The antibiotic is commonly used to treat bronchitis, pneumonia and skin infections. The antibiotic was repurposed for the plague and in studies involving non-human primate models, it was effective in protecting animals that received treatment from a bacteria that mimics plague in humans.
The Centers for Disease Control and Prevention (CDC) considers the plague bacteria to be a Category A biothreat because if it is left untreated it has a mortality rate between 50 and 100 percent. Currently, levofloxacin has been the sole antibiotic used, with the risk of antibiotic resistance development it becomes important to develop additional treatment options.
The pathogen can be spread through the air, through direct contact and through the bite of ticks and fleas. The CDC reports that between 1900 and 2012 there have been 1,006 cases of the plague that were confirmed or deemed probable in the U.S., with approximately 80 percent of them in bubonic form. The World Health Organization reports that reported plague infection cases average between 1,000 and 2,000 on an annual basis.
DVIDS states that the plague has potential to be a threat if it were weaponized.