What is the pathophysiology of disseminated coccidioidomycosis?

Updated: Aug 27, 2019
  • Author: Duane R Hospenthal, MD, PhD, FACP, FIDSA, FASTMH; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

In some individuals, Coccidioides leaves the lungs to establish disseminated lesions in distant parts of the body. To establish extrapulmonary sites of infection, the fungal elements must move from the bronchiole into the lung parenchyma and enter and leave the vascular space.

Initially, the organism may spread via lymphatic drainage of infected macrophages from the initial terminal bronchiole lesion, as demonstrated by sequential involvement of the hilar nodes, followed by the paratracheal and then supraclavicular nodes, and finally reaching the common lymphatic duct.

From the thoracic duct, spread of the infection becomes hematogenous. Certain host factors, clinical findings, and laboratory findings suggest dissemination including advanced age, immunocompromised state, late stages of pregnancy, and ethnic or racial factors (see Epidemiology).

With dissemination, cell-mediated immunity can become impaired further, often reflected by anergy to coccidioidal skin tests. The mechanism for this effect on cell-mediated immunity is unclear, although many theories have been postulated. Antigen overload, suppressor cells, formation of immune complexes, and elaboration of immunosuppressive substances by the fungi may contribute to the impairment in cell-mediated immunity. [4] Eventually, immunity may recover with treatment and control of the coccidioidomycosis.


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