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Symposium Emerging vector borne viral diseases - Lelystad, November 28, 2008 - report from Christine Bijl
 
Betty, Resie and I attended the vector symposium in Lelystad.

For the greatest part the programme was very interesting with speakers from the Netherlands, Spain, USA, Turkey and South Africa. I raised my hand three times for questions and remarks.

We started off with Prof. Willem Takken, entomologist of WUR (Wageningen University & Research Centre). He sketched the wide range of vector borne animal and human diseases. The title of his presentation was "Do we need to worry?" I think we didn't need his words to say YES.

We then heard Armin Elbers, BTV specialist of Lelystad. Giving a vast expose on BTV8. Not much news. He was reluctant to say anything about BTV6, as clearly this was not his field.

Then we all woke up when José Sanchez Vizcaino, Prof. of Madrid University  (internet link) started talking. He is an expert on AHS (African Horse sickness). He said "Horses are not sheep". A dead sheep is nasty but when horses die the world collapses.

He specifically warned about the late reporting of symptoms in the field. By the time the first samples get to the lab, the disease could have been around for a month or more. We already know a lot about the vectors, we have diagnostic tests with result after 4 hrs. We need a good vaccine and Spain is working on that, because the MLV vaccines from SA give a lot of trouble such as infecting the midges and possible virulence. The SA Modification is aimed at control. The EU needs eradication.

And, very important, we need better training of the field people, keepers and vets. They are the eyes of the animals.

Because IT IS COMING! We have the vectors, the temperature is getting "better and better", and we have the horses.

Question: why are you mostly concerned about (African Horse sickness) serotypes 4 and 7.

Answer: they circulate in the African areas where the big dust winds come from sweeping over southern Europe.

Remark: Happy to hear Spain is developing better vaccines, because if the zebras were tested negative on leaving Africa and tested negative on arriving in Portugal, and still brought AHS to Spain, we surely need the vaccines fast.

Prof. Marion Koopmans (Netherlands), veterinarian, public health virologist, working for the Public health institute, gave a presentation on WNV (West Nile virus). An arboviral infection with impact on public health. An illness that is under reported, because it is not usually recognized. The symptoms of encephalitis in humans and horses occur with a certain frequency in Europe. There should be more awareness of possible cases. Many travellers come back with a disease and symptoms are treated. So monitoring of WNV should be done in areas with these occurrences. This problem should be tackled at European level, knowing how dramatically WNV has spread all over Northern America, mainly due to a mutation of the virus and crows becoming the main vectors.

Prof. Richard Bowen (USA), his presentation was rather technical about two models for testing their (Colorado State University) vaccines' efficacy on horses. WNV was introduced in New York in 1999 then widely spread by wild birds, especially by the American crows.

Question: Why do we emphasise  the spread of wild birds so much? We obviously cannot do anything about the birds. We can do something about the introduction, which is as always through transports and movements of animals. Shouldn't we have stricter rules and control on  the transport  of living animals?

Answer: Yes, we should.

Then Prof. Onder Ergonul (Turkey) gave us an expose about CCHF (Crimean-Congo hemorrhagic fever). Humans become infected through tick bites and by blood contact with infected animals. This year in Turkey there was a sudden rise in human cases (nearly 2000). Global warming seems to be the major reason. There is no vaccine. There is a useful drug when used in the early stage of the disease.

Janusz Paweska (SA) told us about RVFV (Rift Valley Fever). The good news is there is only one serotype. The bad news is that it is a zoonotic disease, spread by the mosquito. Infected eggs survive in dried mud (essential for hatching). They hatch when the pools flood in the wet season, which results in outbreaks in humans and ruminants. Apart from spreading due to the climate change, the spread to other areas could also be wind-borne.

Ron Bergevoet (Netherlands), researcher at WUR and LEI (Agricultural Economics Institute), told us we need global solutions to tackle the global problem of emerging (exotic) (animal) diseases. Global commitment, sharing data.

Finally Rob Moormann, senior researcher at CVI (Central Veterinary Institute) and organiser of the symposium told us about the activities of the Institute. With the climate change, globalization, migration and lack of efficient and safe vaccines control is of the utmost necessity. High costs and huge mortality rates in humans and animals urged CVI to work on new types of vaccines, (DIVA-vaccines for BTV, AI, AHS) and specifically on modified Live virus-vaccines.

Question: Why work on MLV-vaccines when in Africa there is so much expertise? Or do you work together with them? Why more specifically work on MLV for BTV? We have an efficient vaccine? Could maybe type 6 have escaped from here?

Answer: I don't know about type 6 escaping. And we are working on MLV because inactivated vaccines have to be administered yearly and we need a DIVA vaccine.

Question: Why are you researching an AHS-vaccine when Merial is already testing an inactivated vaccine in SA? Do you cooperate with Merial?

Answer: No cooperation with Merial. Conditions in Africa are not the same as ours, African horses are not the same as ours. But there is a knowledge exchange between CVI and Onderstepoort and some cooperation.

 

Afterwards during drinks we had a nice talk with several of the speakers and researchers, among which were Moormann and Piet v Rijn (BTV expert). I asked them again about the CVI-vaccine development. They said that there has been no response from Merial. There is however good cooperation with Intervet and Pfizer.

 

And they ‘know' because the labs are too secure - ( like Pirbright? I asked) - that type 6 did not escape from CVI; they are still comparing the exact print of the outbreak virus to the Onderstepoort-MLV. Only if they find an identical match on all parts will they say it came from an MLV-vaccine. And this could have been used by a keeper who prematurely wanted to protect his animals against type 1, using the SA-cocktail containing 1 and 6. And it could also be an illegal transport of animals from Israel, where they vaccinate against type 6, through Bulgaria and Rumania with its poor surveillance etc. It's doubtful if we will ever know the truth.

  I also heard that last week SCOFCAH has decided to create a vaccine bank of all types of AHS vaccines (100,000 doses of each type for double inoculation of 50,000 animals). I thought that was the best news, not only in itself but also because we now know that BT-lessons were learned.

Presentations at   www.cvi.wur.nl/NL/nieuwsagenda

Best wishes,

Christine