The European Union is a hot spot for emerging communicable diseases, and epidemics are usually well underway before they are recognized by traditional epidemiological surveillance. In an effort to identify problems earlier, the European Centre for Disease Prevention and Control (ECDC) has developed modeling tools that predict the conditions and locations at greatest risk for outbreaks.
These models account for diverse causes of epidemics, including global environmental change, social and demographic change and public health systems.
The ECDC tracked 274 epidemics from 2008 to 2013, including vector- and food-borne diseases, sexually transmitted infections, resurgent vaccine preventable diseases, health care-related infections and multi-drug resistant tuberculosis, said Jan Samenza, Ph.D., in a lecture Monday (October 31) at the Yale School of Public Health sponsored by the Climate Change and Health Initiative and Department of Epidemiology of Microbial Diseases.
“Rarely are events caused by one driver. The majority act in concert with other drivers,” said Samenza, who heads the ECDC’s Scientific Assessment Section in Stockholm, Sweden. However, by teasing out the key drivers of these epidemics, the group found that global environmental factors contributed to 61 percent of them.
In conjunction with establishment of a European Environmental and Epidemiology (E3) Network to foster and promote European Union-wide research into environmental infectious disease epidemiology, the ECDC has developed a publicly-available modeling tool, E3 Geoportal. Included in the portal are tools for filtering and interpreting datasets, as well as aggregated geospatial data resources on climate, population density, livestock density, land use, social-economics and other variables.
ECDC epidemiologists have been able to model outtbreaks of vibriosis in Scandinavia and Finland by tracking the surface water temperature and salinity of the Baltic Sea. Normally found in warmer seas, Vibrio bacteria cause gastroenteritis and skin infections. Vibriosis emerged in the Baltic Sea region in the 2000s as a result of rising sea temperatures and is caused by eating raw or undercooked seafood or exposing a wound to infected seawater. With these data, environmental and public health professionals can activate prevention measures during the peak months when conditions are right for a bacterial bloom.
Dr. Semenza’s approach of using predictive models to provide real-time information about the likelihood of infectious disease threat events with the purpose of preventing them from occurring in the first place is in the highest tradition of public health...
Robert Dubrow, MD
Travel and tourism also turn out to be serious drivers of communicable infections, Samenza told a large gathering in Winslow Auditorium. With some 590 million people passing through European airports each year, pathogens are carried across continents on a daily basis. In recent years Europe has seen a resurgence of malaria, chikungunya and dengue, all vector-borne diseases spread by mosquito and human interactions. Using air traffic data, researchers were able to identify traffic from endemic areas of the world to particular cities in southern Europe where environmental conditions were ripe for dengue. Local authorities were able to implement targeted spraying and other mosquito-control measures to prevent epidemics.
“Dr. Semenza’s approach of using predictive models to provide real-time information about the likelihood of infectious disease threat events with the purpose of preventing them from occurring in the first place is in the highest tradition of public health, which emphasizes prevention above all,” said YSPH Professor Robert Dubrow, M.D., director of the school’s Climate Change and Health Initiative.
Semenza was an Epidemic Intelligence Service Officer at the U.S. Centers for Disease Control and Prevention (CDC) in 1995, when a record-breaking heat wave claimed the lives of more than 700 people in Chicago. He led the CDC response to this environmental calamity and revealed the underlying environmental, societal and behavioral causes of heat-related mortality. He also worked internationally on a number of infectious diseases in Uzbekistan, Sudan, Egypt, Denmark, Brazil and Haiti.
Currently he is studying environmental and climatic drivers of infectious disease transmission in Europe. He is particularly interested in environmental and climatic precursors of disease that can be used to anticipate, or even forecast, an upsurge of infectious disease. These epidemic precursors can be monitored through early-warning systems and help us adapt to the challenges of global climate change.