In the Journals

Recorded outbreaks, unique diseases increased since 1980

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October 31, 2014

The number of recorded outbreaks and unique diseases around the world seems to have increased since 1980 whereas per capita cases declined, according to recently published data.

Katherine F. Smith, PhD, of Brown University, and colleagues analyzed infectious disease outbreak data stored in the Global Infectious Disease and Epidemiology Online Network from 1980 to 2013. Along with the number of outbreaks and diseases, they examined per capita cases and disease diversity, defined as a combination number of unique diseases and outbreak evenness.

Data included 12,102 outbreaks of 215 infectious diseases, making up more than 44 million individual cases across 219 countries. Bacteria and viruses composed 70% of recorded illnesses and were responsible for 88% of outbreaks, while zoonotic diseases were responsible for more outbreaks than human-specific diseases (56% vs. 44%) since 1980.

“We live in a world where human populations are increasingly interconnected with one another and with animals — both wildlife and livestock — that host novel pathogens,” Smith said in a press release. “These connections create opportunities for pathogens to switch hosts, cross borders and evolve new strains that are stronger than what we have seen in the past.”

After controlling for disease surveillance, communications, geography and host availability, researchers found that the number of outbreaks, unique diseases and diversity increased since 1980 (P<.0001). The same results were seen upon controlling for Internet usage starting at 1990 with the exception of overall per capita cases, which decreased over time (P=.005).

“Although our finding implies that outbreaks are increasing in impact globally, outbreak cases per capita appear to be declining over time,” the researchers wrote. “Our data suggest that, despite an increase in overall outbreaks, global improvements in prevention, early detection, control and treatment are becoming more effective at reducing the number of people infected.”

Disclosure: The researchers report no relevant financial disclosures.

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