Editing Malaria (section)

==Epidemiology==
[[File:Malaria-death-rates.png|thumb|upright=1.3|left|Estimated number of deaths from malaria per 100,000 people per country<ref>{{cite web |title=Death rate from malaria, 2021 |url=https://ourworldindata.org/grapher/malaria-death-rates?tab=map |publisher=Our World in Data |access-date=7 April 2025}}</ref>]]
[[File:World-map-of-past-and-current-malaria-prevalence-world-development-report-2009.png|thumb|upright=1.3|left|Past and current malaria prevalence in 2009{{cn|date=March 2025}}]]
[[File:Relative incidence of Plasmodium (malaria) species by country of origin for imported cases to non-endemic countries.png|thumb|upright=1.3|left|Relative incidence of ''Plasmodium'' species by country of origin for imported cases to non-endemic countries<ref name="Tatem-2017">{{cite journal | vauthors = Tatem AJ, Jia P, Ordanovich D, Falkner M, Huang Z, Howes R, Hay SI, Gething PW, Smith DL |display-authors=6 | title = The geography of imported malaria to non-endemic countries: a meta-analysis of nationally reported statistics | journal = The Lancet Infectious Diseases | volume = 17 | issue = 1 | pages = 98–107 | date = January 2017 | pmid = 27777030 | pmc = 5392593 | doi = 10.1016/S1473-3099(16)30326-7 | bibcode = 2017LanID..17...98T }}</ref>]]

The WHO estimates that in 2021 there were 247 million total cases of malaria resulting in 619,000 deaths.{{sfn|WHO|2022|p={{page needed|date=July 2024}}}} Children under five years old are the most affected, accounting for 67% of malaria deaths worldwide in 2019.<ref name="WHO-2021">{{cite book|author=WHO|url=https://www.who.int/teams/global-malaria-programme/reports/world-malaria-report-2021|title=World Malaria Report 2021|date=2021|publisher=World Health Organization|isbn=978-92-4-004049-6|location=Switzerland|access-date=2022-01-24|archive-date=2023-05-06|archive-url=https://web.archive.org/web/20230506225435/https://www.who.int/teams/global-malaria-programme/reports/world-malaria-report-2021|url-status=live}}</ref> About 125 million pregnant women are at risk of infection each year; in [[Sub-Saharan Africa]], maternal malaria is associated with up to 200,000 estimated infant deaths yearly.<ref name="Hartman-2010" /> Since 2015, the WHO European Region has been free of malaria. The last country to report an indigenous malaria case was Tajikistan in 2014.{{sfn|WHO|2022|p={{page needed|date=July 2024}}}} There are about 1300–1500 malaria cases per year in the United States.<ref name="Taylor-2012" /> The United States eradicated malaria as a major public health concern in 1951,<ref>{{cite web |publisher=CDC-Centers for Disease Control and Prevention |title=Malaria – About Malaria – History – Elimination of Malaria in the United States (1947–1951) |url=https://www.cdc.gov/malaria/about/history/elimination_us.html |access-date=17 January 2020 |language=en-US |date=28 January 2019 |archive-date=4 May 2012 |archive-url=https://web.archive.org/web/20120504183309/http://www.cdc.gov/malaria/about/history/elimination_us.html |url-status=live }}</ref> though small outbreaks persist.<ref>{{cite web|publisher=Centers for Disease Control and Prevention|date=2019-01-28|title=Malaria – About Malaria – Malaria Transmission in the United States|url=https://www.cdc.gov/malaria/about/us_transmission.html|access-date=2021-09-03|language=en-US|archive-date=2022-07-19|archive-url=https://web.archive.org/web/20220719125248/https://www.cdc.gov/malaria/about/us_transmission.html|url-status=live}}</ref> Locally acquired mosquito-borne malaria occurred in the United States in 2003, when eight cases of locally acquired ''P. vivax'' malaria were identified in Florida, and again in May 2023, in four cases, as well as one case in Texas,<ref>{{cite web |last=Health Alert Network (HAN) |date=2023-06-26 |title=Locally Acquired Malaria Cases Identified in the United States |url=https://emergency.cdc.gov/han/2023/han00494.asp |access-date=2023-06-27 |website=Centers for Disease Control and Prevention |language=en-US |archive-date=2023-06-26 |archive-url=https://web.archive.org/web/20230626220921/https://emergency.cdc.gov/han/2023/han00494.asp |url-status=live }}</ref> and in August in one case in Maryland.<ref>{{cite news |date=2023-08-28 |title=Important Updates on Locally Acquired Malaria Cases Identified in Florida, Texas, and Maryland |language=en-US |work=Health Alert Network (HAN) – 00496 |url=https://emergency.cdc.gov/han/2023/han00496.asp |access-date=2023-08-28 |archive-date=2023-08-28 |archive-url=https://web.archive.org/web/20230828234211/https://emergency.cdc.gov/han/2023/han00496.asp |url-status=live }}</ref> About 900 people died from the disease in Europe between 1993 and 2003.<ref name="Kajfasz-2009" /> Both the global incidence of disease and resulting mortality have declined in recent years. According to the WHO and UNICEF, deaths attributable to malaria in 2015 were reduced by 60%<ref name="UNICEF-2015">{{cite book|title=Achieving the malaria MDG target: reversing the incidence of malaria 2000–2015 |url= http://www.unicef.org/publications/files/Achieving_the_Malaria_MDG_Target.pdf | author = UNICEF|publisher=WHO|access-date=26 December 2015|date=September 2015|isbn=978-92-4-150944-2|url-status=live|archive-url=https://web.archive.org/web/20160105025916/http://www.unicef.org/publications/files/Achieving_the_Malaria_MDG_Target.pdf|archive-date=5 January 2016}}</ref> from a 2000 estimate of 985,000, largely due to the widespread use of insecticide-treated nets and artemisinin-based combination therapies.<ref name="Howitt-2012" /> Between 2000 and 2019, malaria mortality rates among all ages halved from about 30 to 13 per 100,000 population at risk. During this period, malaria deaths among children under five also declined by nearly half (47%) from 781,000 in 2000 to 416,000 in 2019.<ref name="UNICEF DATA"/>

Malaria is presently endemic in a broad band around the equator, in areas of the Americas, many parts of Asia, and much of Africa.  Eighty-five to ninty percent of malaria fatalities occur in Sub-Saharan Africa.<ref name="Layne-2006" /> An estimate for 2009 reported that countries with the highest death rate per 100,000 of population were [[Ivory Coast]] (86.15), [[Angola]] (56.93) and [[Burkina Faso]] (50.66).<ref name="Provost-2011" /> A 2010 estimate indicated the deadliest countries per population were Burkina Faso, [[Mozambique]] and [[Mali]].<ref name="Murray-2012" /> The [[Malaria Atlas Project]] aims to map global [[Endemic (epidemiology)|levels of malaria]], providing a way to determine the global spatial limits of the disease and to assess [[disease burden]].<ref name="Guerra-2007" /><ref name="Hay-2010" /> This effort led to the publication of a map of ''P.&nbsp;falciparum'' endemicity in 2010 and an update in 2019.<ref name="Gething-2011" /><ref>{{cite journal | vauthors = Weiss DJ, Lucas TC, Nguyen M, Nandi AK, Bisanzio D, Battle KE, Cameron E, Twohig KA, Pfeffer DA, Rozier JA, Gibson HS, Rao PC, Casey D, Bertozzi-Villa A, Collins EL, Dalrymple U, Gray N, Harris JR, Howes RE, Kang SY, Keddie SH, May D, Rumisha S, Thorn MP, Barber R, Fullman N, Huynh CK, Kulikoff X, Kutz MJ, Lopez AD, Mokdad AH, Naghavi M, Nguyen G, Shackelford KA, Vos T, Wang H, Smith DL, Lim SS, Murray CJ, Bhatt S, Hay SI, Gething PW |display-authors=6 | title = Mapping the global prevalence, incidence, and mortality of Plasmodium falciparum, 2000–17: a spatial and temporal modelling study | journal = The Lancet | volume = 394 | issue = 10195 | pages = 322–331 | date = July 2019 | pmid = 31229234 | pmc = 6675740 | doi = 10.1016/S0140-6736(19)31097-9 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Battle KE, Lucas TC, Nguyen M, Howes RE, Nandi AK, Twohig KA, Pfeffer DA, Cameron E, Rao PC, Casey D, Gibson HS, Rozier JA, Dalrymple U, Keddie SH, Collins EL, Harris JR, Guerra CA, Thorn MP, Bisanzio D, Fullman N, Huynh CK, Kulikoff X, Kutz MJ, Lopez AD, Mokdad AH, Naghavi M, Nguyen G, Shackelford KA, Vos T, Wang H, Lim SS, Murray CJ, Price RN, Baird JK, Smith DL, Bhatt S, Weiss DJ, Hay SI, Gething PW |display-authors=6 | title = Mapping the global endemicity and clinical burden of Plasmodium vivax, 2000–17: a spatial and temporal modelling study | journal = The Lancet | volume = 394 | issue = 10195 | pages = 332–343 | date = July 2019 | pmid = 31229233 | pmc = 6675736 | doi = 10.1016/S0140-6736(19)31096-7 | doi-access = free }}</ref> As of 2021, 84 countries have endemic malaria.{{sfn|WHO|2022|p={{page needed|date=July 2024}}}}

The geographic distribution of malaria within large regions is complex, and malaria-afflicted and malaria-free areas are often found close to each other.<ref name="Greenwood-2002" /> Malaria is prevalent in tropical and subtropical regions because of rainfall, consistent high temperatures and high humidity, along with stagnant waters where mosquito larvae readily mature, providing them with the environment they need for continuous breeding.<ref name="Jamieson-2006" /> In drier areas, outbreaks of malaria have been predicted with reasonable accuracy by mapping rainfall.<ref name="Abeku-2007" /> Malaria is more common in rural areas than in cities. For example, several cities in the [[Greater Mekong Subregion]] of Southeast Asia are essentially malaria-free, but the disease is prevalent in many rural regions, including along international borders and forest fringes.<ref name="Cui-2012" /> In contrast, malaria in Africa is present in both rural and urban areas, though the risk is lower in the larger cities.<ref name="Machault-2011" />

According to the World Health Organization's 2023 World Malaria Report, there were an estimated 263 million malaria cases globally in 2023, up from 252 million in 2022. The number of malaria deaths stood at 597,000 in 2023, a slight decrease from 600,000 in 2022. The African region continues to bear a disproportionate share of the global malaria burden, accounting for approximately 94% of all cases and 95% of deaths.<ref>{{Cite web |title=Fact sheet about malaria |url=https://www.who.int/news-room/fact-sheets/detail/malaria?utm_source |access-date=2025-03-23 |publisher=World Health Organization |language=en}}</ref>

===Climate change===
{{Further|Climate change and infectious diseases#Malaria}}

[[Climate change]] is likely to affect malaria transmission, but the degree of effect and the areas affected is uncertain.<ref name="Climate Change and Human Health—Risk and Responses">{{cite web|title=Climate Change And Infectious Diseases|url=https://www.who.int/globalchange/climate/en/chapter6.pdf|url-status=live|archive-url=https://web.archive.org/web/20160304063626/http://www.who.int/globalchange/climate/en/chapter6.pdf|archive-date=2016-03-04|work=Climate Change and Human Health—Risk and Responses|publisher=World Health Organization}}</ref> Greater rainfall in certain areas of India, and following an [[El Niño]] event is associated with increased mosquito numbers.<ref>{{cite web|title=Climate change and human health—risks and responses. Summary|url=https://www.who.int/globalchange/climate/summary/en/index5.html|archive-url=https://web.archive.org/web/20031225023503/http://www.who.int/globalchange/climate/summary/en/index5.html|url-status=dead|archive-date=December 25, 2003|access-date=29 October 2018|publisher=World Health Organization}}</ref>

Since 1900 there has been substantial change in temperature and rainfall over Africa.<ref>{{Cite journal|vauthors=Hulme M, Doherty R, Ngara T, New M, Lister D|date=August 2001|title=African climate change: 1900-2100.|url=https://www.int-res.com/articles/cr/17/c017p145.pdf|journal=Climate Research|volume=17|issue=2|pages=145–68|doi=10.3354/cr017145|bibcode=2001ClRes..17..145H|doi-access=free|access-date=2020-09-08|archive-date=2021-06-30|archive-url=https://web.archive.org/web/20210630114729/https://www.int-res.com/articles/cr/17/c017p145.pdf|url-status=live}}</ref> However, factors that contribute to how rainfall results in water for mosquito breeding are complex, incorporating the extent to which it is absorbed into soil and vegetation for example, or rates of runoff and evaporation.<ref name="Smith-2020">{{cite journal | vauthors = Smith MW, Willis T, Alfieri L, James WH, Trigg MA, Yamazaki D, Hardy AJ, Bisselink B, De Roo A, Macklin MG, Thomas CJ |display-authors=6 | title = Incorporating hydrology into climate suitability models changes projections of malaria transmission in Africa | journal = Nature Communications | volume = 11 | issue = 1 | pages = 4353 | date = August 2020 | pmid = 32859908 | pmc = 7455692 | doi = 10.1038/s41467-020-18239-5 | bibcode = 2020NatCo..11.4353S }}</ref> Recent research has provided a more in-depth picture of conditions across Africa, combining a malaria climatic suitability model with a continental-scale model representing real-world hydrological processes.<ref name="Smith-2020" />

====Changes in geographic distribution====

Climate change has led to shifts in malaria-endemic regions, with the disease expanding into higher altitudes and previously malaria-free areas.<ref name=Caminade14>{{cite journal |vauthors=Caminade C, Kovats S, Rocklov J, Tompkins AM, Morse AP, Colón-González FJ, Stenlund H, Martens P, Lloyd SJ |display-authors=6 |title=Impact of climate change on global malaria distribution |journal=Proceedings of the National Academy of Sciences USA |volume=111 |issue=9 |pages=3286–91 |date=March 2014 |pmid=24596427 |pmc=3948226 |doi=10.1073/pnas.1302089111 |doi-access=free |bibcode=2014PNAS..111.3286C }}</ref>
Rising temperatures allow mosquitoes to survive in regions that were once too cold for them, including highland areas in Africa, South America, and parts of Asia.<ref name=Caminade14/>
A study analyzing malaria cases in Ethiopian and Colombian highlands found a strong correlation between increased temperatures and malaria incidence, demonstrating that climate change has made previously inhospitable areas suitable for transmission.<ref name=Siraj14>{{cite journal |vauthors=Siraj AS, Santos-Vega M, Bouma MJ, Yadeta D, Ruiz Carrascal D, Pascual M |title=Altitudinal changes in malaria incidence in highlands of Ethiopia and Colombia |journal=Science |volume=343 |issue=6175 |pages=1154–8 |date=March 2014 |pmid=24604201 |doi=10.1126/science.1244325 |bibcode=2014Sci...343.1154S }}</ref>

====Increased transmission season====

Malaria transmission is highly sensitive to temperature and rainfall patterns.<ref name=Siraj14/> Climate change has led to longer transmission seasons in tropical regions, where mosquitoes can breed year-round due to prolonged periods of high humidity and warm temperatures.<ref name=Sewe21>{{cite journal |vauthors=Colón-González FJ, Sewe MO, Tompkins AM, Sjödin H, Casallas A, Rocklöv J, Caminade C, Lowe R |title=Projecting the risk of mosquito-borne diseases in a warmer and more populated world: a multi-model, multi-scenario intercomparison modelling study |journal=Lancet Planet Health |volume=5 |issue=7 |pages=e404–14 |date=July 2021 |pmid=34245711 |pmc=8280459 |doi=10.1016/S2542-5196(21)00132-7 }}</ref> Research suggests that in parts of sub-Saharan Africa, the malaria transmission season has lengthened by several months, particularly in regions where warming has pushed temperatures into the optimal range for Plasmodium falciparum development.<ref name=Sewe21/> In regions such as West Africa and parts of India, increasing temperatures and prolonged rainy seasons have contributed to a rise in malaria cases.<ref name=Sewe21/> Some studies predict that by 2050, many malaria-endemic areas will experience a 20–30% increase in transmission duration due to warming trends.<ref name=Caminade14/>

====Effects of extreme weather events====

Extreme weather events, such as heavy rainfall, flooding, and droughts, are increasing in frequency and intensity due to climate change, creating favorable conditions for malaria outbreaks.<ref name=Bouma96>{{cite journal |vauthors=Bouma MJ, van der Kaay HJ |title=The El Niño Southern Oscillation and the historic malaria epidemics on the Indian subcontinent and Sri Lanka: an early warning system for future epidemics? |journal=Tropical Medicine & International Health |volume=1 |issue=1 |pages=86–96 |date=February 1996 |pmid=8673827 |doi=10.1046/j.1365-3156.1996.d01-7.x }}</ref> Flooding provides ideal breeding grounds for mosquitoes by forming stagnant water pools, while droughts can also exacerbate malaria by forcing human populations to store water in open containers, which serve as mosquito habitats.<ref name=Bouma96/> This effect has been observed in parts of sub-Saharan Africa and South Asia, where prolonged drought periods were followed by spikes in malaria cases.<ref name=Bouma96/> A review of malaria outbreaks linked to climate variability found that El Niño events, which increase rainfall and temperatures in malaria-endemic regions, have been associated with significant surges in cases.<ref>{{cite journal |vauthors=Hay SI, Shanks GD, Stern DI, Snow RW, Randolph SE, Rogers DJ |title=Climate variability and malaria epidemics in the highlands of East Africa |journal=Trends in Parasitology |volume=21 |issue=2 |pages=52–53 |date=February 2005 |pmid=15664524 |pmc=3173848 |doi=10.1016/j.pt.2004.11.007 }}</ref>

====Resistance and adaptation of vectors====

Higher temperatures accelerate the development of ''Plasmodium'' parasites within mosquitoes, potentially leading to increased transmission efficiency.<ref name=Shapiro17>{{cite journal |vauthors=Shapiro LL, Whitehead SA, Thomas MB |title=Quantifying the effects of temperature on mosquito and parasite traits that determine the transmission potential of human malaria |journal=PLOS Biology |volume=15 |issue=10 |pages=e2003489 |date=October 2017 |pmid=29036170 |pmc=5658182 |doi=10.1371/journal.pbio.2003489 |doi-access=free}}</ref> Additionally, rising temperatures and changing environmental conditions have been linked to the spread of insecticide resistance in mosquito populations, complicating malaria control efforts.<ref name=Shapiro17/> A global survey found that Anopheles mosquitoes in Africa, Asia, and South America have developed increased resistance to commonly used insecticides such as pyrethroids.<ref>{{cite journal |vauthors=Suh PF, Elanga-Ndille E, Tchouakui M, Sandeu MM, Tagne D, Wondji C, Ndo C |title=Impact of insecticide resistance on malaria vector competence: a literature review |journal=Malaria Journal |volume=22 |issue=1 |pages=19 |date=January 2023 |pmid=36650503 |pmc=9847052 |doi=10.1186/s12936-023-04444-2 |doi-access=free}}</ref>
===Urbanization and malaria trends===
Urbanization has a great effect on malaria. There are better healthcare and infrastructure in the cities which then reduce malaria. Whereas poorer areas with bad sanitation allow mosquitoes to thrive which then increase malaria.<ref>{{cite journal |vauthors=Agyemang-Badu SY, Awuah E, Oduro-Kwarteng S, Dzamesi JY, Dom NC, Kanno GG |year=2023 |title=Environmental Management and Sanitation as a Malaria Vector Control Strategy: A Qualitative Cross-Sectional Study Among Stakeholders, Sunyani Municipality, Ghana |journal=Environmental Health Insights |volume=17 |issue=17 |doi=10.1177/11786302221146890|pmid=36620305 |pmc=9817013 |bibcode=2023EnvHI..1711468A }}</ref> Some African cities have more malaria cases compared to suburban areas. In Bangkok, it has been shown that malaria has dropped due to better control.<ref>{{cite journal |vauthors=Sudathip P, Kongkasuriyachai D, Stelmach R, Bisanzio D, Sine J, Sawang S, Kitchakarn S, Sintasath D, Reithinger R |year=2019 |title=The Investment Case for Malaria Elimination in Thailand: A Cost-Benefit Analysis |journal=The American Journal of Tropical Medicine and Hygiene |volume=100 |issue=6 |pages=1445–1453 |doi=10.4269/ajtmh.18-0897|pmid=30994098 |pmc=6553898 }}</ref>