Occurrence of Infectious Laryngotracheitis in Poultry Population of Mizoram, India

A study was undertaken to survey the prevalence of viral diseases of poultry in Mizoram during March 2013 to February 2014. Out of 476 poultry carcasses examined, 208 (43.69%) cases were diagnosed as viral diseases. Only 10 cases of infectious laryngotracheitis (2.10%) could be diagnosed basing on the clinical history, gross and histopathology, which were found to affect the birds older than 3 weeks with higher incidences (40.00%) in 3-6 and 6-9 weeks followed by 9-12 weeks of age (20.00%) with morbidity and mortality rates of 20-40% and 2-5% respectively. All the incidences were found in winter season only, not in summer and rainy seasons. The characteristic signs recorded during the study included conjunctivitis, ocular discharge, mouth breathing, gasping, respiratory rales and coughing of blood, while some birds showed great respiratory distress by extending their neck with prolong difficult inspiration through wide open beak, expectoration of bloody mucus and high mortality while some exhibited mucoid tracheitis, sinusitis, unthriftiness and low mortality. The significant gross lesions were mucoid tracheitis, laryngitis and severe hemorrhages in the trachea which was filled with mucus mixed with blood leading to obstruction. Most striking microscopic changes were severe congestion and hemorrhages of the tracheal mucosa which showed the presence of several syncytial cells with intranuclear inclusion bodies in the epithelium, while sections revealed complete desquamation of tracheal mucosa with infiltration of lymphocytes and plasma cells.