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New Test Allows Earlier Diagnosis of TB in Children
A new test for diagnosing tuberculosis (TB) in children detects roughly two-thirds of cases identified by the current culture test, but in a fraction of the time, according to the results of a study in South Africa supported by the National Institutes of Health (NIH).
The test, known as Xpert MTB/RIF, also detected five times the number of cases identified by examining specimens under the microscope — a preliminary method for diagnosis that is often performed as an initial test, but that must be verified by the culture test.
Xpert MTB/RIF results from respiratory secretions were ready in 24 hours, on average, compared with an average of more than 2 weeks for the culture test used in the study, the researchers found. Previous studies have shown that Xpert MTB/RIF is effective for diagnosing TB in adults and in children with pronounced symptoms of TB who have been admitted to a hospital. Diagnosing TB in children is more difficult than diagnosing the disease in adults because children tend to have much lower levels of the TB bacteria than do adults.
The results of the new study indicated that the ease and speed of diagnosis would be useful for children seen in clinics in resource-limited countries, which often lack the resources for traditional testing that are available in hospitals. The Xpert test also was able to identify children with drug-resistant TB. In addition, the researchers found that the test can readily determine when treatment for TB is not appropriate. Among children who did not have TB, the results of the test came back negative for TB with 99% accuracy.
According to World Health Organization estimates, in 2011 there were 500,000 TB cases and 64,000 deaths among persons younger than 15 years of age.
Source: NIH; July 24, 2013.