DISEASE SUMMARY PAGE

Histoplasmosis in Hedgehogs and Ferrets

Summary Information
Diseases / List of Fungal / Algal Diseases / Disease summary

Alternative Names

  • Histoplasma capsulatum infection. 

Disease Agents

  • Histoplasma capsulatum (J150.24.w1)
  • This is a dimorphic fungus. Moist, humid areas are preferred for growth. In soil, particularly soil contaminated with bird or bat droppings, the mycelial phase produced macroconidia (5 - 18 Ám diameter) and microconidia (2 - 5 Ám diameter). (J34.6.w3)
Infectious Agent(s) Histoplasma capsulatum - Ascomycota - Ascomycetes (Molds, yeasts, lichens) - (Phylum-Division)
Non-infectious Agent(s) --
Physical Agent(s) --

General Description

  • Infection with Histoplasma capsulatum is usually not clinically apparent. Following inhalation of air-borne conidia, phagocytosis occurs in the lungs, which is where primary lesions are generally located. Severe systemic infection may occur associated with splenomegaly, hepatomegaly, leucopaenia, anaemia and emaciation, sometimes diarrhoea following intestinal ulceration and in clinical cases often also involvement of the central nervous system, skin, kidneys and bone marrow. (B47)
Clinical Signs
  • In dogs, weight loss, hepatosplenomegaly, pneumonia, ascites and lymphadenopathy develop. (B627.17.w17)
  • In cats, respiratory signs are typical, while dogs more commonly show gastrointestinal signs. (J34.6.w3)
In Ferrets
  • In a ferret used to hunt rats and rabbits, illness for at least a week; considerable abdominal pain was evident and subnormal body temperature was noted on examination. (J351.28.w1)
  • In a five-year-old ferret, chronic sneezing for five months, development of multiple subcutaneous nodules and cachexia, with rapid weight loss over a period of three weeks after the nodules were first noticed. No obvious findings on thoracic and abdominal radiographs. Death two days after the start of treatment with ketoconazole. (J34.17.w3)
    • Cytological examination of an aspirate from one of the subcutaneous nodules revealed Histoplasma capsulatum. (J34.17.w3)
Gross Pathology
In Ferrets
  • In a ferret used to hunt rats and rabbits:
    • Spleen: greatly enlarged, hyperplastic.
    • Hepatic: Enlarged, soft, friable liver; on the surface and within the parenchyma, multiple small white diffuse areas.

    (J351.28.w1)

Histopathology
In Ferrets
  • In a ferret used to hunt rats and rabbits: (J351.28.w1)
    • Hepatic: Extensive necrosis of cells. In most of the cells in these areas, the cytoplasm was "filled with small parasites, each with a definite nucleus and a surrounding, clear cytoplasmic area." There were from one to more than 20 intracellular organisms per cell.
    • Spleen: Cells containing intracellular parasites.
    • Lung: Small nodular areas in which cells contained parasites.

    (J351.28.w1)

  • In a five-year-old ferret with sneezing, cachexia and subcutaneous nodules: (J34.17.w3)
    • In the lung (interstitium), liver periportal areas and subcutaneous nodules, macrophages contained intracellular Histoplasma. (J34.17.w3)
In Hedgehogs

Further Information

Transmission
  • This organism is usually acquired by inhalation of contaminated dust in an aerosol. (B627.17.w17)
    • This is more likely to occur in endemic areas. In the USA, the organism is endemic in the central areas such as the Ohio, Missouri and Mississippi river basins. (J34.6.w3)
  • Usually, disseminated disease indicates massive exposure or immunosuppression of the host. (J34.6.w3)
Diagnosis
  • Diagnosis can be made on biopsy and identification of the organism; special stains such as PAS assist with this. Definitive diagnosis is made by culturing the organism from affected tissues. (B627.17.w17)
  • A tracheal wash or, preferable, a bronchiolar lavage sample should be examined cytologically for the organism. (J34.6.w3)
  • There may be radiographic signs of pulmonary disease, and a nonregenerative anaemia may be found; these may lead to suspicion of this infection. (J34.6.w3)
  • While AGID and CF tests are available, false positive results may occur in individuals which have been exposed to the organism but recovered, and false negatives can also occur. There is also an intradermal skin test; this too is unreliable. (J34.6.w3)
  • Note: this organism is pathogenic to humans; culturing the organism in a private laboratory is not recommended. (J34.6.w3)
Treatment
  • The treatment of choice is itraconazole. (J34.6.w3)
    • Oral solution is preferred to capsules, as it is more reliably absorbed. (J34.6.w3)
    • In severe cases, amphotericin B can be used in addition to itraconazole. (J34.6.w3)
    • In dogs and cats, prognosis with appropriate treatment is fair to good. (J34.6.w3)
In Ferrets
  • A ferret treated with ketoconazole did not respond to treatment; it died two days after the onset of treatment. (J34.17.w3)
Associated Techniques

Host taxa groups /species

(List does not contain all other species groups affected by this disease)

Author Dr Debra Bourne MA VetMB PhD MRCVS (V.w5)
Referees  

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