Infectious Diseases

Coccidioidomycosis

OVERVIEW: What every practitioner needs to know

Are you sure your patient has coccidioidomycosis? What should you expect to find?

  • Symptoms include fever, cough, pleuritic chest pain, and fatigue.

  • Physical findings include rash (toxic erythema, erythema nodosum, erythema multiforme) and focal crackles on pulmonary auscultation.

How did the patient develop coccidioidomycosis? What was the primary source from which the infection spread?

  • Infection occurs by inhaling the mycelial form of the fungus, which grows in the soil. The distribution of Coccidioides in the soil is spotty and not well defined. Infection may occur by exposure to soil from a specific site or from inhalation of blowing dust. Often, the exposure is not recognized.

  • The major endemic regions for coccidioidomycosis is the southern portion of the San Joaquin Valley; the south central region of Arizona, including the metropolitan areas of Phoenix and Tucson; northern Mexico; and areas of southern Utah, southern New Mexico, and the region alone the Rio Grande River in western Texas. There are other less endemic regions in southern California, as well as Central and South America.

Which individuals are of greater risk of developing coccidioidomycosis?

  • Symptomatic coccidioidomycosis is more likely in African-American and Filipino men, pregnant women, particularly in the second and third trimester, and those with depressed cellular immune systems, including those with HIV infection and low CD4 counts, and those on immunosuppressive therapy, including TNF-alpha inhibitors.

Beware: there are other diseases that can mimic coccidioidomycosis:

  • Community acquired pneumonia

  • Tuberculosis

  • Histoplasmosis

What laboratory studies should you order and what should you expect to find?

Results consistent with the diagnosis

  • Peripheral white blood cell (WBC) count may demonstrate eosinophilia.

Results that confirm the diagnosis

  • Coccidioidal serologic tests: immunodiffusion TP or CF; EIA IgG; unclear if EIA IgM is specific

  • Sputum culture growing Coccidioides species (this is a major laboratory hazard, and the laboratory should be alerted if coccidioidomycosis is suspected.)

What imaging studies will be helpful in making or excluding the diagnosis of coccidioidomycosis?

  • Plain chest radiograph typically demonstrates a focal process (may be upper lobe); diffuse or reticulonodular pattern in severe disease; hilar or mediastinal adenopathy may be present.

  • CT scan of the chest may demonstrate the above changes more dramatically.

What consult service or services would be helpful for making the diagnosis and assisting with treatment?

If you decide the patient has coccidioidomycosis, what therapies should you initiate immediately?

Most patients with primary pulmonary coccidioidomycosis will not require therapy. Among patients without immune compromise, therapy should be considered if the patient has intense night sweats for more than 3 weeks, has lost more than 10% body weight, has extensive pulmonary infiltrates, or has an elevated complement fixation titer greater than 1:16. Patients with suppressed cellular immunity should always be considered for treatment.

Anti-infective agents

If I am not sure what pathogen is causing the infection what anti-infective should I order?

If coccidioidomycosis is suspected and treatment deemed indicated, fluconazole 400 mg daily is an appropriate empiric choice.

Other triazole agents may be useful, including itraconazole, 200 mg bid after a loading dose of 200 mg tid for 3 days; posaconazole, 400 mg bid; and voriconazole, 400 mg bid for 2 doses, then 200 mg bid.

What complications could arise as a consequence of coccidioidomycosis?

Two types of complications of primary pulmonary coccidioidomycosis may occur: local pulmonary and dissemination. Local pulmonary complications include development of a nodule, a cavity and, rarely, pyopneumothorax due to rupture of a cavity into the pleural space. Disseminated disease occurs outside the thoracic cavity. Common sites include skin, bone, joint, and meninges.

What should you tell the family about the patient's prognosis?

  • Prognosis for most forms of pulmonary coccidioidomycosis is very good. The exception is severe, bilateral pneumonia.

How do you contract coccidioidomycosis and how frequent is this disease?

Infection is acquired in nearly all instances by inhaling coccidioidal arthroconidia from the air. Rarely, local infection may occur from inoculation from a contaminated thorn or other object.

Risk of acquiring coccidioidomycosis tends to occur during arid times of the year: summer in California, spring and fall in Arizona.

There is no person-to-person transmission of coccidioidomycosis.

What pathogens are responsible for this disease?

Coccidioidomycosis is caused by the fungus Coccidioides. Two genetic species are now recognized: C. immitis, which appears confined to California; and C. posadasii, the species found in the other endemic areas. There is no clinical difference in the manifestation of illness between the two organisms, and they are not distinguishable in the clinical laboratory.

How do these pathogens cause coccidioidomycosis?

After inhalation, arthrocondia, single-celled hyphal elements, enlarge, round-up, and internal septate to form the pathognomonic structure, the spherule. There is both a polymorphonuclear and a cellular immune response to infection, the latter being protective. Spherules may rupture, releasing packets of endospores, which can propagate local infection. Host control is achieved through a cellular immune response, including granuloma formation.

What other clinical manifestations may help me to diagnose and manage coccidioidomycosis?

A recent or current history of living in the coccidioidal endemic region may help diagnose coccidioidomycosis.

Development of erythema nodosum on the shins or erythema multiforme in a necklace distribution may help diagnose coccidioidomycosis.

What other additional laboratory findings may be ordered?

Coccidioidal serology: EIA, immunodiffusion or true tube precipitan, and complement fixation may be ordered.

How can coccidioidomycosis be prevented?

There are no specific means to prevent infection when living in the endemic area. Avoiding dust and soil and staying indoors during windy days may reduce risk, but these are not proven.

WHAT'S THE EVIDENCE for specific management and treatment recommendations?

Ampel, NM, Giblin, A, Mourani, JP, Galgiani, JN. "Factors and outcomes associated with the decision to treat primary pulmonary coccidioidomycosis". Clin Infect Dis. vol. 48. 2009 Jan 15. pp. 172-8.

(This article includes helpful hints as to how to approach the therapy of coccidioidal pneumonia.)

Valdivia, L, Nix, D, Wright, M. "Coccidioidomycosis as a common cause of community-acquired pneumonia". Emerg Infect Dis.. vol. 12. 2006 Jun. pp. 958-62.

(This paper emphasizes how commonly coccidioidomycosis is a cause of community acquired pneumonia in the endemic area.)

Galgiani, JN, Ampel, NM, Blair, JE. "Coccidioidomycosis". Clin Infect Dis. vol. 41. 2005 Nov 1. pp. 1217-23.

(These are the Infectious Diseases Society of America guidelines for management of coccidioidomycosis.)

DRG CODES and expected length of stay

ICD-10-CM: B38.0

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