March 24 marks World TB Day (WTD) - a day that commemorates Dr. Robert Koch’s 1882 discovery of the tuberculosis (TB) bacterium. At that time, TB was raging through Europe and the Americas, claiming the lives of one out of every seven people. Today, WTD reminds us that tuberculosis remains a global epidemic, causing nearly 1.5 million deaths each year, primarily in lower resourced countries.
TB is not only a global concern - it’s a local one. In California, about 13% of people diagnosed with TB disease die from it annually. Orange County (OC) consistently ranks third in TB cases statewide, behind Los Angeles and San Diego counties. Alarmingly, case numbers have barely declined over the past decade. In 2025, 189 active TB cases were reported in OC, a 14% increase from the previous year’s 166 cases. The good news: TB is curable, and with proper treatment, people can recover fully.
There are two forms of TB: Latent (or inactive) TB Infection (called “LTBI”) and TB disease (active TB). People with LTBI do not have symptoms, usually have a normal chest X-ray (CXR), and are not contagious. LTBI can be detected by a blood test. In most LTBI cases, the bacteria remain inactive for life, but about 10% of people will develop TB disease later - often when the immune system is weakened by age, certain medications, or medical conditions like diabetes, kidney disease, HIV, autoimmune disorders or cancer.
Treating LTBI can decrease the risk of developing TB disease by up to 90%. That is why it is critical for providers to offer treatment and for patients to accept it.
People with TB disease typically have symptoms, an abnormal CXR, and may be contagious to others. Common symptoms of TB disease in the lungs include chronic cough, fevers, chills, sweats at night and/or unexplained weight loss. TB can affect any organ of the body, and disease outside of the lungs is often harder to diagnose.
While anyone can get TB, certain groups face higher risk. About 90% of the TB cases in OC occur in people born in countries with higher prevalence of TB, but it usually occurs decades after they immigrate to the US. Among US-born individuals with TB disease, risk factors include homelessness, incarceration, substance misuse, or travel to countries with high rates of TB. Nearly half of the TB cases in Orange County occur among people aged 65 or older, as aging and other health conditions weaken immunity - increasing the risk of TB becoming active. For information on TB cases and services in Orange County please visit OC Health Care Agency - Pulmonary Disease Services.
To strengthen prevention, AB 2132, effective January 2025 - requires primary care providers to assess patients for TB risk and test those identified as at risk. Individuals born in countries with high TB rates, those with weakened immune system, people who have had close contact with someone with TB disease, or those who have experienced homelessness or incarceration should speak with their doctor about TB testing. For more details, see the California Department of Public Health (CDPH) website CDPH Questions and Answers About AB 2132 - Mandated TB Screening.
Treatment is strongly recommended for anyone who tests positive for LTBI. LTBI treatment is much shorter and easier than treatment for TB disease and may save lives. Remember: an ounce of prevention is worth a pound of cure!
Clinicians play a vital role in ending TB by screening patients at risk, while individuals who may be at risk can take charge of their health by asking their providers about TB testing.
Resources:
OC Health Care Agency TB Clinic
CDPH Questions and Answers About AB 2132 - Mandated TB Screening
About Dr. Helene M. Calvet
Dr. Helene M. Calvet received her MD from UCLA and is board-certified in both Internal Medicine and Infectious Diseases. She has worked in the field of public health for over 25 years, having served in Long Beach as Health Officer and TB controller and in Orange County as Deputy Health Officer. Most recently, she worked in COVID response, leading a team that dealt with more than 500 outbreaks in Long Term Care Facilities, but since 2022, she has focused on TB Control. Currently, she serves as TB Controller and Medical Director of the TB Control Program in Orange County, and as TB Clinician in the Long Beach Health Department. She has published several articles, served on two Centers for Disease Control and Prevention Expert Panels and taught providers throughout Region IX and in 6 countries on public health topics.