Flashcards in Infectious Dz - Fungal Deck (115)
Where is blastomycosis distributed?
On the eastern half of the US, especially in the Mississippi, Ohio, and Saint-Lawrence River values
What type of fungi is Blastomyces dermatitidis?
In what form is Blastomyces dermatitidis in the host?
In what form does Blastomyces dermatitidis exist in the soil as?
a fungal hyphae
What form of Blastomyces dermatitidis is infective?
only the fungal form
By what route does Blastomyces dermatitidis infection occur?
Inhalation (most common) and direct inoculation
What is the incubation time of Blastomyces dermatitidis?
Long incubation - 1-3 months
Where does Blastomyces dermatitidis propagate and how does it get there?
Via hematogenous spread it propagates to the skin, eyes, lymph nodes, bone, and CNS
What is the 'poster dog' for blastomycosis?
Young (2-4 years) and large hunting breeds
What are the risk factors for blastomycosis in dogs?
living near water and proximity to excavated or disturbed soil
Is blastomycosis found in cats?
It is very rare
What are the PE findings associated with blastomycosis?
Non-specific signs of fever, anorexia, and weight loss
Respiratory signs are common
Ocular manifestations - uveitis
What will you find on CBC in a patient with blastomycosis? Chemistry?
CBC - inflammatory leukogram
Chemistry (from most to least common)- Low albumin, high globulin, and hypercalcemia
What will you find on cytology in patients with blastomycosis?
Broad-based budding yeast and pyogranulomatous inflammation with concurrent presence of neutrophils with activated macrophages, lymphocytes, and plasma cels
What will you see on rads in a patient with Blastomycosis?
Variable lung pattern - classically diffuse miliary to nodular
Tracheobronchial enlargement in 25% of cases
Osteolysis with periosteal reaction in bones
What does serology detect for in a suspected Blasto case?
What is the gold standard diagnostic test for blastomycosis?
Galactomannan cell wall test
What is the Galactomannan cell wall test?
It is an antigen test with very high sensitivity. Urine is more sensitive than serum
There is some cross-reactivity with Histoplasma so a cytology will need to be done to confirm
What diagnostic test is not recommended for blastomycosis?
Culture - because it reverts to the fungal form and there is a potential danger for lab personnel
How is blastomycosis treated?
Triazoles - Itraconazole is the drug of choice but Fluconazole may have similar efficacy and Fluconazole and voriconazole achieve better CNS/ocular penetration than itraconazole
Amphotericin B may be warranted in more aggressive/extensive disease
Glucocorticoids for decreasing pulmonary inflammation associated with the fungal die off - avoid high doses
When is surgery indicate to treat blastomycosis?
If there is severe panuveitis that requires enucleation
Is blastomycosis treatment long or short term? When do you know when to stop treatment?
Use Galactomannan assay results to determine presence of fungi
What is the prognosis of blastomycosis?
Variable cure rates - 50-75%
Relapses are common within 2 years
What are the negative prognostic factors of blastomycosis?
CNS involvement, severity of lung disease, and high band count on CBC
What are the differentials to be considered with blastomycosis?
Neoplasia, other systemic mycoses, and systemic protozoal infections
Where is histoplasmosis distributed?
Similar to blasto - north of the equator and in the eastern US in the Ohio and Mississippi river valleys
What causes histoplasmosis?
What type of fungus is histoplasmosis?
How does histoplasmosis infection occur?
It is inhaled or ingested by the host from avian and/or bat guano