Infectious diseases caused 32 percent of deaths worldwide in 2018, according to the World Health Organization (WHO), and 90 percent of these occurred in developing countries. For children younger than five years of age in these countries, infectious diseases caused between 68 and 86 percent of deaths. Poverty, lack of education, inadequate or absent clean water and sanitation systems, crowded living conditions, unsafe sex, limited health care facilities, and lack of vaccines lead to the disproportionate burden of infectious diseases in the developing world. The chronic infectious disease-related disabilities suffered by adults in their prime working years leads to more poverty, continuing the cycle for the next generation.