Background: Malaria in Africa

Malaria Cases and Deaths in South Africa, 1971-2002

Source: South African Department of Health, http://www.aei.org/article/energy-and-the-environment/climate-change-and-mosquito-borne-disease/ (3)

Quick Facts       

•  According to current climatic predictions, Malaria is expected to spread more rapidly and to a wider range, due to warming and changes in precipitation (1,4,9).
• Nine out of 10 of the world's annual one million malaria-caused deaths occur in sub-Saharan Africa (11)
• The spread of Malaria is most prevalent in Africa, where, in 2010 alone, there are an estimated 216 million cases of malaria worldwide, and at least 655,000 deaths, with morbidity and mortality highest in the Sub-Saharan region (12).
• Infants, young children and pregnant women are most highly affected. 
•  Malaria accounts for at least $12 billion in economic losses each year in Africa, with a reduction in annual economic growth estimated at 1.3 percent of gross domestic product(13). 

Cause and Transmission
 

Malaria is caused by the genus of single-celled parasites called Plasmodium. Many species of Plasmodium exist (18). It is most commonly transmitted by Anopheles mosquitoes and reproduces inside human carriers. However, since it is transmitted through blood cells, the parasite can also be passed through shared needles, blood transfusions, and from a mother to her fetus (13).

NIAID - http://www.niaid.nih.gov/topics/malaria/pages/lifecycle.aspx (13)

 
The malarial transmission cycle is  complex. A simplified version is shown at the right. It begins when a female Anopheles mosquito carrying malaria-causing parasites feeds on a human and injects the parasites in the form of spores, or sporozoites, into the bloodstream. These mobile spores travel to the liver and invade liver cells. Over one to two weeks, the sporozoites grow and divide, reproducing over a thousand times within an individual liver cell (13).

The daughter cells of these spores (merozoites) then exit the liver to enter the bloodstream, infecting tens of thousands of blood cells. The parasites reproduce sexually and asexually both in the liver cells and bloodstream. The products of this sexual reproduction are gametocytes. When a mosquito bites an infected human, it ingests these gametocytes, which eventually produce sporozioites that can infect another human once the mosquito bites again (13).

Symptoms

Symptoms occur when Plasmodium causes the bursting of blood cells within a patient. The patient can experience chills, followed by fever, and sweating. The individual is likely to experience headache, malaise, fatigue, muscular pains, occasional nausea, vomiting, and diarrhea. These attacks are recurring, and vary in severity depending on the strain of Plasmodium with which the patient is infected. If left untreated, in most cases the stress on the body will be too severe, and the patient will die (18).