I quote from the Washington Post article from which the map is taken:
The world map reprinted here is a reflection of more than 300,000 medical incidents which were reported in 2014 by companies to International SOS, which specializes in health care and emergency services to clients with business travelers overseas. Based on that data, a panel took into account threats of infectious disease, hygiene and sanitation, frequency of accidents and the availability and quality of the local health infrastructure to determine how risky a trip to a particular country might be.I suspect that the map reflects the risks faced by visitors and expats in these countries and that the risks faced by native residents might be different. The risks faced by the poor are often worse than those faced by those with more resources (who can use those resources to reduce or ameliorate consequences of risks).
The article has more detailed maps that have country names included.