(CNN) -- More than 100 people who attend or work at a southern California high school will be treated with antibiotics after being exposed to tuberculosis, a spokesman for the Riverside County Health Department said Monday.
Of the 1,471 students and staff at Indio High School, 126 -- or 8.6% -- were exposed to tuberculosis, but only one student actually has the illness.
The health department said the students exposed had a 10% chance of getting tuberculosis during their lives if left untreated.
Officials have said they do not fear an outbreak.
The exposure rate is actually less than the 10-15% rate the county expected from the population.
Tuberculosis is an infection caused by a bacterium called Mycobacterium tuberculosis that mainly affects the lungs. It can also infect other parts of the body including the kidneys, spine and brain. TB spreads through the air when a person with an active TB infection coughs, sneezes, speaks or sings. Germs can stay in the air for hours. It cannot be spread through handshakes, sharing food or drink, or kissing.
According to the Centers for Disease Control and Prevention, approximately one-third of the world's 6 billion people are infected with TB.
Treatment of TB requires antibiotics for at least six to nine months, the Mayo Clinic says on its website.
CNN's Casey Wian and Michael Martinez contributed to this story.