Systemic Fungal Infections in Small Animals

Colleen Hock May 12, 2010 http://atlas.arabslab.com/data/8/blasto10.gif

The Mycotic Agents

   Blastomyces dermatitidis Histoplasma capsulatum Coccidioides immitis – All are dimorphic (mold and yeast forms) – Cause primarily respiratory disease by evasion of the host immune response

Blastomycosis

   Blastomyces dermatitidis South east, south central, and upper midwest near river valleys and lakes Moist and shaded areas with increased organic matter (soil and wood) http://www.familyvet.com/Dogs/Fungi.html

Blastomycosis: Clinical Signs

 Dogs: Dyspnea Anorexia Depression Lameness Lymphadenopathy Skin Lesions +/- occular manifestations +/- Orchitis  Cats: Dyspnea Nasal discharge Cough Lethargy Weight loss

**Pneumonia and weight loss are the most common presentations**

Blastomycosis

http://veterinarymedicine.dvm360.com/vetmed/ArticleStandard/Articl e/detail/596603 Occular blastomycosis: Panophthalmitis http://www.njmoldinspection.com/vetmycology/vetblastomycosis.html

Cutaneous blastomycosis: Dermatitis

Blastomycosis: Pathogenesis

Inhale spores  Deposit in the alveoli  Acute Pulmonary Phase  Self-limiting control of asexual reproduction  Asexual budding, not eliminated by the immune system OR the patient is immunocompromised Lymphatic and Hematogenous Spread of spores Inflammation in skin, bones, LN’s,  eyes, CNS, and/or reproductive tract   Pyogranulomatous Inflammation within the lungs

Blastomycosis: Diagnosis

  History, Clinical signs, and Diagnostic findings Definitive diagnosis must show the organism  Cytology: TTW, BAL, LN aspirates, fluid from the anterior chamber of the eye, draining tracts, prostatic fluid, and CSF Never Culture Blastomyces because of danger to personnel http://www.pharmacy-and-drugs.com/illnessessimages/blastomycosis2.jpg

Blastomycosis: Diagnosis

  Serology (AGID) is helpful if the organism cannot be definitively diagnosed.

- Sensitivity and Specificity > 90% Thoracic Radiographs indicated when respiratory signs present: - interstitial pattern - nodular interstitial pattern/diffuse miliary - tracheobronchial lymphadenopathy

Blastomycosis: Pyogranulomatous Inflammation

http://www.vet.uga.edu/vpp/clerk/mordecai/index.php

Nodular Interstitial Pattern/Diffuse Milliary Pattern Differentials

-Lymphoma -Fungal pneumonia -Pneumoconiosis -Hematogenous bacterial pneumonia -Metastases from thyroid or mammary carcinoma www.vet.uga.edu/vpp/clerk/mordecai/figure1.jpg

Blastomycosis: Fungal Granuloma Differentials

-Tumor metastases -Fungal granuloma -Parasitic granuloma -Abscesses -Lymphoma -Malignant histiocytosis -Lymphoid granulomatosis -Cysts/Fluid filled bullae http://veterinarymedicine.dvm360.com/vetmed/ArticleStandard/Article/detail/596603

Fungal Osteomyelitis: Blastomyces dermatitidis

http://cal.vet.upenn.edu/p rojects/saortho/chapter_3 7/37mast.htm

Fungal Osteomyelitis vs. Bone Tumors

  http://people.upei.ca/lpack/vetrad/VCA%20341/VCA%20 341%20Lecture%207%20Musculoskeletal%20Part%201.

ppt#362,49,Fungal Osteomyelitis http://www.acvs.org/AnimalOwners/HealthConditions/SmallA nimalTopics/BoneTumorsinCatsandDogs/

Blastomycosis: Treatment

  Amphotercin B - IV, nephrotoxic - Lipid soluble form that is less toxic Iatroconazole - less toxic - oral administration - more expensive http://www.cvs.com/CVSApp/images/health/A1055050.JPG

Histoplasmosis

    Histoplasma capsulatum Found in soil near avian species (especially starlings) and bats 3 forms in dogs: pulmonary, disseminated, and subclinical Rare and progressive in cats

http://www.familyvet.com/Dogs/Fungi.html

Histoplasmosis: Clinical Signs

 Dogs - coughing - dyspnea - anorexia - weight loss - depression - ascites - ulcerated oral and/or nasal mucosa - anemia - lymphadenopathy - thrombocytopenia - fever - diarrhea  Cats - weight loss - lethargy - fever (fluctuant) http://cat.uab.cat/Publications/2005/SEP05/starlings.jpg

Histoplasmosis: Pathogenesis

Inhale or ingest microconidia or hyhae  Conversion to yeast within the host  Yeasts engulfed by macrophages and they replicate intracellularly  Immune system is overwhelmed  Clear infection  Hematogenous and Lymphatic spread

Histoplasmosis: Diagnosis

    Cytology: exudates, TTW, FNA (LN’s), and Bone Marrow Histopathology Serology Blood smear http://www.google.ca/imgres?imgurl=http://www.vet.uga.edu/vpp/cler k/edison/Fig4ADJ

Histoplasmosis: Diagnosis

 Radiographs: - pulmonary interstitial pattern with miliary or nodular infiltrates - Abdomen: hepatomegaly, splenomegaly, and ascites - Gastogram: Barium highlights thickening of the intestinal wall and mucosa - Abdominal Ultrasound for gi thickening - Bone: osteolysis with periosteal proliferation  Endemic areas: may see patients with calcification in the thorax or abdomen secondary to persistence of the organism

Histoplasmosis

http://www.vet.uga.edu/vpp/clerk/edison/Fig4ADJ.jpg

Histoplasmosis

http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/51108.htm

Histoplasmosis

http://www.vet.uga.edu/vpp/clerk/edison/index.php

Histoplasmosis: Fungal osteomyelitis

http://cal.vet.upenn.edu/projects/saortho/c hapter_37/37F8.jpg

Histoplasmosis: Treatment

 Iatroconazole: lower toxicity http://www.my-online-pharmacy.net/i/products/sporanox.jpg

Coccidiomycosis

    Coccidioides immitis Soil in arid or semi-arid regions Virulent reputation Epidemics after rainy season followed by a drought

http://www.familyvet.com/Dogs/Fungi.html

Coccidiomycosis: Clinical Signs

 Dogs - dyspnea - anorexia - cough - weight loss - lameness - draining tracts - abscesses - lymphadenopathy - meningitis    Signs can range from flu-like symptoms to severe pneumonia when pulmonary tissue involved Can see extensive damage to bones, joints, skin, and CNS when dissemination occurs Fatal when immunocompromised

Coccidiomycosis: Pathogenesis

Inhalation of infective arthroconidia  Deposition in the lung  Microenvironment induces endosporulation  Removed by mononuclear cells   Endospores released Subclinical or clearance of organisms  Immunocompromised patients  Extensive lung damage  Dissemination

Coccidiomycosis: Diagnosis

    Cytology: exudate, TTW, LN or bone biopsy Wet mount with 10% KOH - endospores 2-5 um - spherules 10-100 um - mycelial form= dangerous Serology Radiographs: Thorax and bones

Coccidiomycosis: wet mount

http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/51104.htm

Coccidiomycosis

http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/51104.htm

Coccidiomycosis: Fungal osteomyelitis http://www.familyvet.com/Dogs/Fungi.html

Coccidiomycosis: fungal osteomyelitis http://cal.vet.upenn.edu/projects/saortho/chapter_37/37mast.htm

Coccidiomycosis: Treatment

  Ketoconazole: helps to prevent dissemination Iatroconazole www.amercianvetonline.com

              

References

http://www.vet.uga.edu/vpp/clerk/mordecai/index.php

http://www.familyvet.com/Dogs/Fungi.html

http://cal.vet.upenn.edu/projects/saortho/chapter_37/37mast.htm

http://www.acvs.org/AnimalOwners/HealthConditions/SmallAnimalTopics/Bon eTumorsinCatsandDogs/ http://www.pharmacy-and-drugs.com/illnessessimages/blastomycosis2.jpg

http://veterinarymedicine.dvm360.com/vetmed/ArticleStandard/Article/detail/ 596603 http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/51108.htm

http://www.vet.uga.edu/vpp/clerk/edison/Fig4ADJ.jpg

http://www.vet.uga.edu/vpp/clerk/edison/index.php

http://cal.vet.upenn.edu/projects/saortho/chapter_37/37F8.jpg

http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/51104.htm

http://www.vet.uga.edu/vpp/clerk/edison/index Songer, J.G., & Post, K.W. (2003). Veterinary Microbiology. St Louis: Elsevier.

http://www.acvs.org/AnimalOwners/HealthConditions/SmallAnimalTopics/Bon eTumorsinCatsandDogs/ http://people.upei.ca/lpack/vetrad/VCA%20341/VCA%20341%20Lecture%20 7%20Musculoskeletal%20Part%201.ppt#362,49,Fungal Osteomyelitis