Detecting tuberculosis at an early stage in people living with HIV

According the World Health Organisation (WHO), about 25% of the world’s population is infected with mycobacterium tuberculosis (MTB). For most, MTB remains in its latent stage, but in some the disease may become active.

Radiological and CT diagnostics are expensive and ineffective for the early and accurate detection of subclinical tuberculosis, so researchers from Germany and the United States studied the use of blood-based biomarkers in combination with sputum analysis. The study, called AFRICOS, lasted for five years, and the results were published in Medicalxpress magazine. 

"The progression of latent TB to active disease can be life-threatening to people living with HIV, so an early biomarker for active TB disease could be a critical tool to profoundly improve clinical outcomes for patients with this co-infection." said Col. Julie Ake, M.D., the director of MHRP and the AFRICOS lead investigator.

AFRICOS study

The study was conducted from 2013 to 2018 in several African countries. 2,014 people living with HIV took part in the testing.

During the period of observation participants were screened for the active form of TB using the Xpert MTB/RIF diagnostic test. In addition, the team studied longitudinal samples of mononuclear blood cells before, during and after the diagnosis of tuberculosis in patients with an active and latent form of the disease.

Based on the samples collected, the researchers analysed the activation station of MBT-specific CD4 cells as a surrogate biomarker for diagnosis tuberculosis in patients who are HIV positive.

Results

Laboratory analysis showed that the MTB-specific activation of CD4+ T-cells distinguished active TB from latent TB with a sensitivity of 86%. In many cases, the transition of latent to active TB (as shown by the analysis of the MTB-specific T-tells) began 6-12 months before the diagnosis of clinical symptoms, and the appearance of bacterial in sputum.

The data obtained from AFRICOS indicates that the use of a blood-based biomarker can contribute to the early detection of tuberculosis. This, in turn, will improve the clinical outcomes of the disease, as well as help stop further the spread of tuberculosis.