BVD TI vs PI

[kenny thomas]

Will a calf or cow that has been exposed to BVD and is TI show up as a positive in an ear notch test? The more I read the more confused I am.

 

[Bright Raven]

Will a calf or cow that has been exposed to BVD and is TI show up as a positive in an ear notch test? The more I read the more confused I am.

Kenny. This really gets complicated. I have read detailed publications on BVD and it takes a lot to get it clear in your head so don't feel like the lone ranger.

An animal that gets exposed after birth ( versus in utero) is TI. As I understand it, they are seropositive. If a calf gets exposed in utero, then the resulting calf after birth becomes PI and will shed the virus. The PI calf will also be seropositive. That makes them a hazard. The TI will test seropositive. That is how I read the publications. I usually rely on the Merck Veterinarian Manual. I am busy right now but I will reread it to make sure I am posting this correctly.

Edited to add: I think the ear sample test is designed to be a little different than a blood titer test. If Lucky_P reads this, he will know.

 

[kenny thomas]

I understand the TI and PI but could I get a false positive test from the TI?
Not mine but I hauled a calf yesterday that tested positive. His mother was raised there and no cattle added to the herd. No cattle nearby even. Maybe from deer?

 

[Bright Raven]

I understand the TI and PI but could I get a false positive test from the TI?
Not mine but I hauled a calf yesterday that tested positive. His mother was raised there and no cattle added to the herd. No cattle nearby even. Maybe from deer?

The ear wedge test can be used to determine PI.

It takes more than one test to determine the difference between PI infected and TI infected. As follows:

Antigen ELISA and rtPCR are currently the most frequently performed tests to detect virus or viral antigen. Individual testing of ear tissue tag samples or serum samples is performed. It is vital that repeat testing is performed on positive samples to distinguish between acute, transiently infected cattle and PIs. A second positive result, acquired at least three weeks after the primary result, indicates a PI animal. rtPCR can also be used on bulk tank milk (BTM) samples to detect any PI cows contributing to the tank. It is reported that the maximum number of contributing cows from which a PI can be detected is 300.

 

[Bright Raven]

The TI animal does test positive. As follows:

TI calves may also test positive for BVD virus. However, due to the immune response in TI calves a repeat test 3-4 weeks later should be negative, whereas a PI should always give a positive result. It is expected that around 0.6-0.7% (6-7 calves per 1,000) will test positive for BVD virus.

What you are really want to know:

Was the calf that tested positive a TI or PI? You need to see the test to answer that.

 

[kenny thomas]

The TI animal does test positive. As follows:

TI calves may also test positive for BVD virus. However, due to the immune response in TI calves a repeat test 3-4 weeks later should be negative, whereas a PI should always give a positive result. It is expected that around 0.6-0.7% (6-7 calves per 1,000) will test positive for BVD virus.

What you are really want to know:

Was the calf that tested positive a TI or PI? You need to see the test to answer that.

Ok, the calf was isolated today and will be retested later.
So your saying I need to see the next test 3 weeks from now?

 

[Bright Raven]

The TI animal does test positive. As follows:

TI calves may also test positive for BVD virus. However, due to the immune response in TI calves a repeat test 3-4 weeks later should be negative, whereas a PI should always give a positive result. It is expected that around 0.6-0.7% (6-7 calves per 1,000) will test positive for BVD virus.

What you are really want to know:

Was the calf that tested positive a TI or PI? You need to see the test to answer that.

Ok, the calf was isolated today and will be retested later.
So your saying I need to see the next test 3 weeks from now?

If the ear wedge was tested, that test alone can confirm a PI calf.

What they are saying there is this. If it is a TI, it may test positive but once the immune response to the infection occurs, the test will show negative as the antibodies decrease. Thus, two tests are needed in TI to determine if the calf is still infected. Remember, a TI calf does not stay infected and once it fights off the pathogen, it stops being contagious.

 

[kenny thomas]

That's the answers I was looking for. Thank you.
For some reason there seems to be too many calves testing positive lately. Or it might be because more of us are testing feeder calves. Most of the calves here have never seen a chute so rarely vaccinated till we buy them

 

[kenny thomas]

Ok, now your thoughts on Bovela one shot vaccine for BVD? For calves and all cows even if pregnant.

 

[kenny thomas]

The more I read it may not be available in the US

 

[Bright Raven]

Ok, now your thoughts on Bovela one shot vaccine for BVD? For calves and all cows even if pregnant.

Remember this. The reason it is safe is because it only covers BVD. Here is what few people realize. The only component of MLV fetal protection vaccines that has a HIGH RISK of abortion in cattle not previously exposed is IBR.

Thus, a vaccine with only BVD is naturally safe. Having got that clear. That is definitely an advantage if you need to protect cattle from BVD and they are vulnerable to IBR.

If you have those circumstances, it is great.

PS. You are correct, it may not be available.

 

[kenny thomas]

Don't you hate it when I'm thinking at least half straight? Too many somewhat sensible questions. I have been a good old man today. Hahaha

 

[Bright Raven]

Don't you hate it when I'm thinking at least half straight? Too many somewhat sensible questions. I have been a good old man today. Hahaha

Lol. They are very good questions. BVD is nasty. It is about as easy to transmit as the cold virus is in humans.

 

[kenny thomas]

Don't you hate it when I'm thinking at least half straight? Too many somewhat sensible questions. I have been a good old man today. Hahaha

Lol. They are very good questions. BVD is nasty. It is about as easy to transmit as the cold virus is in humans.

And unlike most things it's very easy to test right on the farm. And fairly inexpensive. A little over $4 per test and we test 2 in each sample. If something test positive then we separate those and test each.

 

[wbvs58]

Ron, just to confuse things though basically you have the jist of it.
A PI calf will not be seropositive as this is what the problem is with a PI, they don't recognise the virus as being foreign hence don't develop antibodies to it.
Both a PI and a TI will test positive on an ear notch PCR test as it tests for actual virus not antibodies however the TI should be negative a few weeks later once it develops antibodies and eliminates the virus.

Ken

 

[Jeanne - Simme Valley]

"His mother was raised there and no cattle added to the herd. No cattle nearby even. Maybe from deer?"
Also to clear up this statement. PEOPLE are a huge transmitter of disease. You visit another farm, or someone visits your farm and your/their boots are carrying contaminants. I don't know about deer?

 

[sstterry]

I have really enjoyed this thread, even though most of it went right over my head.

 

[Bright Raven]

Ron, just to confuse things though basically you have the jist of it.
A PI calf will not be seropositive as this is what the problem is with a PI, they don't recognise the virus as being foreign hence don't develop antibodies to it.
Both a PI and a TI will test positive on an ear notch PCR test as it tests for actual virus not antibodies however the TI should be negative a few weeks later once it develops antibodies and eliminates the virus.

Ken

Thanks Ken. BVD is a challenge to get straight. That bit of information is very helpful.

 

[Bright Raven]

Ok, now your thoughts on Bovela one shot vaccine for BVD? For calves and all cows even if pregnant.

Remember this. The reason it is safe is because it only covers BVD. Here is what few people realize. The only component of MLV fetal protection vaccines that has a HIGH RISK of abortion in cattle not previously exposed is IBR.

Thus, a vaccine with only BVD is naturally safe. Having got that clear. That is definitely an advantage if you need to protect cattle from BVD and they are vulnerable to IBR.

If you have those circumstances, it is great.

PS. You are correct, it may not be available.

Kenny

I want to be clear. Bovela One Shot is a MLV preparation of only BVD. It is described as being effective in only one shot.

My point about IBR needs to be further explained. The fetal protection (ex. Bovi Shield Gold FP 5) vaccines include IBR, BVD Type 1 and 2, BRSV AND PI3. Those are the FP5. The only components that can cause abortion from giving the vaccine are the IBR and BVD components. However, in studies conducted by Zoetis, it has been found that the IBR component is the highest risk of causing abortions due to the vaccine (per personal conversation with Zoetis Veterinarian Staff). This is why a vacvine with only BVD would be less of a risk if you were giving it in a herd of cattle that had not previously been exposed to a fetal protection MLV vaccine.

PS: there are also American made vaccines for only BVD. If my memory serves me, they also only require one shot. I will look it up and check.

 

[Bright Raven]

Kenny

You don't need the Bovela One Shot. There are BVD MLV only vaccines available in the US. Here is an example. It provides 9 months of immunity on first shot.