Hookworm was a fact of American life a century ago. In this photo, circa 1912, from Faulkner County, Arkansas, resident gather outside a "dispensary" for free treatment.
A patient with the H7N9 avian flu is treated in a hospital in Wuhan, in central China's Hubei province, in February of this year. The 2017 outbreak was the deadliest in China since H7N9 first appeared in humans in 2013.
The growths on Muhammad Taluli's hands were from a severe case of a rare condition called epidermodysplasia verruciformis — sometimes called "tree man" disease because the tumors can resemble wood or bark.
The typical asymmetrical lymphedema (lower limb swelling) seen in podoconiosis. The skin on the affected limbs is thickened with warty and mossy nodules. The toes are disfigured with joint fixation typical of advanced podoconiosis disease.
Christine Kihembo/ASTMH & AJTMH
After the 2010 earthquake, NGOs dumped hundreds of thousands of gallons of raw sewage at the end of the Port-au-Prince city landfill, which borders the sea and is not lined with an impermeable material.
Marie Arago for NPR
An HIV-positive mother in Thailand plays with her son, who did not contract the virus in utero. Thailand has eliminated mother-to-child transmission of HIV, according to the World Health Organization.
A worker fogs a neighborhood on the outskirts of Colombo in Sri Lanka in an effort to ward off mosquitoes. The country is facing an outbreak of dengue fever, a mosquito-borne disease.
Ishara S. Kodikara/AFP/Getty Images