Rates of latent tuberculosis in health care staff in Russia.
BACKGROUND
Russia is one of 22 high burden tuberculosis (TB) countries. Identifying individuals, particularly health care workers (HCWs) with latent tuberculosis infection (LTBI), and determining the rate of infection, can assist TB control through chemoprophylaxis and improving institutional cross-infection strategies. The objective of the study was to estimate the prevalence and determine the relative risks and risk factors for infection, within a vertically organised TB service in a country with universal bacille Calmette-Guérin (BCG) vaccination.


RESULTS
We conducted a cross-sectional study to assess the prevalence of and risk factors for LTBI among unexposed students, minimally exposed medical students, primary care health providers, and TB hospital health providers in Samara, Russian Federation. We used a novel in vitro assay (for gamma-interferon [IFN-gamma]) release to establish LTBI and a questionnaire to address risk factors. LTBI was seen in 40.8% (107/262) of staff and was significantly higher in doctors and nurses (39.1% [90/230]) than in students (8.7% [32/368]) (relative risk [RR] 4.5; 95% confidence interval [CI] 3.1-6.5) and in TB service versus primary health doctors and nurses: respectively 46.9% (45/96) versus 29.3% (34/116) (RR 1.6; 95% CI 1.1-2.3). There was a gradient of LTBI, proportional to exposure, in medical students, primary health care providers, and TB doctors: respectively, 10.1% (24/238), 25.5% (14/55), and 55% (22/40). LTBI was also high in TB laboratory workers: 11/18 (61.1%).


CONCLUSIONS
IFN-gamma assays have a useful role in screening HCWs with a high risk of LTBI and who are BCG vaccinated. TB HCWs were at significantly higher risk of having LTBI. Larger cohort studies are needed to evaluate the individual risks of active TB development in positive individuals and the effectiveness of preventive therapy based on IFN-gamma test results.
Drobniewski
Francis
F
Health Protection Agency Mycobacterium Reference Unit and Clinical TB and HIV Group, Institute of Cell and Molecular Sciences, Queen Mary College, University of London, London, United Kingdom. f.drobniewski@qmul.ac.uk
Balabanova
Yanina
Y
Zakamova
Elena
E
Nikolayevskyy
Vladyslav
V
Fedorin
Ivan
I
D000293:Adolescent; D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006282:Health Personnel; D006801:Humans; D017758:Infectious Disease Transmission, Patient-to-Professional; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D012426:Russia / Q000453:epidemiology; D012959:Socioeconomic Factors; D014376:Tuberculosis / Q000453:epidemiology* / Q000635:transmission