The epidemic of foot-and-mouth disease in Saskatchewan, Canada, 1951-1952.

The epidemic of foot-and-mouth disease in Saskatchewan in 1951 and 1952 was studied in order to determine origins of outbreaks and methods of spread. The epidemic was initially considered to be vesicular stomatitis and foot-and-mouth disease was not recognized until February 1952, three months after the initial infection. The reports prepared at that time were reviewed in order to obtain details of the numbers of animals infected and the source and date of infection for the outbreaks. Methods of spread were rated according to their likelihood. The introduction of infection by an immigrant through his clothes as well as by sausage was possible. The sequence of events from the first outbreak to the spread from a feedlot/packing plant and from a dairy farm, which failed to report the disease, were clarified. Methods of spread included movement of animals, animal products and people and the airborne route. Milk delivery and artificial insemination did not result in spread of infection. The quarantine of affected farms reduced spread by animals and deterred visits by people. The original diagnosis of vesicular stomatitis was due to misinterpretation of a lesion in an inoculated horse. Laboratory tests established the presence of foot-and-mouth disease. The limited extent of the epidemic, despite the delay in diagnosis, is attributed to (i) the low density of cattle, (ii) few infected pigs and hence less airborne virus and (iii) absence of waste food feeding and milk collection in addition to the limited quarantine imposed.