Cryptococcus, Histoplasmosis, Blastomyces, Coccidioides Flashcards
Common features of Cryptococcus, Histoplasmosis, Blastomyces, Coccidioides
Inhalation of spores transform into yeast or alternative form in lung
Cell mediated immunity is required for protection, if inadequate dissemination throughout body and chronic disease results
Granulomas or pyogranulomas are characteristic lesions
Location and travel history is important for diagnosis
Long term antifungal therapy is needed to treat them all, no vaccines available
Cryptococcus Features
Dimorphic, encapsulated yeast, **polysaccharide capsule
C. neoformans reservoir
Birds- pigeon guano
C. neoformans causes disease in what type of host
Immunocompromised hosts
C. neoformans is located where
Worldwide
C. neoforma Disease is what in what
Most common systemic fungal disease in cats
Cryptococcosis in cats- a localized infection in upper respiratory tract resulting in lesions which can spread to surrounding areas (eyes and skin- skin lesions common) or through cribiform plate to brain causing cryptococcomas
Cryptococcosis diagnosis
Stain sample with India ink and capsule will not uptake the stain- so reverse stain
In histology can stain with mucicarmine to stain capsule rose red
Culture or capsule serotyping- can measure quantitatively using capsule antigen circulating in the blood, any value is significant
Cryptococcosis Treatment
Surgically remove granulomas and treat with antifungals, but poor prognosis if in brain
Need to treat for 2 months after titer value is zero
Histoplasma capsulatum is found where
Mold form and spores in soil after being excreted from bird and bat feces and yeast forms in vivo, birds are reservoirs
In Mississippi and Ohio river valleys and parts of central and South America
Cryptococcus, Histoplasmosis, Blastomyces, Coccidioides Mold forms are
Infectious
Histoplasma capsulatum Transmission
Inhaled microclamidia from soil infected with spores/mold from bird/bat droppings get to macrophages in lungs and are phagocytosed, yeast cells develop and kill macrophage and disease can be disseminated from there because macrophage takes it to lymphnodes
Histoplasmosis common symptom is
Disease occurs commonly in Dogs, cats, and humans however no overt symptoms
Pneumonia is only in a small percentage of animals (dogs and cats)
Disseminated histoplasmosis leads to
Weight loss and diarrhea (in dogs most common)
Histoplasmosis diagnosis
Culture and look for dimorphism
Or a cytology looking for yeast in macrophages
Or histopathology of biopsy
Or serology for antigen but is sensitive not specific for histoplasma
Histoplasmosis treatment
4-6 months of antifungal therapy only in animals with clinical disease only
Blastomyces type of fungus
Dimorphic
Blastomyces found where
Moist soil in Midwest and southeast and Mississippi River basin and distribution expanding
Blastomyces Transmission
Spores/microconidia are inhaled from moist area and become yeast form and goes to lung and disseminates through blood form there. Most infected dogs live within 400 meters of a lake or river
Blastomyces Can be destroyed by
Cell mediated immunity
What symptoms can happen from Blastomycosis
Only 5% of dogs develop pneumonia and disseminated disease- usually immunosuppressed
Disseminated disease can cause skin lesions or even ocular disease and bone involvement/ infection
Blastomycosis Diagnosis
Cytology/ histopathy to visualize broad-based budding yeast in sample
Or culture on Sabouraud’s agar
Blastomycosis treatment
Long term Antifungals for 2-3 months at minimum and recurrence post therapy is common and restrict immunocomprimised dogs from lakes and creeks
Coccidiodes species are
Coccidioides immitis and posadasii
Coccidiodes species are Found where
In soil as mold form in west..
Coccidiodes in soil form
Hyphae fragment to create arthroconidia which go to top of soil and will germinate after rainstorm or dust storms or other forms of soil disruption can make them airborne
Once inhaled can form spherules in host (not a yeast a specific fungal form) with release endospores in animal
Coccidiodes Is dimorphic?
Yes but no yeast form- forms spherules and mold
Are animals infected with Coccidiodes contagious
No only arthroconidia are infectious
Disease from Coccidiodes
Valley fever/ Coccidioidomycosis
Symptoms of valley fever
Pneumonia and high fever and cough (granulomas in lung) and dissemination but rare but can cause infection of bone- lameness, limping, arthritis
most infected dogs are asymptomatic
Coccidioidomycosis/ valley fever diagnosis
Clinical signs and location, Cytology, histology, and serology but not specific
Coccidioidomycosis Culture done?
No it is a select agent and biohazard
Coccidioidomycosis Reportable?
Yes
Coccidioidomycosis Treatment
Long term antifungal therapy but prognosis for disseminated disease is poor
Be careful in areas it is found during dust storms or construction sites for immunocompromised animals
Blastomyces dogs vs. humans
dogs are 10x more susceptible than humans
What dimorphic fungus is the most virulent in the US
Coccidioides spp
