Malaria: cause, symptoms, treatment and prevention

Malaria is a mosquito borne disease. It is an infectious disease. This disease is characterized by fever with chills and rigors, headache and fatigue, vomiting and loose motions. In some patients along with the symptoms there is jaundice. 

In 2019, 229 million cases of malaria were estimated by WHO in the world. Nearly four lakh people died of malaria in 2019. According to this WHO estimate, children of age under five years are most vulnerable to malaria. Most severely affected regions for sub Saharan Africa and southeast Asia.

brown map on map
Africa
earth globe with googly eyes on gray background
Asian countries

What is the cause of malaria?

Malaria is caused by parasite infection only Plasmodium falciparum, Plasmodium ovale, Plasmodium vivax, Plasmodium malariae, and Plasmodium knowlesi.

Among these infections of plasmodium falciparum malaria are more serious.

Malaria Parasites
Plasmodium falciparum
Plasmodium vivax
Plasmodium ovale
Plasmodium malarae
Plasmodium knowlesci
Cause of malaria

How does malaria spread?

mosquito biting on skin
Mosquito bite
Photo by Jimmy Chan on Pexels.com

Malaria can spread from one person to another. It spreads by mosquito bites. Female anopheles mosquito bites a person with malaria, and then it again, bites another person who is susceptible to malaria, the susceptible person gets the infection.

What is the incubation period of malaria?

Incubation period is a characteristic of infectious disease. It indicates the time period between exposure to the infectious agent and development of the first symptom of the disease.

The malaria incubation period depends upon the parasite. It ranges from 7 to 30 days for different types of malaria depending on the parasite infecting the person.

Life cycle of plasmodium parasite

life cycle of plasmodium by Bbkkk

Life cycle of plasmodium parasites continues in humans and mosquitoes. 

Sporozoite
Merozoites
Trophozoites
Schizonts
Gametes
Ookinetes
Hypnozoites
Life forms of Plasmodium

Female anopheles mosquito bites human and motile forms of parasites sporozoites enter the blood. From blood sporozoites are carried to the liver. These sporozoites infect the liver cells of hepatocytes. 

In the liver cells called hepatocytes these sporozoites multiply many times by asexual multiplication to produce merozoites. When there are too many merozoites the liver cells rupture releasing these merozoites to blood. In blood these merozoites infect red cells and produce ring forms of trophozoites and schizonts.

Also the sexual form of parasites that is gamatocytes are produced. From them male and female gametes are produced.

These gametes when are sucked by mosquito into gut they become mature and enters the mosquito blood. They fuse there to form ookinetes. They are secreted by mosquito salivary glands and enter humans as sporozoites to infect the human.

Plasmodium vivax and plasmodium ovale can form hypnozoites in the liver. These hypnozoites may remain in the liver even after parasites from blood are cleared. They may get activated to form merozoites causing relapse of malaria.

Recurrence of malaria is because of relapse or reinfection. Relapse is activation of malaria hypnozoites from the liver. Reinfection is type of recurrence because of new infection.

What are symptoms of malaria?

Symptoms of malaria can be severe or can be mild. Severe symptoms of malaria can cause death. 75% of all deaths caused by malaria are caused by falciparum malaria.

Following are the symptoms of malaria.

Initial symptoms are malaise and weakness.

Fever is another common syndrome of malaria. This fever can be mild initially and then there is moderate to high grade fever. This fever is of intermittent type. Fever is associated with chills and rigors. It decreases with excessive sweating. Fever occurs when parasites are released into the blood from the cells.

Intermittent
Moderate to high grade
Chills and rigors
(Shivering)
Sweating
Then temperature comes to normal
characteristics of malaria fever

Patients may have headaches that can be moderate to severe.

Some malaria patients may have nausea and vomiting.

Abdominal pain and loose motion and other symptoms of malaria.

Patience makes the skin yellowish because of jaundice.

In a few cases there is bleeding because of decreased platelet count.

There is muscle and joint pain.

Some patients of malaria have a cough.

Patients may have rapid heart rate and rapid breathing.

Fatigue and weakness
Headache
Fever
Chills and rigors
Vomiting
Abdominal pain
Cough
Muscles and joints pain
Symptoms of malaria

Complicated malaria

Complications of malaria are cerebral malaria, kidney failure, pneumonia, bleeding, severe anaemia, hypoglycemia, retinal damage, coagulopathy.

Malaria cases are classified as complicated malaria if they have following features.

  • Altered consciousness
  • At least 2 convulsions
  • Not able to walk
  • Loss of power in one or more limbs
  • Inability to feed
  • Low blood pressure
  • Breathing difficulty
  • Bleeding
  • Low blood glucose levels
  • Kidney failure or haemoglobin in urine
  • Circulatory shock
  • Acidosis

How to diagnose malaria?

On clinical suspicion because of history and physical examination findings, doctors suggest tests to diagnose malaria.

HBCBC
Peripheral Blood smear
Rapid diagnostic test like
malaria antigen test
Tests for malaria
  • Peripheral blood smear is done to detect malaria parasites in the blood. In this test blood taken from peripheral veins is spread on a glass slide. The glass slide is examined under a microscope which may show parasite forms in blood red cells. This test can be 90% sensitive to detect malaria under optimum conditions.
  • Rapid diagnostic tests for malaria are antigen based tests to detect antigens of malaria parasites. They are easy to do but have less sensitivity.
  • Other features of malaria are normal WBC counts, decreased platelets and increased bilirubin levels.

What is the treatment of malaria?

Treatment of malaria includes antimalarial drugs and treating the complications.

Antimalarial drugs help to kill the parasites which have infected the person.

Uncomplicated
Falciparum
Uncomplicated
Non
falciparum
Complicated
malaria
Artemether +
Lumifantrin
Cloroquine + primaquineArtesunate
Artemether +
Mefloquine
Artemether +
Lumifantrin
Quinine
Artemether +
Mefloquin
Supportive care
Malaria treatment

Uncomplicated falciparum malaria

Uncomplicated falciparum malaria can be treated with artemisinin. Artemisinin derivatives combination is currently recommended to treat the uncomplicated falciparum malaria.

  • Artemether lumefantrine combination is most widely used to treat these cases. Six dose regimen is more effective than a smaller number of doses.
  • Artemether-mefloquine combination is also equally good to treat uncomplicated cases.

Uncomplicated non falciparum malaria

Usually uncomplicated falciparum malaria cases do not need hospitalization. The treatment can be done at home with oral medications. For the treatment of these cases chloroquine or artemisinin combination therapy can be used.

Infection of the Plasmodium vivax needs treatment of blood form and liver form of the parasite. To kill the liver form of parasites, primaquine is the preferred drug. Primaquine is given for 2 weeks at least.

Complicated malaria

Almost all the cases of complicated malaria are caused by Plasmodium falciparum malaria. This form of malaria needs treatment with intravenous form of drugs.

For treatment of such malaria artemisinin artesunate or quinine is recommended. In early pregnancy quinine is preferred and late pregnancy artesunate can be used.

Supportive care

Along with antimalarial drugs supportive care is needed to treat their cases of uncomplicated and complicated malaria.

For the treatment of fever medication like paracetamol can be used. 

For the treatment of nausea vomiting medication like ondansetron can be used. 

It is vital to maintain the hydration of the patient. If a patient is able to eat, oral rehydration therapy is recommended. If not intravenous fluid is given to the patient.

Complicated malaria is treated in ICU settings of the hospital. Patient may need support for breathing if there is breathing difficulty.

Patients may need anticonvulsants if shows convulsions.

Other vital parameters like heart rate, blood pressure, blood sugar level is to be monitored and treated. Blood potassium levels may decrease and acidosis may occur, should be managed with appropriate therapy. 

Other complications like bleeding, severe anaemia and kidney failure may need intervention.




Leave a Reply