New Vision (Kampala)

18 February 2013

Uganda: Are You Treating Imaginary Malaria Parasites?

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Many people attribute common disease symptoms such as a fever, headache and general body weakness to malaria. Without a confirmed diagnosis of the suspected disease, they rush to treat themselves with antimalarials of their choice.

Others walk into pharmacies or drug shops and purchase the anti-malarials over the counter.

But who says malaria is the only disease that brings about the above symptoms? Instead of walking into a pharmacy without a diagnosis, have you considered going to the laboratory to have some tests run?

Importance of a microscopic test:

A microscopic laboratory test for malaria not only reveals the presence or absence of the malaria parasite in your blood, but also shows the parasite species and the extent to which the parasites have multiplied in the body.

This information is vital for the physicians as they make a diagnosis and prescribe medication.

It enables them to administer the most appropriate treatment for the parasite detected and to monitor the progress of the disease as well as the effectiveness of the administered medication.

There are four common malaria parasite species that can be detected. These are; plasmodium falciparum which causes the most severe form of malaria; plasmodium malariae, ovale and vivax.

Plasmodium vivax and ovale, if not treated appropriately, have the ability to take vacations in body sites like the liver and resurface later, causing a fresh malaria infection.

Diagnosis:

The diagnosis of malaria is commonly done by microscopic examination of blood films and the use of malaria rapid diagnostic tests. Microscopic diagnosis of malaria is the most economic, preferred and reliable method for diagnosis of malaria

The rapid diagnostic tests can only be used to determine if the parasites are present in the blood. However, the number of parasites cannot be determined by this method.

This method does not require a qualified microscopist and can be done within five to 20 minutes unlike microscopy which requires 20-60 minutes or more.

Molecular methods which involve identification of the parasite DNA are the most accurate methods, however, they are expensive and require a specialised laboratory.

Microscopic diagnosis of malaria involves identification of a malaria parasite or its products in the blood of the patient. A drop of the patient's blood is collected by pricking the finger, or from a larger venous blood specimen.

A thin or thick film is then made on a glass slide (blood smear), dried, dipped in a reagent that stains the malaria parasites and examined under a microscope at a 1,000-fold magnification.

Malaria parasites are recognisable by their physical features and by the appearance of the red blood cells they have infected. Parasites can also be identified at their different growth stages.

The thick films are more sensitive than the thin films so they are able to pick up even low levels of infection. The thin film, on the other hand, is better than the thick film for species' identification since the parasite morphology is not distorted in this film.

A number of methods can be used to quantify the parasites detected, but the commonest is the plus system.

The higher the pluses, the more severe the malaria. Some laboratory technicians and technologists give patients results with notes such as "scanty malaria".

This means the parasites detected are few. However in this case, it is always important that the technicians and technologists report the exact number of parasites that have been seen in the different microscopic fields examined.

The writer is a laboratory technologist

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