Earlier in February, approximately fifty cases of tuberculosis were confirmed among students at Archbishop Riordan High School, San Francisco. The high school transitioned to remote learning while students underwent extensive screening for the disease-causing bacteria. Testing started three weeks ago. Since then, over two hundred students tested positive for the infection.
“The risk to the general public remains low”
On Friday, the San Francisco Public Health Department reported 204 diagnoses of latent TB at Archbishop Riordan High School. Latent tuberculosis, as covered previously, is a dormant form of the disease. While the bacteria is present and viable, the immune system effectively walls it off. That makes it incommunicable, or non spreadable. That said, there is no telling how long it stays that way. It may lie dormant for weeks, months, even years. Latent TB can activate at any time with no precipitating factors, like a ticking clock without a countdown.
A culture of Mycobacterium tuberculosis. Note its colonial morphology, the colorless rough surface, which are typical morphologic characteristics seen in Mycobacterium tuberculosis colonial growth. Creative commons.
The outbreak at Riordan High proves how insidious an illness tuberculosis is. Apparently, it has been too long since the last tuberculosis epidemic that many forgot the disease still exists. The last TB epidemic in the United States stretched from 1985–1992. It coincided with the height of the AIDS crisis, as immunocompromised people are particularly vulnerable to this opportunistic infection. Viruses and bacteria that sicken people with uncompromised immune systems might kill someone whose body cannot fight off pathogens.
Over 200 students with latent tuberculosis will undergo a strict antibiotic regimen that may span up to a year. The private Catholic high school adjacent to City College’s main campus appears to be the outbreak’s epicenter. Mission Local reports that the SF Public Health Department received 1,261 tests from the school. A total of 219 came back positive.
Meanwhile, SFPDH Officer Dr. Susan Philip says “the risk to the general public remains low.” Dr. Philip added that contact tracing and testing are essential tools for mitigating future outbreaks and safe-guarding public health.
What we know so far
The 204 cases of latent TB comprise 16% of the Riordan students, faculty, and staff tested for it. That means up to fifteen people may have active tuberculosis. Symptoms range in severity, with persistent cough accompanied by bloody sputum and fatigue being most common. In extreme, late-stage cases, the disease migrates to the rest of the body. Sores erupt on the neck and groin, anywhere with a lymph node. Lesions may form in the brain, causing neurological distress with sometimes irreversible effects. Some active TB patients present with minor symptoms, or none.
Positive cases will receive chest x-rays to check for tubercles, the tell-tale, potato-shaped lumps for which the disease is named. Active tuberculosis is communicable, and easily transmitted. It favors poorly ventilated areas where crowds gather to swap particles through speech, dialogue, song: offices, schools, churches. Riordan High recently cleared all faculty and staff and 99% of the student population for in-person attendance.
Diseases like pertussis (whooping cough), chickenpox, and measles are alarmingly contagious. Once notified, researchers race around the clock to get ahead of its rapid spread. Tuberculosis is less contagious than measles, or COVID-19 for that matter. It takes very little virus to sicken somebody. One man’s sneeze is another man’s upper respiratory infection.
TB however has an astonishingly long incubation rate. Research suggests chronic, cumulative exposure to the bacteria is necessary first. TB can gain a strong foothold in a community well before anyone presents with symptoms. Exposure-to-first-symptoms is generally regarded as two to three weeks. Those living with latent TB are reportedly most at risk of developing active TB within two years of exposure.
Through contact tracing, the SF Public Health Department constructed a timeline of the Riordan High outbreak. SFDPH issued a Health Advisory for city clinicians after a third case of active TB was identified in January. Suspicions of an outbreak at Riordan were brewing in December when schoolwide testing for the illness. The first active case had been confirmed in November, but the very first hint of something wrong came even earlier. In September, one student sought medical attention after two weeks of coughing.
Risk to the public might remain low, but it’s never a bad idea to mask up. On the bus, the train, in class, wherever crowds gather, protect yourself. Protect your health and that of your loved ones. Today’s federal government sure won’t.
