INFECTIOUS AGENTS - Bovine Respiratory Disease Complex Flashcards
What is Bovine Respiratory Disease Complex (BRDC)?
A multifactorial disorder caused by interactions between viral and bacterial pathogens together with environmental risk factors
Describe briefly the pathogenesis of bovine respiratory disease complex (BRDC)
An environmental stressor, sometimes coupled by a viral infection results in the suppression of the host immune system and a secondary bacterial infection in the lower respiratory tract
List three environmental stressors associated with bovine respiratory disease complex (BRDC)
Transport
Overcrowding
Inadequate ventilation
List three viruses associated with bovine respiratory disease complex (BRDC)
Respira tory syncytial virus (RSV)
Parainfluenza virus type 3 (PI3)
Bovine herpes virus type 1
What are the four clinical signs of a respiratory syncytial virus (RSV) infection?
Nasal discharge
Coughing
Frothy saliva
Fast laboured breathing
Which disease is usually caused by bovine herpes type 1?
Infectious bovine rhinitis
What are the four clinical signs of a bovine herpes type 1 virus?
Purulent nasal discharge
Ocular discharge
Inappetence
Coughing
(T/F) Bovine herpes virus type 1 is a latent infection
TRUE. Bovine herpes type 1 virus will reactivate when the animals are under stress
List four samples that can be taken to diagnose a respiratory viral infection
Ocular swab
Nasal swab
Blood sample
Broncho-alveolar lavage
List three bacteria associated with bovine respiratory disease complex
Mannhaemia haemolytica
Pasteurella multocida
Histophillus somni
What are the four general characteristics of respiratory bacteria?
Gram negative (G-)
Non-motile
Facultative anaerobe
Mesophile
What is the structural difference between lipopolysaccharide (LPS) and lipooligosaccharide (LOS)?
Lipopolysaccharide (LPS) has a larger O-side chain than lipooligosaccharide (LOS)
Which bacteria has an outer membrane made up of lipooligosaccharide (LOS)?
Histophillus somni
What is the endotoxic effect of lipopolysaccharide (LPS)?
Lipopolysaccharide (LPS) triggers the complement pathway and coagulation cascade, increasing vascular permeability resulting in oedema, recruits immune cells and increases coagulation and fibrin deposition in the lungs
Which two bacteria are commensal bacteria of the upper respiratory tract?
Mannhaemia haemolytica
Pasteurella multocida
Mannhaemia haemolytica exhibits β-haemolysis. What does this mean?
When cultured on blood agar, Mannhaemia haemolytica will completely haemolyse the erythrocytes
Which exotoxin is produced by Mannhaemia haemolytica?
Leukotoxin
What is the function of leukotoxin produced by Mannhaemia haemolytica?
Lysis of alveolar macrophages and neutrophils
What are the two main virulence factors of Pasteurella multocida?
Capsule
Dermonecrotoxin exotoxin
Which disease involves dermonecrotoxin?
Atrophic rhinitis
Why is Histophillus somni host specific to cattle?
Histophillus somni is host specific to cattle because this bacteria produces iron binding proteins that are specific to cattle
What are the two main virulence factors of Histophillus somni?
Capsule
Haemolysin exotoxin
Histophillus somni is fastidious. What does this mean?
Fastidious bacteria are challenging to culture
What needs to be added to an agar plate in order to culture Histophillus somni?
CO2
NAD
