Friday, May 25, 2007

Anti-malarial Drugs

Anti-malarial Drugs

Malaria is one of the main killing diseases in the tropics and is most likely to affect children and people who live in or travel to such places.

The disease is caused by protozoa whose life cycle is far from simple. The malaria parasite, which is called Plasmodium, lives in and depends on the female Anopheles mosquito during one part of its life cycle. It lives in and depends on human beings during other parts of its life cycle.

Transferred to humans in the saliva of the female mosquito as she penetrates ("bites") the skin, the malaria parasite enters the bloodstream and settles in the liver, here it multiplies asexually.

Following its stay in the liver, the parasite (or plasmodium) enters another phase of its life cycle, circulating in the bloodstream, penetrating and destroying red blood cells and reproducing again. If the plasmodia then transfers back to a female Anopheles mosquito via another "bite", they breed sexually and are again ready to start a human infection.

Following the emergence of plasmodia from the liver, the symptoms of malaria occur: episodes of high fever and profuse sweating alternate with equally agonizing episodes of shivering and chills. One of the four strains of malaria (Plasmodium falciparum) can produce a single severe attack that can be fatal unless treated. The others cause recurrent attacks, sometimes extending over many years.

A number of drugs are available for preventing malaria, the choice depending on the region in which the disease can be contracted and the resistance to the commonly used drugs. In most malarial areas, Plasmodium Falciparum is resistant to Chloroquine. In all regions, three drugs are commonly used: Quinine, Mefloquine and Malarone.

Choice of Drugs

The parts of the world in which malaria is prevalent and travel to which may make anti-malarial drug treatment advisable, can be divided into six zones. Due to drug resistance, specific anti-malarials are recommended for each zone.

Zone 1 — North Africa and the Middle East: Chloroquine, and Proguanil in areas of Chloroquine resistance.

Zone 2 — Sub Saharan Africa : Mefloquine or Chloroquine with Proguanil

Zone 3 — South Asia : Mefloquine or Chloroquine with Proguanil

Zone 4 — Southeast Asia : Mefloquine in high risk areas or Chloroquine with Proguanil; Doxycycline in Mefloquine resistant areas

Zone 5 — Oceania : Mefloquine or Doxycycline

Zone 6 — Latin America, Central America : Chloroquine or Proguanil. South America : Mefloquine in high risk areas or Chloroquine with Proguanil

As prevalent strains of malaria change very rapidly, you must always seek specific medical advice before travelling to any of these areas.




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