World’s deadliest disease rips across California as clusters discovered at schools

California health officials are scrambling after tuberculosis exposures were confirmed at multiple schools as cases of the world’s deadliest infectious disease continue climbing across the state.

Fresno County officials confirmed a cluster at Justin Garza High School, where one active infection was found, though authorities did not specify whether the case involved a student or staff, according to ABC30.

Officials emphasized no one on campus is currently contagious, but 22 out of 169 people exposed have tested positive for the infection, though they show no symptoms yet.

Health officials are teaming up with the school for contact tracing and testing, urging anyone who feels unwell to stay home.

Symptoms of tuberculosis can include coughing up blood, a cough lasting more than three weeks, fatigue, and unintentional weight loss.

The bacterial disease, which typically attacks the lungs, appears in both active and latent forms.

Meanwhile, San Diego County officials announced Wednesday a potential TB exposure was also reported at Sunset Elementary School in San Ysidro.

According to county officials, the possible exposure occurred between July 5, 2025, and Oct. 21, 2025.

Health officials are working with the San Ysidro Elementary School District to alert families and staff, offering free TB screenings to students and employees who may be at higher risk.

The county said those at highest risk may have already been contacted. TB spreads through the air when someone with active tuberculosis coughs, speaks, sings, or breathes.

County Public Health Officer Sayone Thihalolipavan warned that symptoms of active TB include “persistent cough, fever, night sweats, and unexplained weight loss.”

“Most people who become infected after exposure to tuberculosis do not get sick right away,” Thihalolipavan said.

“This is called latent TB infection. Some who become infected with tuberculosis will become ill in the future, sometimes even years later, if their latent TB infection is not treated.

“For people who think they may have been exposed, blood tests and skin tests are an effective way to determine an infection.”

San Diego County has seen TB cases steadily rise in recent years, from 193 reported cases in 2020 to 265 in 2025.

These recent school exposures are just the latest in a troubling series of incidents unfolding across California.

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