Compromising hopes of containing the disease, latent TB remains dormant for life for most people.
One third of all people world-wide are infected with ‘latent’ tuberculosis (TB), a dormant form of the disease, which combined with immune-suppressing illnesses, is a threat to containing the epidemic, according to Jane Carter, president of the International Union Against Tuberculosis and Lung Disease.
Speaking at a briefing ahead of the 45th Union World Conference on Lung Health in Spain she said that public health officials have neglected looking into latent TB because of the need to prioritise the identification and treatment of the active and contagious form of the disease.
Research has shown that latent TB only progresses to active illness in an estimated 10% of those infected and remains dormant for life for most people.
Most TB infections happen when bacteria in the air, coughed out by those with active TB, enters the lungs, said Mario Raviglione, director of the World Health Organisation’s TB programme.
“Once it’s in the lungs that’s when our immune system reacts. We are capable of containing it if our immune systems works well.”
However, if a person’s immune system becomes compromised at a later stage, through contracting HIV or developing diabetes for example, it is “not capable of containing [the TB] anymore and that explodes and causes the disease”, he said.
Treating those with latent TB is another strategy to end the disease, requiring treatment with only one drug instead of the four used in active TB, and “if you’re cured it’s hard for you to get infected again”, according to Carter.
“Except in countries like South Africa which have an incredibly high level of community exposure,” she added.
Lee Reichman, a TB expert from the United States, explained that treating latent TB in South Africa is “somewhat
effective” but not enough to warrant its implementation as a public health
policy because patients have such a high chance of being infected again soon
after being cured.
According to a 2011 a review published in the Journal of Infectious Diseases as much as 89% of South African adults have latent TB.
According to Carter, it is not known if treating latent TB in countries like South Africa, with high burdens of the disease, will be effective. She said it is an approach that can be effective in some settings and should be explored.
The issue is, however, receiving global attention with a new set of guidelines on the treatment of latent TB being released by the World Health Organisation on Wednesday.
Amy Green attended the 45th Union World Conference on Lung Health as part of a National Press Foundation funded fellowship