Studies on Pasteurella multocida. IX. Levamisole-Induced Augmentation of Immune Responses to a Live Fowl Cholera Vaccine

SUMMARY Levamisole, a broad-spectrum anthelmintic, had immunostimulating effects in turkeys when administered together with the CU strain of Pasteurella multocida. Vaccinated turkeys treated with levamisole had persistent higher systemic humoral immunity and cell-mediated immune responses than turkeys which had only the vaccine. Data generated from two trials also showed that although only 78.57% of the turkeys (55 out of 70) which were vaccinated survived challenge at the end of 17 weeks postvaccination, survival was 91.67% (66 out of 72) in turkeys that were vaccinated and treated with levamisole. These results suggest that levamisole may be used to augment the immune response in vivo and, possibly, to enhance resistance in turkeys to Pasteurella infection. Additional experiments are needed, however, before any definitive statements can be made about the immunoenhancing effect of levamisole on live fowl cholera vaccine.