Retrospective analysis of submissions to the World Reference Laboratory for foot-and-mouth disease: What can these data tell us about the role of small ruminants in disease epidemiology?

Epidemiological studies can be useful to understand the dynamics of foot-and mouth disease (FMD) virus. Clinical signs of FMD in small ruminants are often difficult to spot, which may lead to an under appreciation of their epidemiological importance in the spread (and therefore control) of FMD. To elucidate the impact of FMD surveillance in small ruminants, retrospective analyses were performed using data collected by the World Reference Laboratory for Foot-and-Mouth Disease. The total number of samples included in these analyses was 32,802, with an average of 444 samples collected per year between 1958 and 2023. When samples were classified into domesticated species groups, the most represented group were Large Ruminant (n = 15021), followed by Small Ruminant (n = 1972), Pigs (n = 1486) and Wildlife (n = 294). Within the domesticated species group, 73.4 % of Pigs and 72.2 % of Large Ruminant samples were FMD virus positive, while Small Ruminant samples had significantly fewer FMD virus positive results (30.0 %). Of the positive samples within the small Ruminant group, serotype O accounted for 86.0 % of the records. These analyses highlight the relative contribution of FMDV positive samples from sheep and goats to global surveillance activities and the potential involvement of small ruminants in maintenance of serotype O. These findings emphasise the importance of these species in control strategies in endemic countries and the necessity to provide specific small ruminant guidelines for FMD diagnostic testing.