First report of human Mycobacterium bovis infection in a veterinary laboratory worker in the Republic of Korea

Abstract

Background: In the Republic of Korea, the previous surveillance system for zoonotic tuberculosis (TB) involved the X-ray testing of humans in contact with Mycobacterium bovis-infected livestock. In contrast, the updated surveillance system incorporates the genotyping of cultured Mycobacterium isolates for high-risk occupational groups. This study aimed to systematically document the detection, diagnosis, assessment, and response in the epidemic investigation of zoonotic TB in a laboratory worker in the Republic of Korea.

Methods: M. bovis was confirmed using spoligotyping and whole genome sequencing. Clinical characteristics were reviewed through epidemiological investigation and interviews with the affected individual. Transmission routes and secondary spread were assessed via field epidemiological investigations and contact evaluations using chest X-ray and interferon gamma release assay for latent TB infection.

Results: A 56-year-old laboratory worker presented with chest X-ray findings compatible with TB and subsequently tested positive for M. bovis. She had no clinical or family history of TB and remained asymptomatic. She completed a 6 month treatment regimen of isoniazid, rifampin, ethambutol, and pyrazinamide without hospitalization. Although no direct transmission pathways for zoonotic TB were identified, her work in a laboratory, processing specimens for zoonotic TB, indicated potential laboratory related exposure.

Conclusion: This case underscores the importance of stringent use of personal protective equipment among high-risk occupational groups and the implementation of an enhanced surveillance system to report zoonotic TB. These findings highlight the need for a One Health approach and proactive surveillance, emphasizing the necessity of refining and strengthening surveillance systems for precise monitoring and an effective response.

Keywords: High-risk group; Laboratory worker; Mycobacterium bovis; Occupational exposure; One Health; Zoonoses.

Figure 1.

Phylogenetic analysis of Mycobacterium bovis strains. The core genome multilocus sequence typing of M. bovis was analyzed using Ridom SeqSphere+ ver. 8.5.0 (Ridom GmbH). A phylogenetic tree was constructed using the M. bovis whole genome sequences registered in the National Center for Biotechnology Information database with the unweighted pair-group method with arithmetic mean method based on 2,612 loci for the Mycobacterium tuberculosis complex.

Figure 2.

Timeline of the detection of zoonotic tuberculosis. TB, tuberculosis; KDCA, Korea Disease Control and Prevention Agency; WGS, whole genome sequencing; M. bovis, Mycobacterium bovis; APQA, Animal and Plant Quarantine Agency; ME, Ministry of Environment.