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Malaria

What is Malaria?

Malaria is an infectious disease characterized by repeated attacks of high fever with chills. The disease occurs due to infection by the Plasmodium parasite, which enters the body through biting of female Anopheles mosquito carrying the parasite. Malaria most commonly occurs in the tropical countries. Out of the five Plasmodium species of parasites, P.falciparum and P.vivax are responsible for most cases of malaria. Treatment options depend on the species of the infecting Plasmodium parasite, the severity of symptoms and age of the infected person.

Untreated Malaria

Greater awareness about the dangers of malaria has prompted the development of more effective measures to prevent infection or rapidly institute treatment. Untreated malaria leads to number of complications like respiratory distress, organ failure especially kidney, confusion and coma with involvement of the brain. Malaria is a fatal infection once it progresses and treatment is not forthcoming. Life threatening complications are more likely to arise with untreated cases and patients who are immunocompromised. Globally malaria kills almost 1 million people every year.

Picture of the malaria parasite from Wikimedia Commons

Malaria Symptoms

The common symptoms of malaria include :

  • Fever
  • Headache
  • Generalized body ache
  • Lethargy
  • Nausea and vomiting
  • Loss of appetite
  • Jaundice

Malaria Fever

  • A high fever typically preceded by severe chills and shivering.
  • Fever usually lasts for 1 to 2 hours and its periodicity depends upon the infective species.
  • Periodicity is about 48 hours for P. vivax, P.ovale and P. falciparum whereas it is about 72 hours for P.malariae.
  • Initially the patient may not present with classical pattern of fever but small spikes of fever with long standing fever following the classical pattern developing thereafter.

Cerebral Malaria

P.falciparum causes cerebral malaria characterized by some specific symptoms like :

  • High fever associated with confusion, disorientation, delirium
  • Abnormal body posture
  • Convulsions
  • Coma

Malaria Complications

As the infection progresses and if the appropriate treatment is not forthcoming, complications may arise. These complications may present with :

  • Enlargement of liver and spleen
  • Low blood sugar
  • Impaired renal function marked by cola-colored urine is passed due to presence of broken RBCs in urine.
  • Shortness of breath due to lung infection and fluid accumulation in the lung

Malaria in Pregnancy

Malaria in pregnant girls or women can jeopardize fetal development and the unborn child’s life. Ideally endemic areas should be avoided during pregnancy but this may not be avoidable. The complications associated with malaria in pregnancy includes :

  • Miscarriage
  • Stillbirth
  • Low birth weight babies
  • Increased risk of death during infancy

Malaria Causes

Parasites

Malaria occurs due to infection with the Plasmodium protozoa. There are five species of Plasmodium responsible for malaria in humans, namely :

  1. P.falciparum
  2. P. vivax
  3. P.malariae
  4. P.ovale
  5. P. knowlesi

Among these species, falciparum malaria is responsible for majority of deaths and is also the most commonly identified species, followed by vivax. However, vivax malaria is more common in adults outside Africa.

Life Cycle

Malaria occurs in humans by bite of female anopheles mosquito carrying the protozoa. The infective form of the parasites (sporozites) thus enters the blood and reaches liver where they multiply asexually into thousands of merozoites. These merozoites then infect the red blood cells. Ultimately the red cells burst releasing the merozoites thereby initiating the infective phase characterized by fever. The merozoites then develop into male and female gametocytes.

When a female anopheles mosquito bites an infected person, the gametocytes enter the mosquito blood. The male and female gametes fuse and form zygotes which mature into the infective form sporozoites. Thus the cycle in human is again repeated. Symptoms of malaria may recur after a symptom free interval (relapse) because of persistence of hyponozoites in liver, typically seen P. vivax and P.ovale infection.

Picture depicting the life cycle of the malaria parasite from Wikimedia Commons

Transmission

The Anopheles mosquitoes are the main vector for human transmission. People living in high risk areas in Africa and Asia, and people traveling to these endemic regions are at the greatest risk of being bitten and developing malaria. Apart from being spread by the bite of an infected mosquito, other modes of transmission are :

  • Transfusion of infected blood.
  • Infected mother to baby during pregnancy.
  • Needle sharing among IV drug users.

Malaria Treatment

Treatment varies to some degree depending upon the species causing the infection. Travelers to endemic areas should use prophylaxis (preventative medication) to avoid contracting malaria even after being bitten by an infected mosquito.

Common antimalarial drugs include :

  • Chloroquine
  • Mefloquine
  • Quinine
  • Artemisinin

Usually combination therapy is recommended to avoid resistance as well as to kill the gametocytes that can be very resilient to some medication.

References :

www.cdc.gov/MALARIA/


Posted by in Infections and Infestations

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