Viral Diseases

4-H Veterinary ScienceExtension Veterinary Medicine

Texas AgriLife Extension ServiceCollege of Veterinary Medicine and Biomedical Sciences

Texas A&M Systemhttp://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 Five infectious diseases

Bacterial Viral Fungal Parasitic Rickettsial

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

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

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

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

Harmful Replication leads to cell death Takes over cell function

How exit cell Budding

Few at a time Lysis

Cell membrane ruptures

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

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

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

Specificity 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 Recent exposure

Normal incubation period Long ago exposure

Replicate/multiply immediately May become dormant Recrudesces

After stressful event

After incubation period may exhibit symptoms

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)

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

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

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

Fowl Pox

Swine Pox

Cow Pox

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

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 Definition

Inflammation of the brain covering (meninges)

Encephalitis Definition

Inflammation of the brain tissue

Causes damage to brain tissues

Digestive System

Gastroenteritis Affects

Stomach Intestines

Highly contagious Symptoms

Vomiting Diarrhea

More severe in young Dehydration and electrolyte imbalance

Types 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 Symptoms

Depression Blindness Partial or complete paralysis Wobbling Seizures Coma Delirium

Vaccination is important No treatment

Types Rabies Equine encephalomyelitis

VEE, WEE, EEE Canine distemper Parvovirus Swine pseudorabies