Unitaid Invests in New TB Tests, as South Africa Study Reports Importance of Better Screening
Many children with tuberculosis don’t receive the necessary treatment because of challenges with diagnosis.

Two-fifths of people with tuberculosis are unaware that they are infected because their diagnosis relies on outdated tests – something Unitaid and partners aim to change with a $30 million investment in new diagnostic technologies to enable same-day results.

Announcing the investment on Tuesday, the global health agency explained that the current diagnosis in low and middle-income countries relies on sputum tests that have low sensitivity, especially in the presence of HIV coinfection, require patients to make multiple visits to health centres and are “largely ineffective in diagnosing children or people in advanced stages of disease who have difficulty producing sputum”.

The announcement comes shortly after the publication in this month’s International Journal of Infectious Diseases of a massive 29-year study of TB in South Africa, which found that incidence and mortality were substantially reduced by the introduction of antiretroviral HIV therapy and increased screening.

South Africa has one of the highest TB rates in the world and the researchers, from the Universities of Cape Town and Stellenbosch, found that 8.8 million people had developed TB, and 2.1 million died during the study period from 1990 to 2019. 

HIV, which weakens a person’s immunity, was responsible for 4.8 million of the cases and 1.4 million deaths.

Testing doubled

The study also estimated the impact on TB incidence of various treatment interventions, finding that antiretroviral therapy (ART) and increased TB screening, were the most effective.

“Between 2005 and 2012, South Africa scaled-up efforts to identify TB cases and testing rates doubled. As a result, there were rapid reductions in TB incidence owing to increased TB screening during this period. In 2019, increased screening led to a 28% reduction in TB incidence,” according to lead author, Mmamapudi Kubjane, a researcher in the School of Public Health and Family Medicine at the University of Cape Town.

The study also found that the provision of ART led to a 20% reduction in TB incidence by 2019. 

“The benefits of ART in reducing incidence depend on CD4 count and duration of ART. HIV-positive individuals who initiate ART earlier at higher CD4 counts and stay on ART for longer experience the greatest benefits of ART,” said Kubjane.

The impact of the other treatment interventions – directly observed therapy (DOTS), isoniazid preventive therapy (IPT), and Xpert MTB/RIF – were “modest” single-figure percentages. Xpert MTB/RIF is a highly sensitive test that can simultaneously detect TB and resistance to the TB drug rifampin (RIF) in less than two hours.

When South Africa introduced this new Xpert MTB/RIF test in 2011 to replace sputum testing, it was expected to bring substantial health benefits – yet clinical trials have found little or no impact on TB mortality, according to recent analyses.

“To understand these dynamics better, modelling studies with detailed diagnostic algorithms that account for empirical treatment are required,” the study recommends.

Combination approaches to diagnosis

This is something that Untaid and its partners could tackle. Unitaid has partnered with FIND, the global alliance for diagnostics and the Liverpool School of Tropical Medicine (LSTM), to evaluate alternative TB sampling approaches, and develop and evaluate combination approaches to diagnosis. 

More than 10 million people each year fall ill with tuberculosis (TB), and an estimated four million people with TB – two out of every five – go undiagnosed, according to Unitaid.

“Efforts to reduce the TB burden are greatly hampered by the large number of people who never receive a diagnosis and therefore do not access treatment,” it adds. 

“For those who do receive a positive diagnosis, the process can be lengthy and sometimes means patients do not start on the correct treatment from the outset, which can lead to drug resistance.”


Image Credits: University of Cape Town Lung Institute.

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