Bovine Virus Diarrhea and PI’s

1. Bovine Virus Diarrhea and PI’s Brendan Kraus, DVM Spur Ridge Vet Hospital Marion, KS

2. What is BVD? • Bovine Virus Diarrhea • 2 Biotypes & 2 Genotypes • A contagious disease transmitted in bodily fluids • Causes a wide range of clinical symptoms • Cause marked suppression of immune system

3. Cytopathic Kills cells in tissue culture Arises from a virus mutation Most common strain in vaccines Noncytopathic Does not change culture cells Most common biotype found in nature Biotypes of BVD(Type does not affect immune response!)

4. Type 1 Original strains of BVD that were isolated Is included in all BVD vaccines *There is some cross protection with vaccines between types 1 & 2 Type 2 This type was more recently discovered Hemorrhagic syndrome strains Is included in most BVD vaccines now Genotypes of BVD

5. 70-90% of infections are subclinical Pneumonia Fever Rhinitis Diarrhea Oral and GI ulcers Immune suppression Abortions Stillborns Birth Defects BVD symptoms

6. Mycoplasma Joint

7. What is Persistent Infection? • A PI calf is born infected with the virus • This can happen if the dam is a PI animal • This can happen if the dam is transiently infected during pregnancy from another animal • *The virus must be non-cytopathic* • The calf must be infected between 40-100 days approximately • During this time the calf has no immune system so it recognizes the virus as “self” and never clears it • After this time, the calf’s immune system is developed enough to fight the virus

8. PI calf (Body does not recognize virus) Virus is always circulating in body May die soon after birth Many are clinically normal This is the natural reservoir of the virus Infected in utero but not PI (infected around or after day 100) Congential defects Skeletal problems Dome shaped head Shortened lower jaw Eye abnormalities Brain defects Abortions Clinically normal calves Calves that are not killed can clear the virus and go on Manifestations of Calves infected in utero

9. PI Calves • PI calves are more likely to die than non-PI calves in the first year • Pneumonia • Diarrhea • Poor doer • Many look and perform like a healthy calf

10. Pasteurella mult. Lungs

11. Mucosal Disease • This is Highly fatal syndrome in which the mucous membranes become ulcerated • Mouth • Stomach • Intestine • Teats • Coronary bands of hooves

12. Abomasal Ulcers

13. Mucosal Dz, cont • For mucosal disease to occur a PI calf (noncytopathic) must be superinfected with a cytopathic strain. • The more closely related the viruses are genetically, the worse the disease • When a noncytopathic virus found in nature mutates to cytopathic & the calf is exposed • When the PI calf’s own noncytopathic strain mutates

14. PI Calf Shedding • PI calves shed the virus their entire life • Some periods they may shed a lot, and others not as much • Virus shed in saliva, tears, urine, feces, blood • There is so much virus shed, that most vaccines cannot protect other cattle against a PI • Continue to infect cow herds and create more PI’s

15. PI Diagnosis • Ear Notch Elisa • Ear Notch Immunohistochemisty • Polymerase Chain Reaction • Virus Isolation These tests can be done at anytime in a PI’s life and only need to be done once. If positive, will always be positive. If negative, can be infected with BVD but will not be a PI If transiently infected, some tests may be positive, but the calf may need to be tested again in a month to confirm PI status

16. BVD Control& Prevention • Vaccination with a vaccine using Type 1 and Type 2 strains • Modified live vaccine creates a stronger, more natural immunity, is cheaper, and less doses required • Newer vaccines have label claims that if given to cow pre-breeding can successfully prevent PI in fetus

17. BVD Control & Prevention, cont. • Test herds for PI calves and remove all animals to quarantine** • Test all dams of PI calves to see if they are also PI • Test all purchased breeding animals before entry into herd

18. Questions?