Tuberculosis Screening

Who should be screened?

San Mateo County’s TB Control Program follows testing recommendations set forth by the Centers for Disease Control (CDC), which include the use of a targeted testing strategy. This strategy entails finding and treating persons with latent tuberculosis infection (LTBI) who are at the highest risk for developing TB disease, and thus would benefit from treatment.

Generally, persons at risk for developing TB disease fall into two broad categories: those who have an increased likelihood of exposure to persons with TB disease and those with clinical conditions or other factors associated with an increased risk of progression from Latent TB to TB disease.

Persons at risk for exposure to persons with TB disease:

• Known close contacts of a person with infectious TB disease.
• Persons who have immigrated from TB-endemic regions of the world.
• Persons who work or reside in facilities or institutions with people who are at high risk for TB, such as hospitals that care for TB patients, homeless shelters, correctional facilities, nursing homes or residential facilities for patients with AIDS.

Conditions and other factors associated with progression from Latent TB to TB disease:

• HIV infection, or AIDS.
• Injection drug use.
• Radiographic evidence of prior healed TB.
• Low body weight (10% below ideal).
• Other medical conditions, such as:
  • Silicosis
  • Diabetes mellitus
  • Chronic renal failure or on hemodialysis
  • Gastrectomy
  • Jejunoileal bypass
  • Solid organ transplant
  • Head and neck cancer
  • Conditions that require prolonged use of corticosteroids or other immunosuppressive agents such as TNF-antagonists
• Recent tuberculin skin test (TST) or interferon gamma release assay (IGRA) converters:
  • TST converters are persons with negative baseline testing results who have a new positive result within a two-year period.
  • IGRA converters are persons with negative baseline testing whom have a new positive result within a two-year period.
• The risk of progression to active TB disease is greatest in the first one or two years after infection.
• Infants and children under the age of five years who have a positive TB test result.

Why should these individuals be screened?

Screening of these high-risk individuals allows for the identification and treatment of new Latent TB cases, while providing the public health benefit of decreasing the reservoir of infection in the community and reducing the number of future TB cases.

Unfocused, population-based testing is not cost-effective or useful and leads to unnecessary treatment. TB testing activities should be conducted only among high-risk groups, with the intent to treat if Latent TB is detected. A decision to test, is a decision to treat. Once active TB disease has been excluded, treatment of Latent TB should be offered to patients regardless of their age.

How to test for Latent TB

San Mateo County encourages the use of one of two interferon gamma release assays (IGRAs), either the QuantiFERON-TB Gold In-Tube test or the T-Spot TB test. The IGRA is a blood test that is specific to M. tuberculosis and does not have false positive results in persons with a history of BCG immunization. These tests are approved for use in adults and children age five and up, and may sometimes be indicated in younger children.

In persons younger than five years and in situations where an IGRA cannot be obtained, a TST should be used. Generally, it is not recommended to test a person with both a TST and an IGRA.

For current tuberculosis diagnosis and treatment guidelines, please follow this link to the CDPH-CTCA Joint Guidelines – CTCA 

San Mateo County TB Testing Clinics

Note: This information is subject to change. Please call ahead to confirm testing information and hours.

Daly City Clinic
380 90th Street, Daly City
(650) 301-8600
Current patients only, by appointment
Test covered by patient insurance

Daly City Youth Health Center
350 90th Street (3rd floor), Daly City
(650) 366-2927
*12-24 years old only
Current patients only, by appointment
Test covered by patient insurance

South San Francisco Clinic
306 Spruce Ave, South San Francisco
(650) 877-7070
Current patients only, by appointment
Test covered by patient insurance

Fair Oaks Health Center
2710 Middlefield Rd, Redwood City
(650) 578-7141
Current patients only, by appointment
Test covered by patient insurance

Sequoia Teen Wellness Center
200 James Ave, Redwood City
(650) 366-2927
*12-24 years old only
Current patients only, walk-in basis with Primary Care Physician Order
Test covered by patient insurance

San Mateo County Mobile Clinic
Location varies by day and time
(650) 573-2786
Schedule
No appointment needed; Patients with or without
health insurance are seen. (*18 years and older,
unless for shelter placement).