Researchers discover method to accurately predict anthrax threat

Researchers created a mathematical model to answer important questions about an anthrax attack, according to a study published on August 15 in the PLOS Pathogens online journal.

The researchers of the study, Adi V. Gundlapalli of George E. Wahlen Department of Veteran Affairs Medical Center and Damon J.A. Toth of the University of Utah, used animal studies involving anthrax and information from two previous histories of anthrax attacks to create their model. The model sought to determine how many cases to expect, when symptoms of exposure onset and the optimal time window to administer antibiotics in the event of an outbreak.

"Anthrax is a well-studied disease and experimental animal data exist, but there is no real good information on dose response for the disease in humans," Gundlapalli said. "We don't want to be overly fearful, but we need to be prepared in the event of a bioterrorism attack with anthrax."

On September 11, 2011, anthrax-laced letters caused five deaths and 17 infections. In the late 1970s, a filter was left off of a vent in a plant used to create anthrax, causing approximately 100 deaths. These studies, along with accounts of anthrax exposure to animals, such as primates, were used to develop the mathematical model.

"By combining the data from Sverdlovsk and prior studies, we can make defensible estimates on how scenarios might play out if anthrax were released in a terrorist attack," Gundlapalli said. "... Our model provides real answers to help policy makers when they need that information."

The new model found that a person who inhales 11,000 spores of anthrax has a 50 percent chance of becoming infected. A person that inhales 1,700 spores has a 10 percent chance of infection and a person that inhales 160 spores has a one percent chance of infection. Researchers also studied optimal time to administer antibiotics to infected persons and found it to be within 60 days.