Viral lung complaint called O.P.A

[Vicki_Ann]

Everything I have read doesn't give a definitive answer to how long the virus survives outside of the sheep, but it's weeks, not months and years. OPA is not known to affect other species so using cattle to graze the pasture following having infected sheep there should be safe enough.

OPA is one of those horrid 'tip of the iceberg' type diseases. Many ewes can show no signs through their life and then die suddenly with what appears to be classic pneumonia. Unless these penumonia and sudden death cases are post mortemed by a vet able to recognise tumours in the lungs (which can be trickier to identify if a secondary pneumonia is present) then it is impossible to say whether a flock has OPA or not. I have seen numerous ewes with very suspicious signs (even the odd one in my own flock) and without a post mortem examination of every dead ewe, it's not possible for anyone to declare their flock free of OPA as no blood tests can reliably prove its presence or absence.

OPA impacts on production quite notably as affected ewes often become thin and waste from 3-4 years old (sometimes younger) and obviously they will not be able to rear lambs effectively or get in lamb once this happens. Not all ewes with OPA have the classic sign of fluid pouring from their nostrils, some may only have a slightly increased resp rate and some exercise intolerance and lag behind when gathered. There is often also a higher proportion of ewes suffering with pneumonia and dying suddenly in affected flocks. Currently, as there is no practical way to prove a flock is free of OPA, de-population is not always recommended for affected flocks as there is a reasonably high risk of buying it back in again when re-stocking.

Interestingly, maintaining sheep in single age groups seems to be an important factor in minimising clinical disease in affected flocks and when Maedi-visna and OPA are both present in the same flock, it is a complete disaster and depopulation and re-stocking from MV-accredited sources is the only practical option here.

It's a complete PITA if I'm honest. I believe Moredun are doing a lot to develop diagnostics for OPA, it would be great if a vaccine could be developed in the future and that is surely the basis of some research but I don't think there will be one available any time soon

 

[cheviot53]

Used to send OPA sheep to the Mordun over 30 yrs ago , so yes progress very slow

 

[Grem]

Everything I have read doesn't give a definitive answer to how long the virus survives outside of the sheep, but it's weeks, not months and years. OPA is not known to affect other species so using cattle to graze the pasture following having infected sheep there should be safe enough.

OPA is one of those horrid 'tip of the iceberg' type diseases. Many ewes can show no signs through their life and then die suddenly with what appears to be classic pneumonia. Unless these penumonia and sudden death cases are post mortemed by a vet able to recognise tumours in the lungs (which can be trickier to identify if a secondary pneumonia is present) then it is impossible to say whether a flock has OPA or not. I have seen numerous ewes with very suspicious signs (even the odd one in my own flock) and without a post mortem examination of every dead ewe, it's not possible for anyone to declare their flock free of OPA as no blood tests can reliably prove its presence or absence.

OPA impacts on production quite notably as affected ewes often become thin and waste from 3-4 years old (sometimes younger) and obviously they will not be able to rear lambs effectively or get in lamb once this happens. Not all ewes with OPA have the classic sign of fluid pouring from their nostrils, some may only have a slightly increased resp rate and some exercise intolerance and lag behind when gathered. There is often also a higher proportion of ewes suffering with pneumonia and dying suddenly in affected flocks. Currently, as there is no practical way to prove a flock is free of OPA, de-population is not always recommended for affected flocks as there is a reasonably high risk of buying it back in again when re-stocking.

Interestingly, maintaining sheep in single age groups seems to be an important factor in minimising clinical disease in affected flocks and when Maedi-visna and OPA are both present in the same flock, it is a complete disaster and depopulation and re-stocking from MV-accredited sources is the only practical option here.

It's a complete PITA if I'm honest. I believe Moredun are doing a lot to develop diagnostics for OPA, it would be great if a vaccine could be developed in the future and that is surely the basis of some research but I don't think there will be one available any time soon

 

[Grem]

From what my GP friend says, ALL viruses have the potential to live forever. As the ice over the Arctic Circle melts it could release viruses that have lain dormant for millions of years. Bacteria, on the other hand can only survive a relatively short period without their host.