The Importance of Timely Laboratory Diagnosis in the Treatment of Malaria

Malaria is a parasitic disease caused by the intracellular protozoan Plasmodium and is transmitted to humans through the bite of the Anopheles mosquito. There are four species of Plasmodium: vivax, falciparum, ovale, and malariae. The vivax species is the most common, and falciparum is the most severe, being fatal in certain clinical cases.

A definitive diagnosis of malaria is established by identifying the parasite in peripheral blood. At the Germano de Sousa Laboratory Medicine Center, a rapid screening and diagnostic test is performed on an urgent basis, ensuring effective detection of the disease. Rapid dipstick tests are available that detect malaria antigens (proteins) in a blood sample and indicate a positive result through a color change on the test strip, enabling a rapid, easy-to-perform diagnosis with high sensitivity and specificity.

It is recommended that positive results be followed by blood smears (thin and thick smears) for confirmation and to determine the species and parasitemia level. The thick smear allows for rapid diagnosis, while the thin smear enables identification of the parasite, counting of infected red blood cells, and is useful for monitoring treatment. Since the number of parasites in the blood fluctuates, samples can be collected at 8- to 12-hour intervals over 2 to 3 days to increase the likelihood of detecting the parasites. It is advantageous for sample collection to coincide with the onset of signs and symptoms, when parasites are most likely to be detected in the blood. The diagnosis should only be ruled out after three negative tests, taken 12 hours apart. The blood smear test is currently the gold standard for the detection and identification of malaria.

Molecular tests using polymerase chain reaction (PCR) are also laboratory diagnostic methods. These amplify the parasite’s DNA and allow for the detection and identification of Plasmodium species. This test can be used to confirm the diagnosis and to determine the Plasmodium species when blood smear results are not sufficiently clear.

Malaria can be a deadly disease

Once the parasite enters the bloodstream, it travels to the liver, where the infection develops before re-entering the bloodstream and invading red blood cells. Plasmodium reproduces inside the red blood cells, which then rupture, releasing a greater number of parasites into the serum.

Malaria is one of the most common diseases in tropical regions, particularly in the Americas, Asia, and Africa, making it a serious public health problem. According to the World Health Organization, the annual incidence of this disease is estimated to exceed 500 million new cases, accounting for more than one million deaths per year.

The typical symptoms of malaria infection include fever, headaches, and vomiting, among others, which are similar to those of the flu, thus making diagnosis difficult. Symptoms appear approximately 9 to 14 days after the mosquito bite, although this interval may vary depending on the Plasmodium species causing the infection.

The disease can progress rapidly and lead to the patient’s death within the first few hours after infection, as malaria affects blood flow to vital organs; therefore, timely diagnosis is crucial.

Diagnosis is based on epidemiological history, clinical presentation, and laboratory findings. When managing the patient, it is important to know the epidemiological history—specifically the area of origin and history of recent travel to endemic areas—as well as to fully understand the clinical presentation and symptoms exhibited.

Lisbon, January 23, 2017

For more information, please contact:
Professor Germano de Sousa
germanosousa@cm-lab.com