One of the largest reports of prevalence rates of Plasmodium falciparum - a parasite that causes malaria - in sub-Saharan Africa is described in a study published online this week in Nature. The dataset includes 7.8 million blood samples from more than 30,000 locations and covers 115 years of malaria history.

Bob Snow and colleagues used data on the P. falciparum parasite rate - an index of malaria transmission intensity - to define the long-term nature of malaria transmission. The authors show that sub-Saharan Africa has experienced a decline in the prevalence of P. falciparum from 40% prevalence between 1900 and 1929 to 24% prevalence between 2010 and 2015, a trend that has been interrupted by periods of rapidly increasing and decreasing transmission, which are likely to be the result of several contributing factors. They also reveal that although previous global initiatives have contributed to an unprecedented decline in infection since 2000, reductions have not occurred uniformly throughout the continent, leaving large parts of West and Central Africa with high transmission rates of the disease.