Two-Host, Two-Vector Basic Reproduction Ratio (<i>R</i><sub>0</sub>) for Bluetongue

Turner, Joanne ORCID: 0000-0002-0258-2353, Bowers, Roger G ORCID: 0000-0001-8207-297X and Baylis, Matthew ORCID: 0000-0003-0335-187X
(2013) Two-Host, Two-Vector Basic Reproduction Ratio (<i>R</i><sub>0</sub>) for Bluetongue. PLOS ONE, 8 (1). e53128-.

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Mathematical formulations for the basic reproduction ratio (R(0)) exist for several vector-borne diseases. Generally, these are based on models of one-host, one-vector systems or two-host, one-vector systems. For many vector borne diseases, however, two or more vector species often co-occur and, therefore, there is a need for more complex formulations. Here we derive a two-host, two-vector formulation for the R(0) of bluetongue, a vector-borne infection of ruminants that can have serious economic consequences; since 1998 for example, it has led to the deaths of well over 1 million sheep in Europe alone. We illustrate our results by considering the situation in South Africa, where there are two major hosts (sheep, cattle) and two vector species with differing ecologies and competencies as vectors, for which good data exist. We investigate the effects on R(0) of differences in vector abundance, vector competence and vector host preference between vector species. Our results indicate that R(0) can be underestimated if we assume that there is only one vector transmitting the infection (when there are in fact two or more) and/or vector host preferences are overlooked (unless the preferred host is less beneficial or more abundant). The two-host, one-vector formula provides a good approximation when the level of cross-infection between vector species is very small. As this approaches the level of intraspecies infection, a combination of the two-host, one-vector R(0) for each vector species becomes a better estimate. Otherwise, particularly when the level of cross-infection is high, the two-host, two-vector formula is required for accurate estimation of R(0). Our results are equally relevant to Europe, where at least two vector species, which co-occur in parts of the south, have been implicated in the recent epizootic of bluetongue.

Item Type: Article
Additional Information: © 2013 Turner et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Uncontrolled Keywords: Animals, Cattle, Sheep, Ceratopogonidae, Bluetongue virus, Bluetongue, Insect Vectors, Models, Biological, South Africa, Basic Reproduction Number
Depositing User: Symplectic Admin
Date Deposited: 14 Apr 2015 15:22
Last Modified: 13 Oct 2023 09:06
DOI: 10.1371/journal.pone.0053128
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