Malaria is an Italian word composed of "mala " and "aria," derived from malus (bad), and aeris (air). It was first used to describe a fever (miasma), which was wrongly attributed to exposure to poisonous air rising from marshes. Although the disease had been described in the Hippocratic Collection (460 to 377 BC) and its relation to mosquitoes suggested in the 5th century AD, by the Indian physician Susruta, it was only in 1880 that Charles Laveran, a French physician working in Algeria, discovered the true causative agent as being a sporozoan of the genus Plasmodium. More than a century later, we got to map the malaria genome, identifying a huge number of genes located on 14 chromosomes.Malaria is acquired through the sting of an infected Anopheles mosquito, which injects the sporozoites into the host's dermis. These are carried with the blood stream to the liver, where they mature in the hepatocytes (extra-erythrocytic cycle) to tissue schizonts that release their merozoites into the hepatic sinusoids. The latter invade the red cells, starting the erythrocytic cycle, which comprises ring forms, trophozoites, and, subsequently, schizonts that contain a new generation of merozoites. The parasitized cells are induced by plasmodial DNA to develop a microtubular system that conveys nutrients to the parasite. They eventually rupture and release the merozoites, which repeat the same cycle. A few merozoites are sexually differentiated into male and female gametocytes, which are essential for the completion of the sexual cycle in the vector.
EpidemiologyMalaria is widely spread throughout the world and affects close to 400 million people, most of whom live in Africa, India, Southeast Asia, and Latin America. With the increasing immigration of natives from those regions to Europe and North America, "imported malaria" imposed itself on the list of differential diagnosis of many medical conditions in the West as recurrent fever, jaundice, hemolytic anemia, acute renal failure (ARF), systemic inflammatory response (SIR) syndrome, and posttransplantation pyrexia (1).An increasing number of Caucasians acquire the disease through traveling or living in endemic areas. This risk has been known for many centuries. Celebrities known to have contracted the disease while traveling to Africa or Asia include the Italian poet Guido Cavalcanti in 1300, the British explorer Sir Richard Burton in 1858, and the American president John F. Kennedy while serving in the Pacific during World War II. Malaria in nonimmune Caucasians is notoriously severe, with cerebral and renal complications often supervening with a fatal outcome.Infected mosquitoes can also travel with passengers or cargo and have been reported to transmit the disease to visitors of major European airports ("airport malaria"). They could even establish endemic foci in the West as reported from Belgium and the United States.