Bamako was a critical location for researchers to study, as it represents a number of disconcerting issues related to global child mortality. Recently the fastest-growing city in Africa and one of the fastest-growing cities in the world, Bamako is a picture of the rapid urbanization of the African continent and, more generally, the global south.

This urbanization brings people in closer proximity to health-care and financial resources. But the creation of peri-urban rings of slums, where there’s concentrated poverty and degraded environments, can actually make them more “vulnerable to infectious diseases such as malaria, diarrhoea and pneumonia, to new pandemic outbreaks and to an emerging non-communicable disease burden,” according to the study. That urban structure places Bamako at the center of two competing trends. While Mali is still among the worst places on Earth in terms of infant and child mortality, its overall burden is decreasing over time as advancements in aide, medicine, nutrition, and access to care spread. But that progress could still be threatened by continuing urbanization.

According to Ari Johnson—a physician who is the lead author of the study and a co-founder of Muso, the small nonprofit that launched the pilot program in question—there are a number of health-care barriers that characterize child mortality in Mali, where in 2015, 114 out of 1,000 children died by the age of five.* One of those barriers is cost. “The World Health Organization has estimated that 100 million people every year are driven into poverty by health-care costs,” Johnson said. “Fees are one of the most important barriers that delay or prevent patients—particularly poor patients—from accessing care in time.”

Muso’s 2012 analysis of Mali’s health-care system illustrates those cost barriers using the example of the Yirimadjo area. That study found that “user fees for health care not only decreased utilization of health services, but also resulted in delayed presentation for care, incomplete or inadequate care, compromised food security and household financial security, and reduced agency for women in health-care decision-making.”

In addition to the costs of Mali’s fee-for-service health-care system, Johnson identified several other issues that poor people in the slums of Bamako face that lead to child mortality. “So much depends on when someone gets access to care,” Johnson said. “An illness like malaria can progress and kill within hours of the first symptom. And we also know that patients facing extreme poverty are most likely to get care late or not at all.”

In Mali, as in other sub-Saharan African countries, there are ongoing efforts to overcome those difficulties. Several are “community case management” initiatives, created to diagnose, treat, or refer ill children, especially those at risk for malaria or other deadly fever diseases. The WHO and UNICEF have promoted programs like these for over a decade, and in Mali they’ve been used to address malaria, diarrheal diseases, malnutrition, and pneumonia. But they’ve been implemented primarily in rural contexts—not in any way that could cut through the mountainous disparities at the edges of Mali’s biggest city.