A scientist at Michigan State University in East Lansing has invented a colorimetric biosensing assay that can detect tuberculosis in 10-20 minutes and costs 10 cents per test. It has a 95-99 percent accuracy rate.
A cure for the deadliest strain of TB was recently discovered, but early detection of the disease has been a challenge. In 2016, 10.4 million people contracted TB, and 1.7 million died. The disease is common in low- and medium-income countries.
“Implementation of this approach in rural areas of developing countries would increase case finding and notification and would reduce drug resistance,” says Evangelyn Alocilja, the inventor and a professor of biosystems and agricultural engineering. She lost her aunt and uncle to TB while growing up in the Philippines. “Its use at the first point of contact would facilitate quick treatment in a single clinical visit, thus supporting the World Health Organization’s global strategy to end TB by 2035.”
There are two popularly used methods of TB detection – smear microscopy, which is inexpensive but has only about 50 percent sensitivity, and the Xpert MTB/RIF system, which is sensitive but requires a machine that costs about $40,000 and cartridges that cost $20-$30 per test. Private testing labs charge an average of $70 per test. The system also requires electricity and refrigeration of samples, which aren’t always available in developing countries.
“A few years ago, WHO’s Stop TB program supplied 10 Xpert machines for the Philippines. I pointed out to one collaborator that the machines had to be stretched to cover 100 million people,” says Alocilja. “In many cases, patients with TB infect five-10 people before knowing they have the disease. We simply needed a better way to save more lives.”
Alocilja’s patented approach uses magnetic nanoparticles and bacterial stain mixed with patients’ sputum – a mix of saliva and mucous – samples. The discharge is mixed in a vial and exposed to a magnet. Viewing the samples through a microscope reveals either red clusters of charged nanoparticles (positive) or dispersed brown nanoparticles (negative).
For areas where there are no medical professionals nearby, Alocilja’s team developed a smartphone app using an algorithm that can also review the samples. Accuracy for this method is 85 percent.
Once TB is detected, medical professionals deploying the technology run a DNA test, which verifies the TB strain’s drug resistance.
“We are pleased with how quickly our technique can be administered,” Alocilja says. “In 15 minutes, we can confirm TB, and in 45 minutes we can verify its drug resistance. Being able to conduct this full assessment in an hour – and in a single visit – are critical in tackling this deadly disease.”
Alocilja’s team has published two papers on the effectiveness of the test and are working on two more. The research has been peer reviewed and tested in field studies in Nepal, India, Peru, and Mexico. Alocilja is traveling to present her research and the product. Her next presentation will be in the Philippines and to 10 hospitals in Nepal in November.
Other countries that have expressed interest in Alocilja’s invention include Colombia, Ecuador, Indonesia, Uganda, South Africa, Ghana, and Poland.