The Anopheles mosquito breeds in fresh water like ponds, puddles or slow-moving streams. So malaria tends to occur during the wet season. The female mosquito needs a blood feed in order to nourish her own eggs.
If she happens to bite a person already infected with malaria the parasite can then proceed to the next stage of its life cycle, which takes place within the stomach of the mosquito.
The next night, when the mosquito feeds again, she injects the malaria parasites into the next person's skin, along with her saliva. Once in the blood stream, the parasite invades the red blood cells and then develops and multiplies.
An infected red blood cell has a characteristic appearance under the microscope - the malaria parasite is quite clearly visible within it, looking like a blue signet ring. The presence of the parasites in the blood causes the symptoms of fever, chills, body aches and headache. Malaria can also cause diarrhoea, vomiting, cough and blood-stained urine. Infected red blood cells are not as elastic as they should be.
This means that they can no longer fit through the smallest blood vessels, called capillaries. Because of this they tend to clog up the circulation in the major organs - especially the brain, kidneys and lungs. The higher the parasite count (i.e. the proportion of the red blood cells that are infected), the more extensive will be this clogging process.
In falciparum malaria it is so extensive that it leads to failure of the organs. Death follows quickly. The malaria parasite also makes the red blood cells more fragile, which means that their life span is much reduced. The resulting haemolysis, or destruction of red cells, leads to anaemia. This means that there are not enough red cells in the body to transport oxygen.
The result is that the infected person may become easily fatigued and short of breath. A pregnant woman who is anaemic is more likely to die of post-partum haemorrhage, which means blood loss during delivery.