Experts ramp up efforts to improve TB testing in children
HOUSTON -- (March 24, 2015) - In recognition of today's celebration of World Tuberculosis Day 2015, experts from around the world, including Baylor College of Medicine, celebrated strides and called for continued and increased focus on providing more accurate diagnostic testing for the globally burdensome disease, especially in children.
Tuberculous is a disease of the lungs caused by a germ called Mycobacterium tuberculosis that is usually spread in the air by coughing or sneezing. The germ sets up infection that might sit in the body and cause no harm if controlled by the immune system or it could turn into a deadly disease.
Texas ranks second in the United States for having the highest number of cases of the disease.
"If we could provide more accurate diagnostic testing, it would have a major impact globally, to help prevent the progression of infection to disease and decrease morbidity and mortality in children," said Dr. Anna Mandalakas, associate professor of pediatrics in the section of retrovirology and global health at Baylor and director of the Global Tuberculosis Program at Baylor and Texas Children's Hospital
Children vs. adults
Adults with TB typically have more germs making it easier to spread and detect the disease, she said. "Disease is more difficult to diagnose in children because they have fewer tuberculosis germs in their bodies and are often diagnosed in the later, more serious stage of the disease."
"Half of the children under a year of age who are infected with the tuberculosis germ will develop the disease, but if you identify the infection early you could give children medication to prevent the disease from developing," said Mandalakas. "Adults are less likely to develop the disease following infection."
Risk factors of developing tuberculosis include having a weak immune system (cancer, HIV patients), being elderly and being a young child.
There is effective treatment for most forms of the disease, but it involves many pills taken over an extended period of time (usually between six and 12 months).
"We see many compliance issues due to the long length of treatment," said Mandalakas. "People often stop taking the pills."
Strides in research
Mandalakas and colleagues were commissioned by the World Health Organization to review the use of a new test (called GeneXpert) versus other methods including a microscope test and a culture test to identify the mycobacterium in children.
In a review of 15 studies conducted at sites around the globe, the team found that Xpert does improve upon existing technologies, doing a better job at detecting the disease than smear tests. The team published the results today online in the journal Lancet Respiratory Medicine.
"Smear technology requires identification of the mycobacteria under a microscope," said Mandalakas, senior author of the report. "This test misses a lot of the children with disease as they have fewer germs in their body."
Culture is the gold standard for detecting the mycobacteria, but culture can take up to six weeks to provide the result, Mandalakas said.
Xpert has better sensitivity than smear; and, although less sensitive than culture, Xpert can be completed in only a couple of hours, she said. "In many parts of the world, children have limited access to culture, especially in low income countries where Tuberculosis is most common. Xpert is a better option for children in many parts of the world."
More research needed
All of these tests still miss some children with disease. More research is needed to develop tests that can detect lower levels of the germ and that will work better in children.
Mandalakas and her colleagues are involved in testing new diagnostic platforms and conducting research to understand the immune system better in order to identify improved markers of the disease. "Most importantly, we want to find a way to identify those who may be infected with the germ that will develop the disease, and those that will not, in order to prevent disease more effectively," said Mandalakas.
About Texas Children’s Hospital
Texas Children’s Hospital, a not-for-profit health care organization, is committed to creating a healthier future for children and women throughout the global community by leading in patient care, education and research. Consistently ranked as the best children’s hospital in Texas, and among the top in the nation, Texas Children’s has garnered widespread recognition for its expertise and breakthroughs in pediatric and women’s health. The hospital includes the Jan and Dan Duncan Neurological Research Institute; the Feigin Center for pediatric research; Texas Children’s Pavilion for Women, a comprehensive obstetrics/gynecology facility focusing on high-risk births; Texas Children’s Hospital West Campus, a community hospital in suburban West Houston; and Texas Children’s Hospital The Woodlands, a second community hospital planned to open in 2017. The organization also created the nation’s first HMO for children, has the largest pediatric primary care network in the country and a global health program that’s channeling care to children and women all over the world. Texas Children’s Hospital is affiliated with Baylor College of Medicine. For more information, go to www.texaschildrens.org. Get the latest news by visiting the online newsroom and Twitter at twitter.com/texaschildrens.