Systemic Mycoses

Question 1

Blastomycoses basics

Answer 1

Dimorphic fungus
Grows in mycelial form in soil
Produces infective spores
Dogs, people most commonly infected
Cats less commonly affected

Question 2

Blasto epidemiology

Answer 2

Soil reservoir
Special environmental conditions required for organism survival
- Living near waterway
- Sites recently excavated
Subclinical infection uncommon
Disease reported in strictly indoor animals

Question 3

Blasto distribution

Answer 3

NA dz
Mississippi, MO, and OH river valleys
States with highest endemnicity include IL

Question 4

Blasto path

Answer 4

Most cases by inhalation of spores from mycelial growth in envmt
Direct inoculation into skin rare
Dissemination
- Skin, eyes, bones, LN, brain, testes, mouth, nasal passages, prostate, mammary gland, heart

Question 5

Blasto risk factors

Answer 5

Young, large breed dogs
Sporting breeds and hounds: coonhounds, pointers, Weimeraners
Dobermans and retrievers
Proximity to waterways and exposure to excavation
Dogs 10x more susceptible than people

Question 6

Blasto CS dogs

Answer 6

Anorexia, weight loss, cough, dyspnesa, ocular dz, lameness, skin lesions
Previous Abx therapy

Question 7

Blasto PE dogs

Answer 7

Fever
Lymphadenopathy*
Resp: harsh, dry lung sounds, dyspnea, cough
Ocular: uveitis, chorioretinitis, retinal detachment, panophthalmitis
Skin: ulcerated and draining*
Lameness
CNS: depression, seizures, neuro deficits
Any organ

Question 8

Blasto CS cats

Answer 8

Anorexia, fever, weight loss, lethargy, dyspnea, cough
Fever
Draining skin lesions
Ocular lesions
Respiratory signs

Question 9

Blasto Dx

Answer 9

Cytology/histopath
- Find organism
- Draining skin lesion
- LN aspirate
- Lung aspirate
- Subretinal aspirates
Cytologic rxn is pyogranulomatous and includes nondegenerate N0, M0, and occasional MNGCs; may be plentiful
Culture not recommended!!!

Question 10

Blasto clin path

Answer 10

Normocytic, normochromic anemia
Leukocytosis, left shift
Hyperglobulinemia/hypoalbuminemia
Hypercalcemia

Question 11

Blasto Imaging

Answer 11

Snowstorm chest
Diffuse nodular or interstitial infiltrates
Solitary nodules or masses in chest
Tracheobronchial lymphadenopathy
Fungal osteomyelitis

Question 12

Blasto serology

Answer 12

Antigen detection
- Urine 94%
- Serum 87%
- Cross reactivity with histoplasmosis
- May be negative initially if illness mild
- Miravista labs, Indianapolis
Antibody detection
- Immunodiffusion
- Enzyme immunoassay

Question 13

Blasto prognosis

Answer 13

Strong correlation between extent of lung involvement and survival
25% of dogs die, usually during first week of treatment dt respiratory failure
High urine or blood [Ag} correlates with clinical severity in dogs

Question 14

Blasto treatment

Answer 14

Amphotericin B
Itraconazole
Fluconazole
Glucocorticoids
- To reduce inflammatory response in lung
- To avoid/manage respiratory failure
- Only after starting antifungal treatment

Question 15

Blasto monitoring

Answer 15

Treat 4-6mo or longer
Clinical response, resolution of signs
Serial chest rads
[Ag] declines with effective therapy
- Consider stopping treatment when [Ag] <2ng/mL

Question 16

Histoplasmosis basics

Answer 16

Dimorphic fungi
Infections documented in every continent, except Antarctica
Most prevalent in Americas, India, and southeastern Asia

Question 17

Histo epidemiology

Answer 17

Endemic throughout temperate/subtropical areas of world
Organism isolated from soil in 31 states
Most cases occur in central US in Ohio, MO, and MS
Soil rich in bird or bat feces
Most infections subclinical

Question 18

Histo pathogenesis

Answer 18

Infection acquired by inhalation of microconidia
Incubation period 12-16d
Microconidia convert to yeast phase in lung and reproduce by budding
Yeast phagocytized by cells of mononuclear phagocyte system and replicate further

Question 19

Histo location

Answer 19

Infection limited to pulmonary or lymphatic/hematogenous dissemination
Organs rich in mononuclear phagocytes
Severe clinical disease if
-Dose of spores large
-Immune system of host compromised
Cellular immune system, predominately involving cytokine-mediated M0 killing will bring infection under control in most
T-cell immunity critical for clearance of organism

Question 20

Histo clinical findings in cats

Answer 20

Very susceptible
4mo-14y
Most have disseminated disease
Non-specific C/S: weight loss, fever, anorexia, pale mm
Dyspnea, tachypnea, and abnormal lung sounds in more than 1/2 affected cats

Question 21

Histo CS cats

Answer 21

Peripheral/visceral lymphadenopathy***
Hepatomegaly/splenomegaly
Ocular lesions: conjunctivitis, granulomatous blepharitis, chorioretinitis, retinal detachment, and optic neuritis
Bone lesions with soft-tissue swelling and lameness
Skin infrequently affected with nodular/ulcerated lesions
Rare CS: oral ulcers, nasal polyps, vomiting, diarrhea

Question 22

Histo clinical findings dogs

Answer 22

2mo-14y
Most dogs <4y
Pointers, Weimaraners, and Brittany Spaniels overrepresented
Inappetence, weight loss, fever
Unresponsive to therapy***
Some signs confined to resp tract
- Dyspnea, coughing, abnormal lung sounds

Question 23

Histo CS dogs

Answer 23

Most signs result from disseminated histoplasmosis with GI involvement
- Large bowel diarrhea with tenesmus, mucus, and fresh blood
Pale mm dt blood loss or bone marrow involvement
Small bowel involvement can produce voluminous, watery stool with PLE
Hepatomegaly/splenomegaly, icterus, ascites, visceral lymphadenopathy

Question 24

Histo cytology

Answer 24

Rectal scrapings
BAL
Bone marrow
LN
Liver aspirates
Lung aspirates
Peritoneal/pleural effusions
Granulomatous lesions

Question 25

Histo other Dx

Answer 25

Fungal Isolation - not recommended
Ag detection
Miravista labs, Indianapolis
FIND THE ORGANISM

Question 26

Histo Tx

Answer 26

Itraconazole “standard of care”
Fluconazole
Amphotericin B

Question 27

Coccidiomycosis basics

Answer 27

Valley fever, San Joaquin Valley fever, desert fever, cocci
Dimorphic fungi, immitis and posadasii
Occurs in most mammalian species, but most cases people and dogs

Question 28

Coccidiosis epidemiology

Answer 28

Cocci endemic to hot, semi-arid southwestern US, northern Mexico, and Central America
- California, southern Arizona, southern New Mexico, western Texas, southern Nevada, and Utah
Coccidioides immitis in California
Coccidioides posadasii in Arizona

Question 29

More coccidiosis epidemiology

Answer 29

Grows in soil as mycelia with barrel-shaped arthroconidia
Dormant in mycelial phase during drought
Rain causes germination of arthroconidia and production of mycelia
Infection occurs most often during dry weather following heavy rainfall when arthrospores are dispersed
Cases described in people and animals that have travelled to endemic areas

Question 30

Coccidioides pathogenesis

Answer 30

Time for C&S 2 or more weeks
Sites for dissemination - dogs
- Bone, joints, LN, heart/pericardium, brain, eyes, testes, skin and SQ, spleen, liver, and kidney
Sites for dissemination - cats
- Skin

Question 31

Coccidioides risk factors for dogs

Answer 31

Young (<6y)
Large breed (>22kg)
Outdoor, working, sporting dogs
Boxers, Doberman pinschers, pointers, Australian Shepherds, Beagles, Scottish terriers

Question 32

Coccidioides risk factors for cats

Answer 32

No breed predisposition apparent
More common in middle-aged cats
Neither FeLV nor FIV appears to predispose to feline cocci

Question 33

Host response to coccidiosis

Answer 33

Cell mediated immunity is the key mechanism of defense
- CMI required for resolution
- Prevents against dissemination
Antibody production
- Not believed to play significant role in recovery
- Most useful as a marker of infection
People who have recovered considered immune for life
Subclinical infections common in dogs
- 70% of cases in one prospective study
Relapse is common in dogs and cats
Duration of immunity in dogs and cats?

Question 34

Coccidioides CS in dogs

Answer 34

Fever
Cough
Anorexia
Lethargy
Primary pulmonary:
-Chronic, dry, or moist cough
-Fever, weight loss, anorexia, lethargy
Cough dt lung involvement or tracheal/bronchial constrictiondt hilar lymphadenopathy
Disseminated
- Lameness dt osteomyelitis (most common form in dogs)
- Draining tracts in skin
- Regional lymphadenopathy
- Ocular signs
- CNS signs: Seizures, ataxia, behavioral changes, coma
- Heart, pericardium

Question 35

Coccidioides Dx

Answer 35

Clinical suspicion
Travel history***
PE
Imaging
CBC/serum biochem
Cytology/histopath/culture
Serology

Question 36

Coccidioides Dx challenges

Answer 36

Diverse clinical presentations in both dogs and cats
Better diagnostic tools for clinicians
- Organism typically difficult to isolate
- Clinicians often have to rely on serology
- Must differentiate exposure from active infection
- Future of antigen testing