Multidisciplinary Effort Leading to Effective Tuberculosis Community Outbreak Containment in Israel

Abstract

Tuberculosis (TB) is the second-most prevalent cause of mortality resulting from infectious diseases worldwide. It is caused by bacteria belonging to the Mycobacterium tuberculosis complex (MTBC). In Israel, TB incidence is low, acknowledged by the WHO as being in a pre-elimination phase. Most cases occur among immigrants from high TB incidence regions like the Horn of Africa and the former Soviet Union (FSU), with occasional outbreaks. The outbreak described in this report occurred between 2018 and 2024, increasing the incidence rate of TB in the region. Control of this outbreak posed challenges due to factors including a diverse population (including Ethiopian immigrants, Israeli-born citizens, and immigrants from other countries), economic and social barriers, and hesitancy to disclose information. The unique multidisciplinary team formed to address these challenges, involving the local TB clinic, district health ministry, health maintenance organization (HMO) infectious disease consultant, neighborhood clinic, and National Mycobacterium Reference Laboratory (NMRL), achieved effective treatment and containment. Whole genome sequencing (WGS) proved pivotal in unraveling patient connections during the outbreak. It pinpointed those patients overlooked in initial field investigations, established connections between patients across different health departments, and uncovered the existence of two distinct clusters with separate transmission chains within the same neighborhood. This study underscores collaborative efforts across sectors that successfully contained a challenging outbreak.

Keywords: Israel; epidemiological investigation; outbreak; tuberculosis; whole genome sequencing.

Figure 1

Contact tracing of diagnosed TB patients during TB outbreak: (A,B) show the network of diagnosed TB patients based on traditional field work contact tracing during TB outbreak in the neighborhood. Arrows indicate the most likely source case of infection, suggested by epidemiologic investigation findings. CD = clinical diagnosis; Non-seq = mycobacteria could not be genome sequenced. The figures in grey represent the index patients. Other colors indicate the characteristics of the contact with the source case, as detailed in the legend.

Figure 2

Minimum spanning tree of MTBC isolates relevant to the ongoing epidemiological investigation: The numerical values alongside the lines linking the circles represent the SNP numbers. A cluster of cases is defined when the distance between the isolates in the group is 12 SNPs or fewer. Identical isolates appear in a single circle. The tree shows two clusters, each originating from a different index case. Most of the patients shown in the tree live in the same neighborhood. The patients marked in red were linked to the clusters solely through WGS.