Coccidioidomycosis

What is coccidioidomycosis?

Coccidioidomycosis is a fungal infection that primarily affects the lungs and respiratory tract. It can in rare cases spread to other parts of the body.

Coccidioidomycosis is also known as San Joaquin Valley fever (or simply Valley fever) or desert rheumatism. It occurs in the western United States and parts of Mexico and Central and South America.

What causes coccidioidomycosis?

Coccidioidomycosis is caused by two distinct Coccidiodies species of soil fungus, Coccidioides immitis and Coccidioides posadaii.

The infection occurs through:

• Inhalation of spores during outdoor activities (most common)
• Puncture wounds with infected objects
• Organ transplantation or sexual transmission from an infected individual (rare).

What are the signs and symptoms of coccidioidomycosis?

In 65% of cases, patients with coccidioidomycosis are asymptomatic.

Patients with mild or self-limiting infections will present with:

• Low-grade fever with chills and night sweats
• Fatigue
• Pain (headaches, sore throat, chest pain)
• A cough, with possible sputum production and haemoptysis
• Lower limb/foot swelling
• Loss of appetite
• Rattling of the chest, sometimes with dullness upon percussion over lung fields
• Arthralgias.

Primary cutaneous coccidioidomycosis is very rare and arises from an inoculation injury. It presents as an indurated nodule and is one of the causes of sporotrichoid spread associated with lymphadenopathy.

What is disseminated coccidioidomycosis and what are the signs and symptoms?

Disseminated coccidioidomycosis refers to the spread of lung infection to other organs.

This advance can be rapid and involve the soft tissues, joints, central nervous system, endocrine glands, eyes, liver, kidneys, peritoneal cavity and, most seriously, the meninges (lining around the brain). If untreated, coccidioides infections of the meninges are nearly always fatal.

Patients with disseminated coccidioidomycosis may present with:

• Altered mental status
• Lymph node enlargement
• Neck stiffness
• Swelling/stiffness of the joints
• Light sensitivity
• Unexplained weight loss.

What are the cutaneous features of disseminated coccidioidomycosis?

Cutaneous signs are variable and may include solitary or multiple infected papules, nodules, pustules, abscesses, ulcers and scars.

Reactive manifestations may include:

• Erythema nodosum (common, arising three weeks after the pulmonary infection)
• Erythema multiforme
• An exanthem or toxic erythema (in 10–50% of patients)
• Acute febrile neutrophilic dermatosis (rare)
• Interstitial granulomatous dermatitis (rare).

What are the risk factors for coccidioidomycosis?

Risk factors for coccidioidomycosis include:

• Travel to endemic areas (the southwestern United States and parts of Mexico, Central and South America).
• Immunocompromised status (immunodeficiency, immunosuppressive drugs)
• Pregnancy
• Occupation. Farmers, construction workers, and archaeologists are at risk.
• Sex. Men are at an overall higher risk than females, mostly for occupational reasons.
• Race. Filipino, African, Native Americans or Hispanics with A or B blood types are considered to be at higher risk.
• History of lymphoma, organ transplantation or treatment with tumour necrosis factor (TNF) inhibitors
• Time of year. Incidence is higher in late summer and early autumn due to a combination of dry soil and wind.

How is coccidioidomycosis diagnosed?

Diagnosis of coccidioidomycosis is made through:

• Blood tests to look for coccidioides species
• Sputum smear (KOH microscopy)
• Polymerase chain reaction (PCR) from an infected site
• Isolation of organism in culture and subsequent histological and serological testing.
• Chest X-ray.

More severe cases may require additional testing, including:

• Lung, liver or lymph node or bone marrow biopsy
• Spinal tap (for suspected meningeal involvement)
• Bronchoscopy with lavage
• Skin biopsy. This may show suppurative granulomas containing double-walled refractile spherules with endospores. See pathology of coccidioidomycosis.

How is coccidioidomycosis treated?

• For self-limiting, mild symptoms, supportive care is most common.
• Medication therapy with fluconazole or itraconazole (for moderate cases) or posaconazole or amphotericin B (for severe cases) is standard. This treatment can go on for months or years, and in some patients, lifelong suppression will be necessary.