Investigating the temporal and spatial distribution of foot-and-mouth disease virus serotype C in the Region of South America, 1968-2016.

ABSTRACT

This study investigates the historical temporal trend and geographical distribution of the foot-and-mouth disease virus (FMDv) serotype C in South America; discussing the findings within the context of the actions and strategies carried out for the elimination of foot-and-mouth disease (FMD). This is the first time that such a comprehensive historical compilation has been carried out in the Region; hence, the study is intended as a reference and source of evidence about the presence/absence of FMDv serotype C in South America. Data on the occurrence of FMD were sourced from the Weekly Epidemiological Reports submitted by the countries to Pan American Foot-and-Mouth Disease Center (PANAFTOSA-PAHO/WHO) since 1972, and complemented with other sources of information from the 1968-1971 period. The temporal distribution was examined with local weighted regression (LOESS) to identify two temporal trends, that is, "smoothed" and "over-adjusted", utilising the time-series with the total number of cases per year, at Regional level. Thereafter the outbreaks were aggregated by decades and mapped by the first subnational administrative level. As a result, two major peaks of occurrence were identified, one in the 70s, with up to 1,193 outbreaks, and another in the 80s, with 380. Overall, the investigations show a clear regressive trend in the occurrence of serotype C, with a reduction in the number of outbreaks over-time, and with the subsequent reduction of affected locations. This study illustrates the contrast between the very limited presence over the last 20 years - with only one event in 2004 - and the epidemic situation in the 1970s and 1980s, and suggests that serotype C of FMDv is no longer present in the Region.