What is Coccidioidomycosis?
Coccidioidomycosis (colloquially known as Valley Fever) is caused by the dimorphic fungal species Coccidioides, which lives as mould in the environment.1,2 The fungi exist in mycelium or spherule form and are among the most virulent fungal pathogens.1,2
Pathogenesis
Coccidioides is acquired through inhalation; it initially infects the lungs but can spread to the central nervous system, blood, bones and other organs.2 Invasive coccidioidomycosis is a life-threatening disease, especially in vulnerable patients, but can also affect healthy individuals.2
Epidemiology
Although cases are limited to the Americas, the disease may have global implications given its increasing incidence and potential exposure in those who enter endemic areas.1,2 Global annual incidence rates cannot be assessed due to a lack of studies; however, the incidence rate of coccidioidomycosis is predicted to increase by 164% by 2050 due to the geographical spread of the disease.1,2 The annual number of cases in the USA has been estimated at 150,000; however, this is likely to be an underestimate due to missed diagnoses, and recent data show that a more accurate prediction of the number of cases is 350,000.1
Mortality rates in patients with invasive coccidioidomycosis range from 2 to 13% and are higher in vulnerable patients, such as those with meningitis, compared with healthy individuals.2,3 Median hospital length of stay ranged from 3 to 7 days, with a median of 22.7 days for coccidioidal meningitis.2
Risk factors
Patients who are most at risk include immunocompromised patients, such as patients with cancer and patients undergoing haematopoietic stem cell transplantation (HSCT) or organ transplant.2
Known risk factors include:1,2
- Corticosteroid use
- Anti-tumour necrosis factor medication
- Chemotherapy
- Other immunomodulating therapies
- Being of African descent
- Increasing age (aged over 40–60 years)
- Exposure to dust or soil
Pathogenic species
The two main causative pathogens for coccidioidomycosis are Coccidioides immitis and Coccidioides posadasii, and their incidence is increasing.1
References
- Crum NF. Infect Dis Ther. 2022;11:713–742.
- WHO fungal priority pathogens list to guide research, development and public health action. Geneva: World Health Organization. Available at: https://www.who.int/publications/i/item/9789240060241. Accessed July 2023.
- Thompson GR et al. Lancet Infect Dis. 2021;21:e364–e374.