Pandemics and the Planet of Slums

Mike Davis, a recipient of the MacArthur "genius" award, is author of The Planet of Slums. The following is adapted from an interview with NPQ editor Nathan Gardels.

The global pandemics we see today tend to originate and spread from impoverished slums that push humans into close proximity with animals and food sources, thus providing an incubator for viruses that would otherwise die out or go dormant. Pandemics are thus closely linked to the emergence of "hot zones" in what I call "the planet of slums."

Using conservative definitions by the United Nations Habitat office, there are today 1 billion people living in slums globally. A slum is defined by substandard housing with insecurity of tenure and the absence of one or more urban services and infrastructure—sewage treatment, plumbing, clean water, electricity, paved roads and so on.

While only 6 percent of the city population of developed countries live in slum conditions, the slum population constitutes a staggering 78.2 percent of the urban population in less-developed countries—fully a third of the global urban population.

The cities of the future, rather than being made out of glass and steel as envisioned by earlier generations of urbanists, are instead largely constructed out of crude brick, straw, recycled plastic, cement blocks and scrap wood. Much of the 21st century urban world squats in squalor, surrounded by pollution, excrement and decay. Indeed, the 1 billion city dwellers who inhabit postmodern slums might well look back with envy at the ruins of the sturdy mud homes of Catal Huyuk in Anatolia, erected at the very dawn of city life 9,000 years ago.

What makes today's slums different from the Dickensian inner-city tenements of London in the 19th century is that they are peri-urban—that is, they are largely on the far edges of established cities, neither countryside nor city, usually about 20-30 miles from the city centers.

These sprawling outer zones one sees in China, Indonesia and across Latin America house not only peasants coming to the city, but people being forced out of the cities by eviction or rising rents.

Not only are today's slums larger than in the 19th century, but they are more dense. Though they are low-rise structures, the square footage is tiny with a lot of people living in each shack. They are built haphazardly along narrow footpaths, not the broad grids of the inner city. A small fire can spread to destroy 1,000 units of housing in 15-20 minutes. Infectious diseases travel rapidly in such an environment.

Slums as contiguous swaths of settlement are largest in Latin America—the largest being on the southeastern edges of Mexico City.

There are similar settlement patterns outside Bogota, Colombia, and Lima, Peru. Bombay has the largest slums in South Asia, with about a 500,000 population. But in general the pattern in the subcontinent is more fragmented and less contiguous, as we see in Dhaka, Bangladesh, where a sea of poverty surrounds middle-class enclaves.

In Africa, we see megaslums in Lagos, Nigeria. Gaza in Palestine is one of the world's largest slums. Sadr City in Baghdad is not only one of the largest, but one of the newest, filled with Shiite refugees from when Saddam drained the southern swamps. Port au Prince in Haiti is not a particularly large city, but it is surrounded by the megaslums of Bel Air and Cite Soleil.

Already 15 years ago, bioscientists such as David Baltimore, the Nobel laureate and former president of Caltech, recognized that globalization was changing the ecology of infectious disease. One of the ways that ecology has changed is, with slum conditions, food sources are concentrated in unsanitary conditions in higher numbers and greater density than at any time in human history. Sanitation is a huge—perhaps the biggest issue—in the slums, where clean water and toilets must be shared by thousands. Ninety percent of Latin America's sewage flows untreated into streams and rivers.

In Mumbai, women band together to go to the public toilets between 2 and 5 in the morning for privacy and to avoid sexual assault.

Nairobi is a sanitation nightmare.

In Kinshasa, Congo, the only way people have been able to survive the collapse of the state and the economy is by bringing agriculture into the city. There are chickens and other animals roaming everywhere. These kinds of conditions transform the whole ecology of disease, speeding up transmission among animals and enabling the leap to humans. They create linkages and causal chains that weren't there before.

One example: Urbanization in West Africa has increased demand for protein in diets. At the same time, European companies have driven West African fishermen out of their traditional fishing zones, which provided most of their protein. Without fish for protein, people turned to the bush meat trade in the big logging countries such as Gabon. That demand for bush meat, for example from monkeys or chimps, has broken down all the biological species barriers for disease. People are eating wild mammals that carry exotic diseases like the Ebola virus or HIV.

Recent studies have shown that what HIV required to obtain the critical mass to become a world pandemic was Kinshasa—a hot breeding ground. People out in the bush had been getting HIV from chimpanzees for a long time, but it quickly died out before it could be widely transmitted.

Through today's connections of migration, travel and transport, diseases incubate in such hot conditions, then go global.