Bat histoplasmosis in Alabama

Infection of bats with Histoplasma species

Histoplasma species infect humans and animals, notably bats. Histoplasma species are thermally dimorphic fungi existing in mycelial form in the natural environment and in yeast form in infected tissues. In this narrative literature review, we summarize the occurrence of Histoplasma spp. in different species of bat tissues (n = 49) and in soil admixed with bat guano where the species of bat dwelling nearby has been identified (an additional 18 species likely infected) to provide an up-to-date summary of data. Most positive isolations are from the Americas and Caribbean, with some studies from Thailand, Malaysia, Nigeria, Slovenia, France, and Australia. We also summarize some of the early experimental work to elucidate pathogenicity, latency, immune response, and faecal excretion in bats. Given the recent recognition of the global extent of histoplasmosis, thermal dimorphism in Histoplasma spp., and global heating, additional work on understanding the complex relationship between Histoplasma and bats is desirable.

Brown-red pigment formation by the mycelial phase of a clinical isolate of Histoplasma capsulatum on Staib agar. A preliminary report

In an HIV-positive patient, the suspected diagnosis of histoplasmosis capsulatum (being the first opportunistic infection indicating AIDS) on the basis of histopathological findings in biopsy material could be proved by culture on Staib agar (syn. Guizotia abyssinica creatinine agar, bird seed agar, etc.). On Staib agar, after 4 weeks at 26 degrees C, there was a cockade-like colony growth, consisting of a white centre, followed by a brown-red pigmented zone surrounded by a border of submerged mycelial growth of tan to brownish colour. Morphologically, there was a moderate formation of tuberculate macroconidia and a heavy formation of microconidia. On neutral Sabouraud's dextrose agar, there was a colony formation without pigment (albino type) free of tuberculate macroconidia and microconidia. Proposals for further investigation of these preliminary observations are made.

Bats in the belfry: an outbreak of histoplasmosis

The belfry and attic of a 100-year-old school building located in central Illinois were infested with a colony of big brown bats (Eptesicus fuscus). During the week of April 14, 1980, four workers disturbed the piles of bat droppings in the attic, causing dust to become airborne. Seven to 10 days later, all four workers developed symptoms and chest x-ray findings compatible with acute pulmonary histoplasmosis. Their sera had complement fixation (CF) titers of greater than or equal to 1:32 with fungal antigens and showed M and/or H bands by immunodiffusion tests. An additional 73 persons who had visited the building were also studied, leading to the finding of 16 additional cases of acute pulmonary histoplasmosis, identified on the basis of positive serologies and compatible symptoms. H. capsulatum was isolated from the sputum of one patient and from the soil beneath the hole in the building's eaves where the bats had been entering the attic. Cases were associated with exposure to the attic and with total hours of building exposure when compared with controls. The epidemic curve suggests that sporadic exposures occurred during the spring of 1980, with an epidemic occurring after the bat droppings were disturbed by the four workers.

Isolation of Histoplasma capsulatum from tissues of bats captured in the Aguas Buenas Caves, Aguas Buenos, Puerto Rico

Of 30 bats belonging to four species, only one species, Brachyplylla cavernarum, yielded positive for Histoplasma capsulatum. Bats were collected at the Aguas Buenas Caves in Puerto Rico. The other species are: Artibeus jamaicensis, Monophyllus redmani portoricensis, and Erophylla bibombifrons; these resulted negative for the fungus.