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Screening

General information

Who, Why, How and Where

Who should be screened?

San Mateo County’s tuberculosis (TB) prevention and 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 LTBI 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 LTBI 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 baseline testing results whom have an increase of 10 mm or more in the size of the TST reaction within a 2-year period.
    • IGRA converters are persons with negative baseline testing whom have a new positive result within a 2-year period.
  • The risk of progression to active TB disease is greatest in the first 1 or 2 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 identification and treatment of new LTBI cases, while providing the public health benefit of decreasing the reservoir of infection in the community, 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 LTBI is detected. A decision to test, is a decision to treat. Once active TB disease has been excluded, treatment of LTBI should be offered to patients regardless of their age.

How to test for LTBI

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 5 and up, and may sometimes be indicated in younger children.

In persons <5 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 more information, refer to the California Tuberculosis Controller’s Association (CTCA) IGRA Clinical Guidelines in California (2012), adapted from the Center for Disease Control (CDC) Updated Guidelines for Using Interferon Gamma Release Assays to Detect Mycobacterium tuberculosis Infection (2010).

For current tuberculosis diagnosis and treatment guidelines, please follow this link to the California Tuberculosis Controllers Association guidelines page.

List of local clinics offering TB skin tests

San Mateo County outpatient clinics offering TB skin tests
Note: this information is subject to change. Please confirm in advance with the clinic!
Daly City Clinic
380 90th Street, Daly City
(650) 301-8600
TST & QFT: Mon & Wed 8:45-11AM
APPOINTMENT NEEDED.
$40 per test.
Daly City Youth Health Center
(ages 13-21 years only)
2780 Junipero Serra Boulevard, Daly City
(650) 985-7000
TST & QFT: Mon-Fri 9:30-11:30AM & 1-4PM, except Thurs mornings.
APPOINTMENT NEEDED.
Eligibility: Medi-Cal/HPSM, ACE, CHDP.
New patients require physical to establish care.
South San Francisco Clinic
306 Spruce Avenue, South San Francisco
(650) 877-7070
TST & QFT: Mon-Fri 9-11AM & 1-3:30PM
APPOINTMENT NEEDED FOR CHILDREN ONLY.
Eligibility: Medi-Cal/HPSM, ACE, CHDP.
Insurance screening available on site.
Fair Oaks Health Center
2710 Middlefield Road, Redwood City
(650) 364-6010
QFT only: Mon-Fri 8AM-5PM
APPOINTMENT NEEDED.
Eligibility: Registered patients only (subject to change). Call to inquire.
Sequoia Teen Wellness Center
(ages 12-21 years only)
200 James Avenue, Redwood City
(650) 366-2927
TST & QFT: Mon-Fri 8:30-10:30AM & 1-2:30PM
NO APPOINTMENT NEEDED FOR REGISTERED PATIENTS.
Eligibility: Medi-Cal/HPSM, ACE, CHDP.
If uninsured, call to screen for Gateway Program coverage.
$10 TST, $45 QFT.

San Mateo County Mobile Health Van
(Varies by day, time, and location)
Schedule: www.smchealth.org/mobileclinic
(650) 573-2786
TST & QFT: Mon-Wed
FIRST COME, FIRST SERVED UNTIL FULL.
(No TSTs on Thurs or Fri before Mon holiday.)
TST: $35 per test, $49 for two-step test
QFT: $110 per test ($75 + $35 consultation fee)

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