Evaluation of a molecular and immunological test for the diagnosis of histoplasmosis (Protocol 4250)

Histoplasmosis, a systemic fungal disease caused by Histoplasma capsulatum, is the most common endemic fungal disease in AIDS patients in the United States. Ninety-five percent of patients with AIDS and histoplasmosis develop disseminated disease, and 90% of these have CD4 counts below 200/µL. Histoplasmosis has a global distribution, although incidence data are often not available, the disease is found in Central and South America, as well as in Africa and South-East Asia. In many parts of Latin America, including Colombia, histoplasmosis is endemic and presents a significant problem in AIDS patients. The incidence of histoplasmosis in Latin America is based on large case series studies reported from different centers with mortalities as high as 48%. Justification of the study. New antiretroviral therapy treatments have improved immune status in HIV-infected patients in developed countries. However, in patients from Colombia and other developing countries, there is often limited access to these new anti-HIV drugs. As a result, the incidence of disseminated histoplasmosis continues to increase in developing countries, where the AIDS epidemic is increasing and histoplasmosis is endemic. Therefore, the implementation of new diagnostic tests would have a major impact on public health in large populations of individuals in developing countries. Antibody detection methods offer a quick alternative to microbiological techniques. However, antibody detection is still based on complement fixation (CF) and immunodiffusion (ID) techniques, most of which use non-standard reagents. In addition, the CF test lacks specificity and the ID test is often negative in the acute phase of the disease because of the long time needed to produce detectable amounts of antibodies. In addition, antibody testing may be less useful in immunocompromised patient populations, where antibody production is often limited. Delaying appropriate treatment results in increased mortality and morbidity in these patient populations. Objectives: To evaluate new diagnostic methodology in molecular biology and immunology for the diagnosis of histoplasmosis. Specific 1) To determine whether the presence of antigens for H. capsulatum in HIV-infected patients is a good indicator of disseminated histoplasmosis. 2) Detection of H. capsulatum DNA in clinical samples using real-time PCR methodology. 3) To determine if the results of the tests carried out through molecular biology correlate with the results of the treatment of the disease.