A framework to monitor changes in transmission and epidemiology of emerging pathogens: Lessons from Nipah virus

Abstract : It is of uttermost importance that the global health community develops the surveillance capability to effectively monitor emerging zoonotic pathogens that constitute a major and evolving threat for human health. Here, we propose a comprehensive framework to measure changes in (i) spillover risk, (ii) interhuman transmission, and (iii) morbidity/mortality associated with infections based on six epidemiological key indicators derived from routine surveillance. We demonstrate the indicators' value for the retrospective or real-time assessment of changes in transmission and epidemiological characteristics using data collected through a long-standing, systematic, hospital-based surveillance system for Nipah virus in Bangladesh. We show that while interhuman transmission and morbidity/mortality indicators were stable, the number and geographic extent of spillovers varied significantly over time. Such combination of systematic surveillance and active tracking of transmission and epidemiological indicators should be applied to other high risk emerging pathogens to prevent public health emergencies.