Prevalence of Tuberculosis among Offshore Oil & Gas Workers in Nigeria's Niger Delta by Using the QuantiFERON-TB Gold In-Tube Test-A Preliminary Report

Abstract

Abstract Following detection of two open tuberculosis (TB) cases among offshore installation workers some years ago, screening for latent TB infection using an interferon gamma release assay, QuantiFERON-TB Gold test (QTBGT), was introduced in the oil industry. Since the introduction of QTBGT, this screening has been used as a prerequisite for working offshore with focus on TB diagnosis (active and latent) and monitoring of clinical management. The aim of our retrospective descriptive study was to determine the prevalence of patients with latent or active TB in offshore workers in Nigeria. Methods. We used medical records in order to gather all demographic and medical data of patients who underwent QuantiFERON-TB Gold test (QFT-G Cellestis Limited, Carnegie, Victoria, Australia) within a period of 40 month in our facility. Ages, gender, country of origin and test results of the QTBGT were documented. We furthermore evaluated the findings of chest x rays, and compared findings by age and region of origin of the patients. Results. 2055 workers were screened for tuberculosis infection. 145 patients could not be implemented due to incomplete medical files. Among the remaining 1910 workers tested with QTBGT, 1163 (61%) were negative, 689 (36%) were positive, 43 (2%) had indeterminate results and 15 samples were rejected by the laboratory due to inproper sample handling. In total 2 cases of active tuberculosis were detected. The range of positive samples on different platform ranges from 10 – 50%. 349 of the positive cases were further examined and placed on treatment for latent TB. Out of them 270 (78%) had normal chest x-ray findings; 79 (22%) patients showed hilar shadows. Out of those patients placed on treatment 24 persons were retested in our facilities, 8 did seroconvert to negative while 16 did not, 50% of indeterminate results turned negative on the repeat test. Conclusion. There was good correlation between our findings and the numbers described in literature reflecting the incidence in other study populations QTBGT test appears to be an good screening tool as a safety measure to mitigate spread of TB among offshore workers; it would be highly beneficial if in-cooperated into pre-employment medicals especially in this region, HIV testing can be offered on voluntary basis to workers with positive QTBGT.