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Open Access Research article

Parasitic polymorphism of Coccidioides spp

Bertha Muñoz-Hernández1, Gabriel Palma-Cortés1, Carlos Cabello-Gutiérrez1 and María Angeles Martínez-Rivera2*

Author Affiliations

1 Laboratorio de Micología Médica, Depto. de Investigación en Virología y Micología, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Calzada de Tlalpan No. 4502, Colonia Sección XVI Del. Tlalpan, 14080, México, DF, México

2 Laboratorio de Micología Médica, Depto. de Microbiología. Escuela Nacional de Ciencias Biológicas (ENCB), Instituto Politécnico Nacional (IPN). Carpio y Plan de Ayala s/n, Colonia Casco de Santo Tomás, Del. Miguel Hidalgo, México, DF 11340, México

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BMC Infectious Diseases 2014, 14:213  doi:10.1186/1471-2334-14-213

Published: 21 April 2014



Coccidioides spp. is the ethiological agent of coccidioidomycosis, an infection that can be fatal. Its diagnosis is complicated, due to that it shares clinical and histopathological characteristics with other pulmonary mycoses. Coccidioides spp. is a dimorphic fungus and, in its saprobic phase, grows as a mycelium, forming a large amount of arthroconidia. In susceptible persons, arthroconidia induce dimorphic changes into spherules/endospores, a typical parasitic form of Coccidioides spp. In addition, the diversity of mycelial parasitic forms has been observed in clinical specimens; they are scarcely known and produce errors in diagnosis.


We presented a retrospective study of images from specimens of smears with 15% potassium hydroxide, cytology, and tissue biopsies of a histopathologic collection from patients with coccidioidomycosis seen at a tertiary-care hospital in Mexico City.


The parasitic polymorphism of Coccidioides spp. observed in the clinical specimens was as follows: i) spherules/endospores in different maturation stages; ii) pleomorphic cells (septate hyphae, hyphae composed of ovoid and spherical cells, and arthroconidia), and iii) fungal ball formation (mycelia with septate hyphae and arthroconidia).


The parasitic polymorphism of Coccidioides spp. includes the following: spherules/endospores, arthroconidia, and different forms of mycelia. This knowledge is important for the accurate diagnosis of coccidioidomycosis. In earlier studies, we proposed the integration of this diversity of forms in the Coccidioides spp. parasitic cycle. The microhabitat surrounding the fungus into the host would favor the parasitic polymorphism of this fungus, and this environment may assist in the evolution toward parasitism of Coccidioides spp.

Coccidioidomycosis; Diagnosis of Coccidioides; Parasitic mycelia forms of Coccidioides; Parasitic polymorphism of Coccidioides