Viral disease Flashcards
Why do disease outbreaks occur?
Due to susceptible populations, virus evolution, short-lived immunity, or inadequate vaccines
What is an example of an exotic disease outbreak?
Avian influenza (H5N1) in the UK
What is “Moo Flu”?
H5N1 transmission to dairy cattle, with mammary infection & high virus shedding in milk
What factors contribute to calf respiratory disease?
Multifactorial causes:
- Mixed infections (viral + bacterial)
- Environmental factors
- Emerging agents (e.g. Influenza D)
What is a sporadic disease?
Disease that occurs irregularly & infrequently, affecting only small number of animals without predictable pattern
What is the difference between endemic and exotic diseases?
Endemic diseases are consistently present in specific region or population (e.g. BVD in cattle)
Exotic diseases are not normally found in region but may be introduced (e.g. Foot-and-Mouth Disease in UK)
Give examples of sporadic feline diseases
Feline parvovirus, calcivirus, herpesvirus, Feline infectious peritonitis
Less common due to vaccination – but remain important diseases
Give an example of a sporadic disease in cattle
Malignant catarrhal fever caused by OHV2
What are the economic consequences of viral diseases?
Lost production
Culling costs
Trade restrictions
Control costs (vaccines, biosecurity)
Name some zoonotic viruses of veterinary concern.
Hantaviruses (rodents)
Louping ill virus
European Bat Lyssavirus
SARS-CoV-2
West Nile Virus (USA)
Why are some diseases classified as notifiable?
They have economic or zoonotic importance & need strict control measures
What are common clinical signs of acute viral disease?
Signs depend on site of infection:
- Respiratory, intestinal, neurological, renal etc.
Pyrexia, depression, anorexia commonly seen
Secondary bacterial infections common for intestinal & respiratory infections
What are the clinical signs of cat flu (acute disease)?
Calcivirus, Herpesvirus
Nasal, ocular discharge, pyrexia, anorexia, lethargy
FHV: corneal ulcers
FCV: ocular ulceration
What are the clinical signs of calf respiratory disease (acute disease)?
Cough
Nasal, Ocular discharge
Pyrexia
Depression
Viruses facilitate subsequent infection with bacteria e.g. enhance adhesion or impair local immunity
What are the clinical signs of canine parvovirus (acute disease)?
Vomiting, bloody diarrhoea
Pyrexia
Neutropenia
Villus stunting, crypt dilation and necrosis
Consequence of direct replication and lysis of crypt cells
What are examples of chronic viral diseases & their clinical signs?
Lentiviruses:
- FIV: Immunosuppression
- FeLV: Anemia, lymphoma, gingivostomatitis
What viruses are linked to cancer?
FeLV, FIV (retroviruses)
Marek’s Disease (herpesvirus)
Papillomaviruses (BPV-2, BPV-4)
Name two types of immunological effects caused by viruses
Immunosuppression (e.g., FIV, BVDV)
Immunopathology (e.g., FIP, Malignant Catarrhal Fever)
What are these and what causes them?
Inclusion bodies
Some Herpesvirus or Poxvirus infections
e.g. IBR
Give examples of viruses that can cause prenatal infections
Pestiviruses
- BVD, Border disease
Schmallenberg virus
Parvoviruses
Infection in utero can dramatically affect fetal development
What diagnostic tests are used for viral infections?
Antigen detection
PCR
Antibody tests
What test is commonly used to diagnose canine parvovirus?
SNAP antigen test or PCR
What methods are used to diagnose cat flu?
Oropharyngeal/conjunctival swabs
Virus isolation or PCR
What is the Rivalta test used for?
It helps diagnose wet FIP by detecting characteristic yellow, tacky effusion
Why is diagnosing Feline Infectious Peritonitis (FIP) challenging?
Because FeCoV antibodies can be present without the cat having FIP, and no single test is definitive
(Positive FeCoV antibody test indicates exposure but does not confirm FIP)
What are two key serum markers elevated in FIP cases?
Gamma globulins and alpha-1 acid glycoprotein
What is the most reliable molecular test for FIP?
qPCR, performed on relevant samples like effusions or tissues (not faeces)
How are persistently infected (PI) BVD calves identified?
Diagnosis of persistently infected (PI) calves is main factor for controlling virus on farm
They are:
- Virus positive (test for antigen)
- Antibody negative
(PI animals culled and removed)
How is avian influenza diagnosed?
Tracheal, oropharyngeal and cloacal swabs
Fresh tissue samples
Virus detection by RT-qPCR
Sequencing &/or serotyping to confirm virus subtype (e.g. H5N1) & whether high or low pathogenicity
What are the three main strategies for controlling viral disease?
Biosecurity
- e.g. culling infected animals & closed herds
Husbandry
- e.g. Colostrum, Deep cleaning & Isolation
Vaccination
What are the biosecurity factors that you can control?
