From the Guidelines
Valley fever is transmitted through the inhalation of fungal spores from the Coccidioides species, which live in soil in specific geographic regions. This transmission occurs when soil containing these spores is disturbed by activities like construction, farming, gardening, or natural events such as dust storms and earthquakes, causing the microscopic spores to become airborne 1. Once inhaled into the lungs, these spores can cause infection. It's crucial to note that valley fever cannot spread from person to person, nor can it be transmitted from animals to humans. The risk of infection increases during dry, dusty conditions and in areas where the soil has been disturbed.
Key Points to Consider
- People living in or visiting endemic regions, primarily the southwestern United States (especially Arizona and California's Central Valley) and parts of Mexico and Central and South America, are at higher risk 1.
- To reduce transmission risk, individuals in these areas should avoid dusty conditions when possible, wear masks during dust storms or when working with soil, and consider wetting soil before digging to prevent spores from becoming airborne.
- The estimated numbers of infections per year have risen, with approximately 150,000 cases, highlighting the importance of preventive measures 1.
- Most infections are acquired within the major regions of endemicity, and travelers who have recently visited these regions or previously infected patients with immunosuppression can develop clinical disease and require medical management outside of the endemic region 1.
From the Research
Transmission of Valley Fever
- Valley fever, also known as coccidioidomycosis, is transmitted through the inhalation of airborne spores of the fungus Coccidioides immitis or Coccidioides posadasii 2, 3.
- The spores are found in the arid desert soils of the southwestern US, as well as in parts of Mexico and Central and South America 2.
- The spores can become airborne after natural events such as earthquakes, dust storms, and fires, as well as human-related events like military maneuvers, recreational activities, agriculture, and construction 2.
- There is no person-to-person or zoonotic contagion, and residing in or traveling to areas endemic for Coccidioides is required for the diagnosis 3.
- The incidence of coccidioidomycosis is increasing in endemic areas, and it has been identified as the cause of as many as 17% to 29% of all cases of community-acquired pneumonia in some regions 3.
Modes of Transmission
- The fungal spores can be released into the air when soil is disturbed through excavation, agricultural activities, or any other soil movement 4.
- People who are in close proximity to the disturbed soil can potentially inhale the spores, leading to infection 4.
- The recognized geographic distribution of Coccidioides spp. is expanding, with cases being diagnosed in new areas such as eastern Washington, Oregon, and Utah 2.