Histoplasmosis in domestic cats: new minimally invasive diagnostic techniques

Area of Science:

• Veterinary Mycology
• Diagnostic Immunology
• Feline Infectious Diseases

Background:

• Histoplasmosis is a systemic fungal infection caused by *Histoplasma capsulatum*.
• Accurate and timely diagnosis in cats is crucial for effective treatment and management.
• Minimally invasive diagnostic techniques are needed to improve the diagnostic approach for feline histoplasmosis.

Purpose of the Study:

• To evaluate the efficacy of two minimally invasive diagnostic techniques for detecting *Histoplasma capsulatum* in cats.
• To assess the diagnostic sensitivity and specificity of a semi-quantitative indirect IgG antibody enzyme immunoassay (EIA) using blood serum.
• To assess the diagnostic sensitivity and specificity of a urinary lateral flow assay (LFA) for *H. capsulatum* antigen detection.

Main Methods:

• Eight client-owned domestic cats diagnosed with histoplasmosis were enrolled.
• Blood serum samples were tested using a semi-quantitative indirect IgG antibody EIA.
• Urine samples were tested for *H. capsulatum* antigen using LFA.

Main Results:

• The IgG antibody EIA detected antibodies in 5 out of 8 cats (62.5% sensitivity).
• The urinary LFA detected antigen in 5 out of 7 cats (71.4% sensitivity).
• Combined testing achieved 87.5% sensitivity with 100% specificity for both assays.

Conclusions:

• Semi-quantitative indirect IgG antibody EIA and urinary LFA are valuable minimally invasive tools for diagnosing feline histoplasmosis.
• Employing both EIA and LFA concurrently enhances diagnostic capability for disseminated and pulmonary forms of the disease.
• These techniques offer a promising approach to improving the diagnosis of histoplasmosis in cats.