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
Objectives
 Describe pox diseases
 List and describe common viral respiratory
diseases
 Describe viral abortion diseases
 Describe meningitis and encephalitis
 Describe hepatitis
 Describe anemia
Background
 Remember
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Five infectious diseases
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Bacterial
Viral
Fungal
Parasitic
Rickettsial
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Infectious disease
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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
Viruses
 Viruses
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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
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Antibiotics have no affect
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Treatment is to easy symptoms
Vaccines available
Entrance of virus into cell is “viral infection”
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Virus uses cell structures to replicate new viruses
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Animal viruses look like
 Capsid
 Outer shell
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Core
 Surrounds genetic material
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Envelope
 Kind of life skin around outside of virus
 Lipid bilayer (membrane)
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Genetic material
Function
 Make more viruses
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Harmful
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Replication leads to cell death
Takes over cell function
How exit cell
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Budding
 Few at a time
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Lysis
 Cell membrane ruptures
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All living things can be affected
 Animals
 People
 Plants
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Infectivity
 Single species
 Humans – smallpox
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1-2 Species
 Influenza
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Particular kind of plant
 Tobacco mosaic virus
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Particular species of bacteria
 Lambda bacteriophage – E.coli
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Different kinds of viruses
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Double-stranded DNA
Single-stranded DNA
Double-stranded RNA
Single-stranded RNA
Retroviruses
 Unique kind of single-stranded RNA virus
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Can mutate
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Kill virus
Make new-strain
 Infectivity
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The characteristic of a disease agent that
embodies capability of entering, surviving in,
and multiplying in a susceptible host
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Basically
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How efficiently it invades specific animal’s tissues
 Specificity
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Its ability to infect certain animal species and
tissues
 Symptoms
 Depend on tissue affected
 Skin
 Blood
 Liver
 Uterus
 Fetus
 Brain
 Lungs
 Stomach
 Intestines
 Bloodstream (viremia)
 Phase of the disease
 Exposure – symptoms
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Recent exposure
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Normal incubation period
Long ago exposure
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Replicate/multiply immediately
 May become dormant
 Recrudesces
 After stressful event
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After incubation period may exhibit symptoms
General Conditions
 Hepatitis
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Infectious canine hepatitis (ICH)
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Causes
 Liver inflammation
 Viremia
 Affects liver, kidneys, spleen and lungs
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Not zoonotic
Symptoms
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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
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Prevention
 Vaccine (puppy)
 Anemia
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Systemic viral disease
Transmitted
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Symptoms
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Vectors
Vehicles
Fever
Anemia
Weight loss
Abortion
Examples
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Equine Infectious Anemia (EIA)
Bluetongue – cattle
Leukosis – cattle
Malignant catarrhal fever - cattle
Skin
 Warts
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Definition
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Fibrous tumors of the skin and occasionally the
mucous membranes
Species affected
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Animals
 Cattle, dogs, rabbits
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Transmission
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Humans
Direct contact
Arthropods
Symptoms
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Cauliflower-type growths
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Head
Neck
Shoulder
Mouth
Vulva
Penis
Vaccine available
 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
Fowl Pox
Swine Pox
Fowl Pox
Cow Pox
Respiratory System
 Pneumonitis; Pneumonia
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Contagious infection of the lungs and causes severe
damage to the lung
Causes
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Hemorrhages
Edema
Emphysema
Bacteria can complicate
Symptoms
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Cough
Fever
Heavy breathing
Lethargy
Decreased appetite
 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
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
Nervous System
 Meningitis
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Definition
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Inflammation of the brain covering (meninges)
 Encephalitis
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Definition
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Inflammation of the brain tissue
 Causes damage to brain tissues
Digestive System
 Gastroenteritis
 Affects
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Highly contagious
Symptoms
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Stomach
Intestines
Vomiting
Diarrhea
More severe in young
Dehydration and electrolyte imbalance
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Types
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Rotavirus
Coronavirus
Parvovirus
Feline panleukopenia
Bovine viral diarrhea (BVD)
Swine transmissible gastroenteritis (TGE)
Summarize
Viral condition
Affects
System
Encephalitis
Brain
Nervous
Hepatitis
Liver
General
Anemia
Blood
General
Abortion
Fetus
Reproductive
Meningitis
Meninges
Nervous
Gastroenteritis
Stomach,
intestine
Gastrointestinal
Pneumonitis
Lungs
Respiratory
Warts
Skin
Skin
 Meningoencephalitis
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Symptoms
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Depression
Blindness
Partial or complete paralysis
Wobbling
Seizures
Coma
Delirium
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Vaccination is important
No treatment
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Types
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Rabies
Equine encephalomyelitis
 VEE, WEE, EEE
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Canine distemper
Parvovirus
Swine pseudorabies