Investigation of Investigation of Chronic Disease in a Chronic Disease in a Captive Mara ColonyCaptive Mara Colony

MexicoMexico

Index Case Index Case

July 21, 2001July 21, 2001 2 year old captive born male mara (2 year old captive born male mara (DolichotisDolichotis

patagonumpatagonum) died shortly after presenting with ) died shortly after presenting with weakness and anorexiaweakness and anorexia

Index Case-con’tIndex Case-con’t

Animal had disseminated fungal infection affecting Animal had disseminated fungal infection affecting mostly the liver, adrenal and lymph nodesmostly the liver, adrenal and lymph nodes

Cytology evaluation of the lymph node, adrenal and liver Cytology evaluation of the lymph node, adrenal and liver revealed numerous cytoplasmic yeast-like organismsrevealed numerous cytoplasmic yeast-like organisms 2-4 um in diameter2-4 um in diameter Clear halo surrounding themClear halo surrounding them In the cytoplasm of phagocytic cells and adrenocortical cellsIn the cytoplasm of phagocytic cells and adrenocortical cells

Gomori’s methenamine silver stain positive Gomori’s methenamine silver stain positive Histoplasma capsulatum var capsulatumHistoplasma capsulatum var capsulatum was isolated was isolated

from spleenfrom spleen

Case ConfirmationCase Confirmation

Gross necropsy findingsGross necropsy findings Histological findingsHistological findings Other testingOther testing

Special stainsSpecial stains Transmission electron microscopyTransmission electron microscopy Organism isolationOrganism isolation Exoantigen testExoantigen test ImmunohistochemistryImmunohistochemistry

Establishing Endemic LevelsEstablishing Endemic Levels

Intradermal testingIntradermal testing Common test in humans and equineCommon test in humans and equine Test location on abdomenTest location on abdomen 18/29 animals negative at 72 hours18/29 animals negative at 72 hours

No clinical, hematolgical, radiographic or No clinical, hematolgical, radiographic or immunologic evidence of histoplasmosis in immunologic evidence of histoplasmosis in these animalsthese animals

No prior cases of histoplasmosis in this No prior cases of histoplasmosis in this collectioncollection

Is There An outbreak?Is There An outbreak?

There is no evidence of histoplasmosis previous There is no evidence of histoplasmosis previous to these cases in the entire collectionto these cases in the entire collection

Is there the probability that more animals in the Is there the probability that more animals in the mara colony could have been exposed ot the mara colony could have been exposed ot the disease?disease? Maras use dens dug in the ground, each den is used Maras use dens dug in the ground, each den is used

several times by different femalesseveral times by different females The intradermal testing, that is the only practical The intradermal testing, that is the only practical

way to detect positive animals, was negative.way to detect positive animals, was negative.

Descriptive EpidemiologyDescriptive Epidemiology

Herd historyHerd history Environmental factorsEnvironmental factors

Herd HistoryHerd History

Mara colony at park for >20 yearsMara colony at park for >20 years 1997: 5 animals from Argentina added to group1997: 5 animals from Argentina added to group

1 male, 4 females1 male, 4 females Reproduction good since introduction (66 births)Reproduction good since introduction (66 births)

During time of the index caseDuring time of the index case Herd composed of 29 animalsHerd composed of 29 animals

Environmental FactorsEnvironmental Factors DietDiet

Water Water ad libitumad libitum Oranges, carrots, chopped alfalfa and rabbit pelletsOranges, carrots, chopped alfalfa and rabbit pellets

EnclosureEnclosure 120m120m22

Fenced with 1.20m high wire mesh and bamboo on one sideFenced with 1.20m high wire mesh and bamboo on one side Sandy substrateSandy substrate Often see squirrels (Often see squirrels (Spermophilus variegatusSpermophilus variegatus), Mice (), Mice (Mus musculusMus musculus) )

and various birds inside the enclosure.and various birds inside the enclosure. Often see opossum (Often see opossum (Didelphis virginianaDidelphis virginiana), ringtail cat (), ringtail cat (Bassariscus Bassariscus

astutusastutus) and stray cats () and stray cats (Felis domesticusFelis domesticus) inside the park.) inside the park. Several wild colonies of insectivorous bats (Several wild colonies of insectivorous bats (Tadarida brasiliensisTadarida brasiliensis))

Subsequent CasesSubsequent Cases

April 25, 2002April 25, 2002 Died after presenting with progressive weight Died after presenting with progressive weight

lossloss Severe granulomatous typhlocolitis and Severe granulomatous typhlocolitis and

moderate granulomatous gastrohepatic moderate granulomatous gastrohepatic lymphadenitis lymphadenitis

Similar organisms in the cytoplasm of Similar organisms in the cytoplasm of macrophagesmacrophages

Case #2Case #2 Gross necropsy findingsGross necropsy findings

Thickening of the large intestinal mucosaThickening of the large intestinal mucosa Watery to mucoid small intestinal contentsWatery to mucoid small intestinal contents

HistopathologyHistopathology Severe, chronic grnaulomatous and fibrosing Severe, chronic grnaulomatous and fibrosing

hepatitis and adrenalitis with foci of hepatitis and adrenalitis with foci of necrosuppurative inflammationnecrosuppurative inflammation

Granulomatous typhlocolitisGranulomatous typhlocolitis Adrenocortical cells had abundant similar organisms Adrenocortical cells had abundant similar organisms

in their cytoplasm with no associated lesionin their cytoplasm with no associated lesion Histoplasma capsulatum var. capsulatumHistoplasma capsulatum var. capsulatum was was

isolated from the liver and adrenal gland.isolated from the liver and adrenal gland.

Is This An Outbreak?Is This An Outbreak?

Retrospective review of 54 animals Retrospective review of 54 animals revealed no other lesions compatible with revealed no other lesions compatible with HistoplasmosisHistoplasmosis

Previously non-tested animals were tested Previously non-tested animals were tested with high-dose antigen testingwith high-dose antigen testing All animals negativeAll animals negative

Investigate immune status of animals and Investigate immune status of animals and contamination status of environmentcontamination status of environment

Immune Status and Immune Status and EnvironmentEnvironment

No previous evidence of histoplasmosis in this No previous evidence of histoplasmosis in this mara colonymara colony

High probability that more animals in the colony High probability that more animals in the colony could have been exposed to diseasecould have been exposed to disease

Intradermal testing is the only practical way to Intradermal testing is the only practical way to test these animalstest these animals questionable accuracyquestionable accuracy

Immunological status of the colony would Immunological status of the colony would contribute to presence of disseminated contribute to presence of disseminated histoplasmosis in more animalshistoplasmosis in more animals

HypothesesHypotheses

Unusual susceptibility of this species to Unusual susceptibility of this species to the diseasethe disease

Low immunological status of the groupLow immunological status of the group Predisposing them to diseasePredisposing them to disease

High environmental contaminationHigh environmental contamination

Investigate HypothesisInvestigate Hypothesis

Review literature for similar casesReview literature for similar cases Environmental InvestigationEnvironmental Investigation

Literature ReviewLiterature Review

No reports of disseminated histoplasmosis No reports of disseminated histoplasmosis in maras or any rodent speciesin maras or any rodent species

Report of a localized mucocutaneous Report of a localized mucocutaneous histoplasmosis in a rabbithistoplasmosis in a rabbit

Reports of histoplasmosis affecting the Reports of histoplasmosis affecting the skin and lymph nodes of Badgers in skin and lymph nodes of Badgers in EuropeEurope

Environmental InvestigationEnvironmental Investigation

Environmental sampling of mara areasEnvironmental sampling of mara areas No growthNo growth Mice inoculated with extracts of environmental Mice inoculated with extracts of environmental

samples DID seroconvertsamples DID seroconvert Demonstrates presence of organism in the Demonstrates presence of organism in the

enclosureenclosure

2 bat colonies in the park were sampled2 bat colonies in the park were sampled No culture growthNo culture growth NO seroconversion in miceNO seroconversion in mice

Environmental InvestigationEnvironmental Investigation

Climatic conditions of park does not promote the Climatic conditions of park does not promote the proliferation of the fungusproliferation of the fungus Sandy substrate, low humidity, lack of bird or bat Sandy substrate, low humidity, lack of bird or bat

droppingsdroppings But indirect evidence of fungal presence was foundBut indirect evidence of fungal presence was found

Bats play an important role in fungal Bats play an important role in fungal disseminationdissemination Abundance of insectivorous bats in parkAbundance of insectivorous bats in park

Other carnivorous wild animals in the park could Other carnivorous wild animals in the park could disseminate the fungusdisseminate the fungus Serology is pendingSerology is pending

Treatment and InterventionTreatment and Intervention

DisinfectDisinfect Foot baths with phenolic base productsFoot baths with phenolic base products Dedicated tools to affected areasDedicated tools to affected areas 80cm of dirt removed from enclosure and replaced80cm of dirt removed from enclosure and replaced Disinfection of holding areaDisinfection of holding area

Communicate to staffCommunicate to staff Provided with masksProvided with masks Review of personal hygiene Review of personal hygiene

QuarantineQuarantine All maras moved to quarantineAll maras moved to quarantine

Long TermLong Term

Control of immune status of the colonyControl of immune status of the colony Review sex ratio and demographicsReview sex ratio and demographics Review geneticsReview genetics

Monitor wild bat colonies within the parkMonitor wild bat colonies within the park

ReferencesReferences Chavez-Tapia D.B., R. Vargas-Yañes, G. Rodríguez-Arellanes, G. R. Peña-Sandoval, J. J. Chavez-Tapia D.B., R. Vargas-Yañes, G. Rodríguez-Arellanes, G. R. Peña-Sandoval, J. J.

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Rosas-Rosas A., C. J. Salles, G. Rodríguez-Arellanes, M. L. Taylos, M. M. Garner. 2004. Rosas-Rosas A., C. J. Salles, G. Rodríguez-Arellanes, M. L. Taylos, M. M. Garner. 2004. Disseminated Disseminated Histoplasma capsulatum var. capsulatumHistoplasma capsulatum var. capsulatum infection infection in a captive mara in a captive mara ( ( Dolichotis patagonumDolichotis patagonum) In Press……) In Press……

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