An Overview of Malaria

Malaria is a protozoan parasite transmitted by the female Anopheles mosquito. The Plasmodium is transmitted to the human when the female mosquito feeds on the human as a blood meal. The human blood is ingested by the mosquito while the mosquito's saliva containing Plasmodial sporozoites is simultaneously injected into the human bloodstream.

Life Cycle

With the mosquito's bite, sporozoites enter the human bloodstream and migrate to the liver. In the liver, the sporozoites undergo asexual reproduction, termed schizogony, which results in merozoites. The merozoites enter into the red blood cells, where they proceed to repeat schizogony. Some return to remain indefinitely dormant in the liver, while the remaining merozoites continue their life cycle in the red blood cells.

Within the red blood cells, the merozoites are referred to as trophozoites, which feed on hemoglobin in the red blood cells. At a certain point during schizogony of the trophozoites, microgametocytes (male) and macrogametocytes(female)

When a female Anopheles mosquito takes her blood-meal on an infected individual, she ingests the gametocytic stage of the plasmodium. Within the gut, the gametocytes undergo fertilization, resulting in ookinetes, which burrow under the stomach lining. The ookinetes mature as oocysts, and sporogony now occurs producing thousands of sporozoites. The sporozoites migrate to the salivary glands, where they are injected with the mosquito's next blood-meal.

Symptoms

Symptoms of malaria include bouts of fever, chills, vomiting, sweating, severe headaches, nausea, and in general, malaise. In severe cases, cerebral malaria may occur. This is almost always fatal if it reaches this stage. Symptoms occur as a result of the destruction of red blood cells that the trophozoites have digested. They feed off of hemoglobin, and the waste product that they leave behind acts as a toxin within the body.

Malarial Strains

There are numerous strains of malaria, but only four are generally known to effect humans. They are Plasmodium vivax (episodes every 48 hours), Plasmodium ovale (episodes every 48 hours), Plasmodium malariae (episodes every 72 hours), Plasmodium falciparum (episodes every 48 hours). Of these four, Plasmodium falciparum is the most common in East Africa and may also be the most fatal, as it frequently may result in cerebral malaria.

Protection Against Malaria

Although science has not yet provided a totally guaranteed cure for malaria, there are many measures that may be taken to ensure adequate protection against
contracting malaria. Various methods include practical measures, prophylaxis, and protective chemicals.

Practical methods of protections against malaria may comprise wearing proper clothing that would cover vulnerable areas of skin (as well as leaving less "biteable" area), sleeping with mosquito netting (treated or untreated), attempting to eradicate breeding sites, and the use of insecticides and insect repellents.

Prophylactic measures simply refer to the medicines that may be taken when going into at-risk areas. These are preventative medicines that will kill the parasite upon its attempted entry into the human body. Many of these medicines may also be taken after an individual has contracted malaria. These drugs include Quinine, Atebrin (mepacrine), Chloroquine. Proguanil, Malarone, Maloprim, Fansidar, Mefloquine (Lariam), Halofantrin (Halfan), and Artemisinins.

Protective chemicals contain a wide variety, from simple insect repellents as those mentioned above to severe insecticides such as DDT.