Characterization of Environmental and Clinical Cryptococcus neoformans in Southern Ghana

Cryptococcus neoformans and Cryptococcus gatti are the two most common pathogenic species of the encapsulated yeast genus Cryptococcus and have been linked to fatal neurologic infections in both immunocompromised and healthy individuals. Cryptococcosis, which includes AIDS-defining diseases such as cryptococcal meningitis and meningoencephalitis, is the most frequent fungal infection of the central nervous system, with Africa having the greatest fatality rate. The goal of this study was to identify and characterize C. neoformans from pigeon and bat droppings, which are thought to be environmental reservoirs for the yeast and to determine their relatedness to clinical species. A total of 588 dried and 55 moist pigeon droppings, as well as 50 moist bat droppings, were collected from 18 sites in Ghana’s Greater Accra and Western regions, from sources which included markets, a church, households, and a public park. Seven clinical archived C. neoformans isolates were also retrieved from the Central Laboratory of the Korle-Bu Teaching Hospital (KBTH), Greater Accra. Using conventional methods and partial Multi-Locus Sequence Typing (MLST), 49 Cryptococcus neoformans var grubii were isolated from dried pigeon droppings only, yielding a prevalence of 7%. The sequence type (ST)/MLST group could not be defined based on the available data, although the allele types of the housekeeping genes in some of the isolates were identified. Some clinical strains had allele types that were found among the environmental strains, giving preliminary evidence of possible genetic relatedness, highlighting the need for more comprehensive genomic surveillance approaches, to better characterize environmental and clinical cryptococcal isolate transmission patterns and genetic relationships. This work also adds to the global literature supporting pigeon droppings as favorable ecological niches for Cryptococcus. This study was conducted within a One Health framework, recognizing the interconnected roles of environmental reservoirs, animal-associated sources, and human health in the epidemiology of Cryptococcus infections.