The 2010 TIME 100

Matt Berg looks very calm for a man who will have 100,000 children to look after. That might be because of his humble cell phone.

Berg, 32, is leading the push to track disease in Africa with 160-character text messages, or SMS. As technology director for ChildCount+, he helps oversee a network of community-health workers who regularly examine local children, treat their ills and then text back the status of every sick child they find. This allows for improved health monitoring, faster interventions and better immunization and treatment campaigns.

ChildCount+ has been in existence for only nine months and has already reported more than 20,000 nutrition screenings, 500 cases of malnutrition and 2,000 of malaria. Berg and his colleagues are now scaling up to monitor more than 100,000 children under 5.

The use of technology in Africa has long been Berg's passion, and he's made it his mission to nurture homegrown talent too. He helped establish the Rural Technology Lab in Mali, so local students can take over the job of ensuring their communities' health. Remarkable as Berg's work is, its greatest achievement will come when he's no longer the one doing it.

Verclas is a co-founder of MobileActive.org

TIME 100 Social-Networking Index: 198