Note: This post kicks off a new blog series for 2013 on the transformative power of photography. Each week we will highlight one outstanding Oxfam photo and share more information about the story behind the image. Your feedback and suggestions are welcome!

As the director of the Malawi Health Equity Network, Martha Kwaitane is leveraging a tiny investment of US foreign aid to improve rural people’s access to quality healthcare throughout Malawi.

If you live in Washington, DC, or visit in the city in the coming weeks, you might spot Brett Eloff’s portrait of Kwaitane, above, in the airport or on the Metro. She’s one of four inspiring leaders featured on a brand-new series of Oxfam billboards, which call on US legislators not to cut the global poverty-fighting assistance that helps people like Kwaitane transform their countries.

Read more about Martha Kwaitane and the billboards here.