Modelling outbreak response strategies for preventing spread of emergent Neisseria gonorrhoeae strains in men who have sex with men in Australia

The ability to treat gonorrhoea with current first-line drugs is threatened by the global spread of extensively drug resistant (XDR) Neisseria gonorrhoeae (NG) strains. In Australia, urban transmission is high among men who have sex with men (MSM) and emergence of an imported XDR NG strain in this population could result in an epidemic that would be difficult and costly to control. An individual-based, anatomical site-specific mathematical model of NG transmission among Australian MSM was developed and used to evaluate the potential for elimination of an emergent XDR NG strain under a range of case-based and population-based test-and-treat strategies. When applied upon detection of the imported strain, these strategies enhanced the probability of elimination and reduced the outbreak size compared with current practice. The most effective strategies combined testing targeted at regular and casual partners with increased rates of population testing. However, even with the most effective strategies, outbreaks could persist for up to 2 years post-detection. Our simulations suggest that local elimination of emergent NG XDR strains can be achieved with high probability using combined case-based and population-based test-and-treat strategies. These strategies may be an effective means of preserving current treatments in the event of wider XDR NG emergence.