Tuberculosis contact investigation: an evaluation of yield and guideline adherence, Upper Bavaria, Germany, 2018 to 2022

Abstract

BACKGROUNDContact investigation of index cases is important for tuberculosis (TB) control in low-incidence countries, yet key performance metrics have not been evaluated in Germany.AIMWe aimed to assess the yield of TB contact investigations, compliance with national guidelines and risk factors for infection among contacts.METHODSWe analysed anonymised data of TB patients and their contacts collected between 2018 and 2022 in Upper Bavaria, Germany. We assessed testing coverage, latent TB infection (LTBI), TB yield, primary prophylaxis and preventive treatment coverage. Risk factors for M. tuberculosis infection (positive tuberculin skin test (TST) / interferon-gamma release assay (IGRA) and/or TB diagnosis) among contacts were identified using multivariable logistic regression and classification tree.RESULTSOf the 2,186 contacts of 174 TB patients, 2,022 (92.5%) had a valid TST/IGRA result and/or a TB diagnosis. Of these, 308 (15.2%) had M. tuberculosis infection, including 10 (0.5%) with TB. Of 241 contacts with LTBI, 66 (28.2%) completed preventive treatment. Among 124 children < 5 years, testing coverage was 75.8%, 16.9% received an immediate chest X-ray and 72.7% primary prophylaxis. Key predictors of infection were born outside Germany (odds ratio (OR) = 2.85; 95% confidence interval (CI): 1.94-4.21) and exposure in community housing (OR = 2.65; 95% CI: 1.65-4.30; reference: exposure at work) or household/family (OR = 2.62; 95% CI: 1.74-4.00).CONCLUSIONWe observed high screening coverage of contacts and yield and risk factors comparable to other low-incidence settings. There is room for improvement regarding preventive treatment and screening of children < 5 years.

Keywords: Mycobacterium tuberculosis infection; contact investigation; contact tracing; latent tuberculosis infection; testing coverage; tuberculosis; yield.

Figure 1

Sex and age distribution of contact persons of index patients with active pulmonary tuberculosis, stratified by country of origin (if available), selected districts of Upper Bavaria^a, 2018–2022

Figure 2

Classification tree for prevalence of Mycobacterium tuberculosis infection in contact persons of index patients with active pulmonary tuberculosis, selected districts in Upper Bavaria^a, 2018–2022 (n = 2,022)