Individual variations in infectiousness explain long‐term disease persistence in wildlife populations

Abstract

Viral disease persistence in species without a reservoir host is of importance for public health and disease management. But how can disease persistence be explained? We developed a spatially-explicit individual-based model that takes into account both ecological and viral traits as well as variable space to test disease persistence hypotheses under debate. We introduce a novel concept of modeling alternative disease courses at the individual level, causing transient infections or killing infected animals, with the lethally infected having a variable life-expectancy. We systematically distinguish between disease invasion and persistence. We use classical swine fever (CSF), an economically very important livestock disease in a social host, the wild boar, as a reference system to test and rank the persistence hypotheses under debate. Parameter values for host population demographics and CSF epidemiology reflect current knowledge. Sensitivity analysis of the model parameters revealed that the most important factor for disease persistence is a disease profile with mostly transient, i.e. surviving individuals requiring immunity, and some chronically, long-term infected animals. Immune individuals can constantly produce susceptible offspring, while some chronically infected individuals act as 'super spreaders' in time. Thus, variations in the course of the disease at the individual level are important factors determining persistence, which is usually not taken into account in the prominent measure of epidemiology, i.e. the basic reproductive number R 0 , which reflects the 'reproductive potential' of the infected sub-population. We discuss our results with regard to the general issues of modeling epidemics and disease management issues.

Alternative control strategies against ASF in wild boar populations

“…European situation on several occasions (Dhollander et al 2015;Lange et al 2015Lange et al , 2012EFSA 2012EFSA , 2009Kramer-Schadt S et al 2009;Fernandez et al 2006;Alban et al 2005 neighbouring groups enabling carcass contact transmission to adjacent animals. Additionally, in special scenarios a moribund animal may be forced to leave its core home-range by by intensive drive hunts (expert scenario).…”

Control and eradication of Classic Swine Fever in wild boar

“…The efficiency of monitoring and surveillance systems (MOSS) has to be evaluated with regard to the changing epidemiological situation (Kramer-Schadt et al, 2009). Basically, there are two main tasks: Task 1.…”

Host behaviour and physiology underpin individual variation in avian influenza virus infection in migratory Bewick's swans

“…Yet hosts inevitably vary in their exposure and sensitivity to pathogenic infection. The way in which infection varies between individual hosts is fundamental to the transmission and maintenance of pathogens, as well as their impact on host fitness [3][4][5][6]. It is therefore crucial to identify differential patterns of infection and understand the mechanisms responsible.…”