Bovine viral diarrhoea, bovine herpesvirus and parainfluenza-3 virus infection in three cattle herds in Egypt in 2000.

Abstract

This study reported field outbreaks of bovine viral diarrhoea virus (BVDV) infection, either alone or mixed with bovine herpesvirus-1 (BHV-1) and/or parainfluenza-3 virus (PI-3V) in Egypt during 2000. In Lower Egypt, young calves in three cattle herds in El-Minufiya Province, El-Fayoum Province and in governmental quarantine in El-Behira Province, showed symptoms of enteritis, either alone or accompanied by respiratory manifestations. The affected herds were visited and the diseased animals were clinically examined. Many epidemiological aspects, such as morbidities, mortalities and case fatalities, as well as the abortive rate, were calculated. Ethylenediamine tetra-acetic acid-blood samples, sterile nasal swabs and serum samples were obtained for virological and serological diagnosis. The laboratory investigations revealed that the main cause of calf mortalities in the three herds was infection with BVDV, either alone, as on the El-Minufiya farm, or mixed with PI-3V, as on the El-Fayoum farm, or mixed with both BHV-1 and PI-3V, as in the herd in governmental quarantine in El-Behira Province. A total of nine dead calves from the three herds were submitted for thorough post-mortem examination. Tissue samples from recently dead calves were obtained for immunohistochemical and histopathological studies. The most prominent histopathological findings were massive degeneration, necrosis and erosions of the lining epithelium of the alimentary tract. Most of the lymphoreticular organs were depleted of lymphocytes. In pneumonic cases, bronchopneumonia and atypical interstitial pneumonia were evident. The present study suggested that the immunosuppressive effect of BVDV had predisposed the animals to secondary infection with BHV-1 and PI-3V. This study concluded that concurrent infection with BVDV, BHV-1 and PI-3V should be considered as one of the infectious causes of pneumoenteritis and, subsequently, the high morbidities and mortalities among young calves in Egypt. Preventive and control measures against these infectious agents should therefore be adopted. All animals imported into Egypt should be free from BVDV infection. Control programmes for the detection and removal of BVDV-persistent cattle should be applied in cattle herds all over the country.