RT Journal Article
SR Electronic
T1 Farm productive realities and the dynamics of bovine viral diarrhea (BVD) transmission
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 230045
DO 10.1101/230045
A1 Bryan Iotti
A1 Eugenio Valdano
A1 Lara Savini
A1 Luca Candeloro
A1 Armando Giovannini
A1 Sergio Rosati
A1 Vittoria Colizza
A1 Mario Giacobini
YR 2017
UL http://biorxiv.org/content/early/2017/12/08/230045.abstract
AB Bovine Viral Diarrhea (BVD) is a viral disease that affects cattle and that is endemic to many European countries. It has a markedly negative impact on the economy, through reduced milk production, abortions, and a shorter lifespan of the infected animals. Cows becoming infected during gestation may give birth to Persistently Infected (PI) calves, which remain highly infective throughout their life, due to the lack of immune response to the virus. As a result, they are the key driver of the persistence of the disease both at herd scale, and at the national level. In the latter case, the trade-driven movements of PIs, or gestating cows carrying PIs, are responsible for the spatial dispersion of BVD. Past modeling approaches to BVD transmission have either focused on within-herd or between-herd transmission. A comprehensive portrayal, however, targeting both the generation of PIs within a herd, and their displacement throughout the Country due to trade transactions, is still missing. We overcome this by designing a multiscale metapopulation model of the spatial transmission of BVD, accounting for both within-herd infection dynamics, and its spatial dispersion. We focus on Italy, a country where BVD is endemic and seroprevalence is very high. By integrating simple within-herd dynamics of PI generation, and the highly-resolved cattle movement dataset available, our model requires minimal arbitrary assumptions on its parameterization. Notwithstanding, it accurately captures the dynamics of the BVD epidemic, as demonstrated by the comparison with available prevalence data. We use our model to study the role of the different productive realities of the Italian market, and test possible intervention strategies aimed at prevalence reduction. We find that dairy farms are the main drivers of BVD persistence in Italy, and any control strategy targeting these farms would lead to significantly higher prevalence reduction, with respect to targeting other production compartments. Our multiscale metapopulation model is a simple yet effective tool for studying BVD dispersion and persistence at country level, and is a good instrument for testing targeted strategies aimed at the containment or elimination of this disease. Furthermore, it can readily be applied to any national market for which cattle movement data is available.