Risk And Prevalence of Latent Tuberculosis Infection Among Healthcare Workers of Tertiary Care Hospital in Karachi Pakistan

More than 10 million people fall sick due to TB annually; Pakistan ranks 5th for highest tuberculosis (TB) burden globally. Latent tuberculosis infection (LTBI) is asymptomatic TB infection that can reactivate later on, causing transmission and disease. Health care workers dealing with positive Mycobacterium Tuberculosis (MTB) samples and patients are at high risk of TB infection. In this study, we investigated the frequency of LTBI in health care workers as well as a comparative group of patients suspected to have LTBI by their physicians. A total of 77 healthy healthcare workers (including phlebotomists, medical technologists, nurses, doctors, and faculty members working closely with TB samples or patients) and 104 patients diagnosed with TB were recruited in our study after institutional ethical approval. 3ml of whole blood was collected from study participants and was dispensed into three specific QFT tubes. (NIL, TB, Mitogen). Samples were investigated for interferon specifically released against TB according to the manufacturer’s protocol by using QuantiFERON TB Gold assay kit. Out of 77 healthcare workers, 16.8% (n=13) were positive for LTBI; these included microbiologists, technicians, phlebotomists, and housekeeping staff. However, none of the doctors and medical technologists tested positive. On the other hand, out of 104 patients, 23.1 % (n=24) were found to be positive, 10.5% (n=11) were indeterminate and 65.3% (n=68) were negative for LTB. The one-tail chi-square test revealed 35.14% risk to the highly exposed HCWs with the overall estimated risk of 42.54%. This study reports a high prevalence of LTBI in HCWs. Among the HCWs, microbiologists and technicians were the most affected. Housekeeping staff was also found to have LTBI. This study also found a higher risk for LTBI in technicians, medical technologists, microbiologists, and phlebotomist as compared to doctors and interns. This highlights the importance of regular screening of all HCWs, including housekeeping staff, in order to control and prevent the spread of this disease.