Marcel van Soest, an epidemiologist and the executive director of the World AIDS Campaign (WAC) since 2004, has died, according to a WAC statement. He was 46. Van Soest grew WAC from a one-man operation to a small international agency whose projects range from grassroots programs in Africa to global events like World AIDS Day. After studying epidemiology and social geography at Radboud University in the Netherlands, he earned his master's degree in public health from Johns Hopkins University in Baltimore. Van Soest worked for almost 10 years with Medecins Sans Frontieres Holland.

To read the WAC statement, click here.