Mud Run
A competitor runs through the mud in an obstacle course. Reuters/Phil Noble

Looking for an excuse to skip a mud run? How about eye-eating bacteria?

Texas mom Brittany Williams lost sight in one eye just 12 hours after competing in a mud run. Doctors haven’t pinpointed the exact bacteria, but it was "very aggressive," Williams told ABC News. The infection developed after Williams left in a contact lens in during the mud run, which scratched her cornea and exposed her eye to the bacteria.

Williams had to spend nine days in the hospital and doctors believe that her only hope of regaining her sight will be a full cornea transplant. However, Williams needs to fully recover before surgery, so a transplant could be a year away.

Stories of injury and even death during mud runs have been documented as their popularity has increased. After a 2012 race in Nevada, 22 people were sickened after swallowing contaminated water that was laced with animal feces.

Generally, the risk of contracting a flesh-eating bacteria is low, but once one is contracted the results can be devastating. A 34-year-old Georgia woman lost her hands and feet after contracting the flesh-eating virus, Necrotizing Fasciitis. Likewise, a Florida man lost his foot after contracting group A streptococcus. A different type of deadly bacteria, Vibrio vulnificus, killed four in Florida this year.

The Centers for Disease Control and Prevention recommended strong doses of antibiotics for those inflicted with Necrotizing Fasciitis, group A streptococcus or Vibrio vulnificus. Practices such as hand washing help to prevent the spread of Necrotizing Fasciitis and group A streptococcus. And if you have a bad cut or open sore, staying away from warm water would help curb the risk of contracting Vibrio vulnificus.

Still, it's important to remember that the risk of harm from these bacterial infections is low when compared to other fatal illnesses. In 2014, between 1,000 and 1,800 people died from group A streptococcus, including Necrotizing Fasciitis, and only 35 people died from Vibrio vulnificus. In comparison, between 3,300 and 49,000 Americans die each year due to the flu.