Malaria: Causes, Symptoms, Diagnosis, Treatment, Prognosis and Prevention

It is a disease caused by a parasite and spread by mosquitoes.

It can cause severe symptoms and even be fatal. Some 600,000 people die each year from this disease.

It is more prevalent in tropical areas, these areas where there are large populations of mosquitoes.

People who live in or travel in these areas often receive oral medications or vaccinations to help prevent them from contracting malaria. Some forms of the parasite have become immune to these vaccines.

Malaria is an ancient mosquito-borne disease, but one that still affects millions of people around the world each year, according to the World Health Organization.

Malaria is caused by a parasite that infects a certain type of mosquito, which then passes from person to person through the bite.

The parasite spreads its waste and toxins into the infected blood cell, which is eventually distributed through your bloodstream.

The disease is not contagious, so you cannot catch it by touching it or sitting next to someone who has it. Its mode of transmission is through the mosquito.

Symptoms generally do not appear until seven to 30 days after infection, which can often lead to a late or misdiagnosis.

That is a problem, because these types of errors can cause the parasite to establish itself in the liver, reactivating the disease months or even years after the infected bite.

Symptoms of malaria are similar to the flu and commonly include chills, headache, fatigue, muscle aches, nausea, and vomiting.

Because red blood cells are being lost in the development of the disease, the patient may experience anemia and jaundice (a yellow discoloration of the skin and eyes).

If the infection is not treated, more serious symptoms could appear. These include kidney failure , seizures, mental confusion or even coma and even death.

This type of malaria is extremely rare in some countries.

Malaria still persists in certain regions, such as the tropics and particularly in southern Africa.

There are many challenges ahead in the quest for complete global eradication of the disease, but every year on April 25, it is officially considered World Malaria Day, and we can see the progress that has been made and the work that remains. it must be done.

Causes of malaria

The cause of malaria is by the bite of an infected mosquito that is capable of transmitting a parasite from one individual to another.

A mosquito bites a person who is already infected with malaria and then transfers it to the next person who bites.

The parasite moves through the bloodstream to the liver, where it can survive and remain dormant for months.

Once the parasite grows and matures, it emerges from the liver and moves through the bloodstream.

Once the parasite is in the bloodstream, symptoms begin to appear, and the person can transmit malaria to other people through mosquitoes.


The first symptoms of malaria are usually very similar to those of the flu: aches and pains, fever, headache, among others.

After a few days, the typical paroxysms can occur: chills, followed first by a high fever for a few hours and then profuse sweating.

Between these paroxysms, the patient may feel fine, depending on the type of malaria that has been contracted.

Some forms of malaria are more severe than others, and the time between paroxysms varies, depending on the type of malaria.

Malaria should be suspected in anyone with these types of symptoms who has been in a malaria-infected area.

Malaria is caused by the protozoan parasite Plasmodium.

Human malaria is caused by four different species of Plasmodium: P. falciparum, P. malariae, P. ovale, and P. vivax.

Symptoms of Plasmodium vivax, P. ovale, and P. malariae

The incubation period (the time between a mosquito bite and developing symptoms) is variable, usually between 2 and 3 weeks.

However, in some cases it can take months for the disease to manifest itself.

Initial symptoms are often similar to those of the flu:

  • Mild intermittent fever.
  • Headache.
  • Muscle aches and chills
  • A general feeling of illness (malaise).

After a few days (three to five) the typical paroxysms of malaria begin.

These are usually characterized by chills, followed by fever (up to 40 degrees Celsius) and then sweating.

Paroxysms normally last about 8 to 10 hours.

Between paroxysms, patients often feel remarkably well.

In P. vivax and P. ovale malaria, paroxysms usually recur every 48 hours, while in P. malariae malaria, paroxysms recur every 72 hours.

The paroxysms occur around the same time that the red blood cells burst and release more parasites, and this explains the 48- or 72-hour cycle.

Eventually the body will clear the parasites from the blood and the paroxysms will become less and less severe and disappear.

Symptoms of Plasmodium falciparum

They usually start 10 to 35 days after a mosquito injects the parasite into a person.

Again, there are initial “prodromal” symptoms, followed by malarial paroxysms.

However, unlike the other forms of malaria, the paroxysms are usually not as regular, and patients often have a fever between paroxysms.

Although P. falciparum also causes the breakdown of red blood cells every 48 hours, the timing is not as well coordinated as with the other forms of malaria, hence the less delineated paroxysms.

Also, there are usually more parasites in the blood with falciparum malaria than with the other forms, which is one of the reasons why P. falciparum malaria is more severe than the other forms.

Malaria caused by Plasmodium falciparum is the most serious form of malaria.

The most important and life-threatening complication is cerebral malaria.

Symptoms of cerebral malaria include:

  • High fever.
  • Severe headache
  • Drowsiness.
  • Delusion and confusion.

Cerebral malaria can be fatal. It occurs most often in babies and pregnant women.

Other complications of falciparum malaria include:

  1. “Blackwater fever”: caused by the breakdown of large numbers of red blood cells, releasing hemoglobin (the pigment found in red blood cells) in the urine that gives the urine a darker color.
  2. Kidney failure: probably also due to hemoglobin passing through the kidneys.
  3. Anemia: due to the destruction of all red blood cells.
  4. Pulmonary edema: presence of fluid in the lungs that makes breathing difficult. This is not a common complication.

In the other forms of malaria, delirium can occur when the fever is high, but otherwise brain symptoms are rare.

In all types of malaria, the total white blood cell count is usually normal, but the number of lymphocytes and monocytes, two specific types of white blood cells, increases.

Mild jaundice usually develops if malaria is not treated, and the spleen and liver become enlarged.

Low blood sugar (glucose) levels are common and can be present in people who have high levels of parasites.

Blood sugar levels can drop even further in people who are being treated with quinine.

Sometimes malaria persists when low levels of parasites remain in the blood.

Symptoms include listlessness, periodic headaches, feeling sick, poor appetite, fatigue, and attacks of chills and fever.

The symptoms are considerably milder and the attacks do not last as long as the first attack.

If the person is not treated, the symptoms of malaria caused by P. vivax, P. ovale, or P. malariae subside spontaneously within 10 to 30 days, but may reappear at variable intervals.

Relapses of P. vivax and P. ovale malaria may be related to latent liver stages that periodically release parasites into the blood.

Although P. malariae does not have a liver stage, the parasites can persist in very low numbers in the blood for years and occasionally reach a number high enough to cause symptoms.

Plasmodium falciparum malaria is fatal in up to 20 percent of patients if left untreated.

Diagnosis of malaria

Malaria is diagnosed by blood tests. Early diagnosis and treatment of malaria reduce the disease and prevent deaths.

When you live in or visit areas where you can contract malaria and have symptoms, you should see a medical professional immediately.

Even if you have taken medications to prevent malaria infection during the trip, you may not have been fully protected.

Symptoms can occur during your trip or up to a year after you return home.

Diagnosis, particularly in remote areas lacking laboratory support, often depends on the patient’s symptoms.

However, for a definitive diagnosis to be made, laboratory tests must demonstrate the presence of the malaria parasites or their components.

Parasites can be identified by examining a drop of the patient’s blood under a microscope.

This diagnosis is based on microscopic examination of peripheral blood (Giemsa stain, “thin” or “thick” blood smear).

This test determines infection, calculates the degree of parasitaemia, and identifies specific Plasmodium species.

More sophisticated diagnostic techniques use molecular or immunological approaches.

Molecular confirmation of the findings can be performed in specialized laboratories.

Rapid antigen tests detect parasite-specific antigens by immunochromatography and can differentiate between various species.

Much effort has gone into developing rapid diagnostic tests (RTDs), which can provide results within minutes and identify the presence of parasite antigens.


The type of medicine used depends on the severity of the disease and the type of parasite responsible for it.

The parasites responsible for malaria can become immune to drugs; New and experimental drugs are always being created to combat these serious diseases.

The most effective medications are those that are specifically made to fight the malaria parasite.

Some of the more common medications used to fight the disease include:

  • Chloroquine
  • Quinine sulfate.
  • Hydroxychloroquine.
  • Mefloquina.

Treatment is prescribed, taking into account, in addition to the Plasmodium species, the severity of the infection, the individual patient’s risk factors for severe disease (such as pregnancy).

And the possible resistance of the Plasmodium of the affected patient (according to epidemiological data such as the country of origin or visit).

The administration of drugs such as quinine, chloroquine, mefloquine, atovaquone-proguanil, doxycycline derivatives and artemisinin, should be immediate.

For infection caused by P. vivax, hospitalization is generally not necessary given the mild clinical picture.

In the case of P. vivax treatment, in addition to chloroquine, it is essential to use primaquine to eradicate the hypnozoite stage of the parasite (in the liver) and prevent relapses.

When using primaquine, G6PD testing is essential and if there is a deficiency, an expert should be consulted.

Respiratory support and hospitalization in an intensive care unit (ICU) are necessary for severe forms of malaria (usually caused by P. falciparum).

The most common treatments according to the diagnosis and the Plasmodium species are:

  • Uncomplicated malaria, from P. falciparum or unidentified Plasmodium: Atovacuone-proguanil (malarone), Quinine sulfate + doxycycline o tetracycline o clindamycin, Mefloquine (lariam).
  • Uncomplicated P. vivax malaria: Chloroquine phosphate + primaquine, Hydroxychloroquine (Plaquenil) + primaquine.
  • Complicated malaria (all Plasmodium species): Artesunate (available HCDCP) + doxycycline or clindamycin,


Infection caused by P. falciparum can be fatal if not treated promptly.

With proper treatment, mortality is approximately 10-20%.

A disease severity associated with P. vivax is very rare, but has recently been described in the area of ​​Southeast Asia.

Children under 5 years of age, immunosuppressed patients, and pregnant women are considered to be at increased risk for serious disease and complications, especially in areas with high disease endemicity.

In areas with low endemicity, all age groups are at risk.

Relapses months and up to 5 years after original infection have been observed in P. vivax and P. ovale infections, especially when hypnozoite (primaquine) eradication therapy was not administered.

Infections caused by P. malariae, recrudescence can appear after decades.


There are a couple of things you can do to prevent malaria when visiting highly endemic areas: take an antimalarial medicine and avoid mosquitoes.

Antimalarial medications should be considered 4 to 6 weeks before traveling to a place where malaria transmission occurs.

To protect yourself from all mosquito-borne diseases, here is what you can do to minimize your chances of being bitten:

  • Wear protective clothing, such as long-sleeved shirts, pants, and hats.
  • Apply insect repellent to skin that is not covered. Look for a product that contains at least 7 to 10 percent DEET, such as OFF.
  • If you are staying in a room that is not well protected, you should consider sleeping under an insecticide-treated bed net or mosquito net.