Lauren Fuge
Researchers have created a “lab-in-a-tube” tuberculosis test, with all the ingredients necessary to detect the disease in under an hour.
Costing just AUD$4.3 (US$2.70) per sample, the lab-in-a-tube tuberculosis (LIT-TB) test may fill the critical need for easy-to-administer tests in low- and middle-income countries.
“There’s increasing recognition of the need for affordable, rapid diagnostic tests that can be used at the point of care, especially those that don’t rely on sputum samples,” says Chris Lowbridge, Tuberculosis Program Lead at the Menzies School of Health Research, who was not involved in the development of the new test.
“These are promising early findings – this test shows potential to meet key criteria for TB diagnostics in settings where current tools fall short.”
The scale of the problem
Tuberculosis (TB) is a contagious disease caused by the bacteria Mycobacterium tuberculosis, which spreads through the air and primarily affects the lungs.
TB infects approximately 10 million people every year and kills 1.5 million. It’s one of the world’s leading causes of death from infectious disease, and the leading cause of death among people living with HIV. Drug-susceptible cases can be treated with a six-month course of four antimicrobials, but without treatment, 45% of people with TB die, and nearly all HIV-positive people with TB die.
More than 95% of TB cases occur in developing countries – but the disease is preventable and curable when communities have the resources to detect and treat it.
In 2023, the UN set the target of eradicating tuberculosis by 2030. A better vaccine is one prong of this ambitious plan, along with a new, rapid test for early detection.
It’s estimated that millions of cases go undiagnosed or unreported each year – in 2023 alone, the estimate was 2.7 million. This is largely due to limitations in testing. Current TB tests require expertise, equipment and health care infrastructure that is lacking in areas with a high burden of disease.
Diagnosis is also difficult when many of TB’s symptoms can begin mildly and are also common to other illnesses.
But diagnosis is critical to improve patient outcomes and prevent the disease spreading.
The trials and tribulations of testing
Current methods of diagnosing TB are often either expensive, slow, difficult to administer, or otherwise not suited to low-income or remote areas.
For example, the oldest type of test for TB involves a lab test of sputum (phlegm). But it can take three days to process, and sputum can sometimes be difficult to get from patients such as children and people living with HIV. This is an issue, because these patients are more at risk of the disease progressing, and more at risk of death.
“Current rapid diagnostic tests like GeneXpert are effective, but they’re expensive and require laboratory infrastructure and stable power, which limits their use in many rural and remote areas,” explains Lowbridge.
“There’s a need for affordable, portable diagnostic tools that can be rolled out more widely and used by healthcare workers closer to where people live.”
Researchers around the world are answering this call and developing better detection tests. For example, last year South African researchers developed a “patch” test that could detect the chemical signatures of TB bacteria on a patient’s skin. This test is inexpensive and easy-to-transport, but the patches have to be sent to a lab for analysis.
Now, the new LIT-TB test promises an even quicker response, as reported in a paper published in Science Translational Medicine. The hand-held, battery-powered, lab-in-a-tube test was developed by US and German researchers, led by Brady Youngquist of Tulane University in New Orleans.
Unlike other tests, it doesn’t require sputum samples. Instead, the test is able to detect Mycobacterium tuberculosis in either blood or respiratory samples. It contains everything necessary to process and analyse the sample in a test-tube, and it then sends the result to a portable device.
LIT-TB is also able to detect TB infections out of the lungs without requiring a biopsy, and it can distinguish antibiotic-resistant strains of TB.
The team trialled it on in the Dominican Republic, on a small sample of adults and children aged between 1 and 16. They found the test could detect adult and pediatric TB with high sensitivity and specificity when using samples of serum, saliva, or sputum.
The trial showed that the test meets the World Health Organization’s standard for new tuberculosis diagnostics.
“The results are encouraging,” says Lowbridge. “However, more research is needed to evaluate how the test performs in real-world conditions, particularly in high-burden settings and among groups like children and people living with HIV.”
Australian outlook
Closer to home, Australian researchers are also working on the eradication of TB in Australia and surrounding regions.
In the early 20th century, TB was a major cause of death in Australia. But a national campaign launched by the newly formed Department of Health in the 1920s kickstarted an expansion of TB research and care.
From 1948 to 1976, citizens were provided with free diagnostic chest X-rays, medical care (including free antibiotics) and a financial allowance while undergoing treatment.
As a result, the number of people dying from TB dropped dramatically, from 108.5 deaths per 100,000 population in 1907 to 0.3 deaths per 100,000 population in 2000.
Today, the research continues. Lowbridge’s role with the Menzies Division of Global and Tropical Health Chris sees him working on projects to better understand TB and improve the response to TB in Northern Australia and its neighbours.
“Australia has one of the lowest TB rates globally, but the disease hasn’t been eliminated,” he says. “Around 1,500 people are diagnosed with TB in Australia each year.”
First Nations people are disproportionately affected, at a rate of about 3.8 to 7.5 cases per 100,000 population.
A 2021 review into TB in Australia’s tropical north, co-authored by Lowbridge, recommends that priorities include educating community and health staff to more rapidly diagnose active TB; contact tracing and the use of genomic sequencing to find and diagnose TB; and treating latent TB to “to break transmission chains in Top End remote hotspot regions”.
“Some remote communities still face significant barriers to accessing timely diagnosis and care,” Lowbridge says. “In these settings, a portable, low-cost test that delivers results within an hour could help to reduce the time between someone developing TB and starting effective treatment.”