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Background : Histoplasmosis capsultum is the pathogenic fungi that causes infection worldwide in HIV-infected patients. Histoplasmosis in AIDS usually presents as a disseminated infection. Acoording to previous studies, a peripheral blood smear is one of the useful diagnosis of disseminated histoplasmosis.
Objective : here, we studied the diagnostic property of the peripheral blood smear for diagnosis of disseminated histoplasmosis. We calculated for the diagnostic activity of the blood smear examination in diagnosis of histoplasmosis. We prepared 50 Wright’s stain blood smears from 50 leftover EDTA blood samples from 50 HIV-infected patients in King Chulalongkorn memorial Hospital. Among these 50 cases, 2 cases with the diagnosis of histoplasmosis were included. Each blood smear was sent to the physician in fungal microbiology laboratory, Faculty of Medicine, Chulalongkorn University, for examination.
Results : According to our blood smear examination, there was no case of histoplasmosis. The prevalence from blood smear interpretation was 0% , specificity was 100% and accuracy was 96%.
Conclusion : According to our study, null prevalence of infection was detected although there were also cases with diagnosis of infection in our samples. The sensitivity of the blood smear examination si very poor. Hence, it cannot be used as a screening test. However, the accuracy and specificity of blood smear examination are high, therefore, “no detection of this organism in blood smear’’ cannot be a good rule out test for dissimenated histoplasmosis. Also this is the first report of prevalence study of histoplasmosis in blood smear of HIV seropositive patients in Thailand. Finally, since the microscopic examination, the null prevalence may be due to the experience of our practitioners.
Key Words : histoplasmosis, blood smear, HIV