Malaria: cause, symptoms, treatment, transmission, is there a cure?

Well known for being endemic in some regions, malaria is still a concern for health authorities. 

According to the Ministry of Health, most cases that occur in Brazil are in the Amazon region, in the states of Acre, Amapá, Amazonas, Maranhão, Mato Grosso, Pará, Rondônia, Roraima and Tocantins.

But, even so, other regions must be attentive to the occurrences.

What is malaria?

Malaria is an infection caused by protozoa of the genus Plasmodium , transmitted by Anopheles mosquitoes , characterized by episodes of fever, chills and tremors. The presence of the parasite leads to the destruction of red blood cells (red blood cells) and consequent anemia.

It is still a very common disease, especially in poor countries on the tropical strip of the planet, where there is little access to preventive measures and treatment is lagging behind.

It is estimated that malaria kills about 660,000 people a year and there is still no preventive vaccine. The World Health Organization (WHO) has a program to improve the situation and, every year, releases a report with data on the disease worldwide.

The disease is treated as a medical emergency, as the delay in starting treatment leaves room for the disease to develop until it seriously affects vital organs, including the brain.

In ICD 10 (International Classification of Diseases, tenth edition), malaria is found by codes B50 to B54, depending on the type of parasite causing the infection.

What are the causes of malaria?

Malaria is caused by protozoa of the genus Plasmodium , that is, there is more than one microorganism that causes the disease: P. falciparum , P. malariae , P. vivax and P. ovale . In Brazil, only 3 of these species are found, and the predominant ones are P. vivax and P. falciparum .

These microorganisms attack the liver and bloodstream, destroying red blood cells. It is this destruction that leads to the symptoms of the disease.

The Plasmodium is transmitted by the bite of female gender Anopheles , which feed on human blood. There are more than 400 species of this genus that can transmit the disease.

It is worth remembering that the male does not transmit the disease because it feeds on sap and nectars of plants. Popular names for the transmitting insect are: muriçoca, carapanã, awl, mosquito-nail and bicuda.

Another way of being transmitted is through contact with the blood of an infected person.

Vectors: what is the causative agent of malaria?

Malaria vector mosquitoes are females of the genus Anopheles , which in Brazil includes the following species:

• An. darlingi;
• An. aquasalis;
• An. albitarsis s.;
• An. marajoara;
• An. janconnae;
• An. deaneorum;
• An. oswaldoi;
• An. (Kerteszia) cruzii;
• An. (K.) bellator;
• An. (K.) homunculus.

Malaria cycle: how is transmission?

Malaria transmission generally occurs through a cycle, that is, the microorganism does not directly affect a person, but it needs a vector for this. The malaria cycle takes place as follows:

• An uninfected mosquito bites an infected person. When he feeds on that person’s blood, he is infected by the protozoa present in the bloodstream;
• When biting another person to feed, the mosquito releases a small amount of microorganisms into the individual’s bloodstream;
• The parasites travel to the liver, where they stay for a while until they reach maturation – this can take days, weeks and even years, depending on the species of the parasite;
• When they are mature, the parasites migrate into the bloodstream, using mainly red blood cells for their reproduction, which occurs in an intense and fast way. This multiplication results in the destruction of these cells, causing the symptoms of the disease;
• At that time, if an uninfected mosquito bites the patient, he acquires the parasites for himself, by consuming the victim’s protozoan-filled blood. Thus, the cycle restarts.

Other means of transmission

Malaria is not always transmitted within the cycle. More rarely, it can also be transmitted through exposure to infected blood. This means that protozoa can be easily transmitted in the following situations:

• From mother to fetus: If the mother’s blood is infected, it passes the protozoa to the fetus through placental circulation;
• Blood transfusions: Although there are many tests to prevent disease transmission when donating or receiving blood, blood transfusion is still a risk factor for malaria contraction;
• Sharing syringes and needles: Infected people can pass protozoa to others if they use the same syringes or needles. This tends to happen more frequently in drug users, since, in hospitals, it is customary to discard such materials after use.

Endemic areas: where does malaria most often occur?

Endemic areas are those in which there are continuous records of malaria cases throughout the year. That is, areas where, regardless of the time of year, the number of cases remains more or less stable.

Altogether, there are 88 countries where the disease is endemic, the majority of which are concentrated near Ecuador, being classified as tropical countries.

African countries below the Sahara desert are the most affected and also where there is the highest number of deaths. Other countries that are major areas of malaria transmission are:

• Central American countries;
• Caribe;
• Central, South and Southeast Asia countries;
• Middle East;
• Far East (China);
• Papua New Guinea;
• Solomon Islands and Vanuatu;
• Paraguay;
• Brazil;
• Bolivia;
• Peru;
• Ecuador;
• Colombia;
• Venezuela;
• Guiana;
• Suriname;
• French Guiana.

It is worth remembering that, in Brazil, the most affected areas are the states of the Legal Amazon: Acre, Amapá, Amazonas, Pará, Rondônia, Roraima, western Maranhão, northwestern Tocantins and northern Mato Grosso. However, there are also records along the Atlantic Forest in the southeastern region and in the Paraná River Valley.

Higher regions are lucky: the mosquito does not usually live at altitudes higher than 1500 meters above sea level. In fact, to survive, he needs to be in a place with an average minimum temperature above 15º C.

In addition, it can only reach a population of mosquitoes large enough to transmit the disease in environments with high humidity and average temperatures between 20 and 30º C.

Risk factors

Anyone can be infected, but there are some risk factors that increase the chances of finding mosquito vectors. Are they:

• Living or visiting areas where the disease is endemic, that is, there are a large number of cases per year;
• Living close to rivers, ponds and places where mosquito proliferation is easier;
• Not having access to information, quality medical services or financial conditions to prevent and treat the disease;
• Do not take proper care before exposing yourself to the outdoors.

In addition, there are some groups that suffer more consequences when they contract the disease. Are they:

• Babies and young children;
• Travelers from areas where there is no malaria;
• Pregnant women.

Is it possible to acquire immunity against malaria?

People who live in areas where there is greater exposure to Plasmodium tend to suffer less when they contract the disease. Because?

Basically, frequent exposure to the protozoan is able to create partial immunity , which improves the prognosis of the disease, although it does not prevent new infections. That is, the patient may still be infected again, but the symptoms and complications do not tend to be as severe as in people who have never been infected.

However, this partial immunity is not forever: it lasts only as long as there is still a lot of contact with the parasite. If the person moves to an area where there is no spread of the disease, he may lose that immunity, and, when coming into contact with the protozoan again, suffer consequences as serious as other people.

It is also worth remembering that no case of total immunity has ever been registered. Therefore, even people who have been infected often still cannot acquire full protection against the disease.

What are the symptoms of malaria?

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Malaria symptoms usually appear between 1 and 2 weeks after infection, as the protozoan must mature in the liver before being released into the bloodstream. This quiet time is called the latency period and its duration depends on the species of Plasmodium present in the organism. In some cases, this period can even last for years.

In all cases, the first manifestations of the disease are very similar to the flu :

• Headache;
• Fever;
• Chills and trembling attacks;
• Joint pain;
• Nausea and vomiting;
• Intense Sister;
• Abdominal pain;
• Diarrhea;
• Lack of appetite;
• Tonteira;
• Fatigue.

In many cases, these symptoms are not continuous: they usually come and go every 48 or 72 hours. That is, the symptoms are episodic, even though the disease is not being treated.

In addition, as the disease progresses, it can affect other organs – including the brain -, causing other symptoms that are even more serious, such as:

• Difficulty breathing;
• Renal insufficiency;
• Jaundice (due to the increased presence of bilirubin, resulting from the breakdown of red blood cells);
• Intense weakness;
• Low pressure;
• Convulsions.

What are the cycles of malaria symptoms?

Initially, malaria manifests symptoms such as malaise, headache, body aches and tiredness. Vomiting and nausea may also occur. These symptoms precede the fever. So, in the beginning, the person’s temperature is still normal. 

Gradually, with the intensification of symptoms, chills appear that can vary between 15 minutes and 1 hour, then migrating to a feverish state. 

The picture is usually intense, reaching 41 ° C or more. It takes, on average, 2 to 6 hours for the fever to subside and symptoms such as intense sweating and weakness intensify. 

This condition is quite common in the initial stage of the disease. After this period, the patient may develop fever in cycles.

Is fever a symptom of malaria?

Fever is the main manifestation of the initial stage of the disease. It can be accompanied by chills, tremors, sweating (cold sweat) and headaches. The symptom is when infectious agents enter the bloodstream and invade blood cells. 

The moment the erythrocytes (red blood cells) break, the fever starts.

How is malaria diagnosed?

With symptoms very similar to other conditions, it may take time for the doctor to suspect malaria, especially in areas where the disease is not common.

As it is an emergency, it is extremely important that the patient informs the doctor if he has been in an area where malaria is endemic or if he has been exposed to a situation in which he could have been bitten by an Anopheles mosquito .

The professional capable of diagnosing and treating malaria is the infectious disease specialist , emergency physician and, often, the travel physician .

Upon finding the suspicion of the disease, the doctor may order blood tests whose objectives are:

• Detect microorganisms that cause malaria;
• Identify the specific protozoan that infected the patient;
• Check if the parasite is resistant to drugs;
• The possibility of anemia and damage to other organs.

For this, some tests may take a short time (about 15 minutes), while others take days for the result to come out.

It is worth remembering, however, that the diagnosis can be somewhat difficult in places where malaria is not a common disease, such as in the southernmost states of the country. In these locations, doctors are not familiar with the disease and may suspect other causes of the symptoms.

It is extremely important that, in these cases, the patient makes it clear that he has been in an area where malaria is endemic and that he may have been bitten by an Anopheles mosquito .

Thick drop

In Brazil, the official diagnostic method for malaria is the so-called thick drop . This test consists of subjecting a patient blood sample to observation under a microscope with a vital dye (methylene blue and Giemsa).

This dye allows you to visualize the parasite and differentiate it according to its morphology (shape), in addition to allowing you to have a notion of the concentration of parasites in the bloodstream. It also helps to determine what type of Plasmodium is causing the infection.

Because of the cycle, the amount of parasites in the blood can vary. This means that, depending on the stage of the disease, the test is not able to locate the parasite, resulting in a false negative. In such cases, the test should be repeated every 8 or 12 hours for 4 days.

Antigen research (reagent strip)

Antigen is any substance that the body understands as a threat and stimulates the production of antibodies. Bacteria, parasites, viruses and fungi are full of these substances.

This test is done by placing a blood sample on a test strip, which then detects the presence of these substances. It is not able to differentiate the different types of Plasmodium , but it is one of the fastest tests to confirm the diagnosis of malaria.

Polymerase chain reaction (PCR)

In cases where the results are doubtful, PCR can be used to detect the parasite’s DNA. This may be necessary when there is a mixed infection (caused by more than one type of parasite) or when the microscopic analysis is inaccurate.

Sensitivity tests

Since some parasites are resistant to medications, there are laboratories that collect a sample of the patient’s blood and grow microorganisms in contact with increasing amounts of medication.

This test is useful to identify the extent to which Plasmodium can resist – sometimes, the person may simply need a slightly higher dose – or to identify the genes responsible for the resistance developed.

Antibody screening (serology)

This is not a method to diagnose malaria at the time it happens, but rather to check for the existence of specific antibodies against Plasmodium .

This type of examination is more used in epidemiological studies, in order to identify people who have already been infected by the parasite, even though they no longer have the disease.

Is malaria curable?

Fortunately, yes, malaria can be cured . In the context of this disease, the cure means the total elimination of the parasite in the body. In this way, the body recovers and the person returns to lead a healthy life.

Nowadays, there are effective drugs against parasites of the genus Plasmodium .

However, the misuse of such medications is creating stronger and drug-resistant protozoa. In the coming years, new drugs must be developed to combat the problem, since the transmission of resistant microorganisms may end up making the disease untreatable with current drugs.

Healing from malaria, however, does not mean never being infected again. As stated earlier, some people can even create partial immunity, but anyone can be infected successively by the parasite.

Malaria treatment

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Malaria treatment should begin as soon as it is diagnosed, in order to avoid serious complications. It is usually defined according to some criteria. Are they:

• Which parasite is present in the organism (there may be more than one);
• Severity of symptoms;
• Patient’s age;
• Whether there is pregnancy or not.

From these factors, the doctor can prescribe antimalarial drugs.

Malaria Medicines

Malaria treatment can be done free of charge in public health networks. The most effective way to conduct therapy is through artemisinin (or ACTs). The drug is quite effective in combating the infectious agent and, in general, offers low adverse effects.

• Chloroquine;
• Quinine Sulfate;
• Hydroxychloroquine ;
• Mefloquina;
• Malarone (atovaquona + proguanil).

Unfortunately, some of these medications are no longer effective in certain areas (such as chloroquine), mainly due to the poor administration of the treatment, which allows the creation of resistance by the parasite.

However, the search for antimalarial drugs is not over and there are several researches focused on finding new substances.

Attention!

NEVER self-medicate or stop using a medication without first consulting a doctor. Only he will be able to tell which medication, dosage and duration of treatment is the most suitable for his specific case. The information contained in this website is only intended to inform, not in any way intended to replace the guidance of a specialist or serve as a recommendation for any type of treatment. Always follow the instructions on the package insert and, if symptoms persist, seek medical or pharmaceutical advice.

Malaria in pregnancy

Any illness that occurs during pregnancy can be detrimental to the baby’s development. Care must also be doubled with infectious conditions, since the parasite can travel to the placenta through the mother’s bloodstream.

In places where malaria is endemic, the mother can be infected and show no symptoms because of the “partial immunity” obtained. However, the parasite still reaches the fetus and can have consequences for pregnancy.

Where malaria is not common, the expectant mother is more likely to develop a more severe degree of the disease, since her body concentrates forces to generate a life.

Symptoms and diagnosis in pregnancy

In the mother, the symptoms of malaria can be different, especially from the second trimester of pregnancy. The fever , the main characteristic of the disease, may be absent or be higher , but do not follow the pattern of decline and reappear a few days later.

The pregnant woman may present with cough , diarrhea , muscle pain, headache and general malaise, but the main symptom that raises the hypothesis of treating malaria is the development of anemia .

To make matters worse, the diagnosis during pregnancy can be difficult, since the parasites tend to deviate towards the placenta, instead of following the normal path. Therefore, some blood tests may not be able to detect Plasmodium .

Consequences of malaria during pregnancy

If a pregnant woman is infected with Plasmodium , there are some consequences for the mother and baby. Some of them are:

• Anemia in mother and baby;
• Low weight of the baby at birth;
• Spontaneous abortion;
• Premature birth;
• Death of the baby still in the womb (stillborn).

The reduction in the baby’s weight, in the case of P. falciparum, is usually ⅔ (two thirds) of the weight of a normal baby, regardless of whether it is the first pregnancy or if the mother has already had other children. In P. vivax infections, weight reduction tends to be greater in later pregnancies.

Can pregnant women take medicine for malaria?

There is little data on the use of anti-malarial drugs in pregnant women, as there is a risk of damaging the fetus during research. However, the Ministry of Health has general recommendations for the treatment of pregnant women, depending on the gestational period:

Malaria kills?

Unfortunately, yes, malaria can kill . In fact, the mortality rate of the disease is 20% in severe cases, even with treatment. The main causes of death from malaria are complications such as anemia and organ failure.

Consequences: what are the complications of malaria?

If malaria is not properly diagnosed and treated, it can have serious consequences for the patient. In addition, if the treatment is not done properly, there may be resistance to the drugs, resulting in complications such as:

Anemia

Because of the destruction of red blood cells (erythrocytes), malaria can cause severe anemia.

Hypoglycemia

By helping in the transport of carbohydrates (sugar) in the blood, the destruction of red blood cells decreases the amount of glucose in the bloodstream, a situation called “ hypoglycemia ”.

Pulmonary edema

It is not known exactly why, but in some types of malaria, such as that caused by P. falciparum, there is a high incidence of pulmonary edema . It is believed that if this happens because toxins released by the protozoan damage the alveoli, making them more permeable.

Organ failure

The destruction of red blood cells causes the release of an iron compound, called the heme group, which hinders the functioning of the kidneys, liver and other vital organs. Little by little, the organs lose their function, resulting in organ failure.

Cerebral malaria

Blood cells filled with parasites can end up blocking the small blood vessels in the brain, leading to a lack of blood supplementation to the tissues. This can lead to organ swelling and brain damage, resulting in cognitive sequelae.

Coma

Several of the complications brought about by malaria can result in coma, such as hypoglycemia and cerebral malaria.

Prognosis

The prognosis of malaria is positive when it is treated properly, since the parasite is then expelled from the body. However, cases of severe malaria can kill quickly or leave marks even after healing.

When the disease reaches the brain, it is not uncommon for the individual to have sequelae, such as intellectual and cognitive disabilities, in addition to epilepsy . There are also reports of long-term developmental delay in children who have suffered from severe malaria.

In people infected with resistant parasites, the prognosis is much worse: infections can occur more often, as well as new complications may appear as time goes by.

Malaria prophylaxis: what is the form of prevention?

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Malaria can be prevented, and the best way involves individual protection measures. Some things you can do to avoid getting infected are:

• In transmission areas, stay away from natural insect breeding sites, such as river banks and wetlands;
• Avoid exposure to the open air between late afternoon and dawn, as these are the times when mosquitoes are most active;
• Wear long-sleeved pants and shirts when outdoors, as this limits the area where the mosquito can bite;
• Use DEET-based repellents in a concentration of 30 to 35% for protection for up to 5 hours;
• Pregnant women and young children can use Icaridine-based repellents;
• It is necessary to reapply the repellent from time to time, since its effectiveness tends to decrease after a few hours;
• Repellents are toxic chemicals and, therefore, should be used according to the manufacturer’s guidelines to avoid inconvenience;
• Use curtains and mosquito nets with insecticide on the bed or hammock when you go to sleep;
• Screens on doors and windows help keep mosquitoes out of indoor environments.

Correct use of repellents

Many people have been there: apply the repellent in the morning and, in the late afternoon, be full of bites anyway. This is a sign that the product has not been used properly, which is more often than we would like to admit.

Firstly, it is necessary to ensure that the repellent has a concentration of at least 20 to 35% diethyl ethyl toluamide (DEET). Although there are others, this type of repellent is the most suitable to scare Anopheles .

The problem is that, in Brazil, there is no law that requires manufacturers to place the concentration of the active substance on the labels of repellents. Therefore, we often buy repellents that are weaker than ideal. They protect anyway, but for a considerably shorter time.

Bearing in mind that, in most cases, we do not know how long the repellent is effective, it is recommended to reapply the product every 4 hours. However, depending on the region, reapplying every 4 hours is not enough. Factors such as humidity and perspiration can “wear out” the repellent before the deadline and, therefore, the recommendation is to reapply every 2 hours.

In addition, it is always necessary to reapply the repellent after swimming or wetting the body .

The repellent should be applied to all exposed areas of the body, including the neck and ears, parts that are often overlooked. However, when applying the product on the face, one must avoid passing in the eye area and in the mouth.

Finally, it must be kept in mind that the repellent must be in direct contact with the external environment to function. Therefore, if you need to apply a sunscreen too, do so before using the repellent. Otherwise, the repellent will be “capped” by the protector and will have no effect.

Vaccine

Much is said about a possible malaria vaccine, but it is still in development . Currently, there are tests with promising results that approach more than one solution.

In 2018, the countries of Ghana, Kenya and Malawi intend to implement a pilot program to test a very promising preventive vaccine in babies aged 5 to 17 months. With this, they hope to verify the possibility of extending the use of the vaccine.

While it is not yet available to the entire public, it is imperative to take care of yourself in other ways.

Chemoprophylaxis

Chemoprophylaxis is the use of antimalarial drugs to prevent malaria, being used only in cases of high risk. That is, to travel to endemic areas within Brazil, the use of chemoprophylaxis is not always necessary.

By consulting the doctor before a trip, he can prescribe the medications to prevent the disease from developing if the person becomes infected. Therefore, it is not a way of actually preventing infection, but rather the disease and its complications.

There is no guarantee that, through chemoprophylaxis, the patient will be free of insect bites, infection and even the development of symptoms and complications (remember that in some areas, the parasites have gained resistance?).

In addition, by stopping the drugs after the trip, an infected person may experience the symptoms, because the only thing the drug did was to prevent the parasite from multiplying in the bloodstream, not freeing the patient from the infection itself.

Control measures

Since malaria is transmitted by mosquitoes, vector control is one of the best ways to fight the disease. Therefore, there are several public policies to implement actions that control the proliferation of insects. This is usually done through the elimination of insect breeding sites or measures that eradicate those that are already grown.

Some examples of these practices are:

• Drainage of flooded areas;
• Sanitation;
• Control of aquatic vegetation;
• Improvements in the living conditions of people in endemic areas;
• Rational land use: the way the State uses its land can increase the mosquito population. In Tucuruí (Pará), for example, there was an epidemic of malaria after the installation of the local hydroelectric plant and the consequent formation of a lake;
• Chemical control with indoor spraying (pest control), space fogging and mosquito nets impregnated with long-lasting insecticides.

Although well known and easily prevented, malaria remains a concern for health authorities, especially since it is up to all of us to ensure that the disease is eradicated. Always be forewarned!

If you have any questions, you can ask that we will answer with pleasure!