Malaria – A Deadly Infection Passed On By Mosquitoes (As Seen on House MD)

This is part of our House MD Project series.

Click here to read the connection to the episode (spoiler alert!)

house-s02e10

Danger level: High

What is it?

Malaria is an infection of red blood cells caused by a parasite that’s transmitted by mosquitoes. It kills about 1 million people each year worldwide.

Who gets it?

Modern medicine has made malaria quite rare in the United States and most other developed countries. In other places, though, it still remains common. Worldwide, about 300-500 million people are infected with malaria, with 1-2 million dying of it each year (most of them African children under 5 years of age).

This doesn’t mean you can’t see malaria in your neighborhood if you live elsewhere. Visitors from other places, immigrants, and even plain travelers (like the one on the House episode) can have the disease.

malaria-map

Map of malaria spread around the world (from the WHO website). Areas in shades of blue are those with active malaria spread.

If you visit these areas, you’re naturally more prone to get infected. Some people are at risk of having a severe case of malaria:

  • Young children and infants
  • Travelers from a place where there is no malaria (that’s because there is some immunity to malaria in people living in malaria-infected places)
  • Pregnant women and their fetus

What causes it?

Malaria is caused by a bite from a female mosquito infected with germs (or, more correctly, parasites).

There are 4 types of parasites that can cause malaria. They are called: Plasmodium falciparum (the most common one – accounting for 80% of cases), plasmodium vivax, plasmodium ovale, and plasmodium malariae.

malaria-lifecycle

Image by the country of Los Angeles public health website

Once a female mosquito bites a person with malaria, the parasite gets into its blood stream. Once inside the mosquito, the parasite reproduces and migrates to its salivary glands. Now, when the mosquito bites another person, parasites are injected along with its saliva.

Inside the infected person, the parasites move to the liver, where they multiply and mature. This takes about 1-3 weeks. Then they leave the liver and get into the infected person’s blood cells, where they multiply again, causing the cells’ rupture. The parasite is then free to infect more red blood cells.

This video shows the process using beautiful animation:

In rare cases, there’s no need for a mosquito in order for the infection to pass form one person to another. Examples of such rare cases are transmission of the infection from a mother to her fetus, transfusion of blood contaminated with malaria, or injection with a needle that was used by a malaria infected person.

How does it feel?

Symptoms usually take a few weeks to a few months to appear after the infection, but they may also appear after years.

malaria-symptoms

Once red blood cells begin to rupture and release parasites into the blood stream, a shaking chill appears, followed by high fever. Once body temperature falls again, the person sweats profusely. This ritual of shaking, fever, and sweating repeats in attacks.

Other things that can be felt are fatigue, headaches, body aches, and nausea.

If you’re infected with the plasmodium falciparum type of parasite, the infection can be more dangerous. Since here the infected red blood cells stick to the walls of small blood vessels and clog them, blood supply to organs in the body is interrupted, causing damage to these organs. Examples of such organs include the brain (causing cerebral malaria – like was seen on House), lungs, kidneys, and gastrointestinal tract.

How is it discovered?

When a doctor suspects a person has malaria, a blood sample is taken from them and looked at under a microscope to see the parasites, like can be seen in this picture:

malaria-red-cells

How is it treated?

There are drugs that when taken kill the plasmodium parasites. The type of drug given depends on which of the four types of plasmodium parasites the person got infected with. An example of such a drug is chloroquine.

What happens after treatment?

Most people improve within 24-48 hours of starting taking the drugs, although with plasmodium falciparum, fever can persist for 5 days. Without treatment, malaria can be deadly.


The bottom line – How do I avoid it?

If you know you’ll be travelling to a place where there’s malaria, consult your doctor a few months ahead about drugs you can take before, during and after your trip, that can help protect you.

When you are in one of those countries, you should take measures to avoid contact with mosquitoes. This includes sleeping under a net (preferably sprayed with permethrin, an insecticide), covering your skin (especially from dusk till dawn, the most active mosquito times), spraying your clothing and skin with permethrin, and treating the home you live in with insecticides and with screens on the doors and windows.

Posted in Blood
 

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