Malaria: Causes, Symptoms, Life Cycle

Malaria is a mosquito-borne infectious disease caused by various species of the parasitic protozoan microorganisms called Plasmodium. Malaria was so prevalent during the Roman times that the disease is also called Roman Fever. The credit for actually discovering the parasite is given to Charles Louis Alphonse Laveran, a French physician. He even won the Nobel Prize in 1907 for his findings.

World Malaria Day is celebrated every year on 25 April to highlight the need for the prevention, control and elimination of malaria.

Causes of Malaria

  • Bitten by a malarial vector (Anopheles stephensi)
  • Use of shared and infected syringes.
  • Organ transplantation.
  • Transfusion.
  • From an infected mother to her baby during birth.

Symptoms

Symptoms of malaria are exhibited within 7 to 18 days of being infected. Common symptoms include:

  • Fever, fatigue, chills, vomiting, and headaches
  • Diarrhoea, anaemia and muscle pain
  • Profuse sweating and convulsions
  • Bloody stools.
  • In severe cases, malaria can be devastating; it can lead to seizures, coma and eventually, death.

Malaria Life Cycle

In the life cycle of Plasmodium, a female Anopheles mosquito transmits a motile infective form the sporozoite to a vertebrate host such as a human, Thus acting as a transmission vector. A sporozoite travels through the blood vessels to liver cells, where it reproduces asexually, Producing thousands of merozoites. These infect new red blood cells and initiate a series of asexual multiplication cycles that produce 8 to 24 new infective merozoites, at which point the cells burst and the infective cycle begins anew.malaria-life-cycle
When a fertilized mosquito bites an infected person, gametocytes are taken up with the blood and mature in the mosquito gut. The male and female gametocytes fuse and form an ookinete a fertilized, motile zygote. Ookinetes develop into new sporozoites that migrate to the insect’s salivary glands, ready to infect a new vertebrate host. The sporozoites are injected into the skin, in the saliva, when the mosquito takes a subsequent blood meal.

Only female mosquitoes feed on blood; male mosquitoes feed on plant nectar and do not transmit the disease. Females of the mosquito genus Anopheles prefer to feed at night. They usually start searching for a meal at dusk, and continue through the night until they succeed. Malaria parasites can also be transmitted by blood transfusions, although this is rare.