Prevalence and Molecular Diagnosis of Marek’s Disease in the Chicken Population of Mizoram

Abstract

Marek’s Disease (MD) is an important lympho-proliferative disease of chicken population prevailing throughout the world since its discovery in 1907. Classical form of the disease was predominant for the first fifty years of discovery of the disease which is a neurological form. Acute form of the disease came into the sight from 1960 which is the lympho-proliferative form. In the present study a total of 5605 birds from 33 farms of Mizoram were surveyed during the period from April, 2020 to March, 2021 for screening MD. Post-mortem examination was conducted on 166 dead birds suspected for MD and representative tissue samples were subjected for pathological studies and the disease outbreaks were confirmed by using PCR assay to detect the meq gene of MDV. Outbreak of the disease was confirmed in 8 farms (24.2%) with a morbidity rate of 9.3% to 32% and mortality rate of 2% to 18%. The disease outbreaks were recorded in chickens of 16-18 weeks of age. Affected birds showed flaccid paralysis of legs, wings and progressive loss of body conditions. Greyish white coloured lymphomas of different sizes were frequently observed in liver, spleen, kidney, lungs, proventriculus and mesentery, which represented lympho-proliferation. The 1081bp fragment of meq gene of MDV was successfully amplified in representative tissue samples by PCR, which has confirmed outbreaks of the disease.