<P> The Mantoux tuberculin skin test is often used to screen people at high risk for TB . Those who have been previously immunized may have a false - positive test result . The test may be falsely negative in those with sarcoidosis, Hodgkin's lymphoma, malnutrition, and most notably, active tuberculosis . Interferon gamma release assays, on a blood sample, are recommended in those who are positive to the Mantoux test . These are not affected by immunization or most environmental mycobacteria, so they generate fewer false - positive results . However, they are affected by M. szulgai, M. marinum, and M. kansasii . IGRAs may increase sensitivity when used in addition to the skin test, but may be less sensitive than the skin test when used alone . </P> <P> Tuberculosis prevention and control efforts rely primarily on the vaccination of infants and the detection and appropriate treatment of active cases . The World Health Organization has achieved some success with improved treatment regimens, and a small decrease in case numbers . The US Preventive Services Task Force (USPSTF) recommends screening people who are at high risk for latent tuberculosis with either tuberculin skin tests or interferon - gamma release assays . </P> <P> The only available vaccine as of 2011 is Bacillus Calmette - Guérin (BCG). In children it decreases the risk of getting the infection by 20% and the risk of infection turning into disease by nearly 60% . </P> <P> It is the most widely used vaccine worldwide, with more than 90% of all children being vaccinated . The immunity it induces decreases after about ten years . As tuberculosis is uncommon in most of Canada, the United Kingdom, and the United States, BCG is administered to only those people at high risk . Part of the reasoning against the use of the vaccine is that it makes the tuberculin skin test falsely positive, reducing the test's use in screening . A number of new vaccines are currently in development . </P>

What other sites in the body can be infected by m tuberculosis