Are cattle a carrier of the EHD virus?

I am trying to get info on how the EHD virus survives the winter in cold climates. I know that cattle are a reservoir host for the EHD virus. I would like to know if they are also a carrier in which the virus can harbor and resurface after winter. I am seeking an explanation of this. It is my understanding that the virus can only survive winter in tropical areas where the infectious cycle has adequate temps to continue.

Interesting, I hope someone can answer this one. I was told they can bury their eggs as much as a foot deep in mud so if that is the case it would take a significant freeze to kill them.  If the cattle are reservoir hosts then shouldn't we see them again at the first sign of spring?  But that goes for the mud as well.  Here are a couple things I found just doing a couple quick searches.

 I searched their life cycle and not necessarily our midge but found information on the Swede Midge saying it goes into a cocoon before adulthood and can live in the soil more than a year. 


http://www.omafra.gov.on.ca/english/crops/facts/08-007.htm 


another study in FL which says their mean flight distance is 2km!  So if they can travel a mile......


http://entnemdept.ufl.edu/creatures/aquatic/biting_midges.htm


 


Doesn't answer your question but I found it interesting and relevant. 

There are a few ways the virus might winter. It is possible that the midges/vector pass the virus vertically through their eggs which survive the winter. It is possible that the virus could remain latent over winter in a carrier & become stimulated to resume reproducing if the carrier becomes stressed. There is also the possibility for "transplacental" infection where the virus crosses the placenta to the foetus, thus giving the gestation period  (winter?) free of clinical cases until the young are on the ground.


 


Sharkey

I have a lot of field study time on this and yes I have found midges down as far as 15 inches in the mud. I shot some video of this about a month back from a old pond that  was 95% dried up but had a heavy wet soil with about 4 inches of water. This pond was about 1/4 ac and the midges were so thick in the air it looked like a sand storm. I fogged the area twice a day for two days morning and evening and sprayed the soil and water directly also. On the 3rd day we did not see any more airborne. I monitored  the spot for two more weeks and did a second application directly on the soil a week later after seeing midges about 4 inches in the soil but in testing the soil saw a reduction of about 70% The second ground application did a complete kill. As of yet we have seen no further hatching in the soil.

Last winter was one of the coldest on record in Indiana. I had water lines freeze out in the pasture that had never froze before. They were frozen 2' -3' feet down underneath where the deer had trampled off the snow. I know an excavator who told me under plowed driveways he was digging up water lines where the ground was frozen 4'. I don't see how the midge could have wintered here last winter. I didn't have a positive EHD test confirmed last year. It is plausible that I could have stressed my doe and caused the infection to come out of dormancy by what Sharkey posted. I had stressed the doe more in the pen in which I was hit the worst. They had just been divided up and sorted into seperate pens for pasture breeding and AI. Most of the ones intended for pasture breeding were in the pens they were used to. My AI group were in a new fresh healthy well drained pen on a gentle sloped hillside. It was in that pen that I had the most loss. I still would like to know if the carrier you are inferring is cattle or deer? Each of their immune responses and ability to deal with the virus are very different.

It is mighty nice to see your post. I have not seen you on here in about a year. Thanks for the thought provoking info! Mate

Marsh valley hosted the "bug guy" last year he gave a seminar on the midge its self how it flies and nest. What I got out of it is cattle Carrie EHD the midge has to bite the cow then pass to deer. The reason you see EHD in drought conditions is the water table is most stagnant it drops below all man made drainage letting the midge thrive. Ohio was hit hard in 2012 our natural deer herd is still playing catch up. I heard in our military arsenal they found 70 some deer around one pond.

Freetown

I wish that bug guy Dr. Lee Cohnstaedt were where I could ask him a couple more questions. His knowledge is very helpful to our fight with the bug. I have googled and read so much info about EHD all over the world. I don't understand the science of why it is in these isolated pockets with 100's of miles between. There has to be a reservoir host spreading the virus.

"It is mighty nice to see your post. I have not seen you on here in about a year. Thanks for the thought provoking info! Mate" (Bell)


 


Cheers mate!


Thank you for the warm reply.


 


Sharkey

We will quickly get an EHD vaccine with a high quality adjuvant that works if this is scrutinized. Imagine buying a high dollar deer with confidence it will not die from EHD. This would be a needed shot in the arm to our industry.

Bell990081414078637



We will quickly get an EHD vaccine with a high quality adjuvant that works if this is scrutinized. Imagine buying a high dollar deer with confidence it will not die from EHD. This would be a needed shot in the arm to our industry.




 


Keep in mind that for a vaccine to be really successful there needs to be widespread use to create widespread immunity, basically the virus needs to be eradicated. A vaccine that would have some benefit this year, might not work on a new strain next year. How would you vaccinate all the wild deer or other carriers to eradicate EHD like we have with smallpox virus or restrict it like we have the measeles virus in humans?  I don't know if a vaccine is going to be the silver bullet in managing & abating the effects of EHD long term unless the vaccination rates are very very high.


 


Looking at controlling contact with potential carriers & vectors may prove the wisest way to manage this virus. However, this would also need to be done on a very large scale. Individual farmers are not really going to be able to control or prevent the spread of EHD, so I can see why a vaccine is desirable so as to take back a measure of control over ones own farm. This virus really needs to be tackled on a much greater scale than farm by farm if it is to be managed or eradicated.


 


Just for the record, we have found antibodies for EHD in the blood work on chital & rusa deer down here. I'm not aware of any clinical cases in these species, but one has to wonder how it got here.


 


Sharkey

It is troubling to me as a deer farmer that the likes of Brandon Butler and Ryan Sabalow are allowed to make bold unchecked statements that say deer farmers are putting live stock at risk. Interstate movement of our deer during the summer months months is basically nonexistent. Cattle on the other hand are moved daily interstate all summer while no observation for clinical symptoms of EHD is required before any seasonal movement. Cattle are moved daily interstate from areas where EHD is an ongoing issue and our deer are not. Cattle are very slow moving reservoir host for the midge to feed on for a nourishing blood meal once at their destination.