Health officials in California say a high school is at the center of a tuberculosis outbreak in Sacramento County.
The Sacramento Bee reported Tuesday that four more students at Grant Union High School have contracted active TB.
A student at the school tested positive for the disease earlier this year.
Beyond the Grant cases, four relatives and friends of the student who initially tested positive have also contracted active TB - bringing the total to nine known cases.
Sacramento County Public Health Officer Olivia Kasirye says three related tuberculosis cases is considered an outbreak.
Symptoms of active TB can include a persistent cough and fever. Only active TB can be contagious. It is spread through the air.
County officials say the four additional students are not infectious.