Bill and Melinda Gates in Mapinga, Tanzania, in 2011.
Bill and Melinda Gates in Mapinga, Tanzania, in 2011.
Courtesy Bill & Melinda Gates Foundation
Bill Gates during a site visit to the ACOS Ethiopia processing facility in 2012.
Bill Gates during a site visit to the ACOS Ethiopia processing facility in 2012.
Courtesy Bill & Melinda Gates Foundation
A young boy samples an orange-fleshed sweet potato in a busy market in Mwasonge, Tanzania.
A young boy samples an orange-fleshed sweet potato in a busy market in Mwasonge, Tanzania.
Courtesy Bill & Melinda Gates Foundation
House-to-house polio vaccination team members Heena Khatun and Rukhsar Khatun work in the Kamla Nehru Nagar slum in Patna, India, in December 2010.
House-to-house polio vaccination team members Heena Khatun and Rukhsar Khatun work in the Kamla Nehru Nagar slum in Patna, India, in December 2010.
Courtesy Bill & Melinda Gates Foundation
An ASHA worker visits the Chandan slum to discuss general health concerns and family planning practices with residents in Uttar Pradesh, India, on June 4, 2014.
An ASHA worker visits the Chandan slum to discuss general health concerns and family planning practices with residents in Uttar Pradesh, India, on June 4, 2014.
Courtesy Bill & Melinda Gates Foundation
Melinda Gates meets with a local women's group to discuss sanitation issues in New Delhi in September 2014.
Melinda Gates meets with a local women's group to discuss sanitation issues in New Delhi in September 2014.
Courtesy Bill & Melinda Gates Foundation