High school student Taylor Gaes’ death earlier this month was caused by a rare strain of plague, Colorado health officials report. Gaes, 16, was a star athlete for the Poudre High School Varsity baseball team.

The Larimer County Health Department said Gaes likely contracted the septicemic plague from fleas on a dead rodent or other animal with which he may have come into contact on his family’s ranch in Cherokee Park, north of Fort Collins, Colorado, KDVR, Denver, reported Saturday.

Septicemic plague, one of the three main forms of plague, is caused by bacteria that enter the bloodstream directly. It is rarer than the bubonic or pneumonic plagues, and fewer than 5,000 people contract the disease annually. However, it is almost always fatal if left untreated.

The local health department warned people who attended Gaes’ memorial service on his family’s ranch to watch for flu-like symptoms.

“There is a small chance that others might have been bitten by infected fleas, so anyone who was on the family’s land in the last 7 days should seek medical attention immediately if a fever occurs,” the agency said.

Gaes suddenly became ill and died June 8, one day after turning 16. His friends said they thought he had the flu.

Gaes was a star athlete at his high school, the starting first basemen and No. 2 pitcher for his varsity baseball team. He stood 6-foot-4, 210 pounds, and was considered a college baseball prospect, the Denver Post reported.

“We often talk about Taylor’s potential as an athlete, but he was much more than that," Poudre baseball coach Russell Haigh told the Denver Post. “He was a good friend to all of our players. He was a special young man.”