Millions of latent infections around the world
TB is a global disease
Tuberculosis isn’t just a disease that harms people in developing countries, even if 95 % of all cases appear in those regions. In the Western world, London is the TB capital – with numbers comparable to countries like Rwanda or Guatemala. One-third of London’s boroughs exceed the WHO “high incidence” threshold of 40 cases per 100,000 people, as a 2015 report from the London Assembly shows.
Hall´s story made headlines
Fighting TB in its early latent stage is crucial to prevent its spread, and effective latent TB screening is the most powerful tool available. By implementing the new CDC screening guidelines, experiences like those faced by Hall faced could be avoided. That opinion is shared by Dr. Michael Lauzardo, a pulmonary disease specialist with the University of Florida Health system. “With the increased precision of this blood test, you take the whole issue of vaccination out of the equation.”
Studies have shown that mandating a blood test for immigration screenings is an “exceptionally effective strategy,” says Lauzardo. The skin test, in contrast, has its limitations, “particularly when used on patients who come from countries with historically high rates of TB infection.” Since testing the skin for an antibody response is less precise than a blood test, it returns twice as many false positives for latent infections. “This can lead to people being put unnecessarily on medications, which consume public health resources and can cause side effects." The high rate of false positive skin test results in people vaccinated for BCG can also provide a false sense of security. Lauzardo explains that people from high-risk geographies tend to shrug off the skin test, expecting a positive result because they were vaccinated. “As a result, they don’t seek treatment.”