For diagnostic confirmation of an infection, direct detection methods, such as culture and molecular testing, remain the gold standard. These methods, however, often require invasive specimen collection that may not be suitable for all patients, and sensitivity can vary. Additionally, these organisms can take weeks to grow in culture, limiting their utility in acute diagnosis.
Detection of released antigens from these organisms is an effective alternative direct detection approach that can quickly identify the presence of Histoplasma or Blastomyces infection. Because of similar symptom presentation, however, it’s sometimes difficult to clinically distinguish which pathogen is causative, often requiring physicians to order two separate antigen tests. Additionally, the antigens released from Histoplasma and Blastomyces are very similar, leading to cross-reactivity between the individual assays. This frequently leads to Histoplasma antigens triggering positive results on Blastomyces testing and vice versa.
96.8% overall agreement of the combined Histoplasma and Blastomyces antigen detection assay compared to individual, genus-specific antigen detection assays1
Histoplasma/Blastomyces Test menu
Due to the antigen similarity between the organisms and to reduce the time and cost associated with processing two individual tests, Mayo Clinic Laboratories has validated a single serologic assay to concurrently detect antigens from both fungi. Our combined evaluation capitalizes on the antigen similarity, identifying either fungal infection and facilitating early initiation of antifungal therapy.
Histoplasma capsulatum and Blastomyces dermatitidis complex are among the most prevalent fungal pathogens in the United States. Present in moist soils, these organisms release spores that can cause respiratory infection when inhaled. Among individuals infected with Histoplasma or Blastomyces, about half will develop symptoms. These can include fever, cough, chest pain, fatigue, headache, and body aches, but can progress to more severe illness and even death, particularly in patients who are immunocompromised.
While Histoplasma or Blastomyces have historically inhabited the Mississippi and Ohio river valleys, climate change has enabled an expansion of these organisms into a broader geographic range, putting more individuals at risk for infection.
Fill out the form below and one of our specialists will be in touch.