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Epidemics of chronic diseases: the role of epidemiology

Many countries are prepared to address epidemics of infectious diseases, because they have organizations, training programs, legislation and monitoring systems. Best known is probably the CDC in theUS, but many other countries in Asia, Europe, Latin America and theMiddle Easthave invested in a similar preparedness. The European Union has, for example, established a European CDC to help individual countries cope with preventing the spread of infectious disease, especially when they occur more frequently than expected.

But not all diseases are caused by infections, and other causes may also cluster in time and cause epidemics. We have, for example, at present epidemics in diabetes, obesity, Attention Deficit Hyperactivity Disorder (ADHD) and autism, and many more. We recently had an epidemic of CVD in the developed countries of the world, and we might be having an epidemic in developing countries, but we do not know as we do not have adequate diseases surveillance for chronic diseases. We may also have an epidemic of some cancers, such as cancer of the testes or breast.

What characterizes our response to these epidemics is a slow and uncoordinated response, often with delayed recognition caused by lacking or incomplete surveillance and monitoring systems. One would think we can do better with all these powerful databases, search engines and much better diagnostic and screening procedures.

When an epidemic of a chronic disease is detected, pin-pointing the important causes and consequences is often poorly coordinated. Many activities are done in parallel, and although replication is useful it may not be the most efficient approach at this point in time. Causes may be entirely unknown, as when a small epidemic of vaginal cancer among young women was seen in the Eastern part of theUS. Causes were partly known when cardiovascular diseases increased in frequency in the 1980s. Causes of obesity may be partly known now, but less is known about the causes of ADHD or autism. Even counting new cases in a comparable manner is difficult for some diseases, such as behavioral disorders in childhood or infertility.

Microbiological agents often cross borders, and so do many lifestyle factors or environmental exposures. Epidemics of chronic diseases should therefore be met with an international response where research activities and monitoring should be coordinated, perhaps to the extent that exists for infectious diseases. Some mechanisms exist for coordinating these activities, mainly through the WHO but also by other large international coordinating centers and funding agencies.

Still, much less training has been devoted to addressing epidemics of chronic diseases than has been devoted to infectious diseases. Detailed plans for using the full potential of biomarkers, genetic data and data on external exposures do not really exist. We have no large-scale training programs. We see an increasing interest in Global Health, and many of the new Faculties in Global Health may provide a much better platform for coordinated activities, but so far the focus of global health has been in the traditional arenas of infectious diseases and undernutrition, rather than non-communicable diseases and overweight. As usual, academic activities are concentrated where the money is available.

The IEA believes the time has come to rethink the role epidemiologists can play in order to better contact epidemics of chronic diseases. Many of these epidemics may be much more serious than infectious disease epidemics, and their effects may be much more severe when they hit previously undernourished populations in low and middle income countries as suggested by the diabetes epidemic in South Asia. The forthcoming United Nations high level meeting on non-communicable diseases in September 2011 is likely to provide an important starting point for global action.

We can start by discussing what we can do and what we need to do. Individual and competitive research is a powerful tool but may be insufficient and lacking, especially in countries with limited research resources. The IEA should be prepared to take the initiative, perhaps by making this a theme for one of our coming conferences.

Jørn Olsen, Cesar Victora, Neil Pearce, Shah Ebrahim

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