River Valleys
Also written as USA.
Classic scenario: farmer, Mississippi/Ohio River Valley, intracellular yeast within macrophages. *Histoplasma capsulatum* is an intracellular pathogen that replicates within macrophages.
What our notes say
- Classic scenario: farmer, Mississippi/Ohio River Valley, intracellular yeast within macrophages. *Histoplasma capsulatum* is an intracellular pathogen that replicates within macrophages. (📚 MEDICAL VIROLOGY & MYCOLOGY — MCQ BANK)
- It is endemic in the Mississippi and Ohio River Valleys and infects people exposed to bird/bat droppings in soil. (📚 MEDICAL VIROLOGY & MYCOLOGY — MCQ BANK)
- Endemic to the Ohio and Mississippi River valleys in the USA, parts of East Africa, and Latin America. (Medical Mycology Q&A Section C)
- Endemic to the Ohio and Mississippi River valleys in the USA, and parts of Africa and Latin America. (Medical Mycology Q&A Section A.. )
- Geographic distribution: Mississippi and Ohio River valleys (Medical Mycology Fundamentals: Fungi, Antifungal Drugs & More)
- Endemic area: Mississippi and Ohio River valleys (USA); worldwide in tropical regions (Mycoses: Superficial, Cutaneous & Systemic Fungal Infections)
Study material on River Valleys
- Medical Microbiology III Exam: Viruses, Fungi & Diagnosis
- 📚 MEDICAL VIROLOGY & MYCOLOGY — MCQ BANK
- Lung Pathology — Must-Know
- Respiratory Pathology 1b
- Mycoses: Superficial, Cutaneous & Systemic Fungal Infections
- Medical Mycology Fundamentals: Fungi, Antifungal Drugs & More
- Weekly Year 3: Medical Mycology Exam - August 14, 2026 (Section A: MCQs)
- Medical Mycology Q&A: Fungal Pathogens, Drugs, & Diseases
Practice questions on River Valleys
A patient from the Ohio and Mississippi River Valleys presents with chronic cough, fever, and chest X-ray findings of cavitary lesions. Microscopic examination of sputum shows large, thick-walled, single-budding yeasts with a broad base. This morphology is characteristic of:
- Blastomyces dermatitidis
- Histoplasma capsulatum
- Coccidioides immitis
- Paracoccidioides brasiliensis
Answer: A. The description of large, thick-walled, single-budding yeasts with a broad base, especially in a patient from the Ohio and Mississippi River Valleys, is classic for Blastomyces dermatitidis, the causative agent of blastomycosis.
Farmer in Mississippi, chronic cough, opaque mass on CXR, biopsy shows macrophages with multiple yeast forms. Likely diagnosis: Histoplasma capsulatum is endemic to the Ohio/Mississippi River valleys and lives intracellularly in macrophages. ---
- Coccidioidomycosis
- Histoplasmosis
- Blastomycosis
- Paracoccidioidomycosis
- Sporotrichosis
Answer: B.