Survey of Histoplasma capsulatum in bat guano and status of histoplasmosis in Slovenia, Central Europe

There have been increasing reports on the presence of Histoplasma capsulatum in some European countries. The study investigated the presence of Histoplasma in bat guanos, speleologists with records of visiting Histoplasma-endemic regions and patients with histoplasmosis. A commercial ALPHA Histoplasma Antigen enzyme immunoassay was tested as an alternative methodology to detect Histoplasma in environment and compared with polymerase chain reaction (PCR) assays. The presence of Histoplasma antigen in bat guanos was not confirmed by PCR. Among 14 healthy speleologists, two were indicated as having the Histoplasma antigen in urine, but expressed negative PCR-specific results for the Histoplasma antigen. Five unequivocal cases of imported acute pulmonary histoplasmosis in Slovenia between years 2005 and 2016 were confirmed in patients returning from North and South America after visiting hazardous localities e.g., caves with guano, and places with dust. Currently there is no evidence of autochthonous histoplasmosis in Slovenia, or that bat guano is a source of H. capsulatum. Involvement of histoplasmosis in travellers’ and cavers’ morbidity might be underestimated in non-endemic areas. It is crucial to ensure the use of appropriate protective equipment in Histoplasma hazardous localities, to spread information about this hazardous microbe to vulnerable populations and to monitor the health of the environment. A differential diagnosis for a febrile respiratory disease outbreak in patients returning from endemic regions should trigger routine consideration of possible histoplasmosis.