Causes and Risk Factors of Malaria

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Malaria, also known as the Plasmodium infection, is a parasitic infection—that means it enters the body through a mosquito bite. The mosquito is infected with the virus and transfers it to the person.

Although the Plasmodium parasite is the main cause of the infection, environmental and lifestyle factors play contributing roles. Explore the common and less common causes—they may help you prevent contracting malaria.

malaria causes and risk factors
© Verywell, 2018

Parasitic Transmission 

There are four species of Plasmodium parasite that contribute to human malaria infections. They are:

  • P. falciparum: The species associated with the most severe form of the infection, and is the most common cause of infection.
  • P. vivax: Among the most common.
  • P. malariae: Causes a milder form of the illness.
  • P. ovale: Is relatively rare.

The infection can enter your body through the bite of a female Anopheles mosquito, which serves as a vector (carrier). This mosquito can survive in tropical climates, and it is only in these climates that the disease is transmitted. The mosquito itself acquires the parasite by biting a person who is infected.

How the Parasite Causes Disease

All species of the malaria parasite cause a sequence of events to occur throughout the body, which produces the symptoms of the infection.

After a malaria-carrying mosquito bites a person, the infective form of the parasite, the sporozoite, enters the person’s liver, where it reproduces and enters a new stage in its life cycle, the merozoite stage.

The merozoites, which are produced in the liver, enter the red blood cells. The merozoite form replicates inside red blood cells, causing them to burst, releasing chemicals that produce most of the effects of malaria, such as fevers, chills, and aches. The merozoites that are released when red blood cells burst can travel throughout the body, entering into other red blood cells.

Sometimes, more severe effects occur and the parasites or the parasite-infected red blood cells can damage organs of the body such as the brain, the heart, the lungs, or the kidneys.

Less Common Causes

There are several situations that are associated with a lower risk of malaria transmission.

Immune System Deficiency 

You can become infected with malaria even if you have a normal immune system, but people who have immune system deficiencies, including HIV, are more likely to experience severe effects of the infection.

Pregnancy

Women who are pregnant are at increased risk of malaria infection. There are several proposed reasons for this, including a lowered immune system—which can reactivate previous infection—or a lowered immune system—which makes it more likely for pregnant women who become bit to develop the illness.

Newborn Babies- Transmission From Their Mother

Some babies may be born with malaria infection, acquiring the parasite from the mother, and not from a mosquito vector.

Blood Transfusion

There have been reports of malaria infection that have spread from one person to another through blood transfusions. In these instances, a blood donor who has acquired an infection, usually from a mosquito vector, typically has not yet developed symptoms of the illness.

The transfer of blood cells, which are infected with the parasitic organism, can then allow the parasite to thrive inside the body of the recipient of the blood transfusion.

Lifestyle Factors 

Malaria is an infection that is predominantly spread in certain geographic regions with a tropical climate and an abundance of still water, where the mosquito vector that carries the parasite can survive. Lifestyle factors can play a role in whether or not you are likely to become infected with the parasite.

Living in a Region With a High Rate of Malaria 

Living in a region that is known for malaria substantially increases the risk of becoming infected. While it has been noted that some people living in regions with a high rate of malaria may become immune, many otherwise healthy people with normal immune systems experience serious complications and may die from the infection.

Visiting a Region With a High Rate of Malaria

Travelers who visit regions with a high rate of malaria may become infected, particularly because travelers who have not been exposed to the infection before have not developed immunity to the condition.

Environmental Factors

Some factors increase exposure to malaria, including a lack of protective clothing, exposed sleeping accommodations, lack of insect repellant, and lack of immunization. Especially when traveling, do your best to take proper precautions.

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