Abstract
Increased prevalence of latent tuberculosis infection (LTBI) has been observed among high-risk populations such as healthcare workers (HCWs). The results may depend on the method of LTBI assessment, interferon-gamma release assay (IGRA) and/or tuberculin skin test (TST). Here, we investigated the prevalence and risk factors for LTBI assessed by both IGRAs and TST in HCWs living in Morocco, a country with intermediate tuberculosis (TB) endemicity and high BCG vaccination coverage. HCWs were recruited in two Moroccan hospitals, Rabat and Meknes. All the participants underwent testing for LTBI by both IGRA (QuantiFERON-TB Gold In-Tube, QFT-GIT) and TST. Different combinations of IGRA and TST results defined the LTBI status. Risk factors associated with LTBI were investigated using a mixed-effect logistic regression model. The prevalence of LTBI among 631 HCWs (age range 18–60 years) varied from 40.7% (95%CI 36.9–44.5%) with QFT-GIT to 52% (95%CI 48.2–56.0%) with TST using a 10 mm cut-off. The highest agreement between QFT-GIT and TST (κ = 0.50; 95%CI 0.43–0.56) was observed with the 10 mm cut-off for a positive TST. For a definition of LTBI status using a double positive result for both QFT-GIT and TST, significant associations were found with the following risk factors: being male (OR = 2.21; 95%CI 1.40–3.49; p = 0.0007), belonging to age groups 35–44 years (OR = 2.43; 95%CI 1.45–4.06; p = 0.0007) and even more 45–60 years (OR = 4.81; 95%CI 2.72–8.52; p = 7.10−8), having a family history of TB (OR = 6.62; 95%CI 2.59–16.94; p = 8.10−5), and working at a pulmonology unit (OR = 3.64; 95%CI 1.44–9.23; p = 0.006). Smoking was associated with LTBI status when defined by a positive QFT-GIT result (OR = 1.89; 95%CI 1.12–3.21; p = 0.02). A high prevalence of LTBI was observed among HCWs in two Moroccan hospitals. Male gender, increased age, family history of TB, and working at a pulmonology unit were consistent risk factors associated with LTBI.
Highlights
One quarter of the world population is estimated to have latent tuberculosis infection (LTBI) [1]
We investigated the prevalence and risk factors for LTBI assessed by both interferon-gamma release assay (IGRA) and TST in Healthcare workers (HCWs) from Morocco, a low-middle-income country with an intermediate annual incidence of TB (99/100,000 in 2017), and high Bacillus Calmette-Guerin (BCG) vaccination coverage [15,16]
54% of HCWs were male (n = 341), 47.1% were younger than 35 years old (n = 297) and 44.1% of them worked in a non-clinical department (n = 278)
Summary
One quarter of the world population is estimated to have latent tuberculosis infection (LTBI) [1]. At this stage, infected subjects do not experience clinical symptoms and are not contagious. They have a 5–10% life-time risk of developing active tuberculosis (TB) [2], which is most pronounced during the early stage of infection [3], thereby becoming an important source of TB contagion. Several studies have investigated the prevalence of and the risk factors for LTBI in HCWs [4,5,6,7] in countries highly endemic for TB. Reported pooled prevalences ranged from 37 to 63% in these recent meta-analyses [4,5,6,7] with a variability depending on important factors such as countries’ income, Bacillus Calmette-Guerin (BCG) vaccination coverage, and LTBI status definition
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