Viral Disease in Ruminant Sukolrat Boonyayatra DVM, M.S. Clinic for Ruminant, FVM. CMU.
Disease topic including: • Bovine Ephemeral Fever • Bovine Respiratory Syncytial Virus • Parainfluenza-3 • Bovine Viral Diarrhea • Infectious Bovine Rhinotracheitis • Foot and Mouth Disease • Bovine Spongioform Encephalopathy • Rinderpest • Lumpy Skin Disease • Papillomavirus • Pseudocowpox
BOVINE EPHEMERAL FEVER (Three-day sickness, Bovine Epizootic Fever, Three-day stiffsickness, Dragon boat disease)
Definition • a noncontagious epizootic arthropod-borne viral disease • cattle and water buffaloes • sudden onset of fever • depression • stiffness • lameness • rapid recovery
Etiology • Family Rhabdoviridae 1. Genus Vesiculovirus Type Species vesicular stomatitis Indiana virus 2. Genus Lyssavirus Type Species rabies virus 3. Genus Ephemerovirus Type Species Bovine ephemeral fever virus 4. Genus Cytorhabdovirus Type Species lettuce necrotic yellows virus 5. Genus Nucleorhabdovirus Type Species potato yellow dwarf virus
Epidemiology • first described in South Africa in 1906 • tropical, subtropical, and temperate countries in Africa, Asia, and Australia • Thailand since 1984
Transmission • Insect bite • not spread from cow to cow • Culicoides • Mosquitoes
Clinical Signs (1) • Depressed • High fever (105-107 F) with biphasic or triphasic fever • Serous ocular and nasal discharge • Anorexia • Decreased milk production • Weight loss • Stiffness and lameness • More severe in high BW animals
Clinical Signs (2) • Severe case Muscle stiffness Drag feet when forced to walk Lying down, with hide limbs outstretched- to relieve muscle cramp Lie down for three days
Clinical Signs (3) • Morbidity may reach to 30% • Low mortality • Causes of the death • Pneumonia from secondary infection • Muscle damaged and inflammation from long period lying down • Pregnancy toxemia (fatty liver syndrome)
Gross lesions • the small amounts of fibrin-rich fluid in the pleural,peritoneal, pericardial cavities and joint capsules • the synovial surfaces of the spine may have fibrin plaques. • The lungs may have patchy edema. • Lymphadenitis • Focal necrosis can be found in major muscle groups in some cases.
Hematology • an absolute rise in leukocyte numbers • a rapid fall in circulating lymphocytes • a return to normal levels after 3-4 days • The serum fibrinogen level rises to 3-4 times the normal level and returns to normal 1-2 weeks after recovery. • The total serum calcium level falls to 1.8 mmol-1 during the febrile phases and returns to normal on recovery. • This is the biochemical event that causes the reversible early paralysis.
Diagnosis • Clinical signs • Sero-conversion: paired serum • SN test • ELISA • Gross lesion
Differential Diagnosis • Bluetongue • Babesiosis • Blackleg
Treatment • Recovery with no treatment • In severe cases • Anti-inflammatory drug: NSAIDs • Fluid therapy and calcium • Broad spectrum ABO Recovery period3-4 wks.
Prevention and Control • Vector control • Vaccine: Attenuated lived virus vaccine (Australia)
Bovine Respiratory Syncytial Virus (BRSV) • Bovine respiratory disease complex (BRD) • Synergistically infect with bacteria to cause pneumonia • Pasteurella haemolytica • P. multocida • Haemophillus somnus • 1960: The existence of BRSV • 1970: Isolation of BRSV from an outbreak (Switzerland) • 1974: Isolation of BRSV in USA • 1978: An attenuated lived vaccine was available in Europe. • 1984: An attenuated lived vaccine (USA) • 1988: Inactivated vaccines were commercially available in USA
Etiology • Family Paramyxoviridae • Genus Pneumovirus • Human Respiratory Syncytial Virus (HRSV) • Bovine Respiratory Syncytial Virus (BRSV) • Ovine Respiratory Syncytial Virus (ORSV) • Turkey Rhinotracheitis virus “Single stranded RNA virus that replicate in the cytoplasm and mature by budding from apical cell membrane”
Epidemiology • Worldwide distribution in the cattle population • High seropositive ranging from 65-75% (USA) before vaccine was introduced • BRSV was determined to be involved in • 14% of respiratory infections in UK • 32% of outbreaks of calf pneumonia in North Ireland • 53% of respiratory outbreaks in Belgium • 71% of the outbreaks of calf pneumonia in Minnesota
Clinical signs • Initial signs • A decreased appetite • Milk depression • Nasal and lacrimal discharge (serous to mucoid) • Increased respiratory rate • Progress signs • Elevated BT (104-108 F) • Dyspnea • Opened mouth breathing • Hyperpnea (abdominal breathing) • Cough • Increased bronchial and bronchovesicular sounds, and fine crackles • Decreased milk production • Duration of disease is variable, lasting from 1-2 weeks • Calf :more severe
Postmortem findings • Atypical interstitial pneumonia (AIP) • Gross findings: • Initially involves the cranioventral lobes • Calves die from severe lung edema and interstitial pneumonia • Lung fail to collapse • Subpleural emphysema • Bronchial and mediastinal lymphnodes are enlarged and edema.
Histopathological findings • Vary depending on stage of viral infection and the secondary bacterial infection • Bronchointerstitial pneumonia with severe bronchiolitis in cranioventral part • Alveolar edema and emphysema are diffusely present • Multinucleated syncytial cells (bronchiolar epithelium) • Bacterial pneumonia: suppurative or fibrous bronchopneuminia
Lung. Multinucleated syncytial cell is prominent within the bronchiole and appears to be arising from the epithelial layer. The lumen is packed with neutrophils. A few neutrophils are also transmigrating the bronchiolar wall and are in the adjacent atelectactic parenchyma. 40X
Pathogenesis (1) • Virus infects epithelial cells in the pulmonary airways • Cytopathic changes and necrosis • Necrotizing bronchiolotis • Alveolar epithelium: interstitial pheumonia • Mixed inflammatory cell infiltration with a predominance of neutrophils
Pathogenesis (2) • May suppress the immune system • Atypical interstitial pneumonia • Necrotizing bronchiolitis: • Extensive viral replication at bronchiolar epithelium • Dyspnea and forced expiration • Emphysema
Immune response to infection • Both dies and recovery from clinically severe have antibody responses to proteins of virus (F and N): may not protective effect • Colostrum IgG-1 do not prevent the infection but make disease less severe • Cell-mediated immune responses may play a protective role
Differential diagnosis • Parainfluenza-3 • IBR • Mycoplasma spp. • Haemophilus somnus • etc…
Diagnosis • Clinical signs • Necropsy • Laboratory Diagnosis Viral isolation Antigen Detection Enzyme Immunoassay Immunofluorescent Antibody Staining Detection of Nucleic acids: PCR Serological Diagnosis
Treatment (1) • ABO: Bacterial pneumonia - Pasteurella haemolytica • P. multocida • Haemophilus somnus • Anti-inflammatory agents • Corticosteroid • Antihistamine • NSAIDs
Treatment (2) • Antiviral therapy: Ribivarin: HRSV • Immunotherapy: Hyperimmune serum : HRSV • Supportive treatment • Dehydration and electrolyte imbalances • Anorectic animals: B-complex vitamins
Prevention and Control • Management: • Stress, ventilation, maternity pen, calf-rearing area • Immunization • Passive Immunization: Modify severity of disease • Vaccination: Modified-lived BRSV vaccine Inactivated BRSV vaccine
IBR, BRSV, PI-3, BVD killed vaccine + Haemophilus somnus bacterin Killed vaccine protects against IBR, BVD, PI3 and BRSV, and Pasteurella haemolytica and Haemophilus.
Viruses - Bovine herpesvirus type1 (IBR) - Bovine herpesvirus type3 (malignant catarrhal fever virus) - Bovine herpesvirus type4 (DN-599, Movar 33/63) - Bovine adenovirus types1 to 8 - Bovine parainfluenza virus type3 - Bovine respiratory syncytial virus - Bovine viral diarrhea virus - Reovirus types1 to 3 - Bovine Rhinovirus types1 and 2 - Bovine Enterovirus types1 to 7 - Calcivirus - Influenza virus (reported from Russia) Bacteria Pasteurella haemolytica Pasteurella multocida Haemophilus somnus Mycoplasma mycoides subspecies mycoides Mycoplasma bovis Mycoplasma dispar Ureaplasma spp. Chlamydial agent - Chlamydia psittaci Infectious Agents Identified in the Bovine Respiratory Disease Complex
Parainfluenza-3 Virus (PI-3) • Enzootic Pneumonia • Etiology • Family Paramyxoviridae • Genus Paramyxovirus
Pathogenesis • Virus infects ciliated respiratory epithelium of the upper and lower respiratory tracts and also alveolar macrophage. • Reduce alveolar macrophage • Facilitate pulmonary bacterial colonization • Infection of calves is rarely fatal, producing mild or subclinical cases.
Epidemiology • World wide distribution • Subclinical • Stress produce more severe clinical case • Disease is commonly seen in calves 2-8 mths. • Thailand: • 1994- 1,788 of 2,070 bulk milk samples were antibody positive (86.3%)
Transmission • Aerosal • Direct contact
Clinical signs • Fever 104-105 F • Rhinitis and pneumonia • Cough (easily by pinching the trachea) • Recovery in few days
Diagnosis • Virus isolation • Immunofluorescent or immunoperoxidase test • Serology: Hemagglutination-Inhibition (HI) Viral Neutralization
Bovine viral diarrhea virus (BVDV) • BVD was first recognised in Canada and the United States in the 1940's. • In 1987, outbreaks of BVD occurred affecting veal calves and older cattle in New York and Pennsylvania. • Beginning in 1992, an outbreak of BVD affected veal calves and dairy herds in Quebec. • Today BVDV infections are seen in all ages of cattle throughout the world and has significant economic impact due to productive and reproductive losses.
Etiology • RNA virus • Family Flaviviridae • Pestivirus 2 biotypes: cytopathogenic (cp) or noncytopathogenic (ncp) Both biotypes of BVDV infect cattle and cause disease, but only ncp BVDV causes persistent infections.
Effect of BVDV infection on cattle • Reproductive failure: Embryonic death, Mummification, Abortions, Stillbirths • Repeated breeding syndrome • Immunosuppression • Congenital defects: Cerebellar hypoplasia, Cataract • Persistent infections: Carrier animals • Acute BVD • Bovine respiratory tract disease • Mucosal disease
Transmission • Persistent infected animals • Acute infected cattle • Semen • Embryo transfer • Rectal sleeves • Contaminated water • Biting insect (experimentally)
Effect of Pregnant Cow Infection Days pregnancyEffect 0-40 Embryonic death 40-120 Abortion or Persistent Infected calf 90-160 Abortion or Congenital defect 160-Parturition Abortion or normal calf