Test detects TB bacteria in children long before disease occurs
Because it can be difficult to detect tuberculosis in young children, the disease may be dangerously advanced by the time it's diagnosed. A new blood test, however, is claimed to detect the presence of TB-causing bacteria up to a year before the disease itself occurs.
There are several reasons why tuberculosis is often missed in babies and toddlers. For one thing, they often don't exhibit typical symptoms – at least, not initially – so caregivers don't think to have them tested in the first place.
Additionally, they can have trouble producing the sputum samples needed to check for TB-causing Mycobacterium tuberculosis microbes in their respiratory system. And because the amount of bacteria in a child's sample is often much smaller than the amount in a sample provided by an adult, standard testing may prove to be inaccurate.
With these limitations in mind, scientists at New Orleans' Tulane University have devised a blood test that checks for a protein known as CFP-10. It's secreted by the bacteria, and may be present in the bloodstream up to 60 weeks before the child actually develops tuberculosis. Only a small blood sample is needed, as an antibody is added to enrich any CFP-10 that may be present, causing it to better show up when analyzed by a mass spectrometer.
When the technology was used to test stored blood samples that had previously been obtained from a total of 519 children, it was found to be 100 percent accurate at identifying the individuals who had been diagnosed with tuberculosis via "gold-standard" testing techniques. Additionally, it also identified 83.7 percent of the children who those traditional tests missed, but who were later diagnosed with TB by their physicians.
The scientists are now developing an inexpensive portable device that could perform the blood tests onsite, in settings such as impoverished communities where lab testing may not be available.
"This is a breakthrough for infants with tuberculosis because we don't have this kind of screening technology to catch early infections among those youngest groups who are most likely to be undiagnosed," says the lead scientist, Dr. Tony Hu. "I hope this method can be pushed forward quickly to reach these children as early as possible."
The research is described in a paper that was recently published in the journal BMC Medicine.
Source: Tulane University