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Anopheline mosquitoes are disease vectors (carriers) that, when infected with Plasmodium parasites, spread malaria to people by piercing the skin. Malaria has been known to human for over 4,000 years and is said to have derived its contemporary name from mal’aria, which means “bad air” in Italian.
According to the report from the World Health Organization (WHO) published in 2014, about 3.3 billion people worldwide are at risk of contracting this disease. The range of symptoms for patients with this disease varies widely, from no fever or any other symptoms at all, to severe disease progression and even death. The mortality rate of patients with complications associated with falciparum malaria is particularly high and calls for immediate treatment.

Malaria is caused by Plasmodium parasites that are spread to humans through the bite of infected Anopheline mosquitoes. There are four species of parasites that cause this disease: Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, and Plasmodium ovale. Two of these - P. falciparum and P. vivax - are the most common. A fifth form of malaria caused by P. knowlesi, a species that usually causes malaria among monkeys in forested areas in Southeast Asia, has recently been reported.
When an Anopheline mosquito takes a blood meal from a human, the sporozoites that are injected with the saliva of the mosquito grow in the person’s liver cells before then migrating to the blood and growing in the red blood cells resulting in merozoite production. These merozoites cause the red blood cells to rupture and will continue to invade red blood cell after another in what is a continual cycle.
It is when these red blood cells rupture that malarial symptoms or attacks occur. Usually, malarial attacks will happen every other day with “tertian parasites” (P. vivax) and every third day with “quartan parasites” (P. malariae). Attacks by falciparum malaria are often irregular.

U.S. Centers for Disease Control and Prevention, "Malaria" Accessed March 19, 2014,

Blood-stage parasites (merozoites) are the cause of all clinical symptoms associated with malaria. When the parasite develops in an erythrocyte, many known and unknown toxic substances collect in that cell. These substances are then dumped into the bloodstream once the infected cell ruptures.
A period of time (incubation period) lasting for seven to thirty days will usually pass before the first symptoms appear. The infection may result in a wide variety of symptoms ranging from very mild or no symptoms at all to severe disease and even death, depending on the type of malaria parasite and whether or not complications exist. With P. vivax and P. ovale infections, patients who have experienced an initial episode with this disease can relapse months or years later without any symptoms present. Malarial relapses are triggered by a different mechanism from the re-manifestations of symptoms due to falciparum malaria that requires particular medical attention.

This malaria causes a daily fever (in some cases, several times a day). Since these fevers occur irregularly, however, they are not an effective diagnostic criterion. Falciparum malaria is characterized by accompanying complications collectively called “severe and complicated malaria”. This refers to cerebral malaria with abnormal behavior, impaired consciousness, seizures, coma and/or other neurologic abnormalities, severe anemia due to hemolysis (destruction of red blood cells), acute respiratory distress syndrome (ARDS), abnormal blood coagulation, and low blood pressure caused by cardiovascular collapse, etc. Some of these symptoms can occur together, making the most serious cause of death from falciparum malaria.

Attacks occur every 48 hours with symptoms that include fever, chills, sweating, headaches, nausea and vomiting, as well as body aches and general malaise.

Attacks occur every 48 to 50 hours, sharing common symptoms with tertian malaria.

Attacks occur every third day.

In general, when diagnosed and treated quickly and correctly, malaria is curable.

Diagnosis requires finding parasites in a Giemsa-stained, thin blood film, usually with a microscope. The so-called “dipstick test” is used for more detailed diagnoses. Further, firm diagnosis requires the confirmation of compatible symptoms such as mild anemia, a slight decrease in blood platelets (thrombocytopenia), and elevated bilirubin and aminotransferases.

The severity of malaria depends on the type of malaria parasites. Symptoms caused by tertian malaria, ovale malaria and quartan malaria are relatively mild, while falciparum malaria causes more serious symptoms, is accompanied by complications, and can be fatal.
Drugs such as chloroquine are administered for vivax malaria, ovale malaria, and quartan malaria. The treatment for falciparum malaria largely depends on the presence or absence of complications.

Artemisinin-based combination therapy (ACT) is the most recommended treatment for falciparum malaria.

Since the mortality rate is high when left untreated, immediate medical attention is essential. The most important objective is to promptly increase concentrations of the therapeutic drugs in the blood and this may require combination treatments based on the artemisinin derivatives, adjunct treatment, and later supportive treatments that include fluid administration.

Eradicating malarial vectors using insecticide-treated mosquito nets and by spraying indoors with residual insecticides are the most recommended preventive techniques. DEET, an insect repellent, is also effective. The Olyset® Net, developed by Sumitomo Chemical, Co. Ltd., is recommended as an insecticidal mosquito net because it is safe and has long-lasting insecticidal efficacy.
Anti-malarial drugs also have some preventive effects. WHO (World Health Organization) recommends sulfadoxine/pyrimethamine for pregnant women beyond early pregnancy as well as three-time administration in children in regions at high risk of infection.

Malaria is often found in areas with high humidity, high temperatures, and high precipitation. The regions with the highest infection risks are sub-Saharan Africa and Papua New Guinea, followed by some parts of Asia, Latin America, and Europe. Ninety seven（97）countries and territories have had continuing malaria transmission as of 2013. Advanced non-endemic countries sometimes encounter the so-called “imported malaria”.

It is estimated that there were about 214 million cases of malarial infection in 2015.

Malaria caused about 438,000 deaths in 2015, with more than 90% of those deaths in Africa.

References

WHO- Malaria, accessed February 16, 2017

CDC- Malaria, accessed February 16, 2017