Some simple rules for estimating reproduction numbers in the presence of reservoir exposure or imported cases.

Some simple rules for estimating reproduction numbers in the presence of reservoir exposure or imported cases. Theor Popul Biol. 2020 Apr 15;: Authors: McLure A, Glass K Abstract For many diseases, the basic reproduction number (R0) is a threshold parameter for disease extinction or survival in isolated populations. However no human population is fully isolated from other human or animal populations. We use compartmental models to derive simple rules for the basic reproduction number in populations where an endemic disease is sustained by a combination of local transmission within the population and exposure from some other source: either a reservoir exposure or imported cases. We introduce the idea of a reservoir-driven or importation-driven disease: diseases that would become extinct in the population of interest without reservoir exposure or imported cases (since R0<1), but nevertheless may be sufficiently transmissible that many or most infections are acquired from humans in that population. We show that in the simplest case, R0<1 if and only if the proportion of infections acquired from the external source exceeds the disease prevalence and explore how population heterogeneity and the interactions of multiple strains affect this rule. We apply these rules in two case studies of Clostridium difficile infection and colonisation: C. difficile in the hospital setting accounting for imported cases, and C. difficile in the gener...
Source: Theoretical Population Biology - Category: Biology Authors: Tags: Theor Popul Biol Source Type: research