Public Health Perspective – Strengthening the Analytical Approach Hayley Teshome Tesfaye, Public Health England 29 September 2014 We commend Horwood et al. (2014) on their recent research article outlining the spatio-temporal epidemiology of the cholera outbreak in Papua New Guinea, 2009–2011. We recognise, from our own experiences in similar situations, the issues of comprehensive data collection within a complex outbreak situation, in a resource-poor setting and within a challenging environment. From a public health perspective, we feel that the analytical approach could have been more robust to aid understanding of the reasons for the spread of the cholera outbreak. For example, the analytical tool SatScan only considers clusters in circles, which may fail to identify spread along a road or path, which is not circular. The authors state in their aim that they will highlight potential mitigation strategies that could be used for future outbreaks of cholera. However, the research article does not provide any data on the local causesof the spread of the outbreak, therefore any potential mitigation strategies are conjecture, rather than based on locally applied evidence. Consideration of the outbreak at the level of each of the 81 geo-referenced health facilities could allow more detailed geographical mapping related to infrastructure, industry, rivers, markets and travel such as road, track or trail. This would give the reader more insight into factors that may facilitate the spread of cholera and possible mitigation strategies. In particular, the cluster analysis of cases occurring in the Morobe province during the first 2 months of the outbreak would have benefited from including additional geographic information. This would have improved the understanding of the transmission in the early phase and thereby address the authors’ aim of identifying mitigation strategies in order to inform future outbreaks. Authors: - Hayley Teshome Tesfaye, Specialty Registrar in Public Health Merav Kliner, Specialty Registrar in Public Health Olukemi Adeyemi, Specialty Registrar in Public Health Sarah Reeves, Foundation Year 2 Doctor Thomas Inns, Epidemiology scientist Valerie Decraene, Senior Epidemiology scientist Alex Stewart, Consultant in Public Health Paul Cleary, Consultant Epidemiologist Competing interests No competing interests.