Epidemiological considerations for malaria reduction by transmission blocking vaccination

Outside of the temperate regions, malaria transmission continues throughout much of the world in a distribution which is not very different to that of one hundred years ago. However, with the notable exception of Africa sub Sahara, the morbidity and mortality due to malaria has generally been reduced to very low levels by comparison with earlier times. In a broad sense the malaria problem today falls into two distinct compartments, 1) how to deal with the remaining problem of malaria in the affected areas outside of sub Saharan Africa and 2) how to manage the, currently, much greater problem of malaria-related morbidity and mortality in Africa sub Sahara. Malaria control campaigns of the past have always placed great emphasis on reducing malaria inoculation rates in the affected populations. This may seem entirely logical, and is, indeed, an absolute requirement where eradication of malaria from an endemic area is the goal. There can, nevertheless, be dangers as well as benefits associated with reducing malaria inoculation rates in previously endemic populations. I discuss here the epidemiological issues which should be taken into account in this respect. I then examine the role that vaccination to reduce malaria inoculation rates in endemic populations--malaria transmission blocking vaccination--could play in malaria control.