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TRIAL BY EXPORT

12 1AlJtumn 2012 1ALPACA WORLD MAGAZINE


TRIAL BY EXPORT

The implications of having sent infected alpacas abroad would be devastating for us arid other UIZ based alpaca owners. ast winter Tracey and I confirmed a sale.of four females and one young male to Jorgen Larsson ofNybo Alpacas in Sweden. We had export ed alpacas to Jรถrgen in the past so we were prepared for the thorough testing requirements for the next export that we had plan ned for the spring. March came and the alpacas were blood tested for Brucellosis and skin tested for bTB in accordance with European law. We also carried out some additional testing on the alpacas including IBR,Johnes Disease and BVD. On a cool March morning our vet arrived and certified the export and shortly afterwards the lorry from John Parker International came and the alpacas were transported to Sweden. The alpacas travelled weil and arrived at Jรถrgen's farm in good health where they were unloaded and then put into quarantine. The Swedish government require alpacas to remain in quarantine in Sweden for 100 days post importation where they were subjected to more testing. As the Swedish quarantine process moved on, the alpacas were in perfeet health and seemed to be enjoying the spring weather.In late May the Swedish authorities decided to begin serological testing all alpacas imported from the UK for bTB as Sweden claims to be bTB free. The choice oftest they decided to use was the Chembio Brock Stat PAK Test which is a blood test that is designed for testing badgers for bTB by looking for antibodies to two antigens associated with a bTB infection. The authorities began to roll out the testing regime and Jorgen's alpacas were first on their list. The vets ca me to Jorgen's farm in the week beginning the 21st of May and took blood from all 5 alpacas and then sent the blood back to the UKfor testing. On the 6th ofJune the samples reached the UK for testing and on the 8th ofJune we were told

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that two alpacas had tested positive to bTB and that they would be destroyed immediately. This obviously came as a huge shock to Tracey and I, not to mention poorJรถrgen in Sweden. On the 12th ofJune the hvo alpacas were slaughtered and post mortem testing began. The press in Sweden, in fact the majority of the Scandinavian press, went public with the result with the main headline being bTB found in alpacas imported to Sweden. We immediately questioned the result as 2 alpacas out of5 alpacas having bTB did not fit the health and bio security profile ofour herd of alpacas in England. Surely this wasn't right?! We also questioned the accuracy of the Brock STAT Pak test as we knew it achieved a minimum of7% false positive results and recent research in the UK indicated a much higher false positive rate when this badger test was used on alpacas. Our farm in Dorset has very tight bio security measures that we set up to limit the disease routes entering our farm . We pride ourselves on having one of the tightest bio secure alpaca farms in the world. We installed a 100% badger proofelectric fence nearly 3 years earlie.r, we operate a 9 month quarantine on all alpacas purchased and entering the herd and these alpacas are tested for a variety ofdiseases before entering the premises. There are disinfection points for all visitors entering the farm and we have a 5 metre non contiguous double fence surrounding the property. Our adult mortality rate was also extremely low; less than 0.5% per year and all deaths have full post mortem examinations carried out and we have never had any confirmation or suspicion ofbTB in the past. Back in February this year our vet, Alastair Hayton from Synergy Farm Health, informed us ofa new ground breaking bTB serological blood test that had been developed by Enfer

ALPACA WORLD MAGAZINE1Au tumn 2012113


TRIAL BY EXPORT

Enfer laboratories, Nass, Ireland

Example of ty pical res ults for 4 Al paca blood samples

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Scientin.c ofIreland with over fSmillion worth ofprivate funding. The Enferplex TB test was developed to accurately detect bTB in live animals and it has been ren.ned for commercial use in cattle and camelids. Enfer Scientin.c are working with Scottish scientists from MV Diagnostics in a joint venture to develop the test in alpacas and other species, induding humans. Before the Swedish situation came to light, Alastair had already suggested that Inca Alpaca might like to become the /irst alpaca herd in the world to have this test performed on every alpaca on the farm with a view to identifying our bTB status. The events in Sweden forced us to take some immediate action to identify our herd 's bTB status. Ifwe did have a problem we wanted to n.nd out right away. After some intense discussions and thought, we decided to have our entire alpaca herd blood tested using the Enferplex Test with a view to proving to the Swedish authority that our herd was serologically dear ofbTB. The science behind the Enferplex Test and the extensive testing that they had already carrjed

'4 1A"",mn Jnl1 l Al PAr A WDRLD MAGAZINE

out on over 120,000 of cattle, 1300 alpacas and many more species gave us the con/idence that the EnferplexTest would give lIS an accurate result with a very low percentage offalse positive results. The brief science of the Enferplex test is: When an alpaca is infected with TB its immune system tries to controi the infection by making cell mediated responses and antibody responses. These are two separate arms of the immune system and act in different ways to try and controi the TB infection. The presenee of these responses can be used to diagnose the fact that the alpaca is infected with TB. Cell mediated responses can be detected by the skin test and by the gamma interferon test. These become positive early in the infection but wane as the disease gets more serious. Antibody responses can be me asured by the Enferplex TB test which can become positive about 2-3 weeks aEter the animal becomes infected and generally gets stronger as time goes on. TB can be a very difficult infection to diagnose. Unfortunately not all animals, whether alpacas, cattle or humans, respond to TB by producing detectable skin, gamma interferon and/ or antibodyresponses at all stages of the infection. Further the skln test is very inaccurate in alpac~s and the gamma interferon test, while be ing a good test for cell mediated responses,IS expensive, takes a long time to per form and requires very specialised facilities and expertise to make it work.

3

4

The Enferplex TB test is hoth sensitive (it is good at detecting infected animals) and specdic (it can be set to mini mise any false positives). It is easy to take the sample and get it to the lab in goo condition, it is relativel}' inexpensive to perform, it is robust and produces objective results, and th, test can produce a result within 3 hours in the lab The Enferplex TB assa)' is a multiplex assa}' which dctects antihodies to seven separate puriiied antigens from the TB organism. The antigens are spotted separately onto plastic and then reacted with serum from the animal. If the animal is infected with TB and has antihodies in its serum these stick to the antigen spots on the plastic. These antibodies can the n be revealed with a stain which cause s the spots to glo\\'. If the animal lIoes not have TB antibodies in its serum the spots will not glo\\'. The .mount oflight produc ed by the spot is a measure of the amount of antibody in the serum and is recordec via a digital camera and computer. Because the antigens are in separate spots, rather than being mixed together as in other antibody tests, the response to each antigen can be measured separately. This makes the test very sensitive an( very spe citic as the number of antigens is greate l than in other tests and you can see exactly whicl antigen s are being responded to by the animal lhe

problem

wIth -r D l;:, lhdl

l! 1I..l1 v

.\.uu d l

d l l l l U .... \;).

only make responses to a few antigens at a time and you need to use a panel ofseven antigens to get the best results. This is true in h,;mans too.


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We pride ourselves on having one ofthe tightest bio secure alpaca farms in the world.

Enferplex test procedure:

1.

Blood sample

2.

Test plate

3.

Test Reader

4.

Results analysis

Sample number l on the extreme left is from an uninfected animal. The other samples are from 3 infected animals and show how the different spots vary in the amount ofglow. This shows that different animals produce different amounts of antibody to the different antigens and emphasises why you need a large number ofantigens in the assay, and that you need to be able to analyse the response to each antigen separately (not all mixed together as in the Idexx and StatPak tests) to get maximum sensitivity and specificity.Back on the farm we quickly made preparations to take blood from the whole herd and, on the morning of the 21st ofjune, three vets and a number of handlers took the blood we needed and it was couriered to lreland for testing. The results shortly followed, out of265 alpacas, 263 alpacas tested completely negative for bTB and 2 alpacas were considered to showa very marginal positive reaction on three antigens. The advice of MV Diagnostics and Enfer Scientific was that these two animals were very likely to be negative as their antigen profiles we re nowhere near the pattern seen in true positives. However, given the vital importance of clearing any doubt, following discussion with Defra, these animals we re sent for a full post mortem carrie d out by the government body AHVLA - Animal Health Veterinary Laboratories Agency - to confirm that they showed no evidence of disease. Both alpacas were found to be completely elear ofbTB and were deemed to have given false positive results in the Enferplex test. This equated to a 0.75% false positive rate when using the Enferplex Test. Meanwhile back in Sweden the authorities had carried out full post mortem examinations on the two Stat Pak positive alpacas and these two alpacas were found to be completely elear ofbTB on visual assessment, microbiology, histopathology and finally by culture. These results ca me as a huge relief for Tracey and I as weil as all the breeders that keep their alpacas on our farm. The implications ofhaving sent infected alpacas abroad would be devastating for us and other UK based alpaca owners. We are now confident that the Stat Pak test results on the two alpacas that were slaughtered in Sweden were false positives. The fact that the Stat Pak test was not validated or licensed for use in alpacas did not stop the Swedish Authorities using it as a test that would undoubtedly change people's lives and businesses forever. Before any attempts of confirmation of disease had been made, the

disease and should be tracked down and checked immediately. After we received our herd negative result for bTB from Enfer Group we began to dig into the procedures that we re followed by the Authorities in Sweden. We immediately made some startling discoveries as to a possible reason the alpacas probably gave a false positive result when tested using the Stat PAK test: Chembio (the manufacturers of the Stat Pak) issue the instructions for the handling ofblood to be tested for bTB as follows: "Samples perform best when tested immediately after collection. Specimens should be immediately refrigerated at 2 to 8°C following collection and can be used up to 3 days. If testing within 3 days is not possible, the specimens should be frozen at -20°C or colder until use. Avoid repeated freezing and thawing." The National Veterinary Institute ofSweden were aske d if the test material (blood) from our alpacas was frozen when it was sent to England, and they said no. The Stat Pak test was carried out in England 8 days after the blood was taken in Sweden. We cannot conflrm that the mishandling of the blood was the result of the positive results or whether it is possibly due to the inherent specificity of the Brock Stat Pak Test{the Brock and Camelid Stat Pak tests no longer appear on the Chembio website as products for sale) ), but it certaini)' has raised some questions. What is for certain is that Tracey and I, as weil as all of our customers and investors, have been through a huge amount of pain and anguish as a result of the positive results this test produced, and the consequent actions of the Swedish authorities, not to mention the heartache Jörgen and his family have had to go through in Sweden when they watched two of their prized alpacas being put to sleep. We have now been fully compensated for the loss of the alpacas by the Swedish Government and they are currently retracting their previous state ments regarding the suspected disease prevalence in our herd. Through the use of the Enferplex Test, we

authorities had noti6e d other Scandinuvian

es[:;tbli~hed

veterinary offices that we were a bTB infected herd and consequently that all alpacas exported to Scandinavia from our farm may have the

bTB and our tough bio security measures will ensure that we remain extremely low risk for years to come. ';;,

tha.t our herd is ;j crol o ~ic a lly ch::ac of

Al PACA WORLD MAGAZINE IAutumn 2012 115

Trial by export  

Trial by export

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