<b>Safety and immunogenicity of an intranasal vaccine against pneumonic mannheimiosis of sheep and goats following field vaccination</b>

Background: Pneumonic mannheimiosis is an important respiratory disease of sheep and goats that inhibits production. It is associated with stress, resulting in between 10% and 40% mortality. The disease should be effectively controlled. Aim: This field vaccination trial evaluates the safety and immunity of a newly manufactured vaccine (STVac7TM) against pneumonic mannheimiosis of sheep and goats. Methods: A sheep and a goat breeder farm were identified before 2 groups of breeder sheep with 80 animals per group, and 2 groups of breeder goats with 50 animals per group were selected. Sheep and goats of Group 1 was vaccinated intranasally, while Group 2 remained unvaccinated. Vaccinations were carried out on weeks 0 and 2. Throughout the 24-week (sheep) and the 12-week (goats) study periods, animal management in both farms remained unchanged. Prior to and at weekly intervals post-vaccination, serum samples were collected from both groups, while nasal swabs were collected at monthly interval. Adverse effects including sneezing, coughing, nasal discharge and mortality were noted weekly throughout the study period. Results: Intranasal vaccination did not cause significant side effects in sheep and goats, although mild nasal discharge and coughing were occasionally observed. Only one non-vaccinated ewe (1.3%; p>0.05) died despite identification of M. haemolytica from the nasal cavity of majority of the sheep and goats. Following vaccination, antibody levels showed significant increase and remained significantly high (p<0.05) throughout the study period. Conclusions: Intranasal vaccination of sheep and goats with STVac7TM is safe and well tolerated, resulting in high serum antibody levels and maintains the health status of the animals during the stressful monsoon season.