A tuberculosis outbreak at a San Francisco Catholic high school has infected or exposed nearly one in five students and staff members, according to city health officials.

The San Francisco Department of Public Health said 252 people connected to Archbishop Riordan High School tested positive for either latent or active tuberculosis between Nov. 10, and April 22.

Officials confirmed seven active TB cases and 241 latent infections within the school community.

Four additional people are still awaiting validation of chest X-ray results.

Health authorities said 228 people with latent tuberculosis are currently undergoing treatment.

Four others either declined treatment or were advised not to take it because of individual medical circumstances, while the treatment status of nine people has not been verified.

“However, latent TB could develop into active TB, a serious illness, if left untreated,” health officials told KRON. “Because of this, it is important for people with latent TB to get treated to protect their long-term health and the health of those around them.”

According to the department, people with latent tuberculosis infections are not contagious.

The school, located at 175 Frida Kahlo Way, now requires all students and staff to complete tuberculosis testing dated after March 9 and have medical clearance on file before returning to campus or participating in off-campus activities.

The outbreak first drew public attention in February, when Northern California health officials announced they were investigating dozens of tuberculosis cases tied to the private Catholic school.

Officials said additional active infections had been identified since November, while additional latent cases were found among people connected to the school community.

Tuberculosis primarily attacks the lungs and can remain dormant in the body for years before becoming dangerous.

People with active TB can spread the disease and develop symptoms, while those with latent infections are not infectious and may not feel sick, though they remain at risk of developing active disease later.

In February, health authorities stated that the risk to the general public remained low, as their primary efforts were centered on the high school community.