Malaria

Malaria
Introduction:
Malaria is a disease caused by one of four types of Plasmodium usually transmitted to humans by the bite of an infected female Anopheles mosquito that previously sucked the blood from a person with malaria. Malaria is one of the leading causes of disease and death in the world. It is estimated that there are 300-500 million new cases every year, with 1.5 to 2.7 million deaths worldwide. It occurs extensively in tropical and subtropical regions. Malaria may have contributed to the decline of the Roman Empire, and was so pervasive in Rome that it was known as the "Roman fever".The term malaria originates from Medieval Italian: mala aria — "bad air";

Etiologic Agent:-
There are four species that commonly cause disease among humans: P. vivax, P. falciparum, P. ovale, and P. malariae. Mixed infections are possible. It is important to understand significant differences among the several species in terms of clinical illness, treatment, prophylaxis, and geographical distribution. Malaria due to P. falciparum causes the most severe symptoms and requires prompt intervention. Malaria parasites have a complex life cycle. After injection into the human host from anopheline mosquitoes, the parasites mature in the liver before being released into the bloodstream and invading red blood cells. The parasites multiply inside the red blood cells, eventually rupturing the cells, releasing more parasites into the bloodstream with accompanying high fevers. Some parasites differentiate into sexual forms (gametocytes) which, if ingested by another mosquito, can lead to the development of another generation of parasites, ready for transmission to another human host. The bloodstream cycle can persist for weeks to years, depending on the species involved. In malaria due to P. vivax and P. ovale, a dormant stage (hypnozoites) can persist indefinitely in the liver. Four species of Plasmodium can infect and be transmitted by humans. Severe disease is largely caused by Plasmodium falciparum. Malaria caused by Plasmodium vivax, Plasmodium ovale and Plasmodium malariae is generally a milder disease that is rarely fatal.