A team led by School of Public Health researchers has created a near real-time surveillance method to identify communities experiencing a high burden of drug-resistant tuberculosis in South Africa using routinely collected laboratory data.
In the study, published in PLOS Medicine, the researchers mapped the highest rates of drug-resistant tuberculosis in the Western Cape Province and tracked changes over five years. The results will help create a method that can lead to more targeted interventions and public health approaches aimed at reducing the number of people who contract the disease.
“Our model of mapping high-burden communities can serve as a roadmap for regions working to reduce TB incidence by initiating treatment as soon as possible,” says study senior author Karen Jacobson, assistant professor of epidemiology at SPH and assistant professor of medicine in the Section of Infectious Diseases at the School of Medicine. “By locating emerging and chronic hotspots of the disease in real time, public health providers can evaluate the most effective interventions and monitor progress towards TB reduction goals.”
South Africa has the highest rates of tuberculosis (TB) in the world, and 4 percent of these cases are resistant to first line treatment. The country also has a centrally collected laboratory database that includes TB tests, making it an ideal location to implement a surveillance system to track drug-resistant TB cases by clinic location.
The researchers developed an algorithm to identify unique patients and episodes of disease from the data, and created heat maps of the region to see which areas were most afflicted between 2008 and 2013.
The group identified 799,779 individuals who had specimens submitted for TB tests from clinics during the study period. They found 28 percent were diagnosed with TB, of which 4.6 percent were resistant to first line tuberculosis treatment. The proportion of drug-resistant cases varied geographically, ranging from 0 percent to 25 percent of TB cases in different parts of the region. There were also significant annual fluctuations in drug-resistant TB percentages at several locations. The communities that saw the highest rates of drug-resistant TB were Cape Town townships and informal settlements, the rural region of the west coast, and areas bordering the Eastern Cape Province.
The researchers wrote that their findings show routinely collected laboratory data is a powerful tool for researchers and providers, allowing for more accurate allocation of resources to treat TB. Recent evidence shows that the TB epidemic is dynamic, and that medication-resistant TB infections are spread through transmission from another individual with drug-resistant TB disease. This indicates that constant monitoring could lead to more effective public health interventions, resulting in fewer cases of medication-resistant TB, the authors wrote.
The study’s lead author was alumnus Avery McIntosh (SPH’14,’17), who was a doctoral student while working on the study. The other SPH coauthors were: Helen Jenkins, assistant professor of biostatistics; and Laura White, associate professor of biostatistics.
The other coauthors were: Mary B. Kleinman and Elizabeth J. Ragan of the School of Medicine and Boston Medical Center; Marinus Barnard, Tania Dolby, and John Simpson of the South Africa National Health Laboratory Service; Dana R. Thomson and Megan B. Murray of Harvard Medical School; and Elizabeth M. Streicher, Paul D. van Helden, and Robin M. Warren of Stellenbosch University in Cape Town, South Africa.