Malaria – Transmission, Symptoms, Treatment and Prevention

Malaria used to be one of the deadliest disease in the past, not so now-a-days due to modern drug interventions through which it can be completely cured very easily.

However, it still is one of the leading cause of death by infections in Pakistan, other Asian countries and sub-Saharan Africa, especially when left untreated.

It was thought earlier that it is bad air, that when comes to an area causes the fever, hence the name MALA-bad AREA-air.

Until the late 19th century, the cause was unknown. It is said that Malaria used to kill 100s of 1000s of people in the past when treatment was not yet discovered, then one day a soldier in Europe who was suffering from malaria fell into a pool of water.

He accidentally ingested water from that pool which treated him, after that everyone from that area started drinking water from that pool and would get better.

Later on, it was found that around and in that pool were plants of cinchona, juices of which would mix in that water, it was then discovered that bark of the cinchona plants contains a chemical known as “quinine”, which can cure malaria.

Transmission from person to person:

Malaria is caused by a parasite named “PLASMODIUM” carried in the saliva of a female Anopheles mosquito. An infected mosquito when bites a healthy person transmit the parasite to that person.

Also, it is a specific stage in the development of the parasite in human blood, during which can it only be transferred to the mosquito from humans. Hence a female Anopheles mosquito with no Plasmodium in its saliva can’t give malaria to another person on its own.

What usually happens is this mosquito when bites and sucks the blood of an already infected person with malaria, at that specific stage of development, would carry the parasite and would then be only able to transmit it to another person.

Malaria can also be transmitted through transfusion of blood products or organ transplant. It is not transmitted through physical contact, eating in the same plates or sharing utensils, hugging, kissing or through sexual intercourse.

Why specifically female anopheles mosquitoe?

It is only the female anopheles mosquito where the parasite is able to complete a step in its development. So if an infected person is bitten by another mosquito would not be able to cause the disease in another individual as the cycle for development of plasmodium would not be completed.

When are malarial infections at peak:

We get patients suffering from malaria the whole year, but days when the incidence increases are when the general population should be more aware of the disease.

As it is carried by a mosquito, it is obvious that the rate of infection would increase during the months of summer, which is true. Therefore the month of JULY and AUGUST is the time when the number of malarial infections rises exponentially.

malaria transmission
malaria transmission via blood

Who is at risk of getting malaria?

There are some areas in Pakistan where the incidence of malaria is higher. Especially the hilly areas in the northern areas of Pakistan.

Though the incidence rate is much lower in Punjab, there are still outbreaks in places where measures for preventions are not taken promptly.

Usually, when a person is infected and he is left untreated, there is a higher chance that he is being bitten by the mosquito and thus that mosquito becomes a carrier.

Next few more people are infected by that mosquito and in no time, more mosquitos are carriers and the infection spread in a matter of days.

Malarial infections are also more common in patients who have repeated transfusion of blood products like patients with thalassemia, hemophilia and aplastic anemia.

Children and pregnant patients are at special risk of getting malarial infections. Malaria in pregnancy can lead to miscarriage. Travelers from non-endemic areas who are pregnant are therefore advised to postpone their visit till delivery.

Malarial species:

The three most important types of this parasite are (P. Falciparum, P. vivax, P. Ovale). What important to know is that >90% of malaria infections are caused by is P. vivax, which fortunately is less dangerous in the sense that development of complications in Vivax type is very rare, so is in P. Ovale.

Falciparum which accounts for <2% of malaria infections is the most dangerous one, and almost always kills a patient when left untreated. Nonetheless, P. Falciparum malaria has an excellent prognosis when treated earlier.

Sometimes P. vivax and P. Ovale stay hidden in the liver and cause an infection again months to years later. During the latent period, the patient would live a completely normal life until the parasites come into the bloodstream again.

Other species include Plasmodium malariae and Plasmodium knowlesi. Plasmodium malariae is associated with renal disease (glomerulonephritis) while Plasmodium knowlesi has similar manifestations as Plasmodium falciparum.

Symptoms and signs of malarial infections:

During the peak season for malaria, anyone with:

  • High Fever ( Usually above 102F ), that starts abruptly and is associated with chills/rigors and sweating, lasts for 1-3hrs and is followed by a complete fever-free period ranging from 48-72hrs

should suspect malaria as the first diagnosis and should get checked by a doctor right away.

Other symptoms that might accompany the fever are headache, weakness, muscle and bone aches. The examination may reveal anemia, enlarged spleen and bruises. These symptoms may also be found in typhoid fever.

In severe cases malaria affects the brain. This is called as cerebral malaria. Cerebral malaria may manifest as high-grade fever with drowsiness, altered mentation, seizures, and coma.

Malarial infections may lead to red blood cell breakdown (hemolysis) and lead to black colored urine. This is also called as blackwater fever.

Other malarial syndromes:

In endemic areas, due to repeated infections, hypersensitivity reaction to the malarial parasite occurs and the body responds by producing antibodies.

This leads to massive enlargement of the spleen and recurrent episodes of low-grade fever and is termed as the hyper-reactive malarial spleen. This was also previously called tropical splenomegaly syndrome.

Another rare manifestation of malaria is called as algid malaria. Patients with algid malaria may present with profuse watery diarrhea and profound shock. This can be rapidly fatal if not corrected early in the course of illness.

How to diagnose malaria:

Diagnosis is very easy, blood from the affected person is taken and put on a slide, the pathologist is able to see the organism under a light microscope.

Both thick and thin films are used, Thick being necessary for the visualization of the parasite and the thin film is required for the identification of the specific species i.e. Vivax, Ovale, malaria, and Falciparum.

Kits for rapid diagnosis are also available these days which would not only tell us about the parasite being present or absent but would also identify the species. Slides are the more reliable hence gold standard for diagnosis.

Other laboratory features include low hemoglobin, low platelets, raised bilirubin, deranged liver function tests, hemoglobin in urine

How to treat malaria:

A three-day artemisinin-based treatment is widely used nowadays in Pakistan which is highly effective against all the species.

Combination of Artemether-lumefantrine is used at hour 0, 8, 24, 36, 48 and 60. It is safe during all the trimesters of pregnancy. The dose depends on the weight of the patient. Other derivatives are also available in the market which is equally effective.

Primaquine is used to kill the parasites that are dormant in the liver.  Chloroquine is also useful in treating P. vivax and P. Ovale malaria but unfortunately, resistance against chloroquine is increasing so physicians prefer the above-mentioned combination therapy.

Serious infections, especially infections caused by P. Falciparum are treated in the hospital and with IV artemisinin derivatives.

malaria prevention
use mosquito repellents

How to prevent yourself from getting malaria?

Since mosquito is the vector and responsible for transmission of the malarial parasite, one should avoid mosquito bites. This is done by adopting the following measures.

  1. Avoid outdoor exposure especially between dusk and dawn. This is the time when a mosquito bites.
  2. Wear clothes with full sleeves and cover yourself to reduce the amount of skin exposure.
  3. Use insect repellents on exposed Parts of the body.
  4. Use mosquito nets treated with insecticides at night while sleeping.

Insect repellents recommended by the CDC for reducing the risk of Malaria include DEET (30 -50%).

It is generally protective for 4 hours and is safe for use in children 2 months of age and above. In addition to insect repellents applied to the skin, permethrin may be used on net and fabrics.  It is available as an aerosol clothing spray.

Permethrin is very effective when used for clotting and bed netting.  It effectively repels mosquitoes for more than one week even with washing and field use.  Nets dripped with permethrin are effective for 3 – 20 washes. Long lasting insecticide repellent can remain effective for as long as three years. The use of vaccines in malaria is still debatable.

Malaria prevention in travelers.

Malaria is an important cause of fever and travelers. Travelers to sub-Saharan Africa and Asia are especially at risk.

In 2010 CDC reported 1700 cases of imported malaria out of which half were falciparum malaria. Falciparum Malaria is known for causing most of the complications related to malaria and is well known for resistant to antibiotics drugs.

Apart from taking all the measures to prevent mosquito bites as described above, travelers from non-endemic areas need to start chemoprophylaxis.

Different classes of drugs are recommended for chemoprophylaxis. These include chloroquine, mefloquine, doxycycline, and atovaquone-proguanil.

Chemoprophylaxis should be started before visiting the endemic areas and be continued up to three weeks after the visit. Pregnant females from non-endemic areas should postpone their visit to endemic areas whenever possible because of the risks of miscarriages.

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