Reviewed By: Pramod Kerkar, MD, FFARCSI

Malaria is an infection caused by the protozoan parasites that belong to the Plasmodium family. There are five types of plasmodium species that are responsible for human malarial infection. These are P. vivax, P. falciparum, P. ovale, P. malariea and P. knowlesi.

How is Malaria Spread?

Malaria is spread by the bite of the female anopheles mosquito carrying the Plasmodium parasite. These mosquitos are generally found between dawn and dusk. Once the mosquito bites a human, the parasite enters the body and reaches the liver. Here the parasite grows and multiplies for a period of time. After this, the parasites leave the liver to travel to the bloodstream where they destroy the red blood cells. This results in malarial symptoms such as anemia, fever, chills, nausea, vomiting, muscle weakness etc. The time taken between the parasite entering the body and the physical manifestation of symptoms is called the incubation period and it can range from as little as 7 days to about a year or more.

How Do You Tell If You Have Malaria?

Your physician shall make the diagnosis by inquiring about your physical symptoms, travel history over the last year (including travel to a malaria prone region) and by inquiring if, there have been outbreaks of this disease in your locality. Once the doctor has these details and your physical examination is indicative of a malarial infection, doctor shall send your blood sample to the lab for confirmation of the parasite’s presence in your blood.

What are the Different Diagnostic Tests For Malarial Infection?

There are many ways to test your blood for the infection. One method is called the blood smear test. Here a definite diagnosis is made by staining and then creating a slide of the infected patient’s blood. This slide is then studied under the microscope to look for presence of the parasite. This test is one of the most common and accepted test and you get your results within a day or two from the lab. However, this technique is arduous, time-consuming and needs an expert microscopist for correct diagnosis.

In case, time is an issue it is preferable to perform another type of test called the rapid diagnostic tests (also called antigen tests) which are known to give back results in a few minutes. One such test is called the QBC test. However, it is still recommended to perform a blood smear test later on as a confirmation.

What is the QBC Test for Malaria?

What is the QBC Test for Malaria?

The QBC test stands for quantitative buffy coat and was the first test to get FDA approval for diagnosing malaria. It can also be used to diagnose blood parasites that cause filariasis and visceral leishmaniasis.

This test takes advantage of distinguishing the healthy red blood cells from the infected red blood cells by focusing on the changes brought in a red blood cell because of the parasitic infection. Firstly, the malarial parasite contains nucleic acid that stains with fluorescent dyes like acridine orange. The healthy red blood cells do not contain nucleic acid and so they will not be stained and this makes it easy to identify the infected cells. Secondly, when a parasite matures within the red blood cell, it reduces the buoyant density of the infected red blood cell.

The test kit contains a capillary tube coated with anticoagulants and acridine orange. This is used to stain malaria parasites for detection using fluorescence microscopy. The red blood cells are not stained and so the parasites within are easily identifiable.

This test is both sensitive and specific and has the benefit of being rapid and cheap as compared to the typical blood smear tests. These tests are also technically easy to perform and interpret.

So, though malaria has been known to be a severe life threatening disease in many regions of the world, with the timely diagnosis and appropriate treatment it has a favorable prognosis.

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Pramod Kerkar

Written, Edited or Reviewed By:

, MD,FFARCSI

Pain Assist Inc.

Last Modified On: April 23, 2018

This article does not provide medical advice. See disclaimer

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