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Abstract

Natural infection of armadillos with Coccidioides immitis was studied in the state of Piauí, northeast of Brazil, endemic for coccidioidomycosis. In 1998, 26 nine-banded armadillos (Dasypus novemcinctus) were captured in 4 different counties. The animals were sacrificed under deep anesthesia with ether. At necropsy fragments of spleen, liver, lungs and heart were homogenized and seeded onto Sabouraud dextrose agar with and without cycloheximide (BBL, USA). Part of each organ was also processed for histological examination. Suspected colonies of filamentous fungi observed after the second week of incubation at room temperature, exhibiting barrel-shaped arthroconidia alternating with empty spaces, were inoculated intraperitoneally into mice. Three armadillos proved to be infected with C. immitis. Mice inoculated with suspected colonies obtained from homogenized spleen of three and liver of two armadillos developed disseminated coccidioidomycosis and immature and mature spherules of C. immitis were disclosed in several organs. For the first time armadillos (D. novemcinctus) were found naturally infected with C. immitis, adding new data on the ecology and on a possible role of these ancestral mammals in the evolutionary life cycle of this fungus.

Local Population Structure and Patterns of Western Hemisphere Dispersal for Coccidioides spp., the Fungal Cause of Valley Fever

“…Although multiple North American mammal species can be infected, rodents, canids, and humans are highly susceptible to succumbing to the disease, allowing infecting strains to reenter into the soil upon death ( 1 , 38 ), and therefore may be considered the most likely “vectors” of transmission of Coccidioides from one locale to another. In South America, llamas and armadillos ( 39 , 40 ) are additionally considered highly susceptible, with the latter being a known source for soil contamination and human exposure ( 41 ). The ecological importance of recent findings of infected bat populations in Brazil remains unknown ( 42 ).…”

The habitat of Coccidioides spp. and the role of animals as reservoirs and disseminators in nature

“…and provide further support to the idea that animals may enrich the soil and act as an important growth factor for this fungus [ 5 ]. Additionally, it has been proposed that infected animals, such as bats and armadillos, may form part of the life cycle of Coccidioides and thus act as reservoirs of the fungus [ 30 , 33 , 34 ].…”

Coccidioidomycosis: epidemiology

“…However, to date, zoonotic transmission to humans has not been reported. Although carcasses or excretions from infected rodents have been hypothesized to play a role in the environmental life cycle of the fungus,14,18 the extent to which rodents or other animals such as bats20 or armadillos21 act as a reservoir for Coccidioides or influence its geographic distribution is still unknown. Comparative whole genome sequencing data suggest that Coccidioides have evolved in response to interaction with an animal host 22…”