THE malaria is a disease caused by protozoan which is mainly transmitted by the bite of the female of some species of genus mosquitoes Anopheles, which are popularly called capuchin, carapanã, beak, between others. As symptoms of the disease, we can mention fever high, chills and sweating, symptoms that usually appear in cyclic patterns. The disease, if not treated properly, can lead to death, being considered a serious public health problem. However, it is important to remember that the treatment is effective, safe and is offered free of charge by SUS.
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What is Malaria?
Malaria is a acute febrile infectious disease caused by a protozoan. The species that can cause malaria in humans are Plasmodium falciparum, P. vivax, P. malariae, P. the valley and P. knowlesi. In Brazil, only three of these species cause malaria in humans: P. falciparum, P. vivax and P. malariae. According to the Ministry of Health, in our country, most cases of the disease are concentrated in the region Amazon, comprising the states of Acre, Amapá, Amazonas, Maranhão, Mato Grosso, Pará, Rondônia, Roraima and Tocantins.
How malaria is transmitted and what is the life cycle of the Plasmodium?
Malaria is a disease usually transmitted by the bite of some mosquitoes of the genus Anopheles contaminated with the protozoan of the genus Plasmodium. Only the female mosquito Anopheles bites the human being and, during the bite, the parasites are inoculated into the human body in a phase in which they are known as sporozoites. These invade the hepatocytes (cells of the liver) and multiply, giving rise to the merozoites, which break up hepatocytes and fall into the bloodstream, where they invade the Red Cells.
In red blood cells, merozoites undergo changes and form trophozoites, which give rise to new merozoites, which break up red blood cells and invade other red blood cells. With that, there are repetitive multiplication cycles. In case of Plasmodium falciparum and P. vivax, the cycle repeats every 48 hours. When red blood cells break, the person has symptoms of the disease, such as fever.
It is important to point out that, inside the red blood cells, sexual forms can develop, called gametocytes, which are ingested by the mosquito when it bites a patient and are essential for the continuation of the cycle. In the body of mosquitoes, these sexual forms form sporozoites, which will infect a new person when they are bitten.
In addition to mosquito bites, malaria can be transmitted in other ways, such as blood transfusion, sharing contaminated needles and mother to child. These forms of transmission, however, are rare.
What are the symptoms of malaria?
Malaria has a incubation period from 7 to 14 days, however this varies according to the causative agent, reaching months. The patient with malaria has symptoms such as chills, sweating and fever, which can reach values above 40 ºC. Symptoms usually appear in cyclic patterns, depending on the causative agent. Can also occur headache, muscle pain, nausea and vomiting.
The severity of the disease varies and depends on factors such as the species of protozoan and the number of parasites in the body. Among the groups most subject to severe forms of malaria, pregnant women and children stand out. In severe malaria, the patient may present anemia, jaundice, bleeding and coma. The disease can lead to death if not treated properly.
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Can I get malaria more than once?
Malaria can be contracted more than once. According to the Ministry of Health, individuals who have had several episodes of malaria can reach a state of partial immunity, with oligosymptomatic, subclinical or asymptomatic. However, it is important to make clear that so far it has not been proven that infections can elicit an immunity to fully protect against the disease.
How is malaria diagnosed?
The symptoms of malaria can easily be confused with those of diseases like yellow fever, dengue and leptospirosis, as they are very unspecific. Thus, the diagnosis must be made by analyzing the symptoms and performing some tests. One of the exams is called thick blood smear microscopy, in which a drop of blood is collected by fingerstick, stained, and the blood slide is analyzed. This is considered the Golden pattern for the diagnosis of the disease. There are also quick tests for the detection of malaria, which are easier to perform and analyze, however they have some disadvantages, such as the inability to differentiate P. vivax, P. malariae and P. the valley, not measure the level of parasitaemia and are also more expensive. Other diagnostic methods are the thin smear and molecular techniques.
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How is malaria treated?
The treatment of malaria is offered free of charge by the Unified Health System (SUS) and includes a series of drugs, which aim, for example, to interrupt blood schizogony (phase of the cycle in which symptoms appear) and the development of sexual forms. The drugs and their doses for the treatment are recommended by the doctor and depend on the type of parasite that infected the individual, age of the patient, severity of the disease and whether the patient has health problems or is a woman pregnant.
How to prevent malaria?
As we have seen throughout the text, malaria is a disease transmitted by the bite of a mosquito, so measures that avoid contact between the mosquito and human beings are forms of prevention. Among the prevention measures, we can mention the use of screens on doors and on windows, mosquito nets, repellents, and clothing that protects arms and legs. So far there is no vaccine against the disease.
By Vanessa Sardinha dos Santos
Biology teacher
