Viral Diseases

1. Viral Diseases 4-H Veterinary Science Extension Veterinary Medicine Texas AgriLife Extension Service College of Veterinary Medicine and Biomedical Sciences Texas A&M System http://aevm.tamu.edu

2. Objectives • Describe pox diseases • List and describe common viral respiratory diseases • Describe viral abortion diseases • Describe meningitis and encephalitis • Describe hepatitis • Describe anemia

3. Background • Remember • Five infectious diseases • Bacterial • Viral • Fungal • Parasitic • Rickettsial

4. Infectious disease • An illness due to a specific infectious agent or its toxic products that arises through transmission of that agent or its products from an infected person, animal or reservoir to a susceptible host, either directly or indirectly

5. Viruses • Viruses • An ultra-microscopic micro-organism, parasitic within living cells and of which many can cause disease. They consist of a strand of nucleic acid (DNA or RNA) that contains genetic instructions concerning viral reproduction that is enveloped by a protein coat • Not alive nor dead, has DNA or RNA, makes copies of itself, must be inside a living cell

6. Antibiotics have no affect • Treatment is to easy symptoms • Vaccines available • Entrance of virus into cell is “viral infection” • Virus uses cell structures to replicate new viruses

7. Animal viruses look like • Capsid • Outer shell • Core • Surrounds genetic material • Envelope • Kind of life skin around outside of virus • Lipid bilayer (membrane) • Genetic material • Function • Make more viruses

8. Harmful • Replication leads to cell death • Takes over cell function • How exit cell • Budding • Few at a time • Lysis • Cell membrane ruptures

9. All living things can be affected • Animals • People • Plants • Infectivity • Single species • Humans – smallpox • 1-2 Species • Influenza • Particular kind of plant • Tobacco mosaic virus • Particular species of bacteria • Lambda bacteriophage – E.coli

10. Different kinds of viruses • Double-stranded DNA • Single-stranded DNA • Double-stranded RNA • Single-stranded RNA • Retroviruses • Unique kind of single-stranded RNA virus • Can mutate • Kill virus • Make new-strain

11. Infectivity • The characteristic of a disease agent that embodies capability of entering, surviving in, and multiplying in a susceptible host • Basically • How efficiently it invades specific animal’s tissues

12. Specificity • Its ability to infect certain animal species and tissues

13. Symptoms • Depend on tissue affected • Skin • Blood • Liver • Uterus • Fetus • Brain • Lungs • Stomach • Intestines • Bloodstream (viremia) • Phase of the disease

14. Exposure – symptoms • Recent exposure • Normal incubation period • Long ago exposure • Replicate/multiply immediately • May become dormant • Recrudesces • After stressful event • After incubation period may exhibit symptoms

15. General Conditions • Hepatitis • Infectious canine hepatitis (ICH) • Causes • Liver inflammation • Viremia • Affects liver, kidneys, spleen and lungs • Not zoonotic • Symptoms • Decreased appetite • Appear depressed • Fever • Opacity of one or both corneas of their eyes (so-called ‘Blue Eye’) one to two weeks later • Respiratory signs • Eye and nose discharge • Cough • Prevention • Vaccine (puppy)

16. Anemia • Systemic viral disease • Transmitted • Vectors • Vehicles • Symptoms • Fever • Anemia • Weight loss • Abortion • Examples • Equine Infectious Anemia (EIA) • Bluetongue – cattle • Leukosis – cattle • Malignant catarrhal fever - cattle

17. Skin • Warts • Definition • Fibrous tumors of the skin and occasionally the mucous membranes • Species affected • Animals • Cattle, dogs, rabbits • Humans • Transmission • Direct contact • Arthropods • Symptoms • Cauliflower-type growths • Head • Neck • Shoulder • Mouth • Vulva • Penis • Vaccine available

18. Pox • Definition • Acute skin condition caused by replication of poxviruses in the skin • Transmission • Direct transmission (through skin) • Arthropods (vectors) • Types of lesions • Bumps • Blisters • Pustules • Crusts • Named after affected animals

19. Fowl Pox Swine Pox Fowl Pox Cow Pox

20. Respiratory System • Pneumonitis; Pneumonia • Contagious infection of the lungs and causes severe damage to the lung • Causes • Hemorrhages • Edema • Emphysema • Bacteria can complicate • Symptoms • Cough • Fever • Heavy breathing • Lethargy • Decreased appetite

21. Viral respiratory diseases • Infectious Bovine Rhinotracheitis (IBR) • Bovine Parainfluenza-3 (PI³) • Equine Rhinopneumonitis • Equine Influenza • Swine Influenza • Canine Infectious Tracheobronchitis (Kennel Cough) • Canine Distemper • Feline Viral Rhinotracheitis (FVR) • Feline Calicivirus (FCV) • Fowl Infectious Bronchitis • Fowl Infectious Laryngotracheitis (LT) • Fowl Influenza

22. Reproductive System • Abortion • Viruses terminate pregnancy by attacking • Fetus • Embryo • Placenta • Uterus • Examples • Swine parvovirus • Infectious bovine rhinotracheitis (IBR) • Bovine viral diarrhea (BVD) • Swine pseudorabies • Equine rhinopneumonitis

23. Nervous System • Meningitis • Definition • Inflammation of the brain covering (meninges) • Encephalitis • Definition • Inflammation of the brain tissue • Causes damage to brain tissues

24. Digestive System • Gastroenteritis • Affects • Stomach • Intestines • Highly contagious • Symptoms • Vomiting • Diarrhea • More severe in young • Dehydration and electrolyte imbalance

25. Types • Rotavirus • Coronavirus • Parvovirus • Feline panleukopenia • Bovine viral diarrhea (BVD) • Swine transmissible gastroenteritis (TGE)

26. Summarize

27. Meningoencephalitis • Symptoms • Depression • Blindness • Partial or complete paralysis • Wobbling • Seizures • Coma • Delirium

28. Vaccination is important • No treatment • Types • Rabies • Equine encephalomyelitis • VEE, WEE, EEE • Canine distemper • Parvovirus • Swine pseudorabies