The most deadly form of tuberculosis is one that lies in wait inside the body for years, attacking at the first sign of weakness. About a third of the global population may carry what is known as latent TB. Slow diagnostic tests mean many will go years without knowing that they are infected. Now, two separate medical innovations aim to detect TB earlier, stopping the deadliest form of the lung disease.
Using a process called fluorescence dilution, scientists are now able label the specific bacteria that cause latent TB and isolate it in order to track its development. This specific labeling process works like a “micro-tweezer,” allowing scientists Samantha Sampson and Jomien Mouton to physically pick out the slow-growing, but deadly bacteria. It’s the same process used to detect salmonella.
They’ve learned that the bacteria creep inside white blood cells—the body’s defense mechanism—where they live until their host’s immune system is susceptible to attack. This information is vital to helping medical scientists understand how to treat drug resistant forms of TB.
Multidrug-resistant TB is a form of the disease that is resistant to first-line medication most commonly used to cure TB. A deadlier form, extensively drug-resistant TB, is impervious to even a second line of treatment, according to Doctors Without Borders.
The World Health Organization estimates that 480,000 cases of multidrug-resistant TB occurred in 2014. Still, only about a quarter of these were detected and reported (pdf). On average, an estimated 9.7% of these cases had the more serious extensively drug-resistant TB.
In 2014, TB killed 1.5 million people and now ranks alongside HIV as the leading cause of death worldwide. In the same year, 6 million new cases of TB were reported to the World Health Organization, but the organization estimates that 37% of new cases went undiagnosed or were not reported, putting the number of people living with TB at about 9.6 million.
Another group of scientists say they have developed a blood test for TB that detects if faster. Until now, the most accurate TB test is a culture test, which takes 10 days to show a positive result and up to 42 days to demonstrate a confirmed negative test. The more common sputum test is inexpensive but labor intensive and only has a 60% sensitivity rate. The test is especially difficult to carry out on children because it requires a nasal tube.
A new method, developed by team of scientists at Stellenbosch University in South Africa, uses a pin prick to measure the blood chemicals of people possibly infected. This centralizes the process, allowing healthcare workers to test patients on the ground and have results in an hour, Professor Gerhard Walzl, one of the test’s inventors told The Conversation.
At $2.50 per test, compared to $45 per culture test and $12 per sputum test, it also promises to be a much cheaper method, according to Walzl. Still in the development phase, the patent will be tested in five African countries over the next three years.
An airborne disease, TB has infected humanity for thousands of years, and remains deadly in some regions. Dramatized during the Victorian era as consumption, it is marked by a hacking cough and a slow wasting away. It seemed a disease of the past for most people in the developed world.
The number of TB cases rose in the US for the first time in 23 years last year. While most new TB cases occurred in South East Asia and the Western Pacific, Africa has the biggest incidence with 281 infections per 100,000 people.
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