Who is at risk for TB?
It is estimated that up to 10% of people infected with M. tuberculosis will develop active tuberculosis (TB) in their lifetime. About one-quarter of the world’s population has a TB infection. The vast majority have no signs or symptoms of TB disease and are not infectious, although they are at risk of developing active TB disease and becoming infectious.
The Centers for Disease Control and Prevention (CDC) and the United States Preventive Services Task Force (USPSTF) recommend testing populations that are at increased risk for TB infection, including (1):
- People who have spent time with someone who has TB disease
- People with HIV infection or another medical problem that weakens the immune system
- People who have symptoms of TB disease (fever, night sweats, cough and weight loss)
- People from a country where TB disease is common (most countries in Latin America, the Caribbean, Africa, Asia, Eastern Europe and Russia)
- People who live or work somewhere in the United States where TB disease is more common (homeless shelters, prison or jails or some nursing homes)
- People who use illegal drugs
TB risk groups should be tested for TB bacteria because they are more likely to get TB disease. The purpose of TB screening is to find cases at an early asymptomatic phase that is easily curable and find latent TB infection (LTBI) among individuals who may benefit from preventive treatment.
The CDC is calling out a testing gap. Can we defuse the TB timebomb?
According to a new study published in the CDC’s Morbidity and Mortality Weekly Report, reported TB incidence (cases per 100,000 persons) increased 9.4%, from 2.2 during 2020 to 2.4 during 2021 but was lower than incidence during 2019 (2.7) (2).
Factors contributing to changes in reported TB during 2020–2021 likely include an actual reduction in TB incidence, delayed or missed TB diagnoses and disruptions in healthcare access (3).
The authors warn that continuing underdiagnosis of TB in the U.S. may derail efforts to eliminate the disease, highlighting the importance of evaluation and treatment of latent tuberculosis infection (LTBI) to prevent progression to TB disease.
How can we get U.S. testing back on track?
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References:
- Centers for Disease Control and Prevention. Testing for Tuberculosis (TB) factsheet. https://www.cdc.gov/tb/publications/factsheets/testing/tb_testing.htm (accessed October 6, 2021)
- Filardo T.D., Feng P., Pratt R.H., Price S.F., Self J.L. (2021) Tuberculosis — United States. MMWR Morb Mortal Wkly Rep 2022;7 1:441, 446.
- Centers for Disease Control and Prevention. Trends in Tuberculosis, 2020. https://www.cdc.gov/tb/publications/factsheets/statistics/tbtrends.htm (accessed April 7, 2022)
- Centers for Disease Control and Prevention. CDC FACT SHEET: TB in the United States, 2021. https://www.cdc.gov/nchhstp/newsroom/docs/factsheets/TB-in-the-US-508.pdf
QFT -Plus is an in vitro diagnostic aid for detection of Mycobacterium tuberculosis infection. QFT-Plus is an indirect test for M. tuberculosis infection (including disease) and is intended for use in conjunction with risk assessment, radiography, and other medical and diagnostic evaluations. QFT-Plus Package Inserts, available in multiple languages, as well as up-to-date licensing information and product-specific disclaimers can be found at www.QuantiFERON.com.
The performance of the USA format of the QFT test has not been extensively evaluated with specimens from individuals who have impaired or altered immune functions, such as those who have HIV infection or AIDS, those who have transplantation managed with immunosuppressive treatment or others who receive immunosuppressive drugs (e.g., corticosteroids, methotrexate, azathioprine, cancer chemotherapy) or in individuals younger than age 17 years.