health Organization. Malaria fact sheet. Available at: https://www.who.int/news-room/fact-sheets/detail/malaria [Accessed 27 Aug 2021].
Lover AA, et al. Malaria elimination: time to target all species. Am J Trop Med Hyg. 2018;99:17–23.
Escalante AA, Pacheco MA. Malaria molecular epidemiology: an evolutionary genetics perspective. Microbiol Spectr. 2019;7:10.1128/microbiolspec.AME-0010-2019.
Plewes K, et al. What’s new in the management of malaria? Infect Dis Clin North Am. 2019;33:39–60.
Milner DA Jr. Malaria pathogenesis. Cold Spring Harbor Perspect Med. 2018;8:a025569.
Gachelin G, et al. Evidence and strategies for malaria prevention and control: a historical analysis. Malar J. 2018;17:96.
Rogerson SJ, et al. Progress towards vaccines to protect pregnant women from malaria. EBioMedicine. 2019;42:12–13.
Palacpac NMQ, Horii T. Malaria vaccine: facing unknowns. F1000Res. 2020;9:F1000 Faculty Rev-296.
World Health Organization. Global technical strategy for malaria 2016–2030. Available at: https://www.who.int/publications/i/item/9789241564991 [Accessed 27 Aug 2021].