A convoy of Syrian Red Crescent trucks arrives in Douma, in the Syrian rebel-held enclave of Eastern Ghouta, on Monday. This aid convoy is the first to reach the besieged area in weeks.
Amer Almohibany/AFP/Getty Images
Smallpox virus, colorized and magnified in this micrograph 42,000 times, is the real concern for biologists working on a cousin virus — horsepox. They're hoping to develop a better vaccine against smallpox, should that human scourge ever be used as a bioweapon.
Chris Bjornberg/Science Source
Workers spray to kill fleas in a public school in Antananarivo, Madagascar's capital. A bite from an infected flea can spread the plague, which has stricken 157 people in the island nation since August.
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A member of the Syrian government forces watches during an evacuation of Syrian rebel fighters and civilians from a opposition-held area of Aleppo on Friday.
George Ourfalia/AFP/Getty Images
One of these candidates will be the next head of WHO. Top row from left: Tedros Adhanom Ghebreyesus, Flavia Bustreo, David Nabarro. Bottom row from left: Miklós Szócska, Sania Nishtar, Philippe Douste-Blazy.
Getty Images, AP and WHO
A government worker sprays mosquito insecticide fog in Kuala Lumpur, Malaysia, earlier this month to block the spread of Zika. The U.S. CDC advises pregnant women to reconsider plans to travel to Malaysia and 10 other countries because of the virus.
Margaret Chan (left), director general of the World Health Organization, is among the dignitaries visiting a military base in Conakry, Guinea, on a tour of west African countries affected by Ebola. Also pictured: Guinean President Alpha Conde (fourth from right) and U.N. Secretary General Ban Ki-Moon (right).