Histoplasmosis

• transmitted from contaminated soil
• common in central and southern U.S (Ohio and Mississippi River Valleys)
• associated with bat droppings from caves
• can give disseminated pulmonary disease, esp. if CD4 <200
• involves RE system --> pancytopenia, lymphadenopathy, and hepatosplenomegaly
• diffuse reticulonodular infiltrates or cavitary lung lesions

(N.B. Anything tuberculosis can do, histoplasmosis can do.)

Dx

The most sensitive and rapid test to detect disseminated histoplasmosis in immunocompromised patients is

Histoplasma antigen immunoassay of the serum or urine (sensitivity >95%)

later, confirmed by fungal blood cultures

Treatment:

No therapy for acute transient pulmonary disease

Itraconazole (for mild to moderate disease)

IV liposomal amphotericin B for 2 weeks followed by itraconazole for 2 years in more severe cases

Cryptococcal meningitis in HIV

only yeast form

has a thick polysaccharide capsule with antiphagocytic properties

fungus is present in soil and bird (esp. pigeon) droppings and infects humans via the respiratory tract and enters the lungs --> then, disseminate