Histoplasmosis Background Histoplasmosis is a systemic fungal disease caused by Histoplasma capsulatum. Transmission occurs through inhalation of the organism. The incubation period ranges from three to 17 days. Signs and symptoms of histoplasmosis include fever, headache, muscle aches, cough and chest pain. Patients who have underlying lung disease may develop chronic lung disease after H. capsulatum infection. Bird and bat droppings are beneficial to the growth of the organism. Diagnosis of infection can be through culture or serology. The M precipitin alone indicates active or past infection. The H precipitin indicates active disease or recent infection. Histoplasmosis can be a severe infection in persons with HIV or other immunocompromising conditions. Approximately 5 percent of persons with AIDS who live in endemic areas may develop histoplasmosis, which frequently disseminates. A study in Georgia found that, among risk factors for histoplasmosis in HIV-infected persons, was working with soil contaminated with bird or bat droppings. Decreased risk was associated with antiretroviral therapy. Case definition The case definition for histoplasmosis in Illinois is either – 1) Isolation of the organism from a clinical specimen in patients with acute onset of flu-like symptoms, or 2) In patients with flu-like symptoms, hilar adenopathy and/or patchy infiltrates found on chest radiograph, if done, and at least one of the follwing a) M or H precipitin bands positive by immunodiffusion b) A four-fold rise between acute and convalescent complement fixation (CF) titers c) A single CF titer of >1:32 d) Demonstration of histoplasma polysaccharide antigen by radioimmunoassay (RIA) in blood or urine, or demonstration of organisms by silver staining blood specimens or biopsy material Descriptive epidemiology • Number of cases reported in Illinois in 2000 – 59 (five-year median = 41) (see Figure 64). At least 18 (35 percent) of these cases were in immunocompromised persons; therefore, it is not possible to determine whether they represent new infections or reactivation of previous infections. • Age – Mean age was 42 (Figure 65). • Race/ethnicity – 81 percent were white and 18 percent were African Americans; 12 percent were Hispanic. • Diagnosis – 13 cases were confirmed by culture. Four were urine antigen positive; 11104 were M band positive by immunodiffusion. • Seasonal variation – No seasonal trend • Outcomes – 63 percent were hospitalized; seven cases were fatal. Summary Almost 60 cases of histoplasmosis were reported in Illinois residents in 2000. More than one-half were hospitalized for their illness. Suggested readings Hajjeh RA, Pappas PG et al. Multicenter case-control study of risk factors for histoplasmosis in human immunodeficiency. CID 2001:32:1215-20.
Posted on: Wed, 25 Sep 2013 21:22:25 +0000
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