A review of leptospirosis in farm animals in Portugal

This paper presents a review of Leptospira infection in farm animals in Portugal which is based mainly on serological results obtained in the National Veterinary Research Laboratory between January 1987 and December 1993. Serum samples were tested by the microscopic agglutination test, at a minimum dilution of 1:100. Positive titres were obtained in 15.3% of the 9,543 bovine samples examined. Sejroe, Pomona, Hebdomadis, Tarassovi and Icterohaemorrhagiae were the principal serogroups which reacted in the tests. A total of 3,195 pigs were tested, of which 20.2% showed positive reactions. The main serogroups which reacted were Australis, Pomona, Cynopteri, Icterohaemorrhagiae and Autumnalis. Field observations on outbreaks of leptospirosis in pigs, along with data obtained from an experimental infection with serovar mozdok in pregnant gilts suggest that this serovar, rather than serovar pomona, may be causing Pomona group infections in pigs. Serum samples from 5,298 sheep were tested and 3.3% gave positive results. The predominant serogroups involved were Canicola, Pomona, Cynopteri, Sejroe and Icterohaemorrhagiae. From the 1,631 goats examined serologically, 5.0% gave positive results, mainly to serogroups Grippotyphosa, Canicola, Pomona, Icterohaemorrhagiae and Pyrogenes. Only 83 serum samples from horses were obtained, of which 43.4% showed positive titres. Serogroups Australis, Autumnalis, Cynopteri and Pyrogenes were those most commonly found. Serological evidence of leptospirosis in farm animals is widespread in Portugal, particularly in cattle and pigs. Leptospirosis in horses needs to be studied further. In an attempt to provide a general view on the occurrence of leptospirosis in these animal species in Portugal, the present results are compared with results obtained in previous studies and are complemented with both previous and recent bacteriological findings.