Bovine Viral Diarrhea(BVD)
How is BVD transmitted?
* Direct contact/nose to nose)* Body fluids ( blood,saliva,semen) Blood sucking insect vectors Fomites Vertical transmission
What is the result of hemorrhagic syndrome?
* Not in PI animals* Bloody diarrhea *Epistaxis* Bleeding from injection sites Mortality can be high
Incubation time for mucosal dz?
1-2 wks
Prognosis for mucosal dz
100% of cattle die in 3-10 days - due to debilitation - chronic mucosal dz
How long do CS last with acute BVD?
2-5 days
Who is a minor source of BVD transmission?
Acutely infected animals - only shed for a defined period of time
Who gets Acute BVD?
Affects unexposed cattle Affects immunocompetent cattle 6-24 months old Considered Primary BVD* the one that causes diarrhea*
What's the only way to really detect PI animals since we can't use antibodies?
Antigen detection - Immunohistochem on skin(ear notch) -Antigen capture ELISA on skin -Virus Isolation
What are the 2 genotypes of BVD?
BVDV Type 1 - 1a -1b BVDV Type 2
What do we mean when we say BVD has biotypes?
Biotypes refer to behavior of the virus in cell culture
Name 2 other dz of the genus Pestivirus
Border dz(sheep) Hog cholera(swine)
CS of PI cattle
Can be clinically normal Often unthrifty and small - PD to infxn - 50% die w/i first year of life
Who are the natural hosts for BVD?
Cattle No diff between beef or dairy Camelids and other ruminants can be infected
Who gets the PI form of BVD?
Cattle that are immunotolerant to BVD - infected in utero <125d gestation
What does the BVD disease state depend on?
Depends on virus and host factors
CS of Mucosal dz
Erosions - mouth to anus Secondary bacterial infections can occur
What 2 things does a positive antibody titer for BVD indicate?
Exposure /Vaccination Current active infection
Family and Genus of BVD
Family Flaviviridae Genus Pestivirus
What types of issues does BVD cause?
GI dz Resp dz Repro dz Congenital abnormalities
What are the viral isolates like for severe acute BVD?
Genotype Type 2
What do we mean when we say BVD has genotypes?
Genotypes refer to antigenic similarity of the virus
Will a PI calf have antibodies against BVD/ have a positive antibody titer?
It recognizes BVD as itself so no Ab against it
What is the prognosis like for Acute BVD?
Low mortality
Why does Acute BVD not affect calves younger than 6 months of age?
Maternal antibodies are still in play at this point
If a PI cow (infected with NCP BVD) is infected with CP BVD then what happens?
New infection; mutation of NCP which leads to * Mucosal dz*
What are the 2 different BVD biotypes?
Noncytopathic/NCP Cytopathic/CP
What types of CS do you see with subclinical dz?
None
Describe how to get PI with BVD
Occurs when a pregnant dam becomes acutely infected with NCP BVD If the fetus is <125 days gestation, the immune system is sitll develping; once born these calves are viremic for life and shed a lot of the virus
CS of Acute BVD
Oral erosions Oculonasal discharge Diarrhea Fever Inappetence
Who is the major source of BVD transmission?
PERSISTENTLY INFECTED ANIMALS
Describe NCP
Predominates in the general population Associated with PI
How do you treat BVD?
Provide supportive care! Broad spectrum antimicrobial therapy could be considered
What type of virus is BVD?
RNA virus
Why do we care about BVD?
Results in decreased performance/weight gain Decrased milk production Reproductive losses Tx of sick animals * substantial costs / economic importance*
2 ways to control BVD
Screen herd members for PI cattle Vaccination
What are the 2 atypical forms of Acute BVD caused by Type 2 BVD(NCP)
Severe Acute BVD Hemorrhagic Syndrome
3 risk factors for BVD
Stocking density Management quality Vax use
What are the 6 possible disease states?
Subclinical BVD Acute BVD Severe Acute BVD PI Mucosal dz Hemorrhagic Syndrome
T/F Both BVDV Type 1 and Type 2 can cause severe disease but disease with TYpe 2 is usually worse
T
T/F Severe Acute BVD is an atypical form of Acute BVD with high morbidity, low mortality and CS resembling mucosal dz
T
T/F The vast majority of BVD infections are subclinical BVD, a serum antibody response occurs and causes immunosuppression
T
T/F Unless you're dealing with a closed herd, the goal with BVD is CONTROL not prevention
T
T/F While there are 2 different biotypes for BVD there are many strains present within each biotype
T
Why does Acute BVD not affect calves older than 24 months of age?
They've been vaccinated or had a subclinical infection
Describe CP biotype
UNCOMMON - mutates from NCP * parent* strain
When do you vaccinate for BVD?
When maternal antibodies have waned Vaccinate all breeding stock before breeding
How can you detect antibodies for BVD?
check for serum neutralizing antibodies
