Abstract:
BACKGROUND: Untreated latent TB infection (LTBI) is a significant risk factor for
active pulmonary tuberculosis, hence predisposing to adverse pregnancy outcomes
and mother to child transmission. The prevalence of latent tuberculosis in
pregnancy and its association, if any, with various socio-demographic, obstetric
and clinical characteristics was evaluated.
METHODS: Northern Tanzania was chosen as the study site. In a cross-sectional
study, a total of 286 pregnant women from 12 weeks gestational age to term were
assessed. Screening was undertaken using an algorithm involving tuberculin skin
testing, symptom screening in the form of a questionnaire, sputum testing for
acid fast bacilli followed by shielded chest X-rays if indicated. HIV serology
was also performed on consenting participants.
RESULTS: Prevalence of latent infection ranged between 26.2% and 37.4% while HIV
sero prevalence was 4.5%. After multivariate logistic analysis it was found that
age, parity, body mass index, gestational age, and HIV sero status did not have
any significant association with tuberculin skin test results. However certain
ethnic groups were found to be less vulnerable to LTBI as compared to others (Chi
square = 10.55, p = 0.03). All sputum smears for acid fast bacilli were negative.
CONCLUSION: The prevalence of latent tuberculosis in pregnant women was found to
be relatively high compared to that of the general population. In endemic areas,
socio-demographic parameters alone are rarely adequate in identifying women
susceptible to TB infection; therefore targeted screening should be conducted for
all pregnant women at high risk for activation (especially HIV positive women).
As opposed to the current policy of passive case detection, there appears to be
an imminent need to move towards active screening. Ethnicity may provide
important clues into genetic and cultural differences which predispose to latent
tuberculosis, and is worth exploring further.
