Dealing with Histoplasma and Paracoccidioides in non-endemic areas
Histoplasma and Paracoccidiodes are both thermodimorphic fungi and endemic in some geographic areas. Paracoccidiomycosis is a systemic fungal disease occurring in Latin America and it is more prevalent in South America. Histoplasma is the infectious agent of histoplasmosis, a disease that is endemic mainly in the American continent but it is now being recognized globally but with hyperendemic areas. The epidemiology of these infections seems to be shifting. Factors such as human migration and tourism, use of immunosuppressive drugs, and organ transplantation are contributing to the increase of this infectious disease.
In non-endemic areas, the medical community is less aware of this type of infections, which may delay the diagnosis, or even lead to a failure in its detection. These infections spread rarely, however they can be fatal if not treated. Since they are not notifiable diseases, the true burden outside of endemic regions is not known. The diagnosis can be difficult: conventional laboratory tests include culture and histological methods that are the gold standard to diagnosis, however, these are slow growing organisms, culture results can take a long time and sensitivity is low. On the other hand, histology can be very sensitive if targeted fungal stains are used (Periodic acid–Schiff, Grocott methenamine silver) but requires practice for identification of typical structures. Despite the development of several molecular methods, these are not included as diagnostic tool for proven infections.
This presentation aims to discuss the new trends in the epidemiology of these endemic infections, to describe our experience in the methods used for laboratory diagnosis of histoplasmosis and paracoccidiomycosis and to discuss how molecular methods contributed to the diagnosis of the cases detected. Two clinical cases already published on the subject will be presented to illustrate the decisive role of the laboratory as for the diagnosis of these infections.