Disease outbreaks are on the rise, but so are prevention and treatment.
Enterovirus. Tuberculosis. Cholera. Measles. Flu. Hepatitis. The number of infectious disease outbreaks and the number of unique illnesses causing them appear to be increasing around the globe, according to a Brown University analysis of more than 12,000 outbreaks affecting 44 million people worldwide over the last 33 years.
“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,” says Katherine Smith, PhD, a colead author of the study, which was published in the Journal of the Royal Society Interface in October 2014. “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.”
Sure enough, animals are the major source of what ails us, with zoonoses (infectious diseases that come from animals) causing 56 percent of outbreaks since 1980. Using outbreak data stored in the Global Infectious Disease and Epidemiology Online Network, the researchers were able to track trends by country and worldwide. For example, from 2000 to 2010, the most common zoonoses included salmonella, E. coli, influenza A, hepatitis A, and anthrax; among human-specific infections during that decade, gastroenteritis, cholera, measles, enterovirus, and bacterial meningitis were the most widespread.
On a more encouraging note, even though the globe is facing more outbreaks from more pathogens, they tend to affect a shrinking proportion of the world population. “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,” the authors wrote. The analysis continues. Smith, an assistant professor of ecology and evolutionary biology, is particularly interested in how global infectious disease patterns will shift with climate and land use change (see Brown Medicine, Spring 2014). “A warmer world, a world with altered landscapes, and a more urban world will undoubtedly have a new disease-scape to consider,” she says.
