The Fungi
Julius P. Kreier in Infection, Resistance, and Immunity, 2022
Coccidioidomycosis is caused by the dimorphic fungus, Coccidioides immitis. This agent is endemic in the southwestern United States, an area characterized by a hot, dry climate. Mycelial growth occurs in rodent burrows where the soil is moist and enriched by animal droppings. After periods of heavy rains the arthroconidia, formed by fragmentation of the hyphae, are carried to the surface and aerosolize upon drying. Arthroconidia are the infectious units which are inhaled by the host. Upon entry into the lung, phase transformation to a spherule takes place. Spherules grow to large sizes, 20 to 80 μm in diameter. Cytoplasmic reorganization occurs within the spherules resulting in the formation of hundreds of endospores, 3 to 4 μm in diameter, which are released upon rupture of the spherule. Each endospore develops into another spherule, thus, continuing the cycle.
Epidemiology of fungal infections: What, where, and when
Mahmoud A. Ghannoum, John R. Perfect in Antifungal Therapy, 2019
Coccidioides immitis is the etiologic agent of coccidioidomycosis. This organism is found in the soil in the southwestern United States, Mexico, Central America (Guatemala, Honduras, Nicaragua), and South America (Argentina, Paraguay, Venezuela and Colombia) in areas of arid to semiarid climate [5,310,311]. Environmental conditions that favor its growth are heat, low altitudes, sparse flora, and alkaline soils. The portal of entry is via inhalation of the arthroconidia, and a single arthroconidium is able to produce respiratory infection. Arthroconidia germinate to produce spherules and endospores, which are released when the spherules rupture. The spherules are surrounded by neutrophils and macrophages, leading to granuloma formation. The organism is resistant to killing by neutrophils and macrophages, and a cell-mediated response is essential. Defects in cell-mediated immunity are associated with dissemination. More than half of the Coccidioides infections are asymptomatic, with about 40% having a self-limited flu-like illness in the ensuing weeks after exposure [5,311,312]. Other manifestations include pneumonia and disseminated disease to other sites including the blood, meninges, joint, bone, skin, and urogenital tract [310,313–317].
Coccidioides
Rossana de Aguiar Cordeiro in Pocket Guide to Mycological Diagnosis, 2019
Coccidioidomycosis is a deep-seated infection caused by two dimorphic fungal species: Coccidioides immitis and C. posadasii. Apparently, both species have similar phenotypical and virulence traits, and may cause severe infections with common signs and symptoms. The disease occurs only in the Americas, primarily in areas situated between the north and south 40° latitudes, and the great majority of cases have come from the United States (Hector & Laniado-Laborin, 2005). However, each species shows a specific pattern of distribution: C. immitis occurs in central and southern California, and C. posadasii occurs in the US states of Nevada, Arizona, New Mexico, and western Texas, as well as in Mexico and Central and South America (Kirkland & Fierer, 2018). Coccidioides spp. are found in soils of desert, arid, or semi-arid areas, where they grow saprophytically in the filamentous form. In nearly all cases, the infection results from the inhalation of conidia produced during the filamentous phase, after deliberately stirring the soil—agriculture, hunting, well digging, etc.—or due to environmental disturbances such as sandstorms and earthquakes (Schneider et al., 1997).
Endemic mycoses: epidemiology and diagnostic strategies
Published in Expert Review of Anti-infective Therapy, 2020
Andrés Tirado-Sánchez, Gloria M. González, Alexandro Bonifaz
CDM (San Joaquin Valley fever) is caused by two cryptic and dimorphic fungi: Coccidioides immitis and Coccidioides posadasii. The first one is found in the Central Valley of California (San Joaquin Valley), but has now been found as far north as east of Washington, where is an emerging infection. C.immitis isolates form a distinctive clade in the phylogenetic tree in this region [67]. C. posadasii, is often found in Arizona, Texas, Utah, Mexico, and Central and South America [68]. The incidence of coccidioidomycosis seems to be increasing nationwide during the last decades, both in regions considered endemic and non-endemic [69], and a total of 95,317 cases were reported between 2011 and 2017 [68,70]. There are three endemic areas in Mexico: the northern zone (which borders the United States and includes Baja California, Sonora, Chihuahua, Coahuila, Nuevo León, and Tamaulipas); Pacific littoral zone (which extends southeast from the north to Michoacán), and the central area (from the northeast border of Coahuila and ends at the edge with Michoacán), although the distribution of cases may be higher since coccidioidomycosis is not a reportable disease in Mexico [67].
Treatment of infections in cancer patients: an update from the neutropenia, infection and myelosuppression study group of the Multinational Association for Supportive Care in Cancer (MASCC)
Published in Expert Review of Clinical Pharmacology, 2021
Bernardo L. Rapoport, Tim Cooksley, Douglas B. Johnson, Ronald Anderson, Vickie R. Shannon
Both the duration (>1 week) and severity (<100 cells/μl) of neutropenia influence the risk of fungal pneumonia [105,106]. Hence, infections caused by gram-negative bacterial pathogens predominate during the early (less 7 days) neutropenic period, while fungal infections caused by Aspergillus, Zygomycetes, and Fusarium spp are common as neutropenia persists beyond 1–2 weeks. The spectrum of pulmonary fungal infections in neutropenic patients includes members of the invasive Aspergillus spp, the non-Aspergillus molds (Scedosporium spp, Fusarium spp, Pseudallescheria boydii), Mucorales spp and the dematiaceous molds [107]. Aspergillus spp, particularly A. fumigatus, is the most frequently identified fungal organism in neutropenic patients. A. niger, A. flavus, and amphotericin- and azole-resistant mold infections have also emerged as important pathogens in this setting [108–110]. Mixed infections with fungal species and respiratory viruses, cytomegalovirus (CMV), and/or gram-negative bacilli are also common. Recent declines in pneumonia caused by endemic fungi, including Histoplasma capsulatum, Coccidioides immitis, and Blastomyces dermatitidis, have been attributed to the use of fluconazole prophylaxis in hematologic malignancies and following HSCT as the standard of care. Rates of Pneumocystis jirovecii pneumonia have declined significantly with the use of trimethoprim-sulfamethoxazole prophylaxis during the neutropenic period after HSCT [111,112].
Advances in the diagnosis of fungal pneumonias
Published in Expert Review of Respiratory Medicine, 2020
Bryan T. Kelly, Kelly M. Pennington, Andrew H. Limper
Coccidioidomycosis is an infection caused by the endemic fungi Coccidioides immitis and Coccidioides posadasii primarily found in the southwest region of the United States and northwestern Mexico [6]. Pulmonary infection is often asymptomatic or mildly symptomatic presenting similar to community-acquired pneumonia. A small number of patients may develop more severe disseminated infection. Patients at increased risk for disseminated infection include immunocompromised patients, pregnant patients, and those of Filipino and African descent, though reasons behind increased dissemination on a racial basis remain unclear [6].
Related Knowledge Centers
- Pathogen
- Coccidioides Posadasii
- Coccidioidomycosis
- Antigen
- Biopsy
- Grocott'S Methenamine Silver Stain
- Select Agent
- Biosafety Level
- Azole
- Teratology