Open Outbreak

Malaria

Also known as: Plasmodium falciparum, Plasmodium vivax

Malaria is an infection spread mainly by the bite of infected Anopheles mosquitoes. In people, it commonly causes fever, tiredness, vomiting and headache. Severe illness can lead to jaundice, seizures, coma or death. The sources retrieved in this session describe malaria as a mosquito-borne disease with symptoms usually starting after a delay rather than immediately after a bite, but they did not provide one single current WHO fact sheet covering all key numbers. One literature source also notes that Plasmodium vivax is not always mild and can relapse because dormant liver stages can wake up later. WHO outbreak notices show that malaria still causes very large surges during crises, including floods and health-service disruption, with major events reported in Pakistan in 2022 and Ethiopia in 2024. Malaria remains a major public-health problem in parts of Africa, Asia, and the Americas. In this session, the evidence for exact global case fatality, reproduction number, and vaccine status was incomplete, so those are marked unknown rather than guessed.

Key facts

TransmissionSpread mainly by bites of infected Anopheles mosquitoes.
Incubationunknown
Case fatalityunknown; in the Ethiopia WHO outbreak notice for 2024, 1157 deaths were reported among over 7.3 million cases (reported CFR 0.02%) in that event, but this is not a general malaria fatality estimate.
Reproduction numberunknown
Vaccineunknown
TreatmentAntimalarial treatment exists; one literature source notes that Plasmodium vivax relapses can be prevented only by 8-aminoquinoline antimalarials.
ReservoirHumans are the reservoir described in the sources retrieved here; transmission occurs through mosquitoes.
Endemic regionsMany tropical and subtropical regions; retrieved sources specifically mention Southeast Asia, the Western Pacific, Africa including the Horn of Africa, and Central and South America.

Transmission

Malaria is described in the sources retrieved here as a mosquito-borne infection. People usually get it from the bite of an infected Anopheles mosquito. That means malaria risk depends not just on the parasite, but also on whether the right mosquitoes are present, whether they are biting humans, and whether weather and local conditions support mosquito breeding. The broader vector-borne disease literature returned in this session also notes that climate and environmental change can shift where vector-borne diseases are able to spread. For a worried reader, the practical point is simple: malaria is not usually caught like a cold from casual contact. It is mainly linked to mosquito exposure in places where transmission is established. WHO outbreak reports also show that floods, displacement, and disrupted health services can quickly raise exposure and make control harder.

Symptoms and severity

The overview source in this session says the usual symptoms of human malaria include fever, fatigue, vomiting and headache. In severe cases, it can cause jaundice, seizures, coma, or death. That is why malaria is treated as a medical urgency when someone has fever after being in an area with malaria transmission. One literature paper retrieved here adds an important caution: Plasmodium vivax has often been labelled “benign,” but increasing evidence suggests its severity and overall burden have been underestimated. WHO’s 2024 Ethiopia outbreak notice shows how serious malaria can still be at population level during a surge, with over 7.3 million reported cases and 1157 deaths in that event. The exact risk for any one person depends on age, immunity from past exposure, parasite species, pregnancy, access to testing, and how quickly effective care is started.

Treatment and vaccines

The sources retrieved in this session did not include a current WHO malaria treatment guideline or fact sheet, so this page avoids giving a full treatment table from memory. What the literature here does show is that antimalarial treatment exists, and that for Plasmodium vivax, relapses come from persistent liver stages called hypnozoites; one review says these can be prevented only by 8-aminoquinoline antimalarials. That matters because a person can seem better and then become ill again later if those liver stages are not addressed. WHO outbreak notices from Pakistan and Ethiopia repeatedly stress the importance of access to diagnosis and treatment during surges, especially when floods or strained health services delay care. The evidence retrieved in this session was not sufficient to give a properly sourced summary of current vaccine recommendations, so vaccine status is marked unknown here rather than guessed.

Where it occurs

Malaria remains established in many tropical and subtropical settings. The literature source on Plasmodium vivax retrieved here says most vivax cases originate from Southeast Asia and the Western Pacific, with many others in Africa and Central and South America, including the Horn of Africa. WHO outbreak notices in this session add concrete recent examples: Ethiopia reported very large malaria numbers in 2024, and Pakistan reported a major surge in 2022 after severe flooding. These notices show that malaria is not evenly distributed within countries. Risk can vary by district, altitude, season, rainfall, population movement, and the strength of local health services. In Ethiopia, WHO said about 75% of the land mass is considered endemic and around 69% of the population in those areas is at risk. So the right question is not just “which country?”, but “which place, season, and conditions?”

Recent history

This site’s archive says malaria has appeared in 7 archived WHO-notice events since 1996. The WHO items returned in this session show notices from 1996 in Ghana, 1998 in the United Republic of Tanzania, 1999 in Burundi and Kenya, 2007 in Jamaica, 2022 in Pakistan, and 2024 in Ethiopia. The pattern is not of one continuous global emergency, but of repeated national or regional surges, often linked to weather shocks, strained health services, or local transmission conditions. Two recent notices stand out. In Pakistan, WHO reported more than 3.4 million suspected cases from January through August 2022 after devastating floods, with over 170 000 laboratory-confirmed cases and most confirmed infections reported as Plasmodium vivax. In Ethiopia, WHO reported over 7.3 million cases and 1157 deaths between 2024-01-01 and 2024-10-20.

What to watch

The clearest warning signs would be changes that make malaria easier to spread or harder to control. One is expansion into new places, especially where climate or environmental change makes mosquito transmission more feasible. Another is sharp rises after floods, displacement, conflict, or health-system disruption, as seen in recent WHO notices from Pakistan and Ethiopia. A third is any sign that the usual pattern has changed: the basic transmission described in the sources here is mosquito-borne, so any credible evidence of sustained spread without mosquito exposure would be unusual and concerning. Public-health teams also watch for treatment failure, parasite resistance, insecticide resistance in mosquitoes, and shortages of key prevention or treatment tools, because these problems can turn a manageable situation into a larger outbreak. For travellers and residents alike, sudden increases in fever illness in a malaria-prone area deserve attention, especially in children and pregnant people.

Updated