Prevalence of Tuberculosis among bedside contacts of Smear Positive Tuberculosis Patients at The University Teaching Hospital, Lusaka, Zambia

Abstract

Background: Screening of contacts of tuberculosis (TB) patients is not routinely done in resourcelimited countries like Zambia despite the World Health Organization (WHO) recommendations, leading to missed opportunities for prevention, early diagnosis and high mortality.
Objective: Main objective was to establish the prevalence of latent and active tuberculosis in bedside contacts of smear-positive index patients and associated risk factors.
Methods: The study was carried at the University Teaching Hospital, a tertiary level facility. We conducted a cross sectional analytical study. We included 64 TB-unexposed and 69 TB-exposed contacts in this analysis. We recruited bedside contacts of smear-positive TB patients (TB Exposed group) in medical wards and contacts of surgical patients (TB Unexposed group) as a comparison group. A structured questionnaire was used to collect data on demographic, laboratory and clinical parameters among them being, age,  gender, residence, relationship index patient's sputum grades BMI and HIV status. Active TB was diagnosed microbiologically and radiologically, while latent tuberculosis infection (LTBI) by tuberculin skin test (TST). Collected data was analysed using STATA 13 to determine the prevalence of TB and LTBI and the associated factors. A p value of < 0.05 was considered statistically significant.
Results: The mean age for TB unexposed and that of TB exposed was of 41.2 [±13.5] years and 40.2 [±14.7] years respectively. The Prevalence of active TB in TB exposed and in TB unexposed was 13.0% and 0% respectively. The prevalence of LTBI among TB exposed and TB unexposed was 83.1% and 38.3% respectively. Active TB in TB exposed bedside contact was associated with duration of hospital stay (AOR 2.45, 95% CI 1.0 – 5.9, p = 0.03) and index patient's sputum grade of 2+ (AOR 4.4, 95% CI 1.07 -18.3, p = 0.04).
Conclusion: Bedside contacts of active TB patients are at an increased risk of contracting both latent and active TB. Further, our findings suggest a significant prevalence of LTBI in the general population of Lusaka. Bedside contact tracing is an effective approach to finding the missing TB patients our setting of a high TB burden country/community. The findings call for an urgent need to institute effective TB control/preventive measures with active case finding as a priority and LTBI screening finding and treatment.

Keywords: Bedside contacts, TB exposure, background exposure, active TB, LTBI.