Pathology of PMWS Associated with Classical Swine Fever Virus, Porcine Parvo Virus and Multidrug Resistant Enteric Escherichia coli Infections in an Organized Swine Farm, Rajasthan, India

Abstract

Background: Postweaning multisystemic wasting syndrome (PMWS) is caused by porcine circovirus type 2 (PCV2). It is a globally emerging clinical condition which affects nursing piglets and growing pigs. PCV2 requires various cofactors for fully development of PMWS. The present report describes the pathology of PMWS associated with classical swine fever virus (CSFV), porcine parvo virus (PPV) and multidrug resistant enteric Escherichia coli infections in an organized swine farm, Rajasthan. In India, this is the first report on pathology of PMWS associated with all the three viruses and multidrug resistant enteric colibacillosis. Methods: Detailed necropsy was conducted on pig carcass submitted to Post-mortem Facility, Division of Pathology, ICAR-Indian Veterinary Research Institute (IVRI), Izatnagar in the year 2017 from an organized swine farm, Rajasthan, India. Heart blood and diarrhoeic intestinal contents were collected aseptically and stored separately at 4°C for bacteriological examination and antibiotic sensitivity test. Tissue samples were collected in sterile container and stored at -40°C for DNA and RNA extraction and polymerase chain reaction (PCR) and also collected in 10% neutral buffered saline for histopathological processing. Result: The organized farm was having history of 33% (200/600) of mortality among 2 months to 6 months old piglets. Gross lesions were wasting, lymphadenopathy, non-collapsed lungs, hydropericardium, hepatomegaly, icterus, enteritis and pale kidneys, button shaped ulcers in the caecum and colon etc. Histopathologically, lymphoid depletion, reticuloendothelial cell proliferation in lymphoid tissue, fibrin thrombi in spleen, severe hepatitis, interstitial pneumonia, interstitial nephritis, severe necrosis in large intestine, meningitis, perivascular cuffing (PVC), gliosis, neuronal degeneration in cerebrum etc were observed. Molecular diagnosis and bacteriological examination confirmed presence of PCV2, PPV, CSFV and multidrug resistant Escherichia coli.