Paratuberculosis in Iceland: epidemiology and control measures, past and present

Paratuberculosis as well as the slow virus infections maedi/visna and jaags iekte came to Iceland in 1933 when 20 sheep of the Karakul breed were impor ted from Halle, Germany. At least live of these sheep were subclinical carr iers of paratuberculosis. Within 16 years paratuberculosis together with th e other Karakul diseases (maedi/visna and jaagsiekte) almost ruined sheep f arming, the main agricultural industry in Iceland. The first clinical case of paratuberculosis in sheep was confirmed in 1938, and in cattle in 1944. The first cattle cases of paratuberculosis appeared on farms where the dise ase had been prevalent in sheep for years. The virulence in cattle appeared to be considerably lower than in sheep. Extensive measures were used to co ntrol the spread of paratuberculosis in sheep. Hundreds of kilometres of fe nces were put up acid used together with natural geographic borders to rest rict the movement of sheep from infected areas. Serological and other immun ological tests were also used to detect and dispose of infected individuals . These measures proved inadequate and the disease could not be eradicated. Culling and restocking of uninfected sheep in endemic areas eradicated mae di/visna and jaagsiekte bur not paratuberculosis. Experiments showed that v accination against paratuberculosis could reduce mortality in sheep by 94%. Vaccination of sheep in endemic areas has been compulsory in Iceland since 1966 and as a result losses have been reduced considerably. Today, serolog y is used to detect and control infection in cattle herds. Furthermore, ser ology is used to control vaccination of sheep and screen for infection in n onendemic areas. The complement fixation (CF) test for paratuberculosis has been used until now, but recently we have started comparing the CF test wi th the CSL absorbed ELISA test. (C) 2000 Elsevier Science B.V. All rights r eserved.