GB Emerging Threats Report

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					GB Emerging Threats                                                                                           Safeguarding
                                                                                                            public and animal


Avian diseases
                                                                          Quarterly Report:          Volume 14, No. 3

                                                                                        July - September (Q3) 2010

These reports aim to identify emerging animal disease related threats. Their production is
underpinned by a large amount of surveillance data and information compiled as part of the Defra
Food and Farming Group animal disease surveillance programme. Some of these data can be
viewed on the VLA website:

VIDA diagnoses are recorded
on     the   VLA   FarmFile                                                                                      page
database and SAC LIMS
database and comply with                Introduction to GB Report                                                     2
agreed diagnostic criteria
against     which    regular            New & Emerging diseases                                                       2
validations and audits are
undertaken.                             Ongoing New & Emerging disease investigations                                 3
The investigational expertise           Unusual diagnoses                                                             4
and               comprehensive
diagnostic laboratory facilities
of both VLA and SAC are                 Changes in disease patterns, industry and risk factors                        5
widely acknowledged, and
unusual                  disease
problems tend to be referred
to       either.      However,
recognised conditions where
there is either no diagnostic
                                         Submission trends: Increase of 9% in the total number of diagnostic
test, or for which a clinical
diagnosis offers sufficient               submissions received by the VLA and SAC compared with Q3-2009, and a 5%
specificity to negate the need            increase in the total number of poultry carcases examined (page 2).
for laboratory investigation,
are      unlikely      to     be         New & Emerging diseases: Infectious coryza confirmed by bacteriological and
represented. The report may               PCR testing in two separate hobby flocks in southern England. This is a well-
therefore be biased in favour             characterised respiratory disease seen in many other parts of the world,
of unusual incidents or those             typically spread by poultry movements and suboptimal biosecurity (pages 2-3).
diseases         that     require
laboratory investigation for
                                         Ongoing New & Emerging disease investigations: Continued detections of
                                          the European IBV QX genotype in commercial and backyard/hobby poultry (p3).
VLA Regional Laboratories
and       SAC       Veterinary           Changes in patterns & industry: This quarter has seen sharp rises in feed
Surveillance Centres have                 prices for all poultry sectors. Free-range egg supply also outstripped market
UKAS      Accreditation    and            demand, lowering egg prices, as the national layer flock peaked at over 34
comply with ISO 17025                     million birds. Therefore, all producers face increased pressure on already tight
                                          margins, and efficiency savings will be sought (pages 6-7).
                                           July-Sept 2010      Vol. 14, No. 3   Avian Diseases Quarterly report

During the period July to September 2010 (Q3-2010), there was an increase of 9% in the total number of
avian diagnostic submissions received by the VLA and SAC compared with the total numbers of avian
diagnostic submissions received during Q3-2009, and a 5% increase in the total number of poultry
carcases examined over the same periods (Figure 1). Comparing the four-year average (Q3-2006 to Q3-
2009) and Q3-2010 shows increases of 3% and 5% respectively in the total number of diagnostic
submissions and the total number of poultry carcases examined. There has been consistent growth and
confidence in the broiler sector, particularly over the past 18 months. However, whilst the layer sector
has undergone a rapid expansion in the last two years, egg supply (particularly free-range flocks) now
exceeds demand. This has had a direct effect on egg price and producer margins. In addition, cereal and
feed prices have risen sharply during Q3-2010, which will have substantial impact on profitability. These
factors are likely to lead to financial difficulties for some producers, and a drive for increased efficiency
across the industry is expected.

Broadly speaking, expanding sectors of the poultry industry typically indicate profitability, buoyant
markets, favourable retailer prices and consumer demand. These conditions are less likely to negatively
impact veterinary consultation and scanning surveillance activities. The reverse may be true when
financial pressure on the industry increases (eg. due to rising production costs and/or reduced retailer
prices), economic downturns are experienced or consumer demand decreases. This may lead to
producers making efficiency savings, including reductions in veterinary costs leading to fewer disease
investigations. However, exceptions to this may include investigation of severe disease and/or
production problems, if novel disease presentations occur, or where statutory disease reporting
requirements exist. Furthermore, some producers may reduce flock sizes, or even go out of business,
and this will affect the size of the poultry industry.

Figure 1: Avian diagnostic submissions and numbers of poultry carcases examined in England & Wales
             and Scotland by the VLA and SAC during the Third Quarter (July-September)


           3,000                                                                             SAC submissions
                                                                                             SAC carcases
           2,500                                                                             VLA submissions
                                                                                             VLA carcases




                       2006         2007           2008            2009          2010


Infectious coryza has been confirmed by bacteriological and PCR testing in two separate hobby flocks in
southern England following scanning surveillance investigations by VLA Regional Laboratories. This is
the first laboratory confirmation of Infectious coryza (IC) by both conventional and molecular testing in
Great Britain (GB), although suspicion of the disease has been reported previously. IC is a well-
characterised bacterial respiratory disease in chickens, caused by Avibacterium paragallinarum, which

                                                 Page 2 of 7
                                          July-Sept 2010      Vol. 14, No. 3   Avian Diseases Quarterly report

does not pose any risk to public health. The disease is of economic importance to the poultry industry in
many parts of the world, for example Asia, the Americas and parts of Africa. It is also endemic in parts of
continental Europe. IC is typically spread by poultry movements and suboptimal biosecurity. The
existence of carrier status is recognised in birds that have been exposed to, or recovered from infection.
Infection in the two hobby flocks in GB is presumed to have been introduced by asymptomatically
infected chickens. Retrospective investigations have also confirmed that there was an IC outbreak in a
small layer chicken flock in Northern England during 2008.

Clinically affected chickens show acute respiratory signs, swelling of the face and nasal discharge. Flock
morbidity is usually high, but mortality low. However, other clinical presentations may be seen when
infection is complicated by the presence of other pathogens, which can alter the clinical presentation.
Co-infection can affect severity and complicate the diagnosis. The effects of disease are also known to
be more severe in multi-age flocks when younger, non-immune birds come into contact with recovered
older birds. Production losses such as reduced growth in broilers and egg drop in layers may also occur.

In the short term, IC has been controlled by antibiotic medication in the affected flocks. Vaccines for IC
are available in other countries and could be used in GB flocks subject to obtaining authorisation from
the Veterinary Medicines Directorate to import a vaccine. It is considered likely that the disease will
spread within the hobby sector because of the widespread networks of bird movements that exist. It is
also possible that IC may reach the commercial sector, particularly flocks that are multi-age and
purchase replacement stock, if good standards of biosecurity are not practised. The role of other birds in
disseminating IC is unknown.

Veterinarians should be mindful of IC in the differential diagnosis of upper respiratory tract disease in
poultry, and the VLA ( would be interested to hear of
any suspect cases.

In addition to performing laboratory and farm investigations, VLA has provided disease alert and
advisory material about the epidemiology and risk of IC and possible treatments to private veterinary
surgeons, VLA and SAC laboratories and the poultry industry. The latter has included the Poultry
Disease Group, NFU Poultry Health Group and the British Veterinary Poultry Association. A summary of
VLA investigations has also been published (Welchman and others, 2010, Infectious coryza in chickens
in Great Britain. Veterinary Record 167: 912-913). This, and other advisory material for vets and poultry
producers are also available on the VLA website:


Previous quarterly GB avian disease surveillance reports have described the detection of strains of the
European Infectious Bronchitis virus (IBV) QX genotype in commercial poultry in GB
( Detection of the European IBV
QX genotype continues in broilers and backyard/hobby poultry, as well as further reports of cases of
false layer syndrome in free-range layer flocks.

Infectious Bronchitis is a well-recognised disease and periodically novel IBV variants emerge. As
described previously, infection with IBV QX-like strains can cause a range of clinical signs in chickens
presenting as respiratory disease and/or nephritis and production losses. The movement of poultry and
fomites are important factors responsible for spread; the role of other factors such as wild birds has not
been fully elucidated. Prevention depends upon maintaining good biosecurity practices and use of IBV
vaccination schedules as appropriate. In response to the detection of European IBV QX in commercial
flocks in GB, poultry producers and companies have reviewed vaccination programmes. Such changes
have been most notable for layer pullets where hatchery spray vaccination of day-old chicks with
Massachusetts-type vaccine has been introduced, a practice routinely performed on the continent.
Further description of the emergence, detection and molecular epidemiology of IBV QX in GB, including
in commercial broilers, have been described by Irvine and others, 2010 (Veterinary Record, 167: pages

                                                Page 3 of 7
                                          July-Sept 2010      Vol. 14, No. 3   Avian Diseases Quarterly report

A variety of endemic poultry diseases were diagnosed during the quarter that may be considered
uncommon and/or unusual. In all of these cases, clinical disease was limited to the affected house or
flock, with no evidence of spread, either to other houses on the same farm, or to epidemiologically linked
premises. Furthermore, whilst the diseases may be infrequently diagnosed, they are more often than not
recognised conditions with well-characterised cause and effect in affected poultry. Where appropriate,
treatment usually resulted in a good clinical response and prevention and control measures were
implemented following the diagnosis of disease. Therefore, no wider threats were recognised and no
specific actions required other than for producers and veterinarians to maintain vigilance for disease
problems and investigate as appropriate.


Inclusion Body Hepatitis (IBH)

IBH, caused by avian adenovirus infection, was confirmed by histopathology in fixed liver samples from
broilers of 10-12 days of age. IBH is occasionally diagnosed in commercial chickens, and is usually the
result of vertical transmission of avian adenoviruses from infected parent flocks, although lateral spread
is possible. Cases were limited to affected houses only, with no evidence of spread. The severity of IBH
outbreaks may be exacerbated by immuno-suppression induced by infection with Infectious Bursal
Disease virus (IBDV - Gumboro) or Chicken Infectious Anaemia virus (CIAV). There is no licensed
vaccine available in the UK. Prevention in integrated commercial companies is targeted on limiting the
introduction of adenovirus infection to parent flocks. Control of other infectious agents, such as IBDV and
CIAV may reduce the severity of clinical disease in affected progeny flocks.

Intestinal coccidiosis

A few unusual cases of intestinal coccidiosis due to heavy infection with Eimeria acervulina and E.
maxima were seen in broilers from 18 to 22 days of age. Flocks were performing well up to this point,
and were on standard in-feed anticoccidial programmes. Increased mortality due to dehydration was
reported and intestinal damage seen with mild mucosal haemorrhages. Response to treatment was
usually good, and further episodes of coccidiosis did not occur in affected flocks. Possible reasons for
these unexpected coccidiosis “breaks” are being investigated, including checking that the required
amount of coccidiostat had been added to the ration. Coccidiosis is ubiquitous in chicken populations
and in commercial broiler production systems disease is usually well controlled, either by in-feed
medication or, increasingly, by vaccination using live attenuated vaccines soon after placement.


Bordetella avium in turkey poults

Bordetella avium isolates were made on two occasions from turkey poults, both associated with
respiratory disease. In one of the investigated cases, snicking was described in two groups of turkeys on
the same site (4 weeks old and 8 weeks old) and lesions of airsacculitis were seen at necropsy. B. avium
and Klebsiella pneumoniae subsp pneumoniae were both isolated from the lung of one bird. In another
incident, marked distension of the infraorbital sinuses by mucus and an airsacculitis was present in 8-
week-old turkeys and Bordetella avium was isolated from the choana and trachea of one bird.
Antimicrobial treatment resulted in a good response. Bordetellosis is otherwise known as turkey coryza,
a highly contagious acute upper respiratory tract disease, primarily in young turkeys. Infected birds are
susceptible to secondary infections, which may alter the clinical presentation, affect severity and
complicate the diagnosis. The disease has been well described, and is distinct from Infectious coryza, a
disease primarily of chickens caused by Avibacterium paragallinarum infection. The disease is
recognised in other parts of the world where turkeys are reared commercially. Good hygiene, biosecurity
and ‘all in-all out’ rearing policies are required for prevention.

                                                Page 4 of 7
                                          July-Sept 2010      Vol. 14, No. 3   Avian Diseases Quarterly report


Spirochaetosis in laying ducks

During investigations into a suspect duck virus enteritis (DVE) outbreak in 18-month-old laying ducks,
pallisading bacteria were detected lining the caecal epithelium. Fly strike was present around the vents
of some of the birds due to faecal staining, although diarrhoea was not described clinically. A further
submission of birds showed diptheresis of the oesophageal mucosa, ulceration of the cloaca and a
degree of hepatic necrosis, although no inclusion bodies were detected on histology and DVE was not
confirmed. However, spirochaetes were detected from the caeca and cultures were identified as
Brachyspira pilosicoli. Avian intestinal spirochaetosis has been described in laying chicken flocks with B.
pilosicoli being one of the pathogenic species. Such infections can lead to weight loss, diarrhoea and
poor egg production in chickens and produce a similar appearance of bacteria lining the large intestine. It
is unusual in our experience to see this condition in ducks. This is likely to be a sporadic case, but a
condition to be aware of.


Spironucleosis in game birds and the impact of weather conditions

The prevailing weather conditions appeared to have had an impact on young pheasants following the
transition from the warm dry conditions of mid summer to cooler, wet conditions in August.
Spironucleosis is a well-recognised condition in game birds and is often encountered as a disease
problem in pheasants during the rearing period and in release pens. This year pheasant poults would in
many cases not have experienced rain until August. Such adverse weather conditions may well have
caused chilling and stress in the birds, and been a factor in causing increased mortality on some sites.
Concurrent spironucleosis may have exacerbated these effects in some instances. Spironucleosis can
be controlled by attention to good management coupled with appropriate antibiotic treatment, using
products under the prescription cascade in the event of outbreaks.

Salmonella Typhimurium DT8
There has been a national increase in reported human cases of S. Typhimurium DT8, a common duck
associated phage type ( A similar
outbreak has occurred in Northern Ireland ( The outbreak has been
associated with the consumption of duck eggs, and consumers and caterers have been reminded by the
Food Standards Agency (FSA) to thoroughly cook duck eggs and handle them hygienically
( There have also been press releases
by the HPA (,
and the VLA and Defra have been working with HPA.

Monophasic salmonellae
Monophasic strains of Salmonella have been detected in both laying and broiler flocks in the UK during
2010. These organisms are not fully serotypeable due to the lack of certain antigens, and often present
as Salmonella types 4,5,12:i:- or 4,12:i:-. Work using determinative and PCR typing can further identify
some of these strains to be most likely monophasic strains of Salmonella Typhimurium. Similar strains
have been associated with outbreaks of disease in animals in other parts of Europe. Interestingly, in this
country, some of the affected sites also rear pigs and monophasic strains of Salmonella have been
detected in pigs also. It is also relevant to note that there appear to be a number of units which are now
setting up in joint pig and laying chicken production in the East of England - often with pig and poultry
houses located near to each other. Monophasic strains of salmonella have also been associated with
human cases of illness in Europe (personal communication, Rob Davies, VLA).

                                                Page 5 of 7
                                                                     July-Sept 2010              Vol. 14, No. 3             Avian Diseases Quarterly report

In the UK, the full impact of these emerging salmonella strains is not yet certain. When the VLA identifies
monophasic strains of salmonella, further zoonosis investigations are performed as a priority, and this
includes farm visits performed by VLA veterinary staff. In addition, the Bacteriology department, VLA
Weybridge, is undertaking some research into the epidemiology of these cases.


Broilers: The numbers of broiler chicks placed has risen each quarter during 2010, and are higher than
the corresponding quarters of 2009 (Figure 2). This reflects a degree of increased confidence in the
industry, although profitability is now being threatened by increased feed prices, particularly of wheat
(see below also).

Layers: Placings of commercial layer chicks were less than during Q3-2009 (Figure 3), reflecting a
reversal in an overall upward trend that has been seen over the last few quarters as the free-range
sector has expanded in preparation for the forthcoming EU-wide ban on conventional cages in 2012.
The national flock reached a peak of over 34 million birds during July 2010, with approximately 43%
being free-range. However, free-range supply now exceeds market demand. The profitability of the layer
industry has been affected by a decline in egg prices (a 5.8% decrease in the second quarter compared
to 2009) and rising feed prices (see below for further comments). This could mean that producers may
be more reluctant to seek veterinary advice for disease problems.

                         Figure 2: Quarterly broiler chick placings                               Figure 3: Quarterly layer chick placings
                         from UK hatcheries, 2008-2010                                            from UK hatcheries, 2008-2010

                    74                                                                           3.1


                    68                                                                           2.7
                    62                                                                           2.3
                         08-4 09-1 09-2 09-3 09-4 10-1 10-2 10-3
                                                                                                       08-4   09-1   09-2   09-3   09-4   10-1   10-2   10-3

The anticipated implementation of the conventional layer cage ban across the EU on 01 January 2012
has also resulted in substantial investment by the UK layer industry in enriched cage systems. This
investment has been estimated as totalling approximately £400 million pounds, equivalent to
approximately £25 per hen in the cage sector of the national layer flock. However, concerns persist
regarding illegal supply and import of eggs from hens in conventional cage systems after the
implementation of the ban.

Turkeys: The number of turkey poults placed was 16.3% higher in September 2010 compared with
September 2009 (Figure 4), although the general industry trend is that turkey numbers are continuing to
                           Figure 4: Quarterly turkey poult placings
                           from UK hatcheries, 2008-2010
                                                                                                        Poultry and poultry meat statistics:

                     1.5                                                                                Egg statistics:

                     1.0                                                                                s/foodfarm/food/eggs/index.htm.

                     0.5                                                                                The comments are supplemented by
                                                                                                        reports from industry and Poultry World.
                           08-4   09-1   09-2   09-3   09-4   10-1   10-2   10-3

                                                                            Page 6 of 7
                                          July-Sept 2010      Vol. 14, No. 3   Avian Diseases Quarterly report

Comments: Cereal prices have also substantially increased during Q3-2010, resulting in feed wheat
price rises of some 40%. Feed represents approximately 60% of the direct costs of commercial poultry
production. Hence, feed price increases are having a direct effect on the profitability of producers and
growers, and as a result efficiency savings will be seen. These may include alterations to feed
composition (possible effects on gut health) and may effect disease investigation and control (eg.
vaccination programmes). Some producers may reduce flock sizes and others may leave the poultry
industry altogether.

Retailers are also coming under pressure to increase the prices they pay to producers to offset the
impact of rising feed prices and other production costs. It has been estimated that the cost of producing
a dozen eggs has increased by 5p and the cost of a chicken by 12p. Chick and pullet prices are also
predicted to increase in 2011 in the face of the existing financial pressures on poultry production costs.
Whilst retailers may be expected to respond by passing on prices rises to consumers, household
incomes and consumer spending are also under continuing pressure with continued uncertainty over
economic recovery. Hence, supermarket price wars may intensify and retailers have been increasing
promotional offers to attract consumers. Therefore, animal protein costs, including egg and poultry meat
prices, may be subject to increasing competition in the future. Submission rates will be monitored
carefully in the future to assess the impact on scanning surveillance.

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