What causes disease outbreaks?

New research finds large-scale, zoonotic outbreaks are driven by different factors Since 1974, contaminated water has been the most common driver of large-scale zoonotic infectious disease outbreaks, according to new research from the Center for the Ecology of Infectious Diseases (CEID) at the University of Georgia. The next two greatest drivers are unusual weather patterns and changes in the abundance of disease vectors such as mosquitos and ticks. Zoonotic diseases occur when pathogens are transmitted from animals to humans—prominent recent outbreaks include Ebola hemorrhagic fever and COVID-19. However, most zoonotic disease outbreaks involve fewer than 100 cases and are quickly brought under control. So what factors drive large-scale outbreaks? In a study published in the Royal Society journal Philosophical Transactions B, researchers investigated over 4,400 zoonotic infectious disease outbreaks. They identified the 100 largest in terms of numbers of human cases, all of which infected thousands to hundreds of thousands of people. From...