Preparation of Fowl Typhoid Vaccine from Field Isolates and Determination of Efficacy

The experiment was conducted to isolate and identify Salmonella gallinarum from field cases to prepare formalin killed vaccine and to determine the efficacy of experimentally prepared fowl typhoid vaccine. A total of 48 chickens were divided into six groups (group A, B, C, D, E and group of unvaccinated control chickens F) including 8 layer chickens of Sonali breed in each group. Chickens in group A, B, C, D and E were vaccinated primarily with experimentally prepared fowl typhoid vaccine with a dose 0.5 ml (4.7 × 107 CFU/ml) through subcutaneous route at the age of 9 weeks and booster dose at 14, 21, 28, 35, 42 days after primary vaccination with the same dose and route respectively. Blood samples were collected to obtain sera from each chicken after 15 days boostering for determination of antibody titre following using passive haemagglutination test. Highest mean antibody titres obtained from Group A, B, C, D and E was 96±12.04. Among the five groups the highest mean antibody titre of 96±12.04 was obtained when vaccine was given at 14, 21, 28 days after primary vaccination. The result of Challenge infection revealed that among the 8 birds of A, B, C, D and E all were protected from virulent challenge and all chickens were died from the group F. These results revealed that experimentally prepared Fowl typhoid vaccine provided 100% protection.