Saw-scaled vipers may be small, but they pack a nasty venomous punch. This one, Echis carinatus sochureki, was used in a study on snake venom. Courtesy of Wolfgang Wüster hide caption

itoggle caption Courtesy of Wolfgang Wüster

Daily medications for young children with HIV include both tablets and liquid drugs in syringes. Andrew Aitchison/In Pictures/Corbis hide caption

itoggle caption Andrew Aitchison/In Pictures/Corbis