The distribution and environmental ecology

of Foot and Mouth Disease

Foot and Mouth Disease is an RNA virus of which there are seven known strains. Although North and Central America, as well as the Caribbean Islands are FMD free, strains A, O, and C are all found in South America. Foot and Mouth Disease outbreaks have occurred throughout the South American continent since the 1890’s. Relating this situation to the basic geographic concept of distance decay, the closer a disease outbreak to the U.S., the more likely the chance of introduction. In the case of FMD from South America, virtual proximity to the U.S. brought on through travel and trade is concerning.  Vaccination programs have reduced the number of outbreaks in South America (Casas Olascoaga et al. 1982), though the disease is considered endemoepidemic in most countries there (Acha and Szyfres 1987). The US has been free of FMD since 1929. However, if FMD were introduced the economic losses would be considerable, not only in terms of impacts to the livestock industry and throughout the food and fiber system. The food and fiber system includes the activities of farmers, processors, manufacturers, wholesalers, retailers, restaurateurs, and transporters which are coordinated to satisfy the changing demands of households, businesses and government, and other nations. Surveillance data used in this study for both FMD virus strains O and A were compiled by PANAFTOSA from 1972 - 2000. PANAFTOSA  is a reference laboratory for FMD in South America. PANAFTOSA  provides monthly reports on FMD surveillance and countries send specimens from outbreaks to Panaftosa for confirmatory testing and typing. Therefore the data used in this study represents incidence data for the type and location of FMD virus in South America.

 

            

These data were manipulated within ArcView 3.2a and ArcGIS 9.0 (ESRI, Redlands, California) and SAS version 9.0 (SAS Inc, North Carolina) to allow for mapping by political unit, the creation of a cartographic animation of FMD spread, and spatial analysis of FMD hotspots using Kernel Density Analysis. The monthly mean number of cases and the annual total number of cases were animated to illustrate the spread of FMD through South America through space and time using the Tracking Analyst extension for ArcView 3.2a.

Click the image (left) to watch a Cartographic Animation of the dispersion of Foot and Mouth Disease throughout South America from 1972—2001.

 

Animation Credits: Andrew Curtis, Sarah Hinman, Jason Blackburn

Standard Deviation (2 SD or greater) maps of Kernel Density Analyses for the monthly average FMD incidence by South American province for the period from 1972—2001.  Blue KDA indicate the intensity of Virus O and red KDA indicate the intensity of Virus A. 

Foot and Mouth Disease Map Gallery

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© LSU WHOCC 2005