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A Report from The Royal Society of Edinburgh’s Working Party on Avian Influenza revised December 2007 The R oyal S ociety of E dinburgh Avian Influenza An Assessment of the Threat to Scotland

Avian Influenza - Royal Society of Edinburgh · Avian Influenza: An Assessment of the Threat to Scotland Introduction 1.1 Avian influenze is a disease of birds resulting from infection

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Page 1: Avian Influenza - Royal Society of Edinburgh · Avian Influenza: An Assessment of the Threat to Scotland Introduction 1.1 Avian influenze is a disease of birds resulting from infection

A Report from The Royal Society ofEdinburgh’s Working Party on AvianInfluenza

revised December 2007

The

Royal Society

of Edinburgh

Avian InfluenzaAn Assessment of the Threat to Scotland

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The Royal Society of Edinburgh

CONTENTS1. Introduction ........................................................................................................................................... 3

2. Wild Birds in Scotland ............................................................................................................................. 3

3. The Scottish Poultry Industry ................................................................................................................... 4

4. H5N1 Disease of Poultry ......................................................................................................................... 4

5. Surveillance Programmes ........................................................................................................................ .5

6. The Diagnosis of HPAI ............................................................................................................................ 6

7. Prevention and Control of Avian Influenza in Poultry ................................................................................ 6

8. Risks to Human Health ........................................................................................................................... 7

9. Conclusions and Recommendations ....................................................................................................... 9

Annex 1: Membership of the RSE Avian Influenza Working Party ................................................................ 10

Annex 2 : List of those who gave Evidence . .............................................................................................. 11

About the Royal Society of Edinburgh ....................................................................................................... 11

Foreword by Professor John Coggins FRSE

The incident at Cellardyke in Fife in April 2006 focussed public attention on the potential dangers that couldresult from an outbreak of avian influenza caused by the H5N1 strain.

The Royal Society of Edinburgh, recognising the need for independent advice, set up a Working Party to assesshow well prepared Scotland is to handle an epidemic of avian influenza. In our Report we recognise the exten-sive work done to minimise the risk to both human health and agriculture. We make recommendations to im-prove both disease prevention measures and the capability of dealing with an outbreak, should this occur inScotland.

This Report has been produced by an expert group, which also took evidence over several months from keypeople involved in this complex issue. We also have had the benefit of the extensive Inquiry undertaken by SirJohn Skehel for the Royal Society of London and the Academy of Medical Sciences. That examined the extent towhich scientific evidence has been incorporated into preparedness for a human flu pandemic in the UK. Weendorse the findings of that study, but have not sought to cover the same ground. We commend the contin-gency planning underway in Scotland for another human influenza pandemic, recognising that it might not becaused by the H5N1 avian influenza virus.

It is important to recognise that avian influenza is a disease of birds and can spread to humans only in excep-tional circumstances. There is no evidence to suggest that there is a risk to humans from the consumption ofeggs or poultry meat, provided it has been properly cooked. There are many forms of the avian influenza virus,not least the H5N1 strain that is currently of concern, and these pose a significant threat to the poultry industryworldwide, including that in Scotland.

The only effective means of protection currently available to the Scottish poultry industry is to prevent the virusspreading to its poultry flocks. It is important, therefore, to detect the presence of the virus in this country at theearliest possible stage, whether in the wild bird population or in domestic or commercial poultry. Equally impor-tant is having effective biosecurity measures in place to protect individual poultry units from the introduction of thevirus. We have concerns about the scope of the wild bird surveillance programme, and recommend that moreresearch is undertaken to quantify the risk of infection from wild birds.

We recognise the potential role of vaccines in the prevention and control of avian influenza. To produce moreeffective and easily administered vaccines will require further research. This should not be inhibited by the con-straints on the current use of vaccines.

I should like to thank all the members of the Working Party and those who gave oral or written evidence; also ourSecretary, Ian Melville who provided extensive assistance in the preparation of the report. The Working Partystands ready to provide further advice, should circumstances require this.

The views expressed in this report do not necessarily represent the views of the RSE Fellowship.

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Avian Influenza: An Assessment of the Threat to Scotland

Introduction

1.1 Avian influenze is a disease of birds resulting frominfection with a type A strain of the influenzavirus. Wild birds, especially waterfowl, are host toa large number of influenza viruses that are typedprimarily by differences in two glycoproteins thatproject from the surface of the virus. Sixteenhaemagglutinin subtypes (H1 – H16) and nineneuraminidase subtypes (N1 – N9) have beenidentified, and viruses with different combinationsof these subtypes have been found in birds andin humans. However, viruses infecting humans areusually specific to humans and, similarly, avianviruses seldom infect humans.

1.2 Most wild birds infected with an influenza virusshow no obvious effects. Low Pathogenic AvianInfluenza (LPAI) has been found in wild birdpopulations throughout the world, and occasion-ally spreads to domestic poultry. The absence ofclinical signs can make the presence of infectiondifficult to detect, although flocks may show signsof respiratory distress, diarrhoea or loss of appe-tite. Some viruses of the H5 and H7 subtypeshave been found to mutate to become highlypathogenic, giving rise to systemic infections,rather than ones restricted to the respiratory andenteric tracts, that can result in the deaths ofwhole flocks within a matter of hours of infec-tion. Highly Pathogenic Avian Influenza (HPAI) ishighly contagious and is a notifiable disease inthe UK and most other countries.

1.3 Outbreaks of avian influenza have occurred in anumber of countries, the first reported in Italy(“fowl plague”) in the late 19th century. In 2003,an outbreak of HPAI in the Netherlands spread toBelgium and Germany affecting some 250 farmsand resulting in the slaughter of more than 28million poultry. The strain of virus was identifiedas H7N7. Prior to 2007, the last outbreak of HPAIin the UK was in a turkey flock in Norfolk in1991.

1.4 One strain of the avian influenza virus, H5N1, isof particular concern at present. The first outbreakcaused by H5N1 was detected in Hong Kong in1997. Prompt action by the Hong Kong authori-ties in destroying the entire population of 1.5million birds in 3 days contained the disease.H5N1 re-emerged in late 2003 in an unprec-edented epidemic sweeping through poultry inmost Asian countries. In many of these countriesH5N1 is now endemic.

1.5 By July 2005 the disease had spread toKazakhstan and Russia, and more recently intoTurkey, Romania and Croatia. The first case in theEuropean Union occurred in Greece and thedisease has now been confirmed in Austria,Denmark, France, Germany, Italy, Spain, Hungary,Poland, the Czech Republic, Slovakia, Slovenia,Sweden and the UK.

Wild Birds in Scotland

2.1 Scotland is home, for at least part of the year, to aconsiderable number of wild birds that arecapable of carrying the influenza virus. Thehigher risk species are water birds, including allspecies of swans and geese, and some species ofducks, waders and gulls. The species that areclassified as near higher risk are the remainder ofthe ducks, waders and gulls as well as terns.

2.2 The majority of these species are, at least to someextent, migratory. East to west migrations implythat birds reaching the shores of Scotland mighthave passed through areas that are infected withthe AI virus. Although east-west movements canoccur for many reasons, the firths and lochs ofScotland are particularly important as feeding andresting areas when the winter temperatures overthe continent of Europe are abnormally low. Atsuch times increased monitoring would beadvisable. North to south (and vice versa) migra-tions generally occur in the autumn and spring.For example, many geese breed in Arctic areas,

such as Greenland and Svalbard, but winter inScotland (and elsewhere in GB and Ireland). It isconsiderably less likely that those birds comingfrom Arctic areas will have passed through in-fected areas. However, the high-risk species thatoverwinter in northern Africa might have passedthrough infected areas before they reach Scot-land.

2.3 Scotland holds substantial populations of thehigher risk and near higher risk species. For thisreason more than half of the extent notified to theEuropean Commission as Specially Protected Areas(Birds Directive of 1979) is located in Scotland.Whilst it remains unknown how far a bird couldtravel once it has become infected with HPAI, anyoutbreak in Scotland has the potential to havenature conservation consequences as well assignificant economic effects.

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3.1 According to the Scottish Executive1, in June 2006there were 1,023 people employed on specialistpoultry farms in Scotland. Although almost 5,000holdings were recorded as keeping laying hens,97% of the laying flock was kept on the 89holdings having flocks of more than 1,000 birds. Itis clear, therefore, that there are many peoplethroughout Scotland who keep poultry primarilyfor domestic egg production or as a hobby.

3.2 Similarly, over 99% of broiler production wasrecorded as taking place on the 75 holdingshaving flocks of more than 10,000 birds, al-though 1,331 holdings were recorded as keepingbroilers and other table birds.

3.3 Chickens are by far the most numerous type ofpoultry kept in Scotland. Although ducks, geeseand turkeys have also been recorded, there is littlecommercial production of these birds.

3.4 The value of egg production for food in Scotlandin 2005 was £31 million, approximately 2% of

the total gross output of Scottish farming. Thevalue of table poultry was higher with corre-sponding figures of £88 million and 5%.

3.5 We understand that in the case of commerciallaying flocks, no birds are hatched in Scotlandand most are brought in from English hatcheries.The situation with broilers is very different withone of the world’s major companies, whichsupplies approximately 50% of the global poultrymeat industry, having a large pedigree unit inScotland.

3.6 Although shooting is an important element inthe rural economy of Scotland, we are not awareof any information on game bird numbers specificto Scotland. In the UK some 40 million pheasantsand 15 million partridges are bred each year, ofwhich 15 million pheasant and 2.6 millionpartridge are shot. In addition, approximately onemillion ducks, mainly mallard, are released eachyear.

4.1 The H5N1 virus has the capacity to wipe outwhole flocks of poultry within a short space oftime. It is very contagious, as demonstrated by itsrapid spread through many countries. If it were tobecome established in Scotland, the implicationsfor our egg and poultry meat producers wouldbe significant. Although the Scottish poultryindustry is small compared with the cattle andsheep industries, it would still impact adversely onthe rural economy.

4.2 Little information exists on the viability of theH5N1 virus in different environments but it isknown that, in addition to being carried by birds,it can be carried on human hands and feet, andpossibly by vehicles. However, the rapid spread ofthe virus, at least in Asia, has been shown to bedue primarily to the movement of infected poultry.There exists the possibility of H5N1 being intro-duced into the UK by the import of infected birds.Poultry chicks, game bird chicks (especially pheas-ants) and mallard ducklings are imported, butmainly from elsewhere in the EU where theincidence of the disease is low and the level ofmonitoring for the disease is high. Moreover, allimported birds are subject to veterinary inspectionand monitoring at an early stage following theirarrival in the country.

4.3 H5N1, unlike other HPAI viruses, is known tohave spread to wild bird populations. This raisesthe possibility that the virus could be introduced

into the UK by migratory birds. Indeed, the ChiefVeterinary Officer (Scotland) considers this to bethe most likely route by which the disease wouldbe introduced into Scotland and the rest of theUK.

4.4 It appears unlikely, however, that the outbreak ofHPAI at a turkey-finishing unit in Suffolk inFebruary 2007 was caused by the disease beingintroduced by wild birds. The virus was confirmedas the H5N1 strain and molecular genetic studiesfound it to be virtually identical to the virusisolated from two outbreaks in geese in Hungaryin January 2007. These results suggest a commonsource for the outbreaks in Suffolk and in Hun-gary, or a direct link between the Hungarianincidents in January 2007 and the Suffolk inci-dent the following month. Investigation of theSuffolk outbreak concluded that there was littleevidence to implicate wild birds and that circum-stantial epidemiological evidence suggested themost likely route for introduction of the virus wasin, or associated with, the transport of turkeymeat from Hungary to the UK.

4.5 The Suffolk outbreak was contained and weunderstand that modelling studies suggest thatthis will be typical of most outbreaks with thedisease not spreading beyond the index case.Professor Woolhouse’s research group at Edin-burgh University was one of six groups fromthroughout the UK brought together under theDEFRA Modelling Consortium for a 6-monthproject looking at the modelling of HPAI. Acommon feature of the models examined was

H5N1 Disease of Poultry

The Scottish Poultry Industry

1 The Scottish Executive is now known as the ScottishGovernment.

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Avian Influenza: An Assessment of the Threat to Scotland

that they drew demographic data on the locationof flocks from the Poultry Register. However, notonly does the Register exclude flocks of less than50 birds but it has been suggested to us that it isincomplete and sometimes inaccurate, at least forScotland, particularly at the level of data requiredfor modelling.

4.6 Another difficulty is the absence in the literatureof information on disease parameters for H5N1infection. Professor Woolhouse’s group has,therefore, employed H7 virus data in its HPAImodelling studies.

4.7 In spite of these limitations, the models hadlooked at a number of disease control options, but

it was emphasised to us that only tentative conclu-sions could be drawn at this stage, and that thesedid not provide a sound basis for policy develop-ment.

4.8 It appears to us that the Consortium was a usefulexercise, not least in identifying the requirementsfor improved demographic data on flocks andmore information on the parameters of H5N1disease. Although we recognise that modellingstudies are only one source of information relativeto HPAI planning, we consider that furtherfunding should be provided to develop andrefine HPAI models.

5.1 Surveillance is being conducted across Europe todetect avian influenza in poultry and wild birds. Inthe UK, all reports of disease in poultry areinvestigated. In addition, blood samples are takenfor testing from randomly selected poultry farms.

5.2 Because the greatest risk of introduction of theH5N1 virus into Scotland is thought to bethrough wild bird movements, a programme ofsurveillance is underway, with samples being takenfrom birds shot by wildfowlers, and from live birdscaught for ringing. Of 381 shot birds tested in GBin 2006 only two tested positive, in both cases fora low pathogenic H5 virus subtype. There were nopositive results from the testing of live birds.

5.3 For the purposes of wild bird monitoring in GB, thecountry has been divided into 100 kilometresquares, each of which has been assessed interms of its importance for the risk species of wildbird. Within Scotland 16 squares have beenidentified as high risk, mainly down the east ofthe country from Angus to the Borders. Withinthis area all reported deaths of wild birds on thelist are investigated, whereas elsewhere onlyreports of ten or more deaths are followed up. Inaddition, Scottish Natural Heritage and the RoyalSociety for the Protection of Birds are monitoringtheir Reserves for the incidence of high mortalityrates.

5.4 Monitoring in GB reflects current EU thinking andconcentrates on wetland birds (section 2.1) asbeing the highest risk. The EU list of high riskspecies is an informed judgement based onfactors such as the east-west movements of birds.The Scottish Government has drawn up its ownlist that includes seven species not found on theEU list. However, we are concerned that theGovernment’s list might not include all high riskspecies and that others, including some of thegulls, might also be relevant.

5.5 We have concerns about the wild bird surveillanceprogramme as it has been described to us. Werecognise that in theory, testing of wild birds, bothlive and dead, could be helpful in detecting theintroduction of the H5N1 virus into Scotland;detecting propagation of the virus within theScottish wild bird population; or in providing earlywarning of a threat to human health, bird conser-vation or the poultry industry. The concentrationon testing of wetland birds suggests the aim is todetect the introduction of the virus at an earlystage, but the limited blind sampling wouldappear inadequate for this purpose.

5.6 Similarly, we doubt the ability of the currentsurveillance to pick up the propagation of thevirus in the wild bird population, or to provideearly warning of a threat to poultry or humans.There is no testing of those gull species that tendto have contact with wetland birds and that arealso frequently found in the vicinity of poultryhouses, and we consider this a major omission.

5.7 Evidence from around the world suggests thatH5N1 does not pose a significant threat to wildbird conservation. Even if it did, there is little thatcould be done to mitigate the effects of thedisease in wild birds. Related to this, it appears tous that wild bird mortality rates vary significantlyfrom year to year and this means there is a lack ofbaseline data to assist in the recognition ofparticularly high mortality rates that merit furtherinvestigation.

5.8 We agree that there is a theoretical risk that wildbirds could play a role in introducing the H5N1virus into Scotland and in infecting poultry,particularly free range birds. However, it is notclear how significant this risk is in practice, andmore work is required to quantify the risk both toinform any wild bird surveillance and to provideguidance to the poultry industry on biosecuritypriorities. If wild bird surveillance is to continue,there is a requirement for greater clarity as to its

Surveillance Programmes

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purpose. Once the purpose is decided, a robustsampling and testing programme should bedesigned on scientific principles that will meet thispurpose.

5.9 We also recommend that further consideration begiven to who should conduct the monitoring.Currently data on wild birds are collected mainlyby NGOs, in particular RSPB. As we understand it,RSPB has received no offer of financial assistance,or recompense from, its agencies or the poultryindustry. We recognise that RSPB is well-qualifiedto carry out this work but take the view that itshould be adequately recompensed for the

monitoring it undertakes relevant to avian influ-enza. Consideration should be given to whetherthe poultry industry, being potentially the princi-pal beneficiary, should be asked to contribute tothe costs of a more effective wild bird monitoringprogramme.

5.10 In the case of an outbreak of H5N1 in a free-range flock, increased monitoring of wild birds inthe vicinity is recommended in order to detect thepossible spread of the virus from the infectedpoultry to the wild bird population.

6.1 An outbreak of HPAI in any group of susceptiblebirds will cause noticeable illness and an increasein the number of dead birds. In the case of anoutbreak in poultry, where the local veterinarysurgeon suspects HPAI the regional State Veteri-nary Service (SVS) will be alerted and will visit thefarm. If the SVS also suspects HPAI, samples ofdead birds will be sent to the Veterinary Laborato-ries Agency (VLA) at Weybridge for laboratoryconfirmation.

6.2 Illness and die-offs in those species of wild birdsconsidered most at risk from AI must also beinvestigated. Sick or freshly dead birds are col-lected and transported, taking precautions toavoid any risk of spreading infection, to thenearest regional veterinary laboratory for post-mortem examination. There are eight such labora-tories in Scotland (Thurso, Inverness, Aberdeen,Perth, Edinburgh, St. Boswell’s, Ayr and Dumfries)run by the Veterinary Services of the ScottishAgricultural College (SAC). If the post-mortemfindings suggest HPAI, a pool of tissues and asample of intestine are sent to VLA Weybridge forlaboratory confirmation.

The Diagnosis of HPAI

6.3 At VLA Weybridge, virus detection in the firstinstance is by real-time reverse transcriptase PCR(RT-PCR). If negative, both the sender of thesamples and the regional SVS office are informed,and no further testing is carried out. If there isevidence of the presence of AI virus, attempts aremade to isolate it and to type it by haemaggluti-nation inhibition testing and nucleotidesequencing before notifying a positive result.Pathogenicity testing is carried out by injectingday-old chicks with the recovered virus.

6.4 Rapid diagnosis is very important and we bothwelcome the development and encourage theintroduction of on–site diagnosis based on PCRtechnology. This will allow action to be takenexpeditiously, although confirmation will still berequired by the World Reference Laboratory(Weybridge).

6.5 In the case of an HPAI outbreak in poultry, culledbirds are tested for the presence of virus, butfollow-up investigations mainly consist of testingsera from live birds for the presence of antibodyto the virus. Serological testing can be carried outin the dedicated facility in Dumfries (which, weunderstand, can be activated within weeks).

Biosecurity

7.1 Everyone to whom we spoke recognised theimportance of biosecurity measures to protectpoultry flocks from the introduction of avianinfluenza, as well as from other diseases. Thepoultry industry in Scotland is aware of theimportance of biosecurity and has adopted goodpractice, with all companies having prepareddetailed biosecurity plans. Companies are respon-sible for their own biosecurity policies, and themeasures employed vary with the level ofbiosecurity attaching to breeding flocks beingconsiderably higher than for laying birds. Clearly,there are limits to what can be achieved by way ofprotection for free-range flocks.

Prevention and Control of Avian Influenza in Poultry

7.2 There is no legislation governing biosecuritymeasures and the Scottish Government RuralDirectorate has no powers to inspect or regulatebiosecurity standards. Although it is clearly in theinterests of the industry itself to be vigilant withregard to biosecurity, it was acknowledged to usthat in practice the implementation of biosecurityplans can fall short of the ideal, particularly attimes when the risk is perceived as low. Forexample, casual visitors to poultry units should beactively discouraged.

7.3 Imports of infected poultry meat are a potentialsource of disease. It is an important aspect ofbiosecurity to ensure that live poultry are sepa-rated from meat plants, that measures are in placeto avoid any possible transfer of virus from meat to

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Avian Influenza: An Assessment of the Threat to Scotland

injection with two doses, 2-3 weeks apart, re-quired for maximum protection. Such vaccineshave been used in some countries, e.g. Mexico, formore than ten years without other control meth-ods. However, while they prevent disease, they donot eliminate the virus, and it may remain unde-tected in flocks with the risk of spread to otherbirds.

7.7 Although stocks of H5N1 vaccines are held byDEFRA for use in an emergency, our understand-ing is that current contingency plans for thecontrol of AI do not include vaccination of do-mestic poultry in advance of an outbreak ofinfection. While the vaccination of broiler birds isnot an option because of their short life-spans,vaccination of laying and breeding flocks could beconsidered if the culling of infected birds, move-ment controls and surveillance methods failed tohalt spread of the virus and the disease becameestablished here. Vaccination of domestic poultrymight also be considered if virus prevalence wereto become so high in the wild bird population thatrepeated ‘spillovers’ of infection to poultry were tooccur.

7.8 Vaccination of collections of rare birds such asthose held for genetic conservation purposes,whether held privately or in zoos, should beallowed if they are at high risk of infection.However, the efficacy of the vaccines in birds otherthan domestic poultry is largely unknown andwould benefit from further research.

7.9 Vaccination as a protective measure could beattractive if more effective, cheap vaccines can bedeveloped, particularly if their method of deliverywere to allow easy administration to large flockswithout the requirement to handle each indi-vidual bird. We recommend that financial supportbe provided for research into, and development of,more effective and “user-friendly” vaccines.

poultry and that waste from meat plants is dis-posed of in ways that ensure it cannot infect wildbirds.

Protection and surveillance zones

7.4 In the case of an outbreak of avian influenza inpoultry in Scotland, strict biosecurity will beimportant in controlling the spread of disease.However, legislative measures will also come intoforce. The European Commission reacted quicklyto the H5N1 threat with legislation intended todemonstrate to other areas of the world a robustapproach to disease control with the aim ofsafeguarding exports, whilst at the same timeallowing for derogations based on risk assess-ment in order not to constrain unnecessarily theindustry within the EU. An EU Directive requiresthe establishment of protection and surveillancezones where HPAI and LPAI of virus subtype H5or H7 is found or suspected in kept birds, orwhen H5N1 is detected in wild birds. Theserequirements of the EU Directive have beentransposed into Scottish legislation that alsodefines the size of zones and the measures thatapply within them, including restrictions on themovements of poultry and eggs.

Culling of infected flocks

7.5 The legislation also makes provision for the cullingof flocks in which HPAI has been confirmed. Thelimited modelling studies of avian influenzaindicate that most outbreaks will not spreadbeyond the index case if prompt action is taken todestroy the infected birds and to trace at-riskcontacts. Current practical experience supportsthis.

Vaccination

7.6 Vaccines offering protection from H5N1 infectionare available commercially. Those licensed for usein Europe contain inactivated virus; these vaccinesrequire to be administered by intramuscular

8.1 It is important to stress that there is no risk ofhuman infection with an avian influenza virusfrom the ingestion of properly cooked poultrymeat or eggs. Direct infection of humans resultsfrom close contact with infected birds, as hashappened in a relatively small number of casesin the Far East. The major concern is that a viruscausing influenza in poultry may evolve to infecthumans and result in human-to-human trans-mission of the disease.

8.2 There were three human influenza pandemicsin the twentieth century beginning in 1918(Spanish influenza, H1N1), in 1957 (Asianinfluenza, H2N2) and in 1968 (Hong Konginfluenza, H3N2), each caused by a virusrelated to an avian influenza virus. In 1997,

Risks to Human Health

H1N1 (Russian influenza) strains re-emerged andcontinue to co-circulate with H3N2 strains today.The World Health Organisation considers that weare closer to another human influenza pandemicthan at any time since 1968. A recent joint studyby the Royal Society and the Academy of MedicalSciences, chaired by Professor Sir John Skehel,examined the extent to which scientific evidence isbeing incorporated into preparedness for apandemic. We endorse the findings of that studyand have not sought to cover the same groundbut to examine only aspects particular to Scot-land.

8.3 Skehel noted “there is general agreement in thescientific community that the risk of a humanpandemic is elevated because of the wide distri-

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humans to date, a pandemic would only develop ifa strain of virus were to evolve with a level ofvirulence such that it could multiply and spreadbefore the death of the host. Moreover if, asreported, a “cytokine storm” is the main cause ofdeath in H5N1 infections in humans, a goodrange of anti-inflammatory drugs is now availableto treat patients.

8.7 Within Scotland the measures being taken inpreparation for a pandemic include stockpiling ofantiviral drugs and masks. The adequacy of thesemeasures is kept under constant review but, untila pandemic occurs, there is no way of knowingexactly what will be required. The intention is touse antiviral drugs for the treatment of patients,but limited prophylactic use might be consideredearly in a pandemic.

8.8 We have explored the potential value of move-ment restrictions as a means of restricting thespread of the disease. It is expected that localschools in the area of an outbreak would close,and most public events would be cancelled. Theevidence from modelling studies suggests thatmovement restrictions would have little impact onthe spread of disease and there is no intention tointroduce restrictions on travel here in the case ofa pandemic. It is difficult to predict how peoplewill react to a pandemic, for example by staying athome. There is little doubt that businesses wouldbe affected significantly, but this is recognised andconsiderable efforts are being devoted to contin-gency planning in both the private and publicsectors.

8.9 We recognise that it is unlikely that a vaccineeffective against a new strain of pandemic influ-enza virus could be produced before the diseaseaffects the UK. Even if a vaccine were to beavailable, there would be significant costs inmaking this available to the whole population. Inaddition, consideration would have to be givento the possible risks of neurological complicationsassociated with the widespread use of a newvaccine. Small stocks of an H5N1 vaccine areavailable and could be used, if appropriate, toprotect key health workers. The hope is that,should there be a pandemic, a vaccine might bedeveloped to protect certain priority groups fromthe second wave of infection.

8.10 Although we recognise the reasons for thecurrent emphasis being placed on preparationsfor a human pandemic caused by the H5N1 virus,H7 and H9 viruses are also known to haveinfected humans. It is quite possible that the nexthuman influenza pandemic will be caused not byH5N1 but by some other strain of virus, and werecommend that those responsible for planningfor dealing with a pandemic take account of thispossibility.

bution of H5N1 viruses, but there is a range ofopinions about the likelihood of a pandemicprimarily because the H5N1 viruses have beenwidely distributed for over a decade without theoccurrence of a pandemic”.

8.4 We have also noted that research suggests thatcurrently circulating strains of H5N1 viruses arebecoming more capable of causing disease inanimals than were earlier strains of the virus. Onestudy has found that ducks infected with H5N1are now shedding more virus for longer periodswithout showing symptoms of illness. Thisfinding has implications for the role of ducks intransmitting disease to other birds, and possiblyalso to mammals including humans. Other studieshave documented H5N1 virus infection in pigs, incats and in dogs. H5N1 has been isolated fromtigers and leopards in zoos in Thailand, andH5N1 virus infection has been reported in a wildstone marten in Germany and in a wild civet cat inVietnam. The H5N1 virus strains that emerged inAsia in 2003 are continuing to evolve and mayadapt in such ways that other mammals alsobecome susceptible to infection.

8.5 In our view, although the H5N1 virus poses athreat to the poultry industry here, as evidencedby the outbreaks in Suffolk and Norfolk, the riskof a new human pandemic strain of virus evolvingin Scotland or elsewhere in the United Kingdomis remote. However, it will be important to detectan incipient pandemic originating elsewhere if weare to be prepared for it striking the UK. It willonly be feasible to produce a meaningful projec-tion of a pandemic if good data are available atan early stage, and this means identification ofchanges in the virus in the first 100 or so cases.The increasing availability of high through put,rapid nucleic acid sequencing equipment willfacilitate this and improve surveillance. Theanalysis of surveillance data with a view to earlydetection of disease events such as pandemicinfluenza and estimation of rates of spreadrequires that the data are shared immediately withmodellers. We recommend that this is afforded ahigh priority in Scotland by the relevant authori-ties, in particular by Health Protection Scotland.

8.6 Very significant planning is being undertaken inScotland in preparation for a possible humaninfluenza pandemic. For the purposes of plan-ning, it is considered not unreasonable to assumesimilar attack and mortality rates to those of thelast two influenza pandemics affecting the UK.However, societal circumstances today are nowvery different with, for example, greater mobilityand smaller household sizes. In addition, scientificadvances mean that the start of a pandemic canbe identified, the causative agent characterisedand effective interventions developed more quicklythan in the past. Although mortality has beenhigh in the small number of H5N1 cases in

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Avian Influenza: An Assessment of the Threat to Scotland

9.1 Avian influenza viruses, not least the H5N1 strainthat is currently of concern, pose a significantthreat to the poultry industry worldwide, includ-ing that in Scotland.

9.2 The only effective means of protection available tothe Scottish poultry industry is to prevent the virusinfecting its poultry flocks. It is important, there-fore, to have the means of detecting the presenceof the virus in this country at an early stage,whether in the wild bird population or in domes-tic or commercial poultry, and to implementbiosecurity measures as quickly as possible toprotect individual poultry units from the introduc-tion of the virus.

We recommend that Scotland should adopt,as soon as it becomes available, the use ofon-site diagnosis based on PCR technology.

9.3 In Scotland, poultry and wild birds are monitoredto detect the presence of avian influenza viruses.This monitoring needs to be done more rigor-ously.

We therefore recommend that:

Research is undertaken to quantify the riskof infection of poultry in Scotland with theH5N1 virus by wild birds.

A review is undertaken of the risk species ofwild bird to be monitored, in particular witha view to including those species of gull thathave contact with wetland birds and are alsofound in the vicinity of poultry houses.

A robust surveillance programme for thewild bird population should be developed onscientific principles.

The surveillance programme should besufficiently flexible to respond to severechanges in weather, that can affect wild birdmigration patterns.

Adequate funding is provided for the scien-tific monitoring of wild birds, and furtherconsideration is given to who should carryout this work, including the collection ofcarcasses.

9.4 We recognise that mathematical modelling studiesprovide useful input to the planning for an avianinfluenza outbreak (paragraphs 4.5–4.8) but thatthe modellers require more robust data on whichto build their models.

There are seven major epidemiological aspects (orrisks) that require addressing:

- the risk of disease introduction to the wild birdpopulation of the UK

- the risk that the infection is propagated in thispopulation

- the risk that the infection is subsequentlyintroduced to domestic and farmed birds

- the risk that the infection is propagated andmaintained in the domestic and farmed birdpopulation

- the risk that the infection spreads from in-fected farm birds to the wild bird population

- the risk that transmission to humans occursfrom wild bird populations

- the risk that transmission to humans occursfrom domestic and farmed bird populations

We recommend that appropriate and rigor-ous risk assessments are applied to thesescenarios, where necessary providing thefunding to collect robust data toparameterise these models.

9.5 We have stressed the importance of biosecurity inprotecting commercial poultry flocks from infec-tion. In drawing up biosecurity plans for theprevention of avian influenza, the poultry industryrequires to be clear as to how the virus is mostlikely to be introduced into one of its units(paragraphs 7.1–7.3).

We recommend that guidance is provided tothe poultry industry on the relative impor-tance of different potential disease vectorsfor avian influenza to inform its biosecurityplanning.

9.6 We recognise the potential role of vaccines in theprevention and control of avian influenza, particu-larly if more effective vaccines that could be moreeasily administered were to become available(paragraphs 7.6–7.9).

We recommend:

That funding is made available for thedevelopment of improved avian influenzavaccines.

The vaccination of collections of rare birds,especially those held for genetic conserva-tion purposes.

Given the problems of implementingbiosecurity for free range birds, we alsorecommend that vaccination of such flocksshould be permitted in a high risk scenario.

Conclusions and recommendations

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The Royal Society of Edinburgh

Annex 1: Membership of the RSE Avian Influenza Working Party

Chair: Professor John Coggins FRSEVice-Principal for the Life Sciences, Medicine & Veterinary Medicine, and Professor of MolecularEnzymology, University of Glasgow

Members: Professor Richard Elliott FRSEProfessor of Virology, Centre for Biomolecular Sciences, University of St Andrews

Professor Peter Kennedy FRSEBurton Professor of Neurology and Head of Division of Clinical Neurosciences, University ofGlasgow, and Consultant Neurologist, Institute of Neurological Sciences, Southern GeneralHospital, Glasgow

Professor Karl Linklater FRSEFormer Principal and Chief Executive, Scottish Agricultural College and Past President of theBritish Veterinary Association

Professor Pat Monaghan FRSEProfessor of Animal Ecology and Joint Research Director of the Institute of Biomedical and LifeSciences, University of Glasgow

Dr Peter NettletonFormer Head of the Virus Surveillance Unit, Moredun Research Institute, Edinburgh

Professor Hugh Pennington FRSEEmeritus Professor of Bacteriology, Institute of Medical Sciences, University of Aberdeen

Professor Stuart Reid FRSEDean of the Faculty of Veterinary Medicine and Professor of Veterinary Informatics and Epidemiol-ogy, University of Glasgow; Professor, Department of Statistics and Modelling Science, Universityof Strathclyde

Professor Michael Usher FRSEFormer Chief Scientist, Scottish Natural Heritage

Secretary: Ian MelvilleResearch Officer, Royal Society of Edinburgh

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Avian Influenza: An Assessment of the Threat to Scotland

Annex 2: List of those who gave evidence

Ms Laura Bates Kilduncan Eggs

Dr John Burlison Scottish Natural Heritage

Dr Harry Burns Chief Medical Officer, Scottish Executive Health Department

Ms Jacqueline Campbell Head of Pandemic Flu Co-ordination Team, Scottish Executive HealthDepartment

Mr Michael Darrah Deans Foods

Dr Colin Galbraith Scottish Natural Heritage

Professor Charles Milne Chief Veterinary Officer, Scottish Executive Environment and Rural AffairsDepartment; Honorary Professor, Royal Veterinary College

Mr Donald Peddie Kilduncan Eggs

Mr Neil Ritchie Animal Health Division, Scottish Executive Environment and Rural AffairsDepartment

Mr Colin Shedden Director (Scotland), British Association for Shooting and Conservation

Mr Kevin Smith Grampian Foods

Dr Bill Stanley Aviagen Ltd

Dr Bradley Turner Aviagen Ltd

Mr Paul Walton Royal Society for the Protection of Birds

Professor Mark Woolhouse FRSE Professor of Infectious Disease Epidemiology, University of Edinburgh

The Royal Society of Edinburgh

The Royal Society of Edinburgh (RSE) is an educational charity, registered in Scotland. Independent and non-party-political, we are working to provide public benefit throughout Scotland and by means of a growing interna-tional programme. The RSE has a peer-elected, multidisciplinary Fellowship of 1400 men and women who areexperts within their fields.

The RSE was created in 1783 by Royal Charter for “the advancement of learning and useful knowledge”. Weseek to provide public benefit in today’s Scotland by:

- Organising lectures, debates and conferences on topical issues of lasting importance, many of which are freeand open to all.

- Conducting independent inquiries on matters of national and international importance.

- Providing educational activities for primary and secondary school students throughout Scotland.

- Distributing over £1.7 million to top researchers and entrepreneurs working in Scotland.

- Showcasing the best of Scotland’s research and development capabilities to the rest of the World.

- Facilitating two-way international exchange to enhance Scotland’s international collaboration in research andenterprise.

- Emphasising the value of educational effort and achievement by encouraging, recognising and rewarding itwith scholarships, financial and other support, prizes and medals.

- Providing expert information on Scientific issues to MSPs & Researchers through the Scottish ParliamentScience Information Service.

www.royalsoced.org.ukTel. 0131 240 5000Fax. 0131 240 5024

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A Report from The Royal Society ofEdinburgh’s Working Party on AvianInfluenza

September 2007

The

Royal Society

of Edinburgh

ISBN 978 0 902198 50 0© The Royal Society of Edinburgh, Revised December 2007

www.royalsoced.org.uk

First EditionISBN 978 0 902198 45 6

© The Royal Society of Edinburgh, September 2007www.royalsoced.org.uk

Avian InfluenzaAn Assessment of the Threat to Scotland