blastomycosis grand rounds
TRANSCRIPT
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{
The No Bueno Blasto
Abigail Schmidt
Blastomycosis
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Signalment: 6 yr old MN German Short-
haired Pointer
History:Progressively
worsening cough over 3 week period
“Ruger” Walters
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Thoracic Radiograph
Blastomyces spp. Antibody Test – Negative
Others (unknown)
Diagnostics Run
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Thoracic Radiograph
**Highly characteristic of Blastomyces infection
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What is Blasto??
Blastomyces dermatitidis
“Gilchrist’s Disease” 1894
Dimorphic fungus
Infective form: mycelial phase
Preferred environment: sandy, acidic soil
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Lifecycle
Thermally dimorphic: mold & yeast phases
At 25oC: mycelia/microscopic conidia mould-like form that mammals can inhale; infectious
At 37oC (in the body): transform into yeast (8-15 microns)
Phase transformation mechanism unknown
Mycelial form
Big Blue Broad Based Budding
yeast
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Pathogenesis
Immune system evasion changing of surface antigens
Dissemination to other locations
**Incubation Period in humans = 30-100 days
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Geographic Distribution
Most reported cases from MS River basin, OH, MO, & western margins of Lake Michigan
International: South Africa, Zimbabwe, India
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Most at Risk for Infection
Male Entire large breed dogs Sporting & Hound breeds
predisposed 2-4 years of age Endemic regions Late Summer & Early Fall
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Clinical Presentation
Depends on site of infection… Lung Disease
increased RE, exercise intolerance, coughing
Loss of appetite, fever, weight loss
Bone lameness Skin ulcerated
lesions, draining abscesses
Eyes hyperemic, & painful with discharge
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{ {Cutaneous Ocular
Typical Lesions
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Diagnostics
Thoracic Imaging Cytologic or histologic
examination Wright’s-Giemsa Stain
Serologic Antibody Urinary Antigen PCR
Bloods
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Ruger vs. Blasto
Chest Rads
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Amphotericin B Intravenous administration Adverse effects: cumulative nephrotoxicosis**Don’t give with steroids!
Itraconazole Expensive, oral medication better absorbed
with food Lag time before clinical response Adverse effects: hepatotoxic
Ketoconazole Less expensive Resolution of disease <50% cases High rate relapse
Treatment**All interfere with ergosterol synthesis**Minimum of 60d treatment necessary**Lung disease requires 90d minimum
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Amphotericin B Intravenous administration Adverse effects: cumulative nephrotoxicosis**Don’t give with steroids!
Itraconazole Expensive, oral medication better absorbed
with food Lag time before clinical response Adverse effects: hepatotoxic
Ketoconazole Less expensive Resolution of disease <50% cases High rate relapse
Can easily rack up $5,000 in treatment costs
Treatment**All interfere with ergosterol synthesis**Minimum of 60d treatment necessary**Lung disease requires 90d minimum
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Good – EXCEPT in cases with Severe pulmonary infectionBrain infection
Deterioration often seen first 2-3 days therapy 50% dogs die within first 7 days treatment Inflammatory response against dying organisms in lungs
Geographic variation in strain virulence
Prognosis
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Level 3 Biological Hazard Classification Human infection associated with occupation & recreational
activities Fishing Camping Outdoor professions i.e. Forest Ranger
Dogs with blasto *aren’t* considered infectious to their owners…however is ZOONOTIC
Can spread to humans from bite/puncture wounds
Veterinary Importance Disease in dogs evident prior to people Owner may have been exposed from same environmental
source as dog
Public Health Concerns
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Thoracic radiograph highly suspicious of Blastomycosis
Tested negative Started treatment with
Ketaconazole and Oxygen cage therapy
Made it through 3 days of treatment before passing
Ruger’s Outcome
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Don’t disregard chronic cough Don’t just treat with steroids No singular test guarantees positive diagnosis Gold Standard of diagnosis:
Combination of clinical signs & cytologic or histopathologic identification of organism from tissues
If disease suspected, make owner aware of exposure risk Recommend seeing own doctor immediately
Take Home Messages
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Dr. Jess Walters-Wright for allowing me to share her boy Ruger’s tale with you.
Special Thanks to…
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Baumgardner, D., Turkal, N. and Paretsky, D. (1996). Blastomycosis in dogs: A fifteen-year survey in a very highly endemic area near Eagle River, Wisconsin, USA. Wilderness & Environmental Medicine, 7(1), pp.1-8.
Botit.botany.wisc.edu, (2015). Blastomyces dermatitidis, cause of blastomycosis, Tom Volk's Fungus of the Month for January2001. http://botit.botany.wisc.edu/toms_fungi/jan2001.html.
Brömel, C. and Sykes, J. (2005). Epidemiology, Diagnosis, and Treatment of Blastomycosis in Dogs and Cats. Clinical Techniques in Small Animal Practice, 20(4), pp.233-239.
Cdc.gov, (2015). CDC - Sources of Blastomycosis. [online] Available at: http://www.cdc.gov/fungal/diseases/blastomycosis/causes.html.
DVM, S. (2015). Canine blastomycosis: A review and update on diagnosis and treatment. [online] dvm360.com. Available at: http://veterinarymedicine.dvm360.com/canine-blastomycosis-review-and-update-diagnosis-and-treatment.
Ettinger, S. and Feldman, E. (2005). Textbook of veterinary internal medicine. St. Louis: Elsevier Saunders.
Health.state.mn.us, (2015). Blastomycosis Basics - Minnesota Dept. of Health. [online] Available at: http://www.health.state.mn.us/divs/idepc/diseases/blastomycosis/basics.html.
Life with Llewellin Setters, (2013). Blastomycosis—What Every Dog Owner Needs to Know - Life with Llewellin Setters. [online] Available at: http://lifewithllewellins.com/blastomycosis-what-every-dog-owner-needs-to-know/.
López-Martínez, R. and Méndéz-Tovar, L. (2012). Blastomycosis. Clinics in Dermatology, 30(6), pp.565-572.
Spector, D., Legendre, A., Wheat, J., Bemis, D., Rohrbach, B., Taboada, J. and Durkin, M. (2008). Antigen and Antibody Testing for the Diagnosis of Blastomycosis in Dogs. Journal of Veterinary Internal Medicine, 22(4), pp.839-843.
VCA Animal Hospitals, (2015). Blastomycosis in Dogs. [online] Available at: http://www.vcahospitals.com/main/pet-health-information/article/animal-health/blastomycosis-in-dogs/437.
References