Risks from Microbes on the Rise: Reasons Why and Ways To Prevent Future Epidemics

Although scientists have long known that animals could transmit infections to humans, they are increasingly concerned about animal-borne diseases. All of the recent high-profile infectious diseases in humans have been acquired from animals: mice carrying hantavirus, cows with bovine spongiform encephalopathy (BSE), chickens with avian influenza, birds and mosquitoes carrying West Nile virus, civet cats infected with severe acute respiratory syndrome (SARS)–associated coronavirus. Raised awareness of these animal-to-human diseases transmitted, called zoonotic diseases, has helped contain their spread, but factors such as changes in land use and global travel mean that these infections are an increasing threat to humans worldwide. “You're definitely going to see infections spreading more quickly across the globe. SARS is a vivid example of that,” said James M. Hughes, MD, an Assistant Surgeon General and director of the Centers for Disease Control and Prevention's (CDC's) National Center for Infectious Diseases.

Zoonotic diseases are noteworthy among emerging diseases, but, in fact, Hughes said, the CDC is currently on high alert for increases in many other emerging and reemerging infectious diseases. Importation of produce from developing countries has added to the incidence of food-borne infections, including newer pathogens such as Cyclospora species and Listeria monocytogenes and better known pathogens such as Salmonella species and hepatitis A virus. Antibiotic misuse increasingly contributes to a growing problem of resistant pathogens. And the 2001 anthrax attacks are a frightening reminder of the potential for bioterrorism involving infectious agents such as the smallpox virus.

The CDC and other public health agencies have been playing catch-up with microbes ever since the early 1990s. From the period following World War II until then, some experts widely believed that effective vaccines and powerful antibiotics, combined with pesticide use and improved water quality and sanitation practices, would conquer infectious diseases. Public health workers and clinicians grew …