Toxoplasmosis in farmed red deer (Cervus elaphus) in Scotland.

Farming of red deer began in Scotland in 1970 when an experimental nucleus was established on a hill farm in Kincardineshire. From 1972 to 1977 sera from these animals were tested by the haemagglutination test (HA) and the Sabin-Feldman dye test (DT) for the presence of antibodies to Toxoplasma gondii. Overall, dye test antibodies (greater than or equal to 1/16) were detected in 32.5 per cent of sera and HA antibodies in only 9.8 per cent. On average 14.1 per cent of the deer tested in 1972, 1973 and 1975 were DT positive while a sharp rise to 51.4 per cent was noted in the 1974 animals. These antibody titres were not sustained nor were they reflected by the HA. Marked animals bled serially throughout the survey confirmed the general low level of antibody in the herd and the spasmodic rise in 1974. Experimentally infected deer showed a rise and subsequent fall in DT antibody levels with persistently low HA titres. Since the correlation between HA and DT antibody titres was generally poor the HA would be of limited value in screening for Toxoplasma antibody in farmed red deer sera. The direct agglutination test was used to examine selected sera and the results indicated its potential screening value.