Pathologic Diagnosis of Infectious Bursal Disease Outbreak In Vaccinated 3-week Old Pullet Chicks on A Small Scale Commercial Poultry Farm In Leleyi-kwali, Abuja, Nigeria: A Case Report

sudden mortality which lasted for seven days with the peak on the third day, was investigated in vaccinated 3-week old pullet chicks. Signs of depression, ruffled feathers, sneezing, huddling together and pasted vents with about 50% morbidity were observed. While chicks were off feed. Vaccination history against Marek’s and Newcastle diseases was reportedly up to date. The first dose of Infectious Bursal Disease (IBD) vaccination was done 12 days before the onset of the outbreak preparatory to the second dose. Detailed post mortem examinations showed multifocal petechial to ecchymotic haemorrhages on the breast and thigh muscles with swollen, oedematous and haemorrhagic bursa of Fabricius in affected chicks. The bursa of Fabricius showed diffuse lymphoid depletion with multifocal vacuolations and eosinophilic cystic follicles. Similar diffuse lymphoid depletion and cytoplasmic vacuolation with fibrinous exudation were also present in then spleen, Serological analysis revealed 88.23% IBD antibody positive sera in affected pullets 16 days after cessation of mortality. A diagnosis of Infectious Bursal Disease outbreak was made based on the observed pathological presentations along with the clinical signs, typical spiked mortality pattern, and serological titre. These findings highlighted the need for continuous pathological investigations as a ready diagnostic tool in vaccinated and unvaccinated pullet chicks in Nigeria where Infectious bursal disease has become endemic.