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Gross and microscopic findings and investigationof the aetiopathogenesis of mycobacteriosis in acaptive population of white-winged ducks (Cairinascutulata)Miguel D. Saggese a , Gary Riggs b , Ian Tizard a , Gerald Bratton c , Robert Taylor c &David N. Phalen a da Department of Veterinary Pathobiology , The Schubot Exotic Bird Health Centerb Akron Zoological Park , Akron, OH, 44203, USAc Department of Veterinary Integrative Biosciences , College of Veterinary Medicineand Biomedical Sciences, Texas A & M University , 4467 TAMU, College Station, TX,77843-4467, USAd The Wildlife Health and Conservation Centre , University of Sydney , Camden, NewSouth Wales, 4475, AustraliaPublished online: 22 Jul 2010.

To cite this article: Miguel D. Saggese , Gary Riggs , Ian Tizard , Gerald Bratton , Robert Taylor & David N. Phalen (2007)Gross and microscopic findings and investigation of the aetiopathogenesis of mycobacteriosis in a captive population ofwhite-winged ducks (Cairina scutulata), Avian Pathology, 36:5, 415-422, DOI: 10.1080/03079450701595909

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Gross and microscopic findings and investigation of theaetiopathogenesis of mycobacteriosis in a captivepopulation of white-winged ducks (Cairina scutulata)

Miguel D. Saggese1*, Gary Riggs2, Ian Tizard1, Gerald Bratton3, Robert Taylor3 andDavid N. Phalen1,4

1The Schubot Exotic Bird Health Center, Department of Veterinary Pathobiology, 2Akron Zoological Park, Akron, OH44203, USA, 3Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences,Texas A & M University, 4467 TAMU, College Station, TX 77843-4467, USA, and 4The Wildlife Health and ConservationCentre, University of Sydney, Camden, New South Wales 4475, Australia

The white-winged duck (Cairina scutulata) is critically endangered. Breeding collections of this duck areestablished in the United Kingdom and the USA. Infection with Mycobacterium avium avium serotype 1 is amajor cause of mortality in the UK collection. In this study, the aetiopathogenesis of deaths occurring in theUS collection was studied. All ducks (n�21) that died over a 21-month period were examined.Mycobacteriosis was diagnosed in 20 ducks, killing 19 of them. Multifocal to diffuse granulomatous lesions,often with abundant intralesional organisms, were seen in all 20 ducks. Unusual manifestations of this diseasewere the extensive involvement of the respiratory system and the absence of multinucleated giant cells.Sequence analysis showed that the ducks were infected with a sequevar of M. a. avium that contains serotypes2, 3, 4, and 9. Given that the long-term ingestion of metals affects immune function, we measured an array ofsuch elements in the liver of six ducks. Concentrations were undetectable or low. The disseminated nature ofthe disease, high concentration of mycobacteria and absence of multinucleated giant cells within lesionssuggest that these ducks were unable to effectively kill the mycobacteria and point to a possible defect orinhibition in cell mediated immunity. Taken together with previously reported UK data, these results suggestthat captive white-winged ducks are highly susceptible to at least two sequevars of M. a. avium and thatmycobacteriosis is a major threat to ex situ breeding. We hypothesize that the minimal heterozygosispreviously shown in these ducks could be contributing to an apparently ineffective immune response.

Introduction

The white-winged duck (Cairina scutulata) is a severelyendangered Southeast Asian species (del Hoyo et al.,

1992; Birdlife International, 2001, 2006). The mainthreats to these birds are loss of suitable habitat (wet-lands and lowland tropical forest) and locally intense

hunting pressure (del Hoyo et al., 1992; Birdlife Inter-national, 2001, 2006). Estimates of the global populationrange from less than 400 to as high as a ‘‘few thousand’’

individuals (Evans et al., 1997; Rose & Scott, 1997).Captive populations have been established at The Wild-fowl and Wetlands Trust, Slimbridge, England, and atthe Sylvan Heights Waterfowl Center, North Carolina,

USA, in an effort to prevent the extinction of thisspecies. The US breeding programme represents the onlyAnseriforme Species Survival Plan of the American Zoo

and Aquarium Association. Currently, there are fewerthan 100 white-winged ducks in North America and 39in England (R. Cromie personal communication, 2006).

The survival of both captive populations has been

jeopardized by the high susceptibility of this species to

mycobacteriosis (Cromie et al., 2000; Riggs, 2005).Reports from the Wildfowl and Wetlands Trust show

that during a period of 16 years up to 84% of captivewhite-winged duck deaths were the result of infectionwith Mycobacterium avium avium serotype 1 (Cromie

et al., 1991, 1992). Mycobacteriosis has also beenreported in captive birds in India (Birdlife International,2006), and recently has been recognized in white-winged

ducks in the Sylvan Heights Waterfowl Center collection(Riggs, 2005). Until now, the percentage of ducks dyingwith mycobacteriosis at the Sylvan Height WaterfowlCenter, the nature and distribution of the lesions in these

birds and the mycobacterial species causing this diseasehave not been reported.

The reasons for this apparently high susceptibility of

white-winged ducks to avian mycobacteriosis are notknown, but it has been speculated that low geneticdiversity, management-related problems and environ-mental factors may all be predisposing factors (Cromie

et al., 2000; Riggs, 2005). Additionally, it is possible that

*To whom correspondence should be addressed. Tel: �1 979 218 3962. E-mail: msaggese@cvm.tamu.edu. Current address: College of Veterinary

Medicine, Western University of Health Sciences, 309 E Second Street, Pomona, CA, 91766-1854. E-mail: msaggese@westernu.edu

Received 14 February 2007

Avian Pathology (October 2007) 36(5), 415�422

ISSN 0307-9457 (print)/ISSN 1465-3338 (online)/07/50415-08 # 2007 Houghton Trust LtdDOI: 10.1080/03079450701595909

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white-winged ducks may be more susceptible to myco-bacterial infection because of immunosuppressive effectsof environmental contaminants such as heavy metals(Stout et al., 2002; Fairbrother et al., 2004; Kalisinskaet al., 2004; Braune & Malone, 2006).

A successful captive breeding programme for anyseverely endangered species depends on the developmentof effective disease control measures. Critical to themanagement of captive populations is a better under-standing of the nature and severity of the disease causedby the infection, and an understanding of the factorsthat lead to the apparent susceptibility of these ducks toinfection. Therefore, the main goals of this study were to:(1) determine the incidence of mycobacteriosis in white-winged ducks that died at the Sylvan Heights WaterfowlCenter during a 21-month period; (2) identify, by DNAsequence analysis, the species and sequevar of Myco-bacterium infecting the ducks; (3) describe the grosslesions and histopathological changes induced by myco-bacteria in these ducks; (4) evaluate liver concentrationsof several heavy metals in these birds; and (5) comparethe results of this study with data reported elsewhere.

Materials and Methods

Specimens. All the white-winged ducks that died at Sylvan Heights

Waterfowl Center from August 2004 to May 2006 (n�21) were

submitted for necropsy. They were submitted frozen and had been

refrigerated before freezing for variable times. Those birds that were

received without having been soaked or wetted previously were weighed.

The liver, spleen, lung, air sac, heart, kidney, pancreas, intestine,

oesophagus, ventriculus, proventriculus, trachea and skeletal muscle

were consistently examined during gross necropsy. The adrenal glands,

gonads, bone marrow and thyroid glands were also examined in 7, 18,

13, and 15 birds, respectively (Table 1). The brain and cerebellum were

not investigated in these birds due to severe postmortem autolysis and

freezing changes. Specimens from these organs were formalin-fixed and

paraffin-embedded. Sections were cut at 4 mm and stained with

haematoxylin and eosin. A second section was stained with the

Ziehl�Neelsen stain. Inflammatory lesions were subjectively graded as

mild, moderate and severe based on the amount of inflammatory cells

within the lesions and the area of tissue affected. The numbers of acid-

fast bacteria were subjectively graded as none, few, moderate, many or

massive. Congo Red staining and green birefringence was employed to

investigate the presence of amyloid in liver and spleen. Table 1 presents

the organs examined histologically for each duck.

Detection of mycobacteria in tissues. Swabs from macerated tissues

sections, either the liver or the lung, from all the ducks examined were

inoculated into 5 ml Middlebrock 7H9 broth (Beckton Dickinson,

Franklin Lakes, New Jersey, USA) containing 0.5% (v/v) glycerol and

10% (v/v) oleic acid�albumin, and were incubated at 398C for up to 4

weeks. Cultures were inspected weekly for microbial growth and

examined for the presence of mycobacteria by Ziehl�Neelsen staining.

Tissues were collected for polymerase chain reaction (PCR) using

cleaned, autoclaved instruments that had been treated with bleach and

formalin. A different set of instruments was used to collect tissues from

each bird and organ to prevent DNA carryover. Tissues were either

processed immediately or stored at �808C until processing. Mycobac-

terial DNA was extracted from affected livers using the Puregene†

Genomic DNA Purification Kit (Gentra Systems, Minneapolis, Min-

nesota, USA) following the instructions of the manufacturer. PCR

screening for mycobacterial DNA was performed using primers T1 (5?-GGGTGACGCG(G/A)CATGGCCCA-3?) and T2 (5?-CGGGTTTCG

TCGTACTCCTT-3?) for amplification of the 236-base-pair dnaJ gene

(Morita et al., 2004). Amplified DNA was visualized after electrophor-

esis on a 1.5% ethidium bromide-stained agarose gel. PCR products

were purified using the QIAquick PCR Purification Kit (Qiagen Inc.,

Valencia, California, USA). Sequencing reactions were performed using

an ABI Prism† Big Dye Terminator v3.0 Cycle Sequencing Kit

(Applied Biosystems Inc., Foster City, California, USA). Nucleotide

sequences were determined with an ABI3100 automated DNA sequen-

cer (Applied Biosystems Inc.). All sequences were aligned using

Clustal X 1.81 (Thompson et al., 1997) and were compared with

sequences retrieved from GeneBank (www.ncbi.nlm.nih.gov/Genbank/

index.html).

Determination of liver heavy metal content. Heavy metal concentrations

in liver samples for the first six white-winged ducks examined were

determined by the technique described by Dehn et al. (2006). Briefly,

samples were chopped and homogenized. Approximately 0.1 g wet

sample homogenate was weighed into tared, acid-washed 50 ml

centrifuge tubes. Three millilitres of trace-metal-grade 69% to 71%

nitric acid (Fisher Scientific Waltham, Maryland, USA) was added to

each tube and the samples were allowed to stand overnight at room

temperature. The next day samples were vortexed and heated in a

microwave. Two millilitres of 30% ultrapure H2O2 (JT Baker UltrexII,

Phillipsburgh, New Jersey, USA) and 1 ml of 37% to 38% trace-metal-

grade HCl (EMD Chemicals Inc., Gibbstown, New Jersey, USA) were

added and samples were again microwaved. Samples were then diluted

with 18 MV/cm deionized water, and were analysed with a blank, a

laboratory control sample, a sample duplicate, a spiked sample, and

certified reference material (Bovine Liver 1577b; National Institute of

Standards and Technology, Boulder, Colorado, USA). Metal concen-

trations were measured using a Spectro Ciros (Spectro Analytical

Instruments Inc., Marlborough, Maryland, USA) inductively coupled

plasma�optical emission spectrometer and by mass spectrometry.

Values are expressed as micrograms per gram of wet tissue.

Results

Macroscopic findings. All 21 birds in the study wereadults. Of the 20 birds with mycobacteriosis, 11 werefemales, seven were males and the sex of two birds wasnot determined. One bird was severely autolysed,complicating gross interpretation of changes. Twentyout of 21 (95.23%) ducks examined had extensive lesionsconsistent with mycobacteriosis (Table 1). All affectedbirds had multiple organ involvement. Avian mycobac-teriosis was assumed to be the cause of death in 19 of theducks because of the extent and severity of the lesionsand the number of organs involved. One duck presenteda craniocephalic trauma in absence of other lesions.Another duck had fractured cervical spine and char-acteristic gross lesions of avian mycobacteriosis; both ofthese ducks were assumed to have died as a result oftrauma. All but one duck had marked atrophy of thepectoral muscles and loss of body fat. The mean bodyweight recorded for 11 ducks was 1315 g (standarddeviation, 9262; range, 1110 to 2003 g) which wassubstantially below the weight range (2150 to 3855 g)reported previously for these ducks (Dunning, 1992).

Hepatomegaly and splenomegaly, of up to two tothree times the normal size, was common in these ducks.Gross lesions characteristic of mycobacteriosis in birdswere found in the lung, liver, spleen, kidney andintestinal serosa of most ducks (Table 1). They consistedof random superficial and deep caseous, firm, irregular,grey or yellow nodules of variable size. Respiratory tractinvolvement was common. Multifocal coalescing granu-lomas were seen in the lungs of all ducks and were soextensive as to replace most of the lung in 18 ducks(Figure 1a). Ten of 20 ducks had an extensive fibrinousair saculitis of all air sacs. The lesions were so severe infive ducks that exudate filled most of the air sac. Asevere diffuse fibrinous tracheitis was present in sevenout of 18 birds (Figure 1b). Two ducks had granuloma-tous lesions in the subcutaneous cervical tissues. It is

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Table 1. Details results of examination of selected organs for macroscopic and microscopic lesions of avian mycobacteriosis in white-winged ducks (C. scutulata)

Duck

Organ 01 02 03 04 05 06 07 08 09 010 011 012 013 014 015 016 017 018 019 020 Percentage of organs

with lesions (N)

Liver �, � �, � �, � �, � �, � �, n �, � �, n �, � �, � �, � �, n �, n �, n �, � �, � �, � �, � �, � �, � 85 (20), 93.3(15)

Spleen �, � n, � �, � �, � �, � �, n �, � �, n �, � �, � n, � n, n �, n �, � n, n �, � �, � �, � �, � �, � 81.3 (16), 100 (15)

Lung �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � 90 (20), 100 (20)

Trachea �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, n �, � n, n �, � �, � �, � �, � n, n 38.9 (18), 64.7 (17)

Hearta �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � n, � �, � �, � �, � �, � �, � 31.6 (19), 45 (20)

Kidney �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � 40 (20), 45 (20)

Oesophagus �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � n, � �, � �, � �, � �, � �, � 0 (19), 40 (20)

Proventriculus �, � �, � �, � �, � �, n �, � �, � �, � �, � �, � �, � �, � �, � �, n n, � �, � �, � �, � �, � �, � 0 (19), 16.7 (18)

Ventriculus �, � �, � �, � �, �, n �, � �, � �, � �, � �, � �, � �, � �, � �, n n, � �, � �, � �, � �, � �, � 0 (19), 5.6 (18)

Intestines �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � n, � �, � �, � �, � �, � �, � 52.6 (19), 70 (20)

Ovary na na �, � na n, n �, � �, � �, � na �, � na na �, � �, � n, � na �, � �, � �, � n, n 30 (10), 45.5 (11)

Testes �, � �, � na �, � na na na na �, � na �, � �, � na na na �, � na na na n, n 0 (7), 0 (7)

Thyroid �, � �, � �, � �, � n, n �, n �, � �, � �, n �, � �, � �, n �, n �, � n, n n, n �, � n, n n, n �, � 0 (15), 0 (11)

Adrenal n, n n, n n, n n, n n, n, �n n, � n, n �, n �, � �, � �, n n, n n, n n, n n, n �, � �, � n, n n, n 0 (7), 0 (5)

Bone marrow �, n �, n �, n �, n �, n �, n �, n �, n �, n �, n �, n �, n n, � n, � n, � n, n n, � n, � �, � n, n 7.7 (13), 50 (6)

Pancreas �, � �, � �, � �, � �, n �, n �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � �, � 0 (20), 0 (18)

Muscle �, � �, � �, � �, � �, n �, � �, � �, � �, � �, � �, n �, � �, � �, � �, � �, � �, � �, � �, � �, � 10 (20), 11.1 (18)

Data presented as macroscopic, microscopic. �, present; �, absent; n, not examined; N, total number examined; na, not applicable. a, Includes pericarditis, myocarditis or both.

Mycobacterio

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possible that these originated in the cervicocephalic airsacs; however, the extent of the lesion made its tissue oforigin impossible to determine. Diffuse fibrinous tofibrous granulomatous inflammation of the serosa ofthe duodenum (five ducks), the pericardium (five ducks),and the ovary (three ducks) was also seen. Five duckshad diffusely enlarged livers without focal lesions. Ayellow, caseous exudate distended the oviduct of onebird. One duck presented with a unilateral conjunctivitiswith a thick fibrinous exudate covering the palbebralconjunctiva of the upper eyelid.

Microscopic findings. Lesions consistent with mycobac-teriosis were not observed in one of the two ducks thatdied from trauma. Severe postmortem changes andfreezing artefacts precluded a detailed analysis of someorgans in some of the ducks. However, even in the birdswith the most severe artefacts, acid-fast organisms andlesions consistent with mycobacterial infection could befound in most organs. The number and percentage oforgans with microscopic lesions are presented (Table 1).

Microscopic lesions could be divided into two basictypes, sometimes overlapping. The first type was discretegranulomas of variable size, with different degrees ofcentral caseation necrosis and with a layer of surround-ing histiocytes and lymphocytes and a fibrous capsule ofvarying thickness. These lesions were observed in theliver, spleen, kidney, lung, heart and on the intestinalserosa (Table 2). Spleens contained less defined granu-

lomas compared with the other organs and had a diffusehistiocytic splenitis in the regions between the granulo-mas. Variable amounts of amyloid were observed aroundcentral veins and vessels and in the space of Disse in theliver as well in the spleen of nine ducks.

The second type of lesion was characterized by a morediffuse granulomatous inflammation, without the for-mation of discrete granulomas. The predominant celltypes in these lesions were histiocytes and to a lesserdegree lymphocytes and plasmacytes. These lesions wereobserved predominantly in the trachea (Figure 2),oesophagus, proventriculus, bone marrow, air sacs,ovary, oviduct and on serosal surfaces (Table 3). Intes-tinal mucosal lesions were rare.

Multinucleated giant cells were absent from the lesionsof all but one duck where they were present ingranulomas of the liver, spleen, kidney and lung. In asecond duck, some cells appeared agglomerated butwithout a clear syncitial pattern.

Results of culture and PCR. All cultures from the liverand/or the lung yielded mycobacteria after 3 to 4 weeksof incubation. An amplicon of expected molecular masswas amplified by PCR from the liver or lung from 19birds histologically confirmed to have mycobacteriosis.The remaining bird with mycobacteriosis was not testedby PCR. The sequences of the amplified dnaJ gene forsix isolates were identical and had 100% identity with thesequevar of Mycobacterium a. avium that containsserotypes 2, 3, 4 and 9 (Morita et al., 2004).

Liver heavy metal concentrations. Liver concentrations ofsilver, aluminium, antimony, arsenic, boron, beryllium,lithium, nickel, lead, mercury, selenium, thorium, ura-nium, and vanadium were below detectable concentra-tions by either mass spectrometry or optical emissionspectrometer (data not shown). Liver concentrations ofbarium, cadmium, cobalt, chromium, molybdenum,strontium and thallium were below detection limits foroptical emission spectrometer but detectable with massspectrometry. However, all concentrations were very low,being just equal or less than three times the detectionlimit concentration (data not shown). One of theducks had a barium liver concentration of 0.215 mg/g,almost four times the detection limit concentration(0.0542 mg/g). Another duck had a cadmium concentra-tion of 0.131 mg/g, six times the minimal detectableconcentrations (0.0216 mg/g), and a thallium concentra-tion of 0.035 mg/g, 3.24 times the minimum detectableconcentration (0.0108 mg/g).

Discussion

This report describes an investigation of the aetiopatho-genesis of avian mycobacteriosis in white-winged ducksthat died during a 21-month period from 2004 to 2006 atthe Sylvan Heights Waterfowl Center in the USA.Mycobacteriosis was found in 20 of 21 ducks examinedand was the confirmed cause of death for 19 of 21 ducks.The incidence of this disease in this population (95.23%)was higher than but similar in scale to the incidencereported in England (Cromie et al., 1991, 1992),indicating that mycobacteriosis is a significant impedi-ment facing ex situ efforts to save this species.

Mycobacterium a. avium serotype 1 was the onlymycobacterium isolated from white-winged ducks kept

Figure 1. Macroscopic lesions in white-winged ducks (Cairina

scutulata) with avian mycobacteriosis. 1a: Severe diffuse fibri-

nous air saculitis and severe multifocal to coalescing granuloma-

tous pneumonia. 1b: Severe diffuse fibrinous tracheitis.

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at the Wildfowl and Wetlands Trust, Slimbridge, Eng-land. These findings led investigators to suggest that M.a. avium serotype 1 may be particularly pathogenic towhite-winged ducks. Serotyping of M. a avium isolates isno longer routinely done and has been largely replacedby genotyping of the isolates. Genotypes can be used topredict serotype in some, but not all, circumstances(Morita et al., 2004). The M. a. avium isolates from thewhite-winged ducks in this study were not serotype 1.Instead, comparative sequence analysis demonstratedthat all the isolates were of a genotype that contained theserotypes 2, 3, 4 and 9. Thus, white-winged ducks aresusceptible to infection with at least two genetic variantsof M. a. avium. The high percentage of both captivepopulations of ducks dying of mycobacteriosis, causedby two different genetic strains of M. a. avium, mightsuggest that both organisms are particularly virulent inthem. Nevertheless, susceptibility of both populations todifferent organisms may also point to a host factorpredisposing to this increased susceptibility. High levelsof contamination of the captive populations’ environ-ment by mycobacteria were also considered. However,this possibility is not supported by the fact that differentspecies of ducks at the Slimbridge collection in theUnited Kingdom also had different incidences of infec-tion for avian mycobacteriosis (Cromie et al., 1991).Mycobacteriosis accounts for one-third of adult deathsin all the species of ducks (33%) in that facility, while inwhite-winged ducks, during a 16-year period, it averaged84%. A much lower rate of mortality also occurs in otherspecies of ducks in the Sylvan Heights collection (G.Riggs, unpublished data).A higher mortality in other

species of ducks should be expected if environmentalcontamination is really the major cause of avianmycobacteriosis in these birds.

It has been suggested that the high incidence ofmycobacteriosis in captive white-winged ducks couldbe explained by evolutionary and genetic characteristicsof these species (Hillgarth & Kear, 1981; Cromie et al.,1991). In the wild, these ducks spend a considerableamount of time perching in trees, with little naturalexposure to soil mycobacteria. As a result, they mayshow reduced natural immunity to these organisms(Hillgarth & Kear, 1981; Cromie et al., 1991). In captivebirds, as a result of pinioning and lack of perching, ahigher exposure to soil or water mycobacteria may occur(Hillgarth & Kear, 1981; Cromie et al., 1991). However,there are few reports of mycobacteriosis in Muscovy’sducks (Sabocanec et al., 2006), with similar habits andclosely related to the white-winged duck (Cairinini tribe),despite its extensive use in agriculture and its commonpresence at zoos and waterfowl collections.

The current genetic diversity of captive white-wingedducks has been estimated as less than 63.5% (Riggs,2005) and could be a more probable explanation for thesusceptibility of captive white-winged ducks to myco-bacteriosis. Increased susceptibility to infectious diseasescaused by decreased genetic diversity has been recog-nized previously in wild animals (O’Brien et al., 1996;Keller & Waller, 2002; Acevedo-Whitehouse et al., 2003).Low heterozygosis at the level of the major histocompat-ibility complex has been recently demonstrated as afactor leading to higher susceptibility to diseases in wildmammals (Acevedo-Whitehouse et al., 2003) and wildbirds (Miller & Lambert, 2004; Bonneaud et al., 2006).

The absence of multinucleated giant cells from thelesions of all but one white-winged duck in our seriesmay provide a clue to the high susceptibility of thepopulation in the United States. Multinucleated giantcells have been reported in other ducks with mycobac-teriosis (Mallick et al., 1970; Thoen & Hines, 1976;Roffe, 1989). The granulomatous lesions seen in thewhite-winged ducks resemble the hyporeactive andpoorly developed granulomas seen in humans withhuman immunodeficiency virus/acquired immune defi-ciency syndrome and tuberculosis (Smith et al., 2000).These poorly developed granulomas do not have multi-nucleated giant cells, have abundant acid-fast organismsand present areas of necrosis surrounded by histiocytes.In many cases they do not completely encircle thegranuloma (Smith et al., 2000). In humans, the abilityto form multinucleated giant cells is considered oneindicator of an effective immune response to tubercu-losis (Byrd, 1998; Smith et al., 2000). Multinucleatedgiant cells may limit the growth as well as the cell to

Table 2. Microscopic findings in organs of white-winged ducks (C. scutulata) with multifocal granulomatous inflammation

Degree of inflammation Number of acid-fast organisms

Organ Mild Moderate Severe None Few Moderate Many Massive

Liver 2 2 7 1 6 4

Spleen 1 14 2 2 4 7

Lung 2 18 1 19

Kidney 9 9

Heart 1 1

Intestinal serose 3 11 12

Skeletal muscle 2 1 2 1

Figure 2. Microscopic lesion in white-winged ducks (Cairina

scutulata) with avian mycobacteriosis. Severe diffuse fibrinous

tracheitis with complete effacement of the mucosal epithelium.

Mycobacteriosis in white-winged ducks 419

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cell spread of Mycobacterium tuberculosis (Byrd, 1998;North & Young, 2004; Dannemberg, 2006). Thesimilarities to our findings in white-winged ducks arestriking and suggest that a similar defect in the immunesystem may occur in these ducks.

Little is known about the mechanism of multinu-cleated giant cell formation in mammals or birds(Anderson, 2000; Smith et al., 2000; Okamoto et al.,2003). However, in humans, cytokines such as inter-leukin-3 and interferon gamma secreted by CD4 Th1lymphocytes (Okamoto et al., 2003) are needed for cellfusion and to confine mycobacteria within these cells(Kunkel et al., 1998; Okamoto et al., 2003). Additionally,in humans, depletion of CD4 T cells results in reactiva-tion of latent M. tuberculosis infections, impairedgranuloma formation and macrophage activation, anda diminished CD8 cytotoxic T-cell response (Smith et al.,2000). The abundance of organisms and the absence ofmultinucleated giant cells in the lesions of these ducksmay suggest a defect in the duck’s ability to killintracellular mycobacteria. It is possible that a defectin cell fusion and multinucleated giant cell formationmay explain why white-winged ducks are so susceptibleto mycobacterial infections. Nevertheless, immunologyof mycobacterial infections is a little studied phenom-enon in birds (Cromie et al., 2000; Tell et al., 2001),compared with humans, cattle and other animal models(Chacon et al., 2004; North & Young, 2004; Dannem-berg, 2006; Flynn, 2006), and we are far from having acomplete understanding of the immune response to thisinfection in most species of birds. The recent discovery ofmarkers that can be used to identify CD4 and CD8 cellsin mallard ducks (Kothlow et al., 2005) may help studieson immunity in other species of ducks.

Amyloidosis is a pathological condition characterizedby the deposition of insoluble fibrillar proteins in varioustissues and organs of the body following prolongedinflammation or infection (Cotran et al., 1999). Amyloiddeposits have been reported previously in birds withchronic inflammatory diseases such as mycobacteriosisand aspergillosis. This lesion is particularly common inwaterfowl (Montali et al., 1976; Schmidt et al., 2003;Meyerholz et al., 2005). Several forms of amyloid havebeen described in mammals, but only amyloid AA hasbeen found in birds (Landman et al., 1998; Cotran et al.,1999; Schmidt et al., 2003). Amyloid AA is a product ofthe proteolytic cleavage of serum amyloid A, an acutephase-protein produced by hepatocytes (Landman et al.,1998). The concentration of serum amyloid A in theblood increases within several hours of the onset of

injury, infection, or inflammation. Production of serumamyloid A is directly stimulated by the cytokines inter-leukin-1, interleukin-6 and tumour necrosis factor-aproduced in response to tissue injury and inflammation(Petersen et al., 2004). The persistent inflammationcaused by chronic mycobacteriosis is a probable causeof the deposition of amyloid in these ducks.

It is generally assumed that most M. a. aviuminfections in birds result from entry of the organismsinto the body through the digestive tract (Montali et al.,1976; Cromie et al., 1991, 1992; Tell et al., 2001; Schmidtet al., 2003). Microbial shedding is also thought to occurthrough the faeces as many birds with mycobacteriosishave severe diffuse granulomatous enteritis. The lesiondistribution in the white-winged ducks in this study,however, was somewhat unusual. In addition to theexpected involvement of the liver and spleen, there wasoften massive involvement of the air sacs, other me-sothelial surfaces, the lung and the upper digestive tract.Lesions in the intestinal mucosa were uncommon, animportant difference from other reports of mycobacter-iosis in birds (Montali et al., 1976; Tell et al., 2001;Schmidt et al., 2003). An aerogenic route of mycobac-terial entry has been previously reported for dabblingducks and other species (Cromie et al., 1991; Gerlach,1997). Unfortunately, there are no previously reporteddescriptions of the pathology of mycobacteriosis inwhite-winged ducks affected by mycobacteriosis. Thisprecludes comparison between these birds and our series.There are also very limited data available on the grossand microscopic pathology in other species of duckswith mycobacteriosis. The liver, spleen and kidneys wereusually the only affected organs (Mallick et al., 1970;Thoen et al., 1976; Roffe, 1989; Cromie et al., 1991).Whether the high prevalence of respiratory lesions seenin our series is the result of inhalation or the result ofpreferred colonization of the respiratory tract by myco-bacteria that enter through a different route is notknown.

Heavy metal concentrations in the liver were deter-mined because metals have the ability to cause immunesuppression, and ducks, because of their feeding beha-viours and aquatic habits, are likely to accumulateenvironmental toxins, especially metals (Di Giulio &Scanlon, 1984; Mateo & Guitart, 2003; Fairbrotheret al., 2004). The absent or low concentrations of heavymetals in these ducks ruled out this possible explanationfor their susceptibility to infection with mycobacteria.Slight elevations in liver barium concentrations in oneduck and slight elevations in both cadmium and thallium

Table 3. Microscopic findings in organs of white-winged ducks (C. scutulata) with diffuse granulomatous inflammation

Degree of inflammation Number of acid-fast organisms

Organ Mild Moderate Severe None Few Moderate Many Massive

Liver 3 1 1 1

Trachea 11 4 3 4

Pericardium 5 1 2 1 2 5

Heart 1 1

Oesophagus 1 5 2 4 4

Proventriculus 3 1 2

Intestinal mucosa 1 1 2

Bone marrow 3 3

Air sacs 10 10

Ovary (stroma) 2 3 5

420 M. D. Saggese et al.

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in another were not considered significant since theseconcentrations were lower than those found in otherspecies of ducks in previous reports (Cohen et al., 2000;Braune and Malone, 2006; Mochizuki et al., 2005).

In conclusion, this study demonstrated that diseasecaused by M. a. avium was the major cause of mortalityin this population of white-winged ducks kept at SylvanHeights Waterfowl Center. In conjunction with reportsfrom the United Kingdom, it can be concluded thatmycobacterial infections are the most significant factorlimiting the ex situ recovery of this species. The reasonfor this high susceptibility to mycobacteriosis is un-known, but a defect in their ability to kill intracellularmycobacteria may be one possible explanation. The lowheterozygosis of these ducks leading to immunodefi-ciency is possible (Cromie et al., 2000; Riggs, 2005), asoccurs in other species of animals with low geneticdiversity (Acevedo-Whitehouse et al., 2003; Bonneaud etal., 2006). If this supposition is correct, additional effortsto maintain this species with the currently availablegenetic stock may prove very difficult. M. a. avium isubiquitous in the environment. Exposure to even lowlevels of the organism may ultimately result in infectionand disease in the white-winged duck no matter whatmanagement efforts are undertaken. A more fruitfulstrategy to save this species may be to establish a newand genetically diverse captive breeding population ofthese ducks from the remaining wild population,together with a scientifically managed breeding pro-gramme assuring the maintenance of genetic diversity.

Acknowledgements

This study received generous support from The SchubotExotic Bird Health Center, Sylvan Height WaterfowlCenter, SSP-American Zoo and Aquarium Association,Association of Avian Veterinarians and Smokey Moun-tain Bird Club. The authors are grateful to Dr PatriciaGray, Dr Darrel Styles, Dr Elizabeth Tomaszewski andMs Debra Turner (The Schubot Exotic Bird HealthCenter, College of Veterinary Medicine, Texas A&MUniversity), Dr David McMurray and Dr ChristineMcFarland (College of Medicine, Texas A&M Univer-sity), and Ms Deborah Dooley, Dr Bryan Brattin andDr Bob Dalhaussen for their assistance with differentaspects of this study.

References

Acevedo-Whitehouse, K., Gulland, F., Greig, D. & Amos, W. (2003).

Disease susceptibility in California sea lions. Nature, 422(6), 35.

Anderson, J.M. (2000). Multinucleated giant cells. Current Opinion in

Hematology, 7, 40�47.

BirdLife International. (2001). Threatened Birds of Asia: The BirdLife

International Red Data Book (pp. 403�440). Cambridge: BirdLife

International.

BirdLife International. (2006). Cairina scutulata. In IUCN 2006 Red

List of Threatened Species. Available online at: www.iucnredlist.org

(19 July 2006).

Bonneaud, C., Peres-Tris, J., Federici, P., Chastel, O. & Sorci, G. (2006).

Major histocompatibility alleles associated with local resistance to

malaria in a passerine. Evolution, 60, 383�389.

Braune, B.M. & Malone, B.J. (2006). Mercury and selenium in livers of

waterfowl harvested in northern Canada. Archives of Environmental

Contaminant Toxicology, 50, 284�289.

Byrd, T.F. (1998). Multinucleated giant cell formation induced by IFN-

g/IL-3 is associated with restriction of virulent Mycobacterium

tuberculosis cell to cell invasion in human monocytes monolayers.

Cellular Immunology, 188, 89�96.

Chacon, O., Bermudez, L.E. & Barletta, R.G. (2004). Johne’s disease,

inflammatory bowel disease, and Mycobacterium paratuberculosis.

Annual Review in Microbiology, 58, 329�363.

Cohen, J.B., Barclay, J.S., Major, A.R. & Fisher, J.P. (2000). Wintering

Greater Scaup as biomonitors of metal contamination in federal

wildlife refuges in the Long Island region. Archives of Environmental

and Contamination Toxicology, 38, 83�92.

Cotran, R.S., Kumar, V. & Collins, T. (1999). Robbins Pathologic Basis

of Diseases, 6th edn (pp. 251�259). Philadelphia, PA: WB Saunders

Co.

Cromie, R.L., Brown, M.J., Price, D.J. & Stanford, J.L. (1991).

Susceptibility of captive wildfowl to avian tuberculosis: the impor-

tance of genetic and environmental factors. Tubercle, 72, 105�109.

Cromie, R.L., Brown, M.J. & Stanford, J.L. (1992). The epidemiology

of avian tuberculosis in white-winged wood duck Cairina scutulata at

The Wildfowl and Wetland Trust, Slimbridge Centre (1976�1991).

Wildfowl, 43, 211�214.

Cromie, R.L., Ash, N.J., Brown, M.J. & Stanford, J.L. (2000). Avian

immune response to Mycobacterium avium: the wildfowl example.

Developmental and Comparative Immunology, 24, 169�185.

Dannemberg, A.M. (2006). Pathogenesis of Human Tuberculosis. In-

sights from the Rabbit Model. Washington, DC: ASM Press.

Dehn, L.A., Follman, E.H., Rosa, C., Duffy, L.K., Thomas, D.L.,

Bratton, G.R., Taylor, R.J. & O?Hara, T.M. (2006). Stable isotope

and trace elements status of subsistence-hunted bowhead and beluga

whales in Alaska and gray whales in Chukotka. Marine Pollution

Bulletin, 52, 302�319.

del Hoyo, J., Sargatal, J. & Cabot, J.(Eds.). (1992). Handbook of the

Birds of the World: Ostriches to Ducks. Barcelona, Spain: Lynx

Editions.

Di Giulio, R.T. & Scanlon, P.F. (1984). Heavy metals in tissues of

waterfowl from the Chesapeake Bay, USA. Environmetal Pollution,

35, 29�48.

Dunning, J.B. (1992). CRC Handbook of Avian Body Masses (p. 21).

Boca Raton, FL: CRC Press.

Evans, T.D., Robichaud, W.G. & Tizard, R.J. (1997). The White-winged

Duck Cairina scutulata in Laos. Wildfowl, 44, 81�96.

Fairbrother, A., Smits, J. & Grasman, K. (2004). Avian inmunotoxicol-

ogy. Journal of Toxicology and Environmental Health B Critical

Review, 7, 105�137.

Flynn, J.L. (2006). Lessons from experimental Mycobacterium tubercu-

losis infections. Microbes Infections, 8, 1179�1188.

Gerlach, H. (1997). Bacteria. In B.W. Ritchie, G.J. Harrison & L.R.

Harrison (Eds.), Avian Medicine: Principles and Application. Lake

Worth, FL: Wingers Publishing.

Hillgarth, N. & Kear, J. (1981). Diseases of perching ducks in captivity.

Wildfowl, 32, 156�162.

Kalisinska, E., Salicki, W., Myslek, P., Kavetska, K.M. & Jackowski, A.

(2004). Using the Mallard to biomonitor heavy metal contamination

of wetlands in north-western Poland. Science Total Environment, 320,

145�161.

Keller, F. & Waller, D.M. (2002). Inbreeding effects in wild popualtions.

Trends in Ecology and Evolution, 17, 230�241.

Kothlow, S., Mannes, N.K., Schaerer, B., Rebeski, D.E., Kaspers, B. &

Schultz, U. (2005). Characterization of duck leucocytes by mono-

clonal antibodies. Developments in Comparative Immunology, 29,

733�748.

Kunkel, S., Lucaks, N., Strieter, R. & Chensue, S. (1998). Animal

models of granulomatous inflammation. Seminars in Respiratory

Infections, 13, 221�228.

Landman, W.J.M., Gruys, E. & Gielkens, A.L.J. (1998). Avian

amyloidosis. Avian Pathology, 27, 437�449.

Mallick, B.B., Chakrabarthy, R.I. & Chattopadhyay, S.K. (1970). Some

observations on the naturally occurring cases of avian tuberculosis in

ducks. Indian Journal of Animal Health, 9, 171�173.

Mateo, R. & Guitart, R. (2003). Heavy metals in livers of Waterbirds

from Spain. Archives of Environmental Contaminant Toxicology, 44,

398�404.

Mycobacteriosis in white-winged ducks 421

Dow

nloa

ded

by [

Inge

nta

Con

tent

Dis

trib

utio

n (P

ublis

hing

Tec

hnol

ogy)

] at

10:

22 0

6 O

ctob

er 2

014

Meyerholz, D.K., Vanloubbeeck, Y.E., Hoistetter, S.J., Jordan, D.M. &

Fales-Williams, A.J. (2005). Surveillance of amyloidosis and other

diseases at necropsy in captive trumpeter swans (Cygnus buccinator).

Journal of Veterinary Diagnostics and Investigation, 17, 295�298.

Miller, H.C. & Lambert, D.M. (2004). Genetic drift outweighs

balancing selection in shaping post-bottleneck major histocompat-

ibility complex variation in New Zealand robins (Petroicidae).

Molecular Ecology, 13, 3709�3721.

Mochizuki, M., Mori, M., Akinaga, M., Yugami, K., Oya, C., Hondo,

R. & Fukiko, U. (2005). Thallium contamination in wild ducks in

Japan. Journal of Wildlife Diseases, 41, 664�668.

Montali, R.J., Bush, M., Thoen, C.O. & Smith, E. (1976). Tuberculosis

in captive exotic birds. Journal of the American Veterinarian Medical

Association, 169, 920�927.

Morita, Y., Maruyama, S., Kabeya, H., Nagai, A., Kozawa, K., Kato,

M., Nakajima, T., Mikami, T., Katsube, Y. & Kimura, H. (2004).

Genetic diversity of the dnaJ gene in the Mycobacterium avium

complex. Journal of Medical Microbiology, 53, 813�817.

North, R.J. & Jung, Y.J. (2004). Immunity to tuberculosis. Annual

Review in Immunology, 22, 599�623.

O’Brien, S.J., Martenson, J.S., Miththapala, S., Janczewski, D.N., Pecon

Slattery, J., Johnson, W.E., Gilbert, D.A., Roelke, M.E., Packer, C.,

Bush, M. & Wildt, D.E. (1996). Conservation genetics of the Felidae.

In J.C. Avise & J.L. Hamrick (Eds.), Conservation Genetics: Case

Histories from Nature (pp. 50�74). New York: Chapman and Hall.

Okamoto, H., Mizuno, K. & Horio, T. (2003). Monocyte-derived

multinucleated giant cells and sarcoidiosis. Journal of Dermatological

Sciences, 31, 119�128.

Petersen, H.H., Nielsen, J.P. & Heegaard, M.H. (2004). Application of

acute phase protein measurements in veterinary clinical chemistry.

Veterinary Research, 35, 163�187.

Riggs, G. (2005). Mycobacterial infection in waterfowl collections: a

conservation perspective. In Proceedings of the 26th Association of

Avian Veterinarians Conference (pp. 70�76), Monterey, CA, USA.

Roffe, T.J. (1989). Isolation of Mycobacterium avium from waterfowl

with polycystic livers. Avian Diseases, 33, 195�198.

Rose, P.M. & Scott, D.A. (1997). Waterfowl Population Estimates, 2nd

edn. Wageningen, The Netherlands: Wetlands International.

Sabocanec, R., Konjevic, D., Curic, S., Cvetnic, Z. & Spicic, S. (2006).

Spontaneous Mycobacterium avium serovar 2 infection in a Muscovy

Duck (Cairina moschata)* a case report. Veterinarski Archiv, 76,

185�192.

Schmidt, R.E., Reavill, D.R. & Phalen, D. (2003). Pathology of

Pet and Aviary Birds. Ames: Blackwell Publishing & Iowa State

Press.

Smith, M.B., Boyars, M.C., Veasey, S. & Woods, G.L. (2000). General-

ized tuberculosis in the acquired immune deficiency syndrome. A

clinicopathologic analysis based on autopsy findings. Archives of

Pathology and Laboratory Medicine, 124, 1267�1274.

Stout, J.H., Trust, K.A., Cochrane, J.F., Suydam, R.S. & Quakenbusch,

L.T. (2002). Environmental contaminants in four eider species

from Alaska and artic Russia. Environmental Pollution, 119, 215�226.

Tell, L., Woods, L. & Cromie, R.L. (2001). Mycobacteriosis in birds.

Revue Scientifique et Technique. Office International des Epizooties, 1,

180�203.

Thoen, C.O. & Himes, E.M. (1976). Isolation of Mycobacterium avium

serotype 3 from a white-headed tree duck (Dendrocygna viduata).

Avian Diseases, 20, 587�592.

Thompson, J.D., Gibson, T., Plewniak, J.F., Jeanmougin, F. & Higgins,

D.G. (1997). The CLUSTAL X windows interface: flexible strategies

for multiple sequence alignment aided by quality analysis tools.

Nucleic Acid Research, 25, 4876�4882.

422 M. D. Saggese et al.

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Non-English Abstracts

Gross and microscopic findings and investigation of theaetiopathogenesis of mycobacteriosis in a captivepopulation of white-winged ducks (Cairina scutulata)

Miguel D. Saggese1, Gary Riggs2, Ian Tizard1, Gerald Bratton3, Robert Taylor3 andDavid N. Phalen1,4

1The Schubot Exotic Bird Health Center, Department of Veterinary Pathobiology, and 2Akron Zoological Park, Akron,OH 44203, USA, and 3Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and BiomedicalSciences, Texas A & M University, 4467 TAMU, College Station, TX 77843-4467, USA, and 4The Wildlife Health andConservation Centre, University of Sydney, Camden, New South Wales 4475, Australia

Observations macroscopiques et microscopiques et investigation de l’etiopathogenie d’une mycobacteriosedans une population de canards a aile blanche (Cairina scutulata) eleves en captiviteLe canard a aile blanche (Cairina scutulata) est en voie d’extinction. Des elevages de reproduction de cecanard se sont etablis au Royaume Uni et aux USA. L’infection par Mycobacterium avium avium de serotype1 est une cause majeure de mortalite dans les elevages au Royaume Uni. Dans cette etude, l’etiopathogeniedes mortalites apparues dans un elevage de collection au USA a ete etudiee. Tous les canards (n�21) quisont morts au cours d’une periode de 2 ans ont ete examines. Une mycobacteriose a ete diagnostiquee chez20 canards, tuant 19 d’entre eux. Des lesions granulomateuses multifocales a diffuses avec souvent des micro-organismes intralesionels nombreux, ont ete observees chez les 20 canards. Les manifestations nonhabituelles de cette maladie ont ete l’implication importante du systeme respiratoire et l’absence de cellulesgeantes multinuclees. L’analyse de sequence a montre que les canards etaient infectes par un sequevar de M.a. avium qui contient les serotypes 2, 3, 4, et 9. Etant donne que l’investigation a long terme des metauxaffecte la fonction immunitaire, nous avons mesure un certain nombre de ces elements dans le foie de 6canards. Les concentrations etaient non detectables ou faibles.. La nature disseminee de la maladie, lesconcentration elevee de mycobacteries et l’absence de cellules geantes multinuclees dans les lesions suggerentque ces canards ont ete incapables d’eliminer les mycobacteries et indiquent un eventuel defaut ou uneinhibition de l’immunite a mediation cellulaire. En prenant en compte des donnees anterieures rapportees auRU, ces resultats suggerent que les canards a aile blanche en captivite sont hautement sensibles a au moinsdeux sequevars de M. a. avium et que la mycobacteriose est une menace majeure pour l’elevage ex situ. Nousformulons l’hypothese que l’heterozygotisme minimal precedemment mis en evidence chez ces canardspourrait contribuer a une reponse immunitaire apparemment inefficace.

Untersuchungen zur Pathologie, Histopathologie und Atiopathogenese der Mykobakteriose in einer inGefangenschaft gehaltenen Population von Malaienenten (Cairina scutulata)Die Malaienente (Cairina scutulata) ist eine vom Aussterben bedrohte Vogelart. In Großbritannien und denUSA sind Zuchtprogramme fur diese Ente etabliert worden. In der britischen Station ist die Infektion mitMycobacterium avium avium-Serotyp 1 eine der Haupttodesursachen. In dieser Studie wurde dieAtiopathogenese der Todesfalle, die in der Station in den USA auftraten, untersucht. Alle Enten (n �21), die in einen Zeitraum von zwei Jahren starben, wurden in die Untersuchung mit einbezogen. Bei 20dieser Enten wurde Mykobakteriose diagnostiziert, die in 19 Fallen auch die Todesursache darstellte. Beiallen 20 Enten wurden multifokale bis diffuse, granulomatose Lasionen oft verbunden mit hochgradigemErregerbefall innerhalb der Veranderungen festgestellt. Eine ungewohnliche Manifestierung der Erkrankungwar die hochgradige Beteiligung des Respirationstrakts bei gleichzeitigem Fehlen von vielkernigenRiesenzellen. Die Sequenzanalyse ließ erkennen, dass die Enten mit einer Sequenzvariante des M. a. aviuminfiziert waren, die die Serotypen 2, 3, 4 und 9 enthielt. Angesichts der Tatsache, dass eine langfristige

Aufnahme von Metallen zu einer Beeintrachtigung von Immunfunktionen fuhrt, haben wir die Lebern vonsechs Enten auf eine Reihe von diesen Elementen untersucht. Die Konzentrationen lagen jedoch unter der

*To whom correspondence should be addressed. Tel: �1 979 218 3962. E-mail: msaggese@cvm.tamu.eduCurrent address: College of Veterinary

Medicine, Western University of Health Sciences, 309 E Second Street, Pomona, CA, 91766-1854. E-mail: msaggese@westernu.edu

Received 14 February 2007

Avian Pathology (October 2007) 36(5), 1�2

ISSN 0307-9457 (print)/ISSN 1465-3338 (online)//50001-02 # 2007 Houghton Trust LtdDOI: 10.1080/03079450701595909

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Nachweisgrenze oder waren gering. Die weite Verbreitung der Erkrankung, der starke Erregerbefall und dieAbwesenheit von vielkernigen Riesenzellen lassen vermuten, dass diese Entenspezies nicht in der Lage ist,Mykobakterien wirksam zu bekampfen, was moglicherweise auf einen Defekt oder eine Hemmung in derzellvermittelten Immunitat zuruckzufuhren ist. Zusammen mit den kurzlich aus Großbritannien ver-offentlichten Daten kann aufgrund dieser Ergebnisse angenommen werden, dass in Gefangenschaftgehaltene Malaienenten fur mindestens zwei M. a. avium-Sequenzvarianten hochempfanglich sind unddass die Mykobakteriose ein erhebliche Bedrohung fur eine ex situ-Zucht darstellt. Wir vermuten, dass die indiesen Enten beobachtete nur geringgradige Heterozygose zu der offensichtlich ineffektiven Immunantwortbeitragen konnte.

Lesiones macroscopicas y microscopicas e investigacion de la etiopatogenia de las micobacteriosis enpoblaciones en cautividad de Patos de Jungla (Cairina scutulata)El pato de Jungla (Cairina scutulata) esta en grave peligro. En USA y Reino Unido se han creado criaderos.La infeccion con el serotipo 1 de Mycobacterium avium avium es la principal causa de mortalidad en loscriaderos de Reino Unido. En este estudio, se investigo la etiopatogenia de las muertes ocurridas en criaderosde USA. Se estudiaron todos los patos (n�21) que murieron durante un periodo de dos anos. Se diagnosticomicobacteriosis en 20 patos, siendo la causa de muerte en 19 de ellos. En los 20 patos se observaron lesionesgranulomatosas multifocales a difusas, asociadas a menudo con gran cantidad de organismos. Algunasmanifestaciones poco comunes de esta enfermedad observadas fueron la ausencia de celulas gigantesmultinucleadas y la afectacion extensa del sistema respiratorio. Los analisis de las secuencias mostraron queun secuevar de M. a. avium que contiene los serotipos 2, 3, 4, y 9 infectaba a los patos. Teniendo en cuentaque la ingestion de metales durante periodos prolongados afecta el funcionamiento del sistema inmune, semidieron un conjunto de estos elementos en el hıgado de seis patos. Las concentraciones resultaron ser bajaso no detectables. La naturaleza sistemica de la enfermedad, la elevada concentracion de micobacterias y laausencia de celulas multinucleadas gigantes en las lesiones sugiere que estos patos eran incapaces de eliminarlas micobacterias de forma efectiva e indica la posible inhibicion o defecto de la inmunidad mediada porcelulas. Estos resultados junto con otros previamente descritos en UK sugieren que los Patos de Jungla encautividad son altamente susceptibles como mınimo a dos secuevares de M. a. avium y que lamicobacteriosis es una de las principales amenazas de la crıa ex situ. Hipotetizamos que la heterocigosismınima previamente demostrada en estos patos podrıa contribuir a una respuesta inmune aparentementeineficaz.

2 M. D. Saggese et al.

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