Ten Things to Know about Valley Fever
Valley fever is a fungal respiratory disease that can be devastating. Learning about valley fever can help you and your doctor recognize the symptoms early.
Valley fever, also called coccidioidomycosis, is an infection caused by the fungus Coccidioides. People can get valley fever by breathing in the microscopic fungal spores from the air, although most people who breathe in the spores don’t get sick.
The disease can be difficult to diagnose, especially if you are unaware of it. Here are ten things you should know about valley fever.
1. Valley fever is caused by a fungus that lives in the environment.
The fungus that causes valley fever, Coccidioides, lives in soil and dust in the southwestern United States (including Arizona, California, Nevada, New Mexico, Utah, and Texas), and parts of Mexico, Central America, and South America.1-6 The fungus was also recently found in south-central Washington state.7
People get valley fever by breathing in the microscopic, airborne fungal spores. Sometimes, the number of people with valley fever increases after there have been weather-related events that stir up more dust than usual, such as earthquakes or dust storms.
Known and suspected areas where the fungus that causes valley fever lives in the United States
2. Valley fever is not contagious.
Valley fever does not generally spread between people.
3. Symptoms of valley fever are usually similar to the flu.
Approximately 40 percent of people who get the fungal infection do not show any symptoms.8 In the other 60 percent, valley fever can cause flu-like symptoms, including:
Coccidioides spores are inhaled and settle into the lungs
- Fatigue (tiredness)
- Shortness of breath
- Night sweats
- Muscle aches or joint pain
- Rash on upper body or legs
The symptoms of valley fever typically appear between one and three weeks after someone inhales the fungal spores. In many people, the symptoms will disappear in a few weeks.9,10 However, in severe cases, the infection can cause chronic pneumonia, and the symptoms can last for years.
In less than 1 percent of people who get valley fever, the infection can spread from the lungs to the rest of the body, causing meningitis (spine and brain infection) or infection in the bones and joints.
4. Valley fever is common in the southwestern United States.
In the U.S., over 65 percent of all valley fever cases occur in Arizona, and 30 percent occur in California. Most other cases occur in Nevada, Utah, and New Mexico.
Studies have shown that in some areas where valley fever is very common, such as southern Arizona, valley fever causes an estimated 15 percent to nearly 30 percent of all community-acquired pneumonias, but that less than 15 percent of patients with pneumonia symptoms are tested for valley fever.11,12 This suggests that there may be many more people with the disease than are reported.
Number of reported valley fever cases in the United States13,14
5. Reported cases have increased.
Some researchers estimate that each year the fungus infects thousands more people, many of whom are sick without knowing the cause or have mild cases that aren’t detected. In 2012, nearly 18,000 cases of valley fever were reported in the United States13, and cases increased by about 15 percent each year from 1998 to 2011.14 Some researchers hypothesize that many milder cases go undiagnosed, which may mean that the reported cases are just the tip of the iceberg.
The increase could be because of:
- More people exposed to the fungus because of increased travel or relocation to the southwestern United States,
- Changes in the way cases of valley fever are being detected and reported to public health officials, or
- Changes in factors such as temperature and rainfall, which can affect the growth of the fungus in the environment and how much of it is circulating in the air.
6. Anyone can get valley fever.
Anyone can get valley fever if they live in or have visited an area where the fungus Coccidioides lives, especially southern Arizona or California’s Central Valley. Although people of any age can get valley fever, it is most common among older adults, particularly those ages 60 and older. People who have recently moved to an area where the disease naturally occurs are at higher risk for infection.
7. Some people are at higher risk for developing the severe form of valley fever.
Groups of people who are more likely to develop the severe form of valley fever or develop an infection that spreads beyond the lungs include:
- People who have weakened immune systems, for example, people who:
- Have HIV/AIDS15
- Have had an organ transplant16
- Are taking medications such as corticosteroids or TNF-inhibitors17
- Pregnant women18
- People who have diabetes19
- People who are Black19-21 or Filipino22
The reasons why some racial/ethnic groups are at higher risk are not completely understood.
8. Some people will need antifungal treatment.
For many people, the infection will go away on its own in a few weeks. However, antifungal treatment is recommended for some patient groups, such as those at high risk for developing the severe forms of the disease. Because the symptoms of valley fever can be similar to those of other respiratory diseases, patients may have delays getting tested and receiving treatment. However, early diagnosis can:
- Reduce the time and money spent looking for other explanations for the patient’s illness,
- Avoid the use of unnecessary antibiotics, and
- Help ease patient anxiety about an unknown illness.
9. It can be difficult to avoid the fungus that causes valley fever.
In areas where valley fever is common, it’s difficult to completely avoid exposure to the fungus. While there is no vaccine to prevent the infection, researchers are working to develop one. People with weakened immune systems or other conditions that put them at high risk for developing the severe form of the disease should consider trying to reduce exposure to the fungus. This is done by limiting activities that disturb soil or generate dust, such as digging or excavation, in areas where the fungus lives.
10. Awareness is key.
The general community and healthcare providers need more awareness about valley fever. Increased awareness could help avoid missed diagnoses. For example, one study showed that valley fever patients who knew about the disease before visiting a doctor were more likely to ask to be tested and were diagnosed sooner than patients who didn’t know about the disease.9
Healthcare providers should be aware that the symptoms of valley fever are similar to those of other common respiratory illnesses and should consider testing for valley fever in patients with flu-like symptoms who live in or have traveled to an area where valley fever is common. People who have symptoms of valley fever and live in or have visited an area where the fungus is common should ask their doctor to test them for the disease.
- Nguyen C, Barker BM, Hoover S, Nix DEA, Neil M., Frelinger JA, Orbach MJ, et al. Recent Advances in Our Understanding of the Environmental, Epidemiological, Immunological, and Clinical Dimensions of Coccidioidomycosis. Clin Microbiol Rev. 2013;26(3):505-25.
- Edwards PQ, Palmer CE. Prevalence of sensitivity to coccidioidin, with special reference to specific and nonspecific reactions to coccidioidin and to histoplasmin. Diseases of the chest. 1957 Jan;31(1):35-60.
- Werner SB, Pappagianis D. Coccidioidomycosis in Northern California. An outbreak among archeology students near Red Bluff. California medicine. 1973 Sep;119(3):16-20.
- Werner SB, Pappagianis D, Heindl I, Mickel A. An epidemic of coccidioidomycosis among archeology students in northern California. N Engl J Med. 1972 Mar 9;286(10):507-12.
- Petersen LR, Marshall SL, Barton-Dickson C, Hajjeh RA, Lindsley MD, Warnock DW, et al. Coccidioidomycosis among workers at an archeological site, northeastern Utah. Emerg Infect Dis. 2004 Apr;10(4):637-42.
- Hector RF, Laniado-Laborin R. Coccidioidomycosis--a fungal disease of the Americas. PLoS medicine. 2005 Jan;2(1):e2.
- Marsden-Haug N, Goldoft M, Ralston C, Limaye AP, Chua J, Hill H, et al. Coccidioidomycosis acquired in Washington State. Clin Infect Dis. 2013 Mar;56(6):847-50.
- Smith CE, Whiting EG, et al. The use of coccidioidin. American review of tuberculosis 1948;57:330-60.
- Tsang CA, Anderson SM, Imholte SB, et al. Enhanced surveillance of coccidioidomycosis, Arizona, USA, 2007-2008. Emerg Infect Dis 2010;16:1738-44.
- Thompson GR, 3rd. Pulmonary coccidioidomycosis. Seminars in respiratory and critical care medicine 2011;32:754-63.
- Valdivia L, Nix D, Wright M, Lindberg E, Fagan T, Lieberman D, et al. Coccidioidomycosis as a common cause of community-acquired pneumonia. Emerg Infect Dis. 2006 Jun;12(6):958-62.
- Chang DC, Anderson S, Wannemuehler K, Engelthaler DM, Erhart L, Sunenshine RH, et al. Testing for coccidioidomycosis among patients with community-acquired pneumonia. Emerg Infect Dis. 2008 Jul;14(7):1053-9.
- CDC. Notice to Readers: Final 2012 Reports of Nationally Notifiable Infectious Diseases, MMWR 62(33);669-682.
- CDC. Increase in Reported Coccidioidomycosis – United States, 1998-2012, MMWR 62(12);217-221.
- Woods CW, McRill C, Plikaytis BD, Rosenstein NE, Mosley D, Boyd D, et al. Coccidioidomycosis in human immunodeficiency virus-infected persons in Arizona, 1994-1997: incidence, risk factors, and prevention. J Infect Dis. 2000 Apr;181(4):1428-34.
- Blair JE, Logan JL. Coccidioidomycosis in solid organ transplantation. Clin Infect Dis. 2001 Nov 1;33(9):1536-44.
- Bergstrom L, Yocum DE, Ampel NM, Villanueva I, Lisse J, Gluck O, et al. Increased risk of coccidioidomycosis in patients treated with tumor necrosis factor alpha antagonists. Arthritis and rheumatism. 2004 Jun;50(6):1959-66.
- Bercovitch RS, Catanzaro A, Schwartz BS, Pappagianis D, Watts DH, Ampel NM. Coccidioidomycosis during pregnancy: a review and recommendations for management. Clin Infect Dis. 2011 Aug;53(4):363-8.
- Rosenstein NE, Emery KW, Werner SB, Kao A, Johnson R, Rogers D, et al. Risk factors for severe pulmonary and disseminated coccidioidomycosis: Kern County, California, 1995-1996. Clin Infect Dis. 2001 Mar 1;32(5):708-15.
- Durry E, Pappagianis D, Werner SB, Hutwagner L, Sun RK, Maurer M, et al. Coccidioidomycosis in Tulare County, California, 1991: reemergence of an endemic disease. J Med Vet Mycol. 1997 Sep-Oct;35(5):321-6.
- Sondermeyer G, Lee L, Gilliss D, Tabnak F, Vugia D. Coccidioidomycosis-associated hospitalizations, California, USA, 2000-2011. Emerg Infect Dis. 2013 Oct;19(10):1590-7.
- Crum NF, Lederman ER, Stafford CM, Parrish JS, Wallace MR. Coccidioidomycosis: a descriptive survey of a reemerging disease. Clinical characteristics and current controversies. Medicine. 2004 May;83(3):149-75.
- Page last reviewed: May 22, 2014
- Page last updated: May 22, 2014
- Content source:
- National Center for Emerging and Zoonotic Infectious Diseases, Division of Foodborne, Waterborne, and Environmental Diseases
- Page maintained by: Office of the Associate Director for Communication, Digital Media Branch, Division of Public Affairs