Serological survey for antibodies reactive with Ehrlichia canis and E. chaffeensis in dogs from the Bloemfontein area, South Africa.

Sera from 161 dogs in the Bloemfontein area in South Africa were tested for the presence of antibodies reactive with Ehrlichia canis and E. chaffeensis by indirect fluorescent antibody testing. Overall, 68 (42%) of the dogs had significant antibody titres (> or = 1/64) against E. canis and 61 (38%) had significant titres (> or = 1/64) against E. chaffeensis. Seven (11%) dogs had higher titres to E. chaffeensis than E. canis (1/2048 and 1/1024 (2 dogs); 1/1024 and 1/512 (2 dogs); 1/2048 and 1/512; 1/512 and 1/256 and 1/512 and < 1/64, respectively). The remaining seropositive dogs had equal (n = 26; 42%) or 2-(n = 17; 25%), 3-(n = 13; 2%) or 4-fold (n = 5; 7%) higher titres against E. canis. Dogs from economically depressed, high-density suburbs (60/112; 48%) had significantly higher prevalences of antibodies against E. canis than those from more affluent, low-density suburbs (8/49; 14%) (chi 2 = 19.38, p < 0.001). Higher titres to E. chaffeensis than E. canis were found in dogs from affluent, low-density suburbs (3/49) and in dogs from economically depressed, high-density suburbs (4/112).