As the Zika virus spread rapidly through the Americas earlier this year, teams of Red Cross volunteers hit the streets, getting the message out about how to interrupt the spread of this mosquito-borne disease, which has been linked to an increase in the birth of babies with microcephaly and to Guillain-Barré syndrome. Zika is transmitted by the same Aedes aegypti mosquito that carries dengue and chikungunya, so the way to stop transmission from these daytime-biting mosquitoes to humans is to reduce the number of places with standing water, where mosquitoes breed, and to wear insect repellent consistently throughout the day, among other measures. “In the battle against Zika, knowledge is power,” says Julie Lyn Hall, the IFRC’s director of health.