A 10-year-old Somali boy being treated for meningitis in May 2009 at a makeshift clinic in Mogadishu. ROBERTO SCHMIDT/AFP hide caption

itoggle caption ROBERTO SCHMIDT/AFP

Nicole Andreacchio, second from the right, was seven months pregnant when she went to get vaccinated against swine flu in Maple Glen, Pa., in October 2009. Matt Rourke/AP hide caption

itoggle caption Matt Rourke/AP

A man helps his dengue fever-stricken daughter in Tegucigalpa, Honduras. In June, Honduran authorities declared a state of emergency due to the high rate of dengue cases reported around the country. Orlando Sierra/AFP hide caption

itoggle caption Orlando Sierra/AFP