Clinicopathological Investigation of Foot and Mouth Disease and Serotype Identification of the Viruses in Cattle of Bangladesh

Abstract

Foot and Mouth Disease (FMD) is a highly contagious viral disease of farm animals. This study was aimed to identify symptoms, characteristics pathology and viral serotypes involved in infected cattle of Bangladesh. Dominant signs observed were salivation, vesicular eruption, lameness and maggot infestations in 66%, 80%, 36% and 14% cattle respectively. Out of 202 infected cattle investigated, 35 were below six months of age. A total of 18 young calves and 8 adult cattle were died due to FMD. Seven young calves and two adult cattle were examined at necropsy, 'Tiger heart disease' was commonly seen both in the young and adult cattle. The 'currant jelly clot' was common in the atrium, ventricles, aorta and veins of the heart of adult cattle. Congested and consolidated lungs, atrophied spleen, and fibrosed udder were grossly seen in the infected and dead cattle. Microscopically, hyalinization of cardiac muscle in young calf and degeneration, necrosis and multifocal lymphocytic infiltration in heart muscle were suggestive for infectivity due to FMD viruses. There were bronchiolitis, pulmonary emphysema, interstitial pneumonia and thickening of interlobular septa of lungs. Cattle survived from the acute infection developed respiratory distress in 15% cattle. Out of 202 samples tested in reverse transcriptase polymerase chain reaction (RT-PCR), 187 samples found to generate positive amplicons. Single infectivity due to FMD viral Serotypes O, A and Asia 1 were seen in 115 (62%), 26 (14%) and 34 (18%) cases, respectively. Seven cattle were co-infected with FMD viral Serotypes O and Asia 1 and four with FMD viral Serotypes O and A. FMD viral serotype O was dominating in cattle all over the country and was related to death of infected young and adult cattle. Cardiac myonecrosis and respiratory failure were the dominant lesions may be related to death of infected animals.