Detecting Presymptomatic Infection Is Necessary to Forecast Major Epidemics in the Earliest Stages of Infectious Disease Outbreaks

Abstract

We assess how presymptomatic infection affects predictability of infectious disease epidemics. We focus on whether or not a major outbreak (i.e. an epidemic that will go on to infect a large number of individuals) can be predicted reliably soon after initial cases of disease have appeared within a population. For emerging epidemics, significant time and effort is spent recording symptomatic cases. Scientific attention has often focused on improving statistical methodologies to estimate disease transmission parameters from these data. Here we show that, even if symptomatic cases are recorded perfectly, and disease spread parameters are estimated exactly, it is impossible to estimate the probability of a major outbreak without ambiguity. Our results therefore provide an upper bound on the accuracy of forecasts of major outbreaks that are constructed using data on symptomatic cases alone. Accurate prediction of whether or not an epidemic will occur requires records of symptomatic individuals to be supplemented with data concerning the true infection status of apparently uninfected individuals. To forecast likely future behavior in the earliest stages of an emerging outbreak, it is therefore vital to develop and deploy accurate diagnostic tests that can determine whether asymptomatic individuals are actually uninfected, or instead are infected but just do not yet show detectable symptoms.

Structure in the variability of the basic reproductive number (R0) for Zika epidemics in the Pacific islands

“…In addition, they were missing in New Caledonia, which leads to strong correlation between our estimation of the observation rate and the fraction of the population involved in the epidemic. Because of the high proportion of asymptomatic or mildly symptomatic cases, the magnitude of the outbreaks is difficult to evaluate without precise seroprevalence data (Metcalf et al, 2016) or detection of mild, asymptomatic or pre-symptomatic infections (Thompson et al, 2016). Considering vectors, no demographic data were available and this partly explains the large variability of our $R_0$ estimations.…”

Nanoswitch-linked immunosorbent assay (NLISA) for fast, sensitive, and specific protein detection

“…Recently, the rapid spread of infectious agents such as Zika virus and Ebola have led to public health incidents throughout the world. High-sensitivity detection is critical for early diagnosis of infectious diseases, with presymptomatic identification helpful for monitoring, forecasting, and ideally limiting epidemics in the early stages of an outbreak (20). Preferably, testing would be done rapidly, inexpensively, and at the point of care.…”

Foundational and Translational Research Opportunities to Improve Plant Health

“…Recent work has shown that adaptive sampling can improve the efficiency of management of some diseases (Parry 2014; Parnell 2014, 2017); however, effective control requires detailed, intensive sampling of host populations which may not be showing symptoms (Cunniffe et al 2016). The distinction between severe, explosive invasions and minor outbreaks which require less expensive intervention is challenging (Thompson et al 2016). Foundational research on both theoretical and actual population dynamics on a landscape scale is essential.…”