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The study, published in PLOS ONE, investigated 25 years of TB treatment in over 8,500 patients in Victoria, 600 of whom were in regional areas. The description of notified TB cases and comparison of treatments in regional and metropolitan areas acknowledges that TB's impact and the effectiveness of interventions can vary significantly based on geographic and demographic factors.

The Royal Melbourne Hospital’s Dr Nompilo Moyo, former Clinical Nurse Consultant at the Victorian Infectious Diseases Service (VIDS) at the Doherty Institute (now lecturer at Federation University) and first co-author of the study, said their findings showed that although TB incidence in regional Victoria from 1995 to 2019 has remained essentially stable, the nature of the notified TB cases reveal notable differences and similarities between regional and metropolitan areas about birthplace, residence and patterns of the strains.

“Our data highlights that a significant portion of TB cases, 66 per cent in regional and 90 per cent in metropolitan areas, were among individuals born overseas,” said Dr Moyo.

“The 25 to 34 age group had the highest proportion of TB cases in both regional and metropolitan settings, with the overseas-born population accounting for 27 per cent of the cases, more than three times higher than the Australian-born population.”  

Metropolitan areas see higher TB case numbers due to denser populations, and young adults are at a higher risk of TB, possibly due to factors like increased mobility and social or economic activities that might expose them to the infection more than other age groups.

The research also noted people living in regional areas are more likely to complete treatment (90 per cent) compared to those in regional areas (85 per cent).

Older males living in regional Victoria are less likely to complete their TB treatment due to difficulties in following up and challenges with medication supervision.

The researchers also found that multidrug-resistant tuberculosis (MDR-TB) poses a significant health challenge, with a similar proportion of MDR-TB cases observed in both regional and metropolitan settings.

Drug-resistant TB is more likely to be found in populations migrating from countries with higher disease prevalence or resistance rates.

“However, cases of extensive drug-resistant TB were exclusively reported in the metropolitan area among overseas-born individuals, suggesting a possibility that these more severe and treatment-resistant forms of TB are currently limited to metropolitan areas,” added Dr Moyo.

Their findings mirror WHO data, which shows that TB primarily affects adults in their most productive years, with more than 80 per cent of cases and deaths reported in low and middle-income countries where some of Australia’s permanent migrations are drawn from.

The Royal Melbourne Hospital’s Professor Justin Denholm, Medical Director of the Victorian Tuberculosis Program at the Doherty Institute and senior co-author said it is essential to understand that living in regional areas is a significant factor in TB management and outcomes worldwide.

“By acknowledging and addressing these disparities, health authorities can implement more effective and equitable TB control strategies that cater to the unique needs of different populations and, in this case, ongoing surveillance and support for immigrants,” said Professor Denholm.

Professor Denholm believes the presence of drug-resistant TB cases, particularly in metropolitan areas, underscores the importance of continued vigilance and tailored public health strategies to address the complexities of TB transmission and treatment.

“Increasing access to TB services in regional areas is crucial as it poses a significant public health challenge with ongoing impact for affected individuals and families,” he added.

Peer review: Moyo, N et al. Tuberculosis notifications in regional Victoria, Australia: Implications for public health care in a low incidence setting. PLOS ONE. (2023). DOI: 10.1371/journal.pone.0282884

Collaboration: The study is the result of cooperation between the Doherty Institute, Department of Health (Victoria), University of New South Wales, Charles Darwin University, Royal Brisbane and Women’s Hospital.