More Progress Needed in TB Treatment and Prevention

Better predictive tools, more preventive measures, and shorter treatment times are needed to improve the incidence and mortality rates of tuberculosis (TB), according to Dr Constance A. Benson.

Benson, who is from the University of California San Diego, outlined the 3 needs in her “Update on tuberculosis treatment and prevention” presentation yesterday at the Conference on Retroviruses and Opportunistic Infections (CROI) 2019.

According to Benson, the World Health Organization reports that a quarter of the world’s population are infected with Mycobacterium tuberculosis and that TB is now the world’s number one infectious cause of death, especially among individuals infected with HIV.

However, only 20% of those who are candidates for screening have completed therapy for latent TB infection, causing Benson to call the activity “dismal.”

“Part of the reason for that is that we do not have very good tools for predicting those individuals who are at highest risk for progression to active TB,” said Benson. “There currently are not global resources or health care infrastructures in the world to actually screen and treat 1.7 billion people, so we need to do better at predicting those who are at higher risk for disease progression and highest risk of transmission when they do progress.”

Researchers are now conducting studies to assess how to improve preventive measures, including through way of identifying biomarkers and developing vaccines.

Benson says there is some good news about the changing epidemiology of tuberculosis.

“We are seeing a decline in the incidence and a slightly steeper decline in mortality associated with TB that translates to about a 1.5% decline per year in TB cases. This is reflected in both the HIV-infected and the HIV-uninfected populations,” said Benson. “Particularly with the HIV infection, this is owed in part to better access to more effective antiretroviral therapy in people who are coinfected, improving their overall survival even in the setting of TB.”

More progress is needed, though. In order to meet the United Nations’ goal of a 95% reduction in the number of TB deaths by 2035 and a 90% reduction in the TB incidence rate by 2035, Benson notes that there will need to be a reduction rate of 10% by 2020, and 17% by 2025.

Currently, Benson says researchers are focusing on shortening the treatment time for both drug-susceptible TB (which can last up to 1 year) and drug-resistant TB (which can take 18 to 24 months).

“Long duration of therapy to multiple drugs are difficult to adhere to. Treatment completion, or lack of ability to adhere to effective drugs, is the single biggest reason for people failing TB treatment,” she explained. “There has been great enthusiasm for exploring a universal regimen that would be applicable regardless of whether patients have drug-susceptible or drug-resistant TB.”

The facts that favorable treatment outcomes for multidrug-resistant TB is 30% worse than for drug-susceptible TB and that there is an emerging subepidemic of multidrug-resistant TB worldwide have researchers especially focusing on optimized, standardized treatment, she said.

“There are significant barriers to the scale-up to new drugs for drug-resistant TB,” said Benson.

Included barriers are the cost of new drugs, lack of training/clinician confidence to use new drugs, and there being no national guidelines for new drugs.

—Colleen Murphy

Reference:

Benson CA. Update on tuberculosis treatment and prevention. Paper presented at: Conference on Retroviruses and Opportunistic Infections; March 4-7, 2019; Seattle, WA. http://www.croiconference.org/sessions/update-tuberculosis-treatment-and-prevention.  Accessed March 5, 2019.