Malaria is a potentially fatal parasitic disease transmitted by mosquitoes. The disease is thought to have originated in marshland areas, from which the alternative name paludism derives from the ancient word "palud" meaning marsh Scientists discovered the real cause of malaria in 1880, a unicellular parasite called Plasmodium. They then discovered that the parasite was transmitted between people by bites from a female Anopheles mosquito which needs blood to feed its eggs.
Currently, more than 40% of the world's population are exposed to malaria and most of these live in the poorest countries. The disease was previously more widespread but was eradicated from many temperate countries in the middle of the XXth century. Malaria now affects tropical and sub-tropical regions and is responsible for 300 million cases of acute disease and at least a million deaths every year.
Ninety per cent of deaths from malaria occur in sub-Saharan Africa mostly in young children. Malaria kills a child in Africa every 30 seconds. Many children who survive an attack of acute malaria can develop learning difficulties or cerebral dysfunction. Pregnant women and the unborn child are also particularly vulnerable from malaria, a major cause of perinatal mortality, low birth weight and maternal anaemia.
There are four types of human malaria Plasmodium vivax, P. malariae, P. ovale and P. falciparum. P. vivaxand P. falciparum are the most common. Falciparum infection is the most severe and can be fatal. Plasmodium falciparum malaria is very widespread in sub-Saharan Africa, where to a large extent it is responsible for the very high mortality rate. There are worrying signs of P. falciparum extending to new regions and of its resurgence in areas where it had been eliminated.
The malaria parasite enters the human host body when an infected anopheles mosquito feeds on blood. The parasite then undergoes a series of transformations during its complex life cycle. As a result of these changes the Plasmodia escape from the immune system, infect the liver and red blood cells and ultimately develop into a form which is able to reinfect a mosquito if it bites an infected person. The parasite undergoes further changes inside the body of the mosquito until it is able to reinfect a human host when the female mosquito feeds on blood another time, 10 or 14 days later.
The symptoms of malaria develop approximately 9 to 14 days after the bite from the infected mosquito. This time period varies depending on the species of Plasmodium. Malaria is generally associated with high temperature, headaches, vomiting and other flu-like symptoms. Untreated, or if the parasites are resistant to the drugs available, the infection can progress rapidly and become potentially fatal. Malaria can kill by infecting and destroying red blood cells (anaemia) and by obstructing the capillaries which carry blood to the brain (cerebral malaria) and other vital organs.
Malaria parasites have become resistant to successive drugs and many insecticides no longer have an effect on the mosquitoes which transmit the disease. Despite years of research, few promising candidate vaccines have been developed and although researchers are increasing their efforts, it will be years at best before an effective vaccine is discovered.
Science does not have a miracle solution for malaria yet and many doubt that a single solution will ever be found. Nevertheless, there are effective economic strategies to fight, treat, and prevent the disease, and the world-wide 'Faire reculer le paludisme' (push back malaria) partnership is actively promoting these in Africa and in other endemic malarial regions. Mosquitoes impregnated with insecticide can reduce the transmission of malaria and infant mortality. Prevention of malaria in pregnant women is resulting in an improvement in maternal health and in the health and survival of infants. Lives can be saved by rapid access to treatment with effective modern drugs. The use of these and other measures on a large scale will produce a significant fall in the burden of morbidity and mortality from malaria.