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

BACKGROUND: Coccidioidomycosis, a potentially fatal fungal infection, is considered an emergent mycotic disease because of the increased incidence of fungal infections registered over recent years. Infection occurs through the inhalation of arthroconidia from two main species of Coccidioides: Coccidioides immitis and C. posadasii, which are both endemic to arid and semi-arid regions of North America. Coccidioides species not only infect humans but can also infect other mammals (land, aquatic, wild or domestic), reptiles and birds. OBJECTIVE: To obtain information regarding the habitat of Coccidioides spp. and the animals infected by this fungus and to identify the role that infected animals play as reservoirs and disseminators of this fungus in nature. MATERIALS: A literature review was conducted to identify the habitat of Coccidioides spp. and the infected non-human animal species targeted by this fungus. RESULTS AND CONCLUSIONS: This review allows us to suggest that Coccidioides spp. may be classified as halotolerant organisms; nevertheless, to perpetuate their life cycle, these organisms depend on different animal species (reservoirs) that serve as a link with the environment, by acting as disseminators of the fungi in nature.

Viability and molecular authentication of Coccidioides spp. isolates from the Instituto de Medicina Tropical de São Paulo culture collection, Brazil / Viabilidade e autenticação molecular de isolados de Coccidioides spp. da coleção de culturas do Instituto de Medicina Tropical de São Paulo, Brasil

Coccidioidomycosis is an emerging fungal disease in Brazil; adequate maintenance and authentication of Coccidioides isolates are essential for research into genetic diversity of the environmental organisms, as well as for understanding the human disease. Seventeen Coccidioides isolates maintained under mineral oil since 1975 in the Instituto de Medicina Tropical de São Paulo (IMTSP) culture collection, Brazil, were evaluated with respect to their viability, morphological characteristics and genetic features in order to authenticate these fungal cultures. Only five isolates were viable after almost 30 years, showing typical morphological characteristics, and sequencing analysis using Coi-F and Coi-R primers revealed 99% identity with Coccidioides genera. These five isolates were then preserved in liquid nitrogen and sterile water, and remained viable after two years of storage under these conditions, maintaining the same features.

Coccidioidomicose é uma doença emergente no Brasil; a manutenção adequada e autenticação de isolados de Coccidioides spp são essenciais para a pesquisa em diversidade genética de micro-organismos, bem como para a compreensão da doença em humanos. Dezessete isolados de Coccidioides preservados em óleo mineral desde 1975 na coleção de culturas do Instituto de Medicina Tropical de São Paulo (IMTSP) foram avaliados com relação à viabilidade, características morfológicas e genéticas, com o objetivo de autenticação das culturas fúngicas. Dos 17 isolados, apenas cinco foram viáveis após quase 30 anos mantidos em óleo mineral, apresentando características morfológicas e moleculares típicas do gênero, o sequenciamento utilizando os oligonucleotídeos Coi-F e Coi-R revelou identidade de 99% com isolados de Coccidioides. Estes cinco isolados foram preservados em nitrogênio líquido e água destilada esterilizada, e permaneceram viáveis após dois anos de armazenamento sob estas condições, mantendo as mesmas características.

Viability and molecular authentication of Coccidioides spp. isolates from the Instituto de Medicina Tropical de São Paulo culture collection, Brazil.

Coccidioidomycosis is an emerging fungal disease in Brazil; adequate maintenance and authentication of Coccidioides isolates are essential for research into genetic diversity of the environmental organisms, as well as for understanding the human disease. Seventeen Coccidioides isolates maintained under mineral oil since 1975 in the Instituto de Medicina Tropical de São Paulo (IMTSP) culture collection, Brazil, were evaluated with respect to their viability, morphological characteristics and genetic features in order to authenticate these fungal cultures. Only five isolates were viable after almost 30 years, showing typical morphological characteristics, and sequencing analysis using Coi-F and Coi-R primers revealed 99% identity with Coccidioides genera. These five isolates were then preserved in liquid nitrogen and sterile water, and remained viable after two years of storage under these conditions, maintaining the same features.

Ecological niche modeling of Coccidioides spp. in western North American deserts.

Coccidioidomycosis is an endemic infectious disease in western North American deserts caused by the dimorphic ascomycete Coccidioides spp. Even though there has been an increase in the number of reported cases in the last years, few positive isolations have been obtained from soil samples in endemic areas for the disease. This low correlation between epidemiological and environmental data prompted us to better characterize the fundamental ecological niche of this important fungal pathogen. By using a combination of environmental variables and geospatially referenced points, where positive isolations had been obtained in southern California and Arizona (USA) and Sonora (Mexico), we have applied Genetic Algorithm for Rule Set Production (GARP) and Geographical Information Systems (GIS) to characterize the most likely ecological conditions favorable for the presence of the fungus. This model, based on environmental variables, allowed us to identify hotspots for the presence of the fungus in areas of southern California, Arizona, Texas, Baja California, and northern Mexico, whereas an alternative model based on bioclimatic variables gave us much broader probable distribution areas. We have overlapped the hotspots obtained with the environmental model with the available epidemiological information and have found a high match. Our model suggests that the most probable fundamental ecological niche for Coccidioides spp. is found in the arid lands of the North American deserts and provides the methodological basis to further characterize the realized ecological niche of Coccidioides spp., which would ultimately contribute to design smart field-sampling strategies.

Phenotypic characterization and ecological features of Coccidioides spp. from Northeast Brazil.

This study extends phenotypic and ecological knowledge of Coccidioides spp., by describing its recovery from soils of Ceará State (Northeast Brazil) and analyzing the in vitro features of the growth of its vegetative phase. Following a human coccidioidomycosis case, Coccidioides spp. strains were isolated from 3 of 14 soil samples collected in an armadillo's burrow. Mycological analysis showed colonies with glabrous, velvety or cottony texture and an increasing quantity of arthroconidia. The overall growth rates of the strains were slower in 8% NaCl medium, maximum growth rate was obtained at 30 degrees C, and their pH tolerance ranged from 4.0 to 11.0. Several carbohydrates and polyalcohol sources could be efficiently metabolized by Coccidioides spp. strains in the mycelial form. Total absence of growth was observed in media supplemented with either L-aspartic acid or L-histidine. Whereas intense growth was found when strains were incubated with any other aminoacid sources studied. Coccidioides spp. strains did not grow in the presence of Tween 60 and Tween 80, but exhibited intense growth in Tween 20. Nicotinic acid and the toxic compounds caffeic acid and phenol could not be metabolized by any strain. All of the strains were positive for urease production and displayed intense growth in media containing cycloheximide concentrations ranging from 0.01 and 0.05%, but did not grow at 0.1 and 0.2%. The present findings confirm the importance of armadillos burrows in the ecology of Coccidioides spp. in Northeast Brazil and indicate that the fungus is a very physiologically versatile organism.

Parasitic mycelial forms of coccidioides species in Mexican patients.

Of 26 cases of coccidioidomycosis reported here, 15 showed hyphae, atypical parasitic structures of Coccidioides spp. in fresh cytologic and/or histologic specimen preparations. The finding of this morphology could have implications which should be considered, especially when the disease affects areas of nonendemicity.

Epidemiology of coccidioidomycosis.

Coccidioides immitis naturally occurs in the soil and air of certain areas of the New World. These are generally arid to semiarid areas that have relatively modest rainfall, mild winters, and prolonged hot seasons. Coccidioidomycosis is usually a disease of human and nonhuman residents of these areas; but visitors may develop the disease after entering these areas and returning home long distances from the endemic areas. Inhalation (rarely percutaneous introduction) of arthroconidia of C. immitis leads to usually benign but occasionally severe and even fatal infection. Recovery from or asymptomatic infection leads to resistance to reinfection. Exposure to soil (dust) means that certain occupations are more likely to be exposed to C. immitis. Persistence of the organism in the soil means that infections will be encountered in the future, particularly as long as susceptible newcomers continue to enter endemic areas. Those who have been infected and recovered generally will be resistant to later infection, although exacerbation may occur as a result of superimposed immunosuppression.