Signs, Symptoms, and Complications of Malaria
- Fever, fatigue, vomiting, and headaches are common symptoms
- Severe cases can cause jaundice, seizures, coma, or death
- Symptoms usually appear 10 to 15 days after being bitten by an infected mosquito
- Recurrences of the disease can occur if not properly treated
- Reinfection usually causes milder symptoms in those who have recently survived an infection
- Respiratory distress can occur in severe cases
- HIV coinfection increases mortality
- Kidney failure may occur, leading to blackwater fever
- Cerebral malaria can result in encephalopathy and retinal whitening
- Enlarged spleen, enlarged liver, severe headache, low blood sugar, and haemoglobin in the urine may occur
Cause and Transmission of Malaria
- Malaria is caused by infection with parasites in the Plasmodium genus
- Six species of Plasmodium can infect humans, with P. falciparum and P. vivax being the most common
- P. falciparum is associated with the majority of deaths
- P. vivax can also cause potentially life-threatening conditions
- P. vivax is more common outside Africa
- Malaria is transmitted through the bite of infected Anopheles mosquitoes
- Mosquitoes become infected by biting a person who already has malaria
- The parasites, called sporozoites, travel to the liver and multiply
- Infected hepatocytes release merozoites into the bloodstream
- Merozoites invade red blood cells and replicate, spreading the infection
Diagnosis and Treatment of Malaria
- Malaria is typically diagnosed through microscopic examination of blood or rapid diagnostic tests
- Polymerase chain reaction methods can detect the parasites' DNA but are not widely used in malaria-endemic areas
- Preventing mosquito bites is crucial in reducing the risk of malaria
- Several medications are available to prevent and treat malaria
- Artemisinin-based combination therapy is the recommended treatment for malaria
Impact and Prevalence of Malaria
- Malaria is most prevalent in tropical and subtropical regions around the equator
- In 2021, there were 247 million cases of malaria worldwide, resulting in an estimated 619,000 deaths
- 77% of deaths occurred in children under 5 years old
- Sub-Saharan Africa had the highest number of cases and deaths
- Malaria is associated with poverty and has a significant negative impact on economic development, costing Africa $12 billion annually
Prevention and Control of Malaria
- Two malaria vaccines, RTS,S and Malaria vaccine#R21/Matrix-M, are approved for use in children by the WHO
- Methods used to prevent malaria include medications, mosquito elimination, and prevention of mosquito bites
- Insecticide-treated nets (ITNs) and indoor residual spraying (IRS) have significantly contributed to the decrease in malaria cases
- ITNs help reduce infection rates and transmission of malaria
- Indoor residual spraying involves spraying insecticides on the walls inside homes
- Modifying houses can be a sustainable strategy to prevent malaria
- Efforts to decrease mosquito larvae and open water availability can also help control malaria
Malaria is a mosquito-borne infectious disease that affects humans and other vertebrates. Human malaria causes symptoms that typically include fever, fatigue, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. Symptoms usually begin 10 to 15 days after being bitten by an infected Anopheles mosquito. If not properly treated, people may have recurrences of the disease months later. In those who have recently survived an infection, reinfection usually causes milder symptoms. This partial resistance disappears over months to years if the person has no continuing exposure to malaria.
| Malaria | |
|---|---|
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| Malaria parasite connecting to a red blood cell | |
| Pronunciation | |
| Specialty | Infectious disease |
| Symptoms | Fever, vomiting, headache, yellow skin |
| Complications | seizures, coma, organ failure, anemia, cerebral malaria |
| Usual onset | 10–15 days post exposure |
| Causes | Plasmodium transmitted to humans by Anopheles mosquitoes |
| Diagnostic method | Examination of the blood, antigen detection tests |
| Prevention | Mosquito nets, insect repellent, mosquito control, medications |
| Medication | Antimalarial medication |
| Frequency | 247 million (2021) |
| Deaths | 619,000 (2021) |
Human malaria is caused by single-celled microorganisms of the Plasmodium group. It is spread exclusively through bites of infected female Anopheles mosquitoes. The mosquito bite introduces the parasites from the mosquito's saliva into a person's blood. The parasites travel to the liver where they mature and reproduce. Five species of Plasmodium can infect and be spread by humans. Most deaths are caused by P. falciparum, whereas P. vivax, P. ovale, and P. malariae generally cause a milder form of malaria. The species P. knowlesi rarely causes disease in humans. Malaria is typically diagnosed by the microscopic examination of blood using blood films, or with antigen-based rapid diagnostic tests. Methods that use the polymerase chain reaction to detect the parasite's DNA have been developed, but they are not widely used in areas where malaria is common, due to their cost and complexity.
The risk of disease can be reduced by preventing mosquito bites through the use of mosquito nets and insect repellents or with mosquito-control measures such as spraying insecticides and draining standing water. Several medications are available to prevent malaria for travellers in areas where the disease is common. Occasional doses of the combination medication sulfadoxine/pyrimethamine are recommended in infants and after the first trimester of pregnancy in areas with high rates of malaria. As of 2023, two malaria vaccines have been endorsed by the World Health Organization. The recommended treatment for malaria is a combination of antimalarial medications that includes artemisinin. The second medication may be either mefloquine, lumefantrine, or sulfadoxine/pyrimethamine. Quinine, along with doxycycline, may be used if artemisinin is not available. In areas where the disease is common, malaria should be confirmed if possible before treatment is started due to concerns of increasing drug resistance. Resistance among the parasites has developed to several antimalarial medications; for example, chloroquine-resistant P. falciparum has spread to most malarial areas, and resistance to artemisinin has become a problem in some parts of Southeast Asia.
The disease is widespread in the tropical and subtropical regions that exist in a broad band around the equator. This includes much of sub-Saharan Africa, Asia, and Latin America. In 2021, some 247 million cases of malaria worldwide resulted in an estimated 619,000 deaths, with 77 percent being 5 years old or less. Around 95% of the cases and deaths occurred in sub-Saharan Africa. Rates of disease decreased from 2010 to 2014, but increased from 2015 to 2021. According to UNICEF, nearly every minute, a child under five died of malaria in 2021, and "many of these deaths are preventable and treatable". Malaria is commonly associated with poverty and has a significant negative effect on economic development. In Africa, it is estimated to result in losses of US$12 billion a year due to increased healthcare costs, lost ability to work, and adverse effects on tourism.
