Viral Diseases

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Viral Diseases

• 4-H Veterinary Science
• Extension Veterinary Medicine
• Texas AgriLife Extension Service
• College of Veterinary Medicine and Biomedical
  Sciences
• Texas AM System
• http//aevm.tamu.edu

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Objectives

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

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Background

• Remember
• Five infectious diseases
• Bacterial
• Viral
• Fungal
• Parasitic
• Rickettsial

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• 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

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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

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• 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

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• 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

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

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• 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

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• 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

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• 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 animals
  tissues

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

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

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• 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

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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)

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• 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

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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

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• 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

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• Fowl Pox

Swine Pox
Fowl Pox
Cow Pox
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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

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• 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

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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

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Nervous System

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

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Digestive System

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

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

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

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