Location: Foreign Animal Disease ResearchTitle: Phylogeographic analysis of the 2000-2002 foot-and-mouth disease epidemic in Argentina Author
Submitted to: Infection, Genetics and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2016
Publication Date: 4/11/2016
Citation: Brito, B., Konig, G., Cabanne, S., Perez-Beascoechea, C., Rodriguez, L.L., Perez, A. 2016. Phylogeographic analysis of the 2000-2002 foot-and-mouth disease epidemic in Argentina. Infection, Genetics and Evolution. 41:93-99. Interpretive Summary: Foot-and-mouth disease (FMD) is a highly transmissible disease of livestock that is very costly and difficult to eradicate when in emerges in previously disease free countries. FMD is the main trade barrier to animals and animal products worldwide. Countries invest billions of dollars to control and eradicate the FMD virus though vaccination and strict control of animal movement. Such was the case in Argentina where, after decades of combating the disease, the country was declared free of the virus in 1999 and vaccination programs were discontinued. However, the disease reappeared in 2000, spread rapidly throughout the country, and affected more than 2500 herds. Available records and viral strains afforded us a unique opportunity to assess the progression of this FMD epidemic by analyzing virus evolution. We determined the genetic sequence of the different viruses obtained during the epidemic and used it to estimate the spread pattern of FMD virus. The epidemic was one of the largest reported in an FMD-free country. We showed that, as the number of cases increased during the epidemic, so did the genetic variation. The data obtained could be used to predict the spread of future FMD outbreaks in previously disease-free countries.
Technical Abstract: Foot-and-mouth disease (FMD) is a highly transmissible disease of livestock. FMD has been eradicated from many countries and the consequences of FMD epidemics are, in some cases, devastating. That was the case of Argentina in 2000-2002, where within few months, FMD virus spread throughout most of the country and affected more than 2,500 herds. Available records and viral strains from this epidemic afforded us a unique opportunity to assess the progression of this FMD epidemic by analyzing virus evolution. We used whole genome sequences of 30 randomly sampled viruses to reconstruct the transmission history of FMD virus using a relaxed random walk diffusion approach. The objective of the study here was to estimate the spread pattern of FMDV A/Arg/01 in one of the largest epidemics reported in a disease-free country. To determine if the approximate overall genetic diversification of the virus was related to the number of outbreaks, we constructed a Bayesian Skyline Plot and compared it with the epidemic curve and the within-herd transmission rate. We describe the spread of the virus throughout the epidemic, and show that the genetic temporal diversity of the virus was associated with the increasing number of outbreaks in the exponential phase of the epidemic. Results demonstrate that genetic data collected during an epidemic can be informative of epidemiological indicators, being a valuable tool to quantify disease incidence and spread and, ultimately, forecast the course of an epidemic.