Defining malaria and its causes

What is malaria?

A disease which mostly affects tropical and subtropical areas, malaria is one of the world’s biggest killers. When contracted, malaria can be a life-threatening disease if left untreated or if severe complications occur.

An infection is typically caused by parasites (Plasmodium parasites) in the bloodstream after being bitten by an infected female Anopheles mosquito. This is the only mosquito known to carry the parasite and spread the disease. Carriers of this parasite, a bite from an infected mosquito quickly transmits it through the bloodstream to the liver.

Once the parasite reaches the liver, it matures and begins to target a person’s red blood cells within a matter of days. Once the red blood cells have been infected, they multiply (reproduce) and burst open. A person will begin to feel unwell within 48 to 72 hours of infection and experience symptoms in cycles that last a few days at a time as red blood cells are continuously targeted by the parasite. Chills and fever are typical symptoms associated with this recurrent cycle.

The plasmodium parasite thrives in tropical and subtropical climates (such as Africa, Southern Asia, South and Central America), making these areas of the world incredibly high-risk. Billions of people are at risk of malaria every day and up to half a million people die from the disease each year.

Preventative measures to help reduce the occurrence of mosquito bites in high-risk areas are one way many are trying to gain control of the disease. Bed nets (mosquito nets) which help to protect people from bites while they sleep are somewhat effective.

Another means of prevention is medication (although drugs cannot offer 100% protection due to parasites consistently becoming immune), which travellers, in particular, are encouraged to take before entering high-risk areas (during and after their trip too).

There are 5 known species of the Plasmodium parasite:

  • P.falciparum: This parasite species mostly occurs in the tropics and subtropics (close to the equator) and can lead to life-threatening complications within a matter of days following infection. This species is known to be resistant to antimalarial medications and an infection with this parasite typically requires combination treatment.
  • P. vivax / P. malariae / P. ovale / P. knowlesi: The species, P. vivax and P. malariae occur in tropical areas. The species P. knowlesi is typically found in Southeast Asia. The malaria causing parasite P. ovale is typically seen in Western Africa, but can occur in other high-risk areas too. An infection with the parasite species P. knowlesi is often most life-threatening and may be fatal (but is not generally resistant to medication treatment). Infections with P.vivax, P. malariae or P. ovale aren’t usually life-threatening and have high recovery rates within a month of treatment (as they are generally not resistant to medications). Relapses are common with P.vivax, P. ovale and P.knowlesi parasite infections (as the parasite can remain in the liver) which may require further medication treatment.
NEXT How is malaria transmitted?

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