Millions of people across sub-Saharan Africa rely on cattle for their survival. But the spectre of East Coast Fever is a constant presence, threatening to decimate entire herds and the communities that depend on them. East Coast Fever is a disease caused by a parasite. Once infected cows rapidly lose weight, develop sores, and eventually die. But thanks partly to a grant from the Bill and Melnda Gates Foundation, scientists are now working on a new vaccine.