ISSN 2398-2942      

Histoplasma capsulatum

icanis
Contributor(s):

Melissa Kennedy

Synonym(s): H. capsulatum


Introduction

Classification

Taxonomy

  • Dimorphic fungus.

Active Forms

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Clinical Effects

Epidemiology

Habitat

  • Free-living dimorphic fungus.
  • Prefers neutral to alkaline soil with nitrogen enrichment, in areas with annual rainfall of 35-50 in.
  • Found in topsoil, especially in the presence of bird and bat feces.
  • Birds are passive carriers.
  • Bats undergo intestinal infections.

Lifecycle

  • Free-living form consists of septate hyphae producing microconidia and macroconidia, (asexual reproductive units).
  • Becomes a yeast in animal hosts or suitable culture → reproduces by budding.
  • A sexual state, Ajellomyces capsulatus, has been described.

Transmission

  • Inhalation, possibly ingestion and occasionally wound infection.

Pathological effects

  • Disseminated disease in humans and dogs is found in association with immunosuppression.
  • Thoracic lymph nodes become enlarged and lungs may contain nodules.
  • May disseminate to skin, mucous membranes, abdomen, central nervous system and bone marrow, also intestines.
  • Dogs: chronic intractable cough , diarrhea Diarrhea: chronic , emaciation and pyrexia. Unresponsive to antibiotics.
  • Cats: emaciation, pyrexia, dyspnea, ocular lesions.

Other Host Effects

  • Found in the top soil of endemic areas, particularly in the presence of bird and bat guano.
  • Birds are mainly passive carriers.
  • Bats undergo intestinal infection.
  • Subclinical infections are common in dogs, cats and humans.

Control

Control via chemotherapies

Vaccination

  • Not available.

Diagnosis

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Kowalewich N, Hawkins E C, Skowronek A J et al (1993) Identification of Histoplasma capsulatum organisms in the pleural and peritoneal effusions of a dog. JAVMA 202 (3), 423-426 PubMed.
  • Meadows R L, MacWilliams P S, Dzata G et al (1992) Diagnosis of histoplasmosis in a dog by cytologic examination of CSF. Vet Clin Pathol 21 (4), 122-125 PubMed.
  • Davies S F & Colbert R L (1990) Concurrent human and canine histoplasmosis from cutting decayed wood. Annals of Intern Med 113 (3), 252-253 PubMed.
  • Clinkenbeard K D, Wolf A M, Cowell R L et al (1989) Canine disseminated histoplasmosis. Comp Cont Ed Pract Vet 11 (11), 1347-1351, 1354-1360 VetMedResource.

Can’t find what you’re looking for?

We have an ever growing content library on Vetlexicon so if you ever find we haven't covered something that you need please fill in the form below and let us know!

 
 
 
 

To show you are not a Bot please can you enter the number showing adjacent to this field

 Security code