New research shows urbanization may be bad for people’s health, unless planners develop cities that allow healthier lifestyles and environments. The U.N. estimates much of the developing and developed world will be urbanized by 2050.

In this photo taken Oct. 30, 2008, offices and apartment buildings are shown in Beijing, China. In the sprawling megacities of Beijing, Shanghai and Chongqing, where populations exceed 10 million people, extreme urban density means that the number of people living within a few blocks equals those in a whole mid-size U.S. city. China’s urban population soared to 607 million last year out of a population of 1.3 billion. Three decades ago nearly 80 percent lived in the countryside, but urbanization continues unabated as job-seeking rural migrants flood into cities. The scale and pace continues to soar, and by current trends, the urban population will hit one billion by 2030. (AP Photo/Elizabeth Dalziel)

Rural sub-Saharan Africa is seeing rapidly increasing urbanization. Something, researchers say, “could lead to an explosion” in rates of heart disease and diabetes.

They estimate more than a half-billion people now live in rural areas of the continent, where there are lower rates of non-communicable diseases. But that’s changing and they warn that even small changes toward urbanization could affect health.

Dr. Manjinder, joint senior author of the study, which appears in the journal PLOS Medicine, said, “We think in lots of low and middle income countries around the world – and not specifically to countries in Africa – that one is going to see a massive change in the burden of such diseases, such as diabetes and heart disease. And this comes together with an existing high burden of endemic infection and chronic infectious diseases, but also this parallel rise in these noncommunicable diseases.”

He said chronic infections can worsen the effects of noncommunicable diseases that accompany urbanization.

“Chronic infections can lead to an increased risk of such diseases. For example, HIV, its treatment and the potential risk of those factors on heart disease and diabetes risk. We know that Hepatitis C virus is an oncogenic virus. It’s a cancer causing virus and together with HIV may increase the risk of cancers.”

Urbanization does have an upside with greater access to education and healthcare, for example. But researchers warn it can be a double-edged sword.

With urbanization there are also lifestyle changes, such as adopting a more Western diet that’s high in fat, sugar and salt, less physical activity, greater alcohol consumption and weight gain.

Sandhu said, “We can see a compounding effect of all these inter-related risk factors on increasing the burden of risk. And I think Africa is a good example of trying to understand urbanicity, but also it’s a good example of where this could occur again in other regions around the world where similar events and scenarios and environments are occurring.”

Dr. Sandhu is with the Department of Public Health and Primary Care at the University of Cambridge and the Wellcome Trust Sanger Institute.

Researchers base their findings on more than 7,300 people living in 25 villages in Uganda. Each person in the study was given – what’s called – an urbanicity score. It measured lifestyle risk factors as rural areas became more urbanized.

“The interesting thing about studying rural communities is that one can see that the civil infrastructure is relatively nascent. It’s a building and growing infrastructure. And if one can think about what facets of that changing infrastructure [are] potentially associated with risk of noncommunicable diseases, one may think about addressing and perhaps changing or building an environment that is more conducive to a healthy lifestyle,” he said.

Sandhu said risk factors created by urbanization should be considered when coming up with replacements for the expiring Millennium Development Goals.

“I think that should be a paramount goal to at least consider how the impact of those changing civil infrastructures are potentially leading to a change in lifestyle and other behavioral risk factors that are leading to an increased risk of chronic diseases, such as diabetes and heart disease,” he said.

Joining Cambridge researchers in the study were those from the Uganda Virus Research Institute, Australia’s Deakin University and the London School of Hygiene and Tropical Medicine.