In the U.S., doctors no longer have the option of treating gonorrhea with a pill. Instead, they are advised to use an injectable antibiotic, which is still effective against the bacteria.
Chiara Andolina, a malaria researcher in Thailand, feeds her mosquito colony by letting the insects bite her right arm. These mosquitoes are picky and will dine only on live human blood.
Ben de la Cruz/NPR
Mosquitoes like this one can carry the virus that causes dengue fever, which may become a bigger problem in some regions as biodiversity is lost.
James Gathany/CDC Public Health Image Library
A health official culls chickens on a poultry farm in a village on the outskirts of Katmandu, Nepal. Chickens suspected of being infected with H5N1 bird flu were found in the area in October.
Prakash Mathema/AFP/Getty Images