The crowded streets of Kolkata, India, are only going to get more crowded. Randy Olson/National Geographic hide caption

itoggle caption Randy Olson/National Geographic

Syrian refugees live in makeshift shelters in the Beqaa Valley in Lebanon, just a few miles west of the Syrian border. Jason Beaubien/NPR hide caption

itoggle caption Jason Beaubien/NPR

A baby helps make history. The Kenyan child is receiving the new malaria vaccine — the first ever that can wipe out a parasite — as part of a clinical trial. Karel Prinsloo/AP hide caption

itoggle caption Karel Prinsloo/AP

Ioanna Mattke holds Raven, one of six hens that her family owns. The Mattkes have raised Raven since she was a day old. Jason Beaubien/NPR hide caption

itoggle caption Jason Beaubien/NPR
Alyson Hurt/NPR

At the health clinic in Minjibir, Nigeria, a child is immunized for polio. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

A police officer guards the home of a family under a 21-day Ebola quarantine in Freetown, Sierra Leone, back in March. Michael Duff/AP hide caption

itoggle caption Michael Duff/AP

A dangerous nuzzle? A man in western Abu Dhabi hugs a camel brought in from Saudi Arabia for beauty contests. Middle East respiratory syndrome circulates in camels across the Arabian Peninsula. Dave Yoder/National Geographic hide caption

itoggle caption Dave Yoder/National Geographic

A student wearing a face mask stands in a public square in Seoul on June 3. More than 200 primary schools shut down as South Korea has struggled to contain an outbreak of the MERS virus. ED JONES/AFP/Getty Images hide caption

itoggle caption ED JONES/AFP/Getty Images

The man who died of Lassa fever flew from West Africa to New York's John F. Kennedy Airport. Spencer Platt/Getty Images hide caption

itoggle caption Spencer Platt/Getty Images

Patients receive treatment at the Chest Disease Hospital in Srinagar, India. The country has one of the highest rates of drug-resistant tuberculosis in the world, in part because antibiotics for the disease are poorly regulated by the government. Dar Yasin/AP hide caption

itoggle caption Dar Yasin/AP

The Ebola outbreak "overwhelmed" the World Health Organization and made it clear the agency must change, WHO's director-general, Dr. Margaret Chan, said Monday in Geneva. Fabrice Coffrini /AFP/Getty Images hide caption

itoggle caption Fabrice Coffrini /AFP/Getty Images