The ambitions are ultimately pan-African. "The goal is to have MedAfrica as a household name in African homes and to provide increased health care to the masses," Kyalo says. "We want to impact the lives in Africa. People still are dying from malaria. The problem is too few heads with vital information."

The platform aggregates information from many sources. So far, it supplies first-aid recommendations from local hospitals, and health alerts and updates from other hospitals, as well as lists of doctors and dentists. The company plans to connect to a data feed from the national Ministry of Health for information on things like disease outbreaks or the discovery of counterfeit drugs. Shimba also hopes to aggregate information from NGOs.

Shimba expects to launch a Yelp-like comment feature by January that would let users comment on the doctors.  "I think the greater value will come when I know not just a laundry list of providers, but also context for who is better," says Erik Hersman, cofounder of Ushahidi, the mobile crisis and event-mapping platform, and a creator of iHub, an organization devoted to bringing together innovators and investors in Nairobi.

"MedAfrica is a continuation of the innovation we continue to see out of the Kenyan tech startup scene," Hersman says. "It gives access to information on doctors, clinics, and other health-care information in a simple way, on simple phones, for ordinary Kenyans."

MedAfrica is, however, still a small effort, and it faces competition from the country's dominant telecom—Safaricom. At nearly the same time that MedAfrica launched, Safaricom forged a partnership with another startup, Call-a-Doc, to allow Safaricom's 18 million subscribers to call ­doctors for expert advice for about two cents a minute. A smaller SMS-based mobile-health effort, called Mpedigree, is rolling out at health-care centers to provide a way to check serial numbers on drugs to make sure counterfeits are not being administered in Kenya.

The fact that nearly 1,000 people daily are downloading the app is "very solid," Hersman says. And Ashbourne adds: "That's a respectable number. Even that people know to do that at all—I think that's pretty impressive."

Mobile health platforms are making a strong showing in other parts of Africa, too. In South Africa, efforts include platforms that give HIV-infected patients automated ways to receive health information and reminders about upcoming doctor visits. In Johannesburg, 10,000 people infected with HIV have taken on these SMS-based alerts, resulting in big declines in missed appointments.

In Ghana and Liberia, a group called Africa Aid is experiencing strong success with MDNet, a system that allows users to call or text doctors for free. Since its founding in 2008, 1,900 physicians in Ghana have logged more than a million calls to patients, the group says.