What happens in malaria, exactly?

What is it?

Malaria is an infectious disease caused by a type of parasitic protozoa. Humans become infected if they are bitten by a mosquito that carries the protozoa.

Typical symptoms of malaria include fever, fatigue, vomiting, and headache. In severe cases the patient’s skin can also turn yellow, and seizures, coma, or death can occur. Symptoms usually begin around 10-15 days after being bitten, and the disease can return even months later if it isn’t properly treated the first time.

Malaria is common in areas near the equator. Last year there were 214 000 000 cases of malaria, resulting in 438 000 deaths. As much as 90% of the deaths took place in Africa. The disease is very costly because of increased health care costs and decreased workforce, and its effects can be very damaging to the economic development of poorer countries.

What causes it?

A certain type of mosquito carries the malaria parasite, and if a person is bitten by this kind of mosquito, the parasite can enter their body and they can develop malaria.

What happens during it?

When the protozoan has first entered the body, it travels with blood to the liver. There it reproduces for a while. The new protozoa then leave the liver – normally they would be detected by the immune system at this point, but the malaria protozoa wrap themselves in the liver cell’s cell membrane so that any white cells coming into contact with them will just mistake them for the body’s own cells. They then start infecting red blood cells. They invade the cell, reproduce until a few new protozoa have formed, and the cell  then bursts releasing the new parasites to infect new cells. Malaria is characterized by waves of fever, and these waves happen when the parasites are periodically released from red blood cells and the body reacts to them.

Hiding inside cells for most of their lives, the malaria protozoa are quite safe from the immune system. If infected red blood cells do, however, pass through the spleen, they will be destroyed. This is why the protozoa make the red blood cells to put a certain kind of protein on their surfaces. These proteins cause the cells to stick to the walls of small blood vessels, so that the cells stop circulating around the body and never end up in the spleen. These blockages can be particularly dangerous if they stop the blood of a pregnant woman flowing to her baby.

How can it be treated?

Prevention is very important. This can be done through preventing mosquito bites and through medication. Mosquito repellents and nets have been found to be very effective. Taking certain medications also reduces the risk of developing malaria significantly, but these medications are only commonly used by short-term visitors and pregnant women due to the cost and the side-effects of long-term use.

When malaria has been acquired, it is treated with medication. The purpose of this is to kill the parasites and to sometimes alleviate symptoms like fever.

 

 

Sources: https://en.wikipedia.org/wiki/Malaria, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2140183/

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