Coccidioidomycosis (Valley Fever)

Valley Fever Surveillance in AZ

The Arizona Department of Health Services has conducted surveillance for coccidioidomycosis for many decades. Changes in laboratory reporting practices and testing methods have significantly influenced the number of cases reported. Laboratories have been required to report positive coccidioidomycosis test results to ADHS since 1997. Since then, the number of reported cases has increased. In 2009, a major commercial laboratory changed its reporting practices for coccidioidomycosis, greatly increasing the total number of reported cases. In 2012, a change in laboratory testing methods contributed to a decrease in the number of reported cases.


Case Definition

The Department of Health defines a case of coccidioidomycosis for surveillance purposes as follows:

Clinical Description

Infection may be asymptomatic or may produce an acute or chronic disease. Although the disease initially resembles an influenza-like illness or pneumonia-like febrile illness primarily involving the bronchopulmonary system, dissemination can occur to multiple organ systems. An illness is typically characterized by one or more of the following:

  • Influenza-like signs and symptoms, including fever, chest pain, cough, myalgia, arthralgia,
  • Headache
  • Pneumonia or other pulmonary lesion, diagnosed by chest X-ray
  • Rashes, including erythema nodosum or erythema multiforme
  • Involvement of bones, joints, or skin by dissemination
  • Meningitis
  • Involvement of viscera and lymph nodes
Laboratory Criteria for Diagnosis

Laboratory-confirmed coccidioidomycosis requires at least one of the following:

  • Cultural, histopathologic, or molecular evidence of presence of Coccidioides species, OR
  • Immunologic evidence of infection
    • Serologic (testing of serum, cerebrospinal fluid (CSF), or other body fluid) by:
      • Detection of coccidioidal IgM by immunodiffusion, enzyme immunoassay (EIA), latex agglutination, or tube precipitin, OR
      • Detection of coccidioidal IgG by immunodiffusion, enzyme immunoassay (EIA), or complement fixation (for complement fixation, titers from blood must be ≥ 1:4; for immunodiffusion or when the specimen is CSF, any titer is considered positive).
  • Coccidioidal skin test conversion from negative to positive after the onset of clinical
    signs and symptoms.

The ADHS case definition for coccidioidomycosis is adapted from the Centers for Disease Control and Prevention case definition, which can be found on CDC's National Notifiable Diseases Surveillance System website. The ADHS case definitions manual can be found on the Case Definitions for Public Health Surveillance webpage.