Even at low incomes, today's fast-growing cities are not centres of disease and mass death as 19th-century European cities were, because modern medicine and basic public health let them keep growing

even at relatively low per capita incomes the emergent cities of the 21st century are not centers of diseases and mass death, as they would have been in Europe in the 19th century. Modern facilities of medicine and rudimentary public health do a remarkable job in enabling huge agglomerations of people, even at low incomes to continue growing.