One million dead a year, 500 million with the disease,

2.5 billion people at risk: this is the malaria balance

sheet in 2007. The distribution and seriousness of

the disease depend on the pathogens and vectors

involved, as well as environmental conditions. Of the

four parasites (Plasmodium) , only P. falciparum kills

although the other three cause debilitating disease

with regular relapses and recrudescence. More than

fifty species of Anopheles can fulfil the vector role

which is essential in transmission of the parasite

between human beings. Climatic factors (temperature

and rainfall), the environment and biogeographical

particularities dictate the distribution of anopheline

species and determine transmission rates. This is why

it makes sense to talk about the biodiversity of malaria.

Today, more than 90% of deaths from malaria occur

in Tropical Africa which is home to only 10% of

humanity. Every 30 seconds a child dies from malaria.

This continent harbours the most effective vectors

(An. gambiae and An. funestus , in particular) and the

climate is highly conducive to transmission of the

disease. Severe malaria is also seen in forest foci in

Southeast Asia, Papua-New Guinea and the Amazon.

In the rest of the tropical and subtropical world,

P. vivax and/or P. malariae cause less severe disease.