Ounce of Prevention is a weekly column which presents recommendations for preventative services derived from The United States Preventive Services Task Force (USPSTF). Each column begins with the name of the condition, the grade provided by the USPSTF as well as the official recommendation, the type of prevention, and more. Each will have a date of publication for the recommendation, referencing the date of the most recent update, not the original publication.
Name of the Condition/Recommendation: Latent tuberculosis screening in adults
Grades: B
Official recommendations: Grade B — The USPSTF recommends screening for LTBI (Latent Tuberculosis Infection) in populations at increased risk.
Type of Prevention: Primary
Month/Year of Publication: May, 2023
The disease tuberculosis comes in two forms; the first is known as active tuberculosis, which comes with symptoms, and can be spread to other people. The second is latent tuberculosis, which will give you a positive skin or blood test for TB, but usually just sits there (your immune system has neutralized it for the present—see below). It is estimated that 30% of those exposed to active TB will develop latent TB, and it was estimated that that was 13 million people in the US in 2012. Approximately 5-10% of those will eventually progress to active tuberculosis if not treated (so 650,000 to 1.3 million cases).
Who are the populations “at increased risk”? If you have ever worked in health care, you know we are one such group and are screened routinely. Another clear group is persons who have had a known contact with the disease. The disease is most common in those born outside the United States (72% of cases). TB is common in Latin America, the Caribbean, Africa, Asia, Eastern Europe, and Russia. In the US, the disease is more common in all minorities recognized by the Census Bureau, and in lower socioeconomic groups, especially those who live or work in congregate settings, such as prisons or homeless shelters. People with any kind of immunosuppression (from cancer chemotherapy, to treatments for psoriasis and other inflammatory diseases, to HIV) are a special case to be discussed below.
The best screening test is a blood test known as IGRA (interferon gamma release assay). Skin tests were the standard but are not considered to be acceptable now in all people over 2 years old. Since the test detects tuberculosis infection only, if you are positive, you would then have to have further testing to determine if your TB is active or latent (usually just a chest X-ray). If you do have latent TB you will be prescribed medications for several months which greatly decrease your chance of it converting to active TB.
It is important to note that even if you are not in one of the “at risk” groups, if you are being considered for immunosuppressive therapy, a group of drugs that is becoming much more widely used (they are quite effective) for psoriasis, rheumatoid arthritis, and other inflammatory diseases, or if you are going to receive chemotherapy that can affect the immune system, you likely will be, and should make sure you are, screened for TB before treatment starts—decreased activity in the immune system can result in a change from latent to active tuberculosis.