(14) - Pythiosis

Question 1

1. Pythiosis occurs most often where?
2. Cats are affected only rarely.
3. Most cases of this disease have been reported in what areas?

Answer 1

1. in cutaneous and subcutaneous tissues and the gastrointestinal tract of dogs, horses and humans.
2. tropical and subtropical areas (In the United States, most cases have originated from states bordering the Gulf of Mexico.)

Question 2

1. Pythium spp. is ubiquitous in soil and aquatic environments.

2. With the definitive identification and taxonomic classification of Pythium insidiosum in the 
class Oomycetes, it is no longer appropriate to group this organism with what?

3. Pythium insidiosum is not only a plant pathogen but also an animal pathogen.
4. Animal become infected how? is damaged skin a necessary prerequisiite for infection?

Answer 2

2. the true fungi

4. stranding in/drinking stagnant water; yes

Question 3

1. In dogs and horses, ulcerated nodules develop, often rapidly, into large, firm to boggy masses
   with draining tracts.
2. are lesions pruritic in dogs/horses?
3. what breed most susc?
4. Horses develop coral-like bodies in the sinus tracts, called what?
5. How common is systemic involvement?

Answer 3

2. very often
3. german shephards
4. kunkers, leeches or roots.
5. rare

Question 4

1. Diagnosis is based on history, clinical signs, cytology, biopsy and fungal culture.
2. Cytologic exam of aspirate or direct smear demonstrates the organisms how often?
3. Biopsy of tissues reveals a granulomatous to pyogranulomatous inflammation with numerous
   wide, occasionally septate, irregularly branching hyphae.
4. Pythium organisms usually require what? stain to be visualized in biopsy tissues.
5. The hyphae of Zygomycetes are very similar to those of what spp?
6. Pythium sp. Grow rapidly at 25 to 37º C on blood agar and Sabouraud’s dextrose agar
7. What are the preferred material for culture?

Answer 4

2. rarely
3. GMS
4. Pythium sp.
5. Excision biopsies (However, leeches, vigorously washed in water can also be used as samples for culture, in horse cases. Leeches are not present in other species.)

Question 5

1. What is the treatment of choice?
2. Because Pythium sp do not share cell wall characteristics with true fungi, antifungal chemotherapy agents (amphotericin B, ketoconazole, flucytosine) have been disappointing in the treatment of this
   disease.
3. Immunotherapy using a vaccine developed with antigen from Pythium insidiosum has been used with success in horses with early lesions
4. Does immunotherapy work well in chronic cases?
5. Has immunotherapy been successful in canine cases of pythiosis?

Answer 5

1. Wide surgical excision ( but recurrence is not uncommon)
2. no
3. no