Frequency of tuberculosis in Farm Workers Exposed to dairy and beef livestock in Colombia

Abstract

The objective of this study was to determine the frequency of tuberculosis (TB) in workers from dairy and beef livestock farms in the northern part of Colombia. Tuberculin skin test and an interferon-gamma release assay (IGRA) were used for diagnosis of latent tuberculosis; sputum samples were taken from respiratory symptomatic subjects, microbiological and molecular tests were done for diagnosis of active TB. Absolute frequencies, percentages, and crude prevalence ratios were calculated, and a robust Poisson Model with adjustment by municipality was made. In 674 farm workers, latent TB frequency was 35.8%. Variables such as having had pulmonary TB (PR 2.82, 95% CI 1.90 - 4.17), having been in contact with people with active TB (PR 1.57, 95% CI 1.24 - 1.98), and having performed some undergraduate or postgraduate study (PR 1.6, 95% CI 1.03 - 2.49), were significantly associated with latent TB. No active tuberculosis disease was confirmed in symptomatic respiratory patients. The exposure level to cattle was not significantly associated with latent TB infection. In conclusion, in the studied population exposure to cattle was not a risk factor for TB, other factors commonly found in general population exposed to human TB were demonstrated.\n\nAuthor summaryZoonotic TB is a disease caused by the transmission of the M. bovis bacteria that is part of the Mycobacterium tuberculosis Complex, through contact with cattle to humans, by the consumption of unpasteurized dairy products from infected animals or by inhalation of aerosols exhaled by sick animals.\n\nThis study investigated the frequency of TB in human population related to cattle, in order to determine if there were risk factors related to TB infection or disease. Finding that there was no significant relationship between being exposed to cattle and having latent TB. However, the results of this study together with other research reported in the literature suggest that research on zoonotic and bovine TB should be continued, especially about epidemiology, diagnostic methods, health systems and interventions coordinated with veterinary services.