AG MED - GI - Bovine Viral Diarrhea Virus & Mucosal Disease Flashcards
What are the biotypes of bovine viral diarrhea (BVD)?
Which cause clinical infection and disease?
Which can cause persistently infected animals?
Non-cytopathic (NCP)
Cytopathic (CP)
BOTH
Non-cytopathic
Name three pestiviruses
BVDV
Border Disease
Hog Cholera
Which BVD biotype is more predominant and persists in cattle populations?
Non-cytopathic
How does cytopathic BVD come about?
Via mutation of non-cytopathic biotype
What causes mucosal disease (MD)?
Co-infection of homologous noncytopathic and cytopathic BVD
What are the two genotypes of BVD?
How many subspecies does each have?
What biotypes does each have?
Are they antigenetically and genetically dissimilar?
Do they cause similar disease syndromes?
Type I
* 21 subspecies
* Noncytopathic and cytopathic
Type II
* 4 subspecies
* Noncytopathic and cytopathic
* Thrombocytopenia
YES
YES
What percentage of the general cattle population is persistently infected with BVD?
What percentage of herds have at least one persistently infected animal?
2% of general cattle population
10 - 50% of herds have at least one persistently infected animal
How long does the bovine viral diarrhea virus last in the environment?
How is bovine diarrhea virus transmitted?
Less than two weeks
Virus is in most body secretions
- direct contact (ingestion, inhalation)
- transplacental (virtually 100%)
- vectors (insects, inanimate)
- semen
What is the range of clinical signs with BVD?
Subclinical ——> death
What factors do the clinical signs of bovine viral diarrhea depend upon? (6)
Immunotolerant vs immunonaive
Immune status
Pregnancy
Gestational age
Environmental stress
Genetic diversity of virus
When does persistent infection for BVD occur?
Which biotype are persistently infected cows infected with?
30 - 150 (or less than 125) days gestation
Noncytopathic
What happens when a pregnant cow becomes infected with bovine viral diarrhea virus?
What are two outcomes for persistently infected calves?
When do 85% of acute cases of BVD occur?
What is the morbidity/mortality for acute BVD?
How long does the acute infection last?
In the first year of life
High morbidity, low mortality
Infected for several weeks; short-lived viremia (2-3 weeks)
Acute BVD damages the epithelium of what three systems?
GIT
Integumentary
Respiratory
Are acute cases of BVD persistently infected or transiently infected?
What clinical signs would you expect to see?
What clinical signs would you expect to see in adult dairy cattle?
Transiently infected
Varying levels of:
- fever, lethargy
- nasal/ocular discharge
- diarrhea/enteritis
- mucosal erosions
- neutropenia
- respiratory disease
Profuse diarrhea and agalactia
What does a typical manifestation of acute BVD look like?
What is thrombocytopenia/hemorrhage syndrome?
What is its mechanism?
What are the clinical signs?
Acute type II noncytopathic bovine viral diarrhea virus
Higher mortality and more severe signs
Virus associated with platelets, megakaryocytes and platelet function is altered
CS: severe GIT bleeding, epistaxis, hyphema, bleeding from injection sites, etc.
What does this photo show?
What condition can be clinically indistinguishable from severe acute bovine viral diarrhea?
Mucosal disease
Clinical signs of mucosal disease
Fever
Lethargy
Dehydration
Diarrhea
Mucosal erosions
Neutropenia
Lymphopenia
Respiratory disease
Acute death
How does a persistent infection of mucosal disease occur?
???
Following fetal infection at less than 125 days with the noncytopathic BVD virus
???
Chronic Mucosal Disease
How long can they survive?
Clinical signs?
What is the most common origin of mucosal disease infection?
What is a rare but possible origin?
Combined infection of antigenically homologous noncytopathic and cytopathic virus caused by:
Spontaneous mutation of NCP —-> CP (common)
Natural or iatrogenic (MLV vaccine) infection (rare)
