Continued tuberculosis transmission in King County

Actions requested

• Be aware that delayed tuberculosis (TB) diagnosis and subsequent TB transmission continues to occur in King County, Washington.
  • In King County, 90–130 people are diagnosed with active TB disease annually, and 100,000 residents are estimated to have untreated latent TB infection (LTBI).
  • Over 85% of King County residents with active TB disease are non-U.S. born.
  • In 2024, there has been an increase in active TB disease cases in King County identified among children who live with family members with risk factors for TB.

Follow the steps below when evaluating for active TB disease.

• Screen patients for TB who have an epidemiologic risk factor for previous TB exposure or a medical risk factor for progression to active TB disease, such as:
  • Born in a country with a high TB burden (a quick approximation is to consider all countries outside of the United States, Canada, Australia, New Zealand, and countries in western and northern Europe to have elevated TB rates).
  • Spent time with someone who has active TB disease.
  • Have medical conditions or are on medications that increase the risk of progression from latent TB infection to active TB disease (e.g., HIV infection, TNF alpha blocker treatment).
  • Children who live with family members or other adults with risk factors for TB, as they are at increased risk for severe TB disease.

Evaluate for compatible signs/symptoms or physical exam findings of active TB disease:

• Any patient: new cough lasting 3 weeks or longer, pleuritic chest pain, hemoptysis, unexplained weight loss, fever, or night sweats
• Children: cough, fever, night sweats, subtle or non-specific symptoms, such as failure to thrive or decreased playfulness or lethargy (review CDC's Tuberculosis in Children)

Obtain a chest x-ray (CXR) first when pulmonary TB is suspected

• If the CXR findings are consistent with pulmonary TB (e.g., presence of a cavity in the upper lung zone), contact the Public Health TB Control Program immediately.
• If the CXR is abnormal but not specific for pulmonary TB, the differential diagnosis is broad. But if there is an epidemiologic or medical risk factor described above, consider obtaining 3 sputum specimens on separate days for Acid-Fast Bacilli (AFB) smear, culture, and TB PCR (e.g., Xpert MTB/RIF).
• Be aware that negative AFB smears and negative TB PCR do not exclude active pulmonary TB (40-50% of patients with culture-positive pulmonary TB have negative AFB smears).
• Contact the Public Health TB Control Program for consultation and CXR review if needed.

Report highly suspected or confirmed cases of active TB before starting treatment to Public Health within 24 hours (206-744-4579). Do not wait for culture confirmation to report the case.

• Evaluate non-U.S.-born individuals from countries with a high TB burden for latent TB infection (LTBI) and treat LTBI if indicated.
  • Check their country of origin: a quick approximation is to consider all countries outside of the United States, Canada, Australia, New Zealand, and countries in western and northern Europe to have elevated TB rates.
  • Check their history of LTBI or TB treatment in the past.
  • If the patient has not received any LTBI or TB treatment, offer an interferon gamma release assay (IGRA: i.e., QuantiFERON or T-SPOT).
  • If IGRA is positive, confirm that the patient does not have active TB diseases by history, physical exam, and CXR before offering LTBI treatment.

Refer to the Washington State LTBI treatment guidance or CDC's LTBI guide for primary health care providers.