Dear All

My apologies for my late participation. This seems to be an excellent discussion. From what I have read, I have a few responses and some new questions to raise.

I agree that we have the technical tools in terms of vaccines and tests to undertake PPR control and eradication. And suspect that if it doesn't already exist, a thermostable vaccine could be produced using a similar method to that used for RP. Or am I wrong about that? If it already exists or can be produced, that may be a key step.
Joining late it can be difficult  to catch up on everything that has been covered in a conference. Almost the first contributions and responses to this conference covered this technical development. A number of thermostable vaccines are being tested or even in use. - Moderator.
 
I may have missed this point elsewhere, but I think that PPR will be more difficult to eradicate than RP (but still achievable) because of the more rapid turnover of small ruminant populations compared to cattle. From the countries where I have worked on SR (Zimbabwe, Nepal, Bangladesh, Albania) I would estimate an annual turnover of 25-33% annually which is much higher than I have seen for cattle in those countries (10-15%) in less intensive production systems. This means that
herd immunity will erode more quickly and may allow continued circulation. I think this means that we should  perhaps concentrate resources in areas with active infections and in nearby areas. Spreading them widely may lead to a marginal herd immunity even at the highest and this may erode below what is required within a very short time. We will need to think of how to apply the vaccine in the field in such a way as to maintain herd immunity throughout the year.
 
Dr Honhold highlights here a very important diference between PPR and RP which has been seen and flagged up in other fora (though little mentioned in this conference so far).  Fortunately, it has been seen as a potential complication to PPR eradication rather than a factor that will stop eradication. If anything it is one more good reason for adopting an epidemiologically-based approach to progressive control of PPR. As the author says, strategies for control must ensure that vaccination is concentrated in areas where it is most needed. - Moderator.
 
 
 
 
Although an issue with this is that small ruminants move longer distances and often faster than do cattle**, so we need a surveillance system that is looking far and wide for the disease. There are also often highly seasonal aspects to these movements around holiday seasons which have been identified as high risk periods for spread to new areas. A separate issue here is that, again in my experience, the disease is often present in an area for a couple of years or so before it is reported. That surprises me because, again in my experience in those areas, the clinical presentation is pretty clear cut when it is finally recognised. It seems that local vets and farmers do not know what it is and don't recognise it quickly, which surprises me. Is it an issue of the importance attached to small ruminants by veterinary services and a lack of knowledge of small ruminant diseases? Is their often being owned and cared for by women a limiting factor in early detection?
 
**Years ago travelling by plane in Ghana I sat beside an old man, the pilot's uncle, who found it quite normal to sit with a goat on his lap all the way from Tamale in the North back down to Accra: 500-600 km in an hour and a half.  Much more recently, fighting through the logjam of trucks waiting to cross from Tanzania into Zambia, I was interested to see how many goats were being carried South on the top of oil tankers and the like. Quite a few.  - Moderator.   

Nick Honhold
BVSc MSc PhD MRCVS DipECVPH
Independent consultant



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