DNA sequencing of the parasites that cause Chagas' disease, African sleeping sickness and leishmaniasis have illustrated that the genomes are so different from humans that it should be possible to identify drug targets and develop vaccines against these diseases. For example, the parasites require sialic acid, a sugar, to construct the complex surface molecules used to evade the human immune response. It should be possible to devise custom drugs to block pathways such as sialic acid uptake and kill the parasites.