Valley Fever Still Making California Workers Sick

People who work outdoors, especially workers who dig or disturb soil, are at risk of becoming sick with Valley fever, a potentially severe illness caused by a fungus found in the soil in parts of California.

California continues to see an increase in cases of Valley fever. To address this ongoing concern, the California Department of Public Health conducted a statewide public awareness campaign, with special focus in the Central Valley and Central Coast, where Valley fever rates are the highest.

The campaign created posters and factsheets workers and employers can use to spread the word and to combat this unexpected ‘visitor’ on the jobsite. Visit Preventing Work-Related Valley Fever to download the new materials.

Contact Fast Response today for questions on Valley Fever.

NEW!! Posters and fact sheets for the workplace

CA Public Health Resources

  • OHB work-related Valley fever web page – find links to new materials for the workplace.
  • CDPH Infectious Diseases Branch Valley fever web page – information for the general public on Valley fever.

Could Be Valley Fever campaign’s animated video, Valley Fever 101, just won a platinum MarCom award for its excellence in marketing and communications.

How do workers get Valley Fever?

In California, Valley Fever is caused by the fungus Coccidioides immitis that lives in the top two to 12 inches of soil in many parts of the state. When soil containing this fungus is disturbed by activities such as digging, vehicles, or by the wind, the fungal spores get into the air. When people breathe the spores into their lungs, they may get Valley Fever. Fungal spores are small particles that can grow and reproduce in the body. The illness is not spread from one person to another.

How do employers know if the fungus is present in soil at their worksites?

The Valley Fever fungal spores are too small to be seen by the naked eye, and there is no reliable way to test the soil for spores before working in a particular place. Some California counties consistently have the Valley Fever fungus present in the soil. In these regions Valley Fever is considered endemic. Health departments track the number of cases of Valley Fever illness that occur. This information is used to map illness rates as seen on the figure above. Employers can contact their local health department for more information about the risk in their counties.

California county-specific coccidioidomycosis
incidence rates, 2011

Where do people get Valley Fever?

Highly endemic counties, i.e., those with the highest rates of Valley Fever (more than 20 cases per 100,000 population per year), are Fresno, Kern, Kings, Madera, Merced, San Luis Obispo, and Tulare. Other counties or parts of counties also have the fungus present.

Anyone, even healthy young people, can get Valley Fever. Once a person has had Valley Fever, their body may develop some immunity against future infections.

How does Valley Fever affect health?

  • Experiments on laboratory animals indicate that a very small dose, 10 spores or fewer, may cause an infection.
  • After breathing in the spores, the following can happen :
  • In about 60% of cases, symptoms are mild
  • In about 40% of cases, symptoms vary from moderate to severe. Usually symptoms are those of a flu-like illness that may last up to a month but goes away on its own. However, some people develop pneumonia (at times severe).
  • In a small proportion of cases (about 5%), disease spreads outside of the lungs causing very serious illness. Parts of the body that may be affected include the brain (meningitis), bones, joints, skin, or other organs.
    This is called disseminated Valley Fever (or disseminated coccidioidomycosis).

Who is at risk for Valley Fever?

Workers who disturb the soil by digging, operating earth-moving equipment, driving vehicles, or working in dusty, wind-blown areas are more likely to breathe in spores and become infected. Some occupations at higher risk for Valley Fever include:

  • Construction workers, including roadbuilding and excavation crews.
  • Archeologists
  • Geologists
  • Wildland firefighters
  • Military personnel
  • Workers in mining, quarrying, gas and oil extraction jobs
  • Agricultural workers*
* Cultivated, irrigated soil may be less likely to contain the fungus compared to undisturbed soils.

What are signs or symptoms of Valley Fever?

When present, symptoms usually occur between seven to 21 days after breathing in spores, and can include :

  • Cough
  • Fever
  • Chest pain
  • Headache
  • Muscle aches
  • Rash on upper trunk or extremities
  • Joint pain in the knees or ankles
  • Fatigue

Symptoms of Valley Fever can be mistaken for other diseases such as the flu (influenza) and TB (tuberculosis), so it is important for workers to obtain medical care for an accurate diagnosis and possible treatment.

Disseminated Valley Fever

Dissemination refers to spread of infection beyond the lungs to other parts of the body. With Valley Fever this usually occurs within the first six to 12 months after the initial illness.

Signs or symptoms of disseminated Valley Fever may vary but usually consist of some combination of the following:

  • Fever
  • Raised skin lesions with irregular surfaces
  • Lymph node swelling, especially in the neck
  • Pain and swelling in one or more joints
  • Recurrent, persistent, new headaches (may be mild)
  • Stiff neck.

Preventing Valley Fever exposure

There is no vaccine to prevent Valley Fever. Employers can reduce worker exposure by incorporating the following elements into the company’s Injury and Illness Prevention Program and project-specific health and safety plans:

1 Determine if the worksite is in an area where Valley Fever is endemic (consistently present). Check with your local health department to determine whether cases have been known to occur in the proximity of your work area. See the map on page 2 to determine whether
your company will be working in an endemic county.

2 Train workers and supervisors on the location of Valley Fever endemic areas, how to recognize symptoms of illness (see page 3), and ways to minimize exposure. Encourage workers to report respiratory symptoms that last more than a week to a crew leader, foreman, or supervisor.

3 Limit workers’ exposure to outdoor dust in disease-endemic areas. For example, suspend work during heavy wind or dust storms and minimize amount of soil disturbed.

4 When soil will be disturbed by heavy equipment or vehicles, wet the soil before disturbing it and continuously wet it while digging to keep dust levels down.

5 Heavy equipment, trucks, and other vehicles generate heavy dust. Provide vehicles with enclosed, air-conditioned cabs and make sure workers keep the windows closed. Heavy equipment cabs should be equipped with high efficiency particulate air (HEPA) filters. Two-way
radios can be used for communication so that the windows can remain closed but allow communication with other workers.

6 Consult the local Air Pollution Control District regarding effective measures to control dust during construction. Measures may include
seeding and using soil binders or paving and laying building pads as soon as possible after grading.

7 When digging a trench or fire line or performing other soil-disturbing tasks, position workers upwind when possible.

8Place overnight camps, especially sleeping quarters and dining halls, away from sources of dust such as roadways.

9 When exposure to dust is unavoidable, provide NIOSH-approved respiratory protection with particulate filters rated as N95, N99, N100, P100, or HEPA. Household materials such as washcloths, bandanas, and handkerchiefs do not protect workers from breathing in dust and spores.

Respirators for employees must be used within a Cal/OSHA compliant respiratory protection program that covers all respirator wearers and includes medical clearance to wear a respirator, fit testing, training, and procedures for cleaning and maintaining respirators.

Different classes of respirators provide different levels of protection according to their Assigned Protection Factor (APF) (see table below). Powered air-purifying respirators (PAPRs) have a battery-powered blower that pulls air in through filters to clean it before delivering it to the wearer’s breathing zone. PAPRs will provide a high level of worker protection, with an APF of 25 or 1000 depending on the model. When PAPRs are not available, provide a well-fitted NIOSH-approved full-face or half-mask respirator with particulate filters.

Fit-tested half-mask or filtering facepiece respirators are expected to reduce exposure by 90% (still allowing about 10% faceseal leakage), which can result in an unacceptable risk of infection when digging where Valley Fever spores are present.

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The table below shows the relative effectiveness of various types of respirators for particles of dust and spores.

Preventing transport of spores

  • Clean tools, equipment, and vehicles with water to remove soil before transporting offsite so that any spores present won’t be re-suspended in air and inhaled at a later time.
  • Provide workers with coveralls or disposable Tyvek™ daily. At the end of the work day, require workers to remove their work clothes at the worksite.
  • Keep street clothes and work clothes separate by providing separate lockers or other storage areas. If possible, store work boots at the worksite; otherwise, have workers use a boot wash before getting into
  • Encourage workers to shower and wash their hair at the workplace (if at a fixed location) or as soon as they get home.

What should employers do if a worker reports Valley Fever symptoms?

  • If the worker disturbed soil or otherwise did dusty work in an endemic area, the employer should send the worker to their workers’ compensation health care provider or occupational medicine clinic. The employer should provide the health care provider with the details about the dust or soil exposure. The worker should give a copy of this fact sheet to the health care provider.
  • When two or more workers report symptoms that suggest Valley Fever, workers should be sent to a single medical provider or occupational medicine clinic for coordinated medical care, if possible. This can facilitate better communication between the medical provider, public health agencies, and employer.
  • Travel through endemic areas has resulted in Valley Fever cases. When a worker who has traveled through an endemic area reports a respiratory illness that lasts more than a week, the employer should send the worker to their workers’ compensation health care provider or occupational medicine clinic.
  • Complete the “Employer’s Report of Occupational Injury or Illness” (Form 5020) for each occupational Valley Fever illness which results in “lost time” or medical treatment beyond first aid.
  • List cases on the Cal/OSHA Form 300, “Log of Work-Related Injuries and Illnesses”.
  • Report immediately any serious injury, illness or death occurring in a place of employment or in connection with any employment to the local Cal/OSHA district office. A “serious injury or illness” is defined in 8 CCR 330(h) found at

What is the treatment for Valley Fever?

Although many people with Valley Fever do not require treatment, those with symptoms should seek medical attention. When Valley Fever is suspected, doctors can order specialized tests to confirm the diagnosis. If treatment is indicated, anti-fungal medications are available. Workers who develop severe or chronic infections may need to stay in the hospital.

It is especially important for people at risk for severe disease, such as people infected with HIV or those with weakened immune systems, to be diagnosed and receive treatment as quickly as possible. People with severe infections need to be treated because advanced Valley Fever can be fatal.

The Occupational Health Branch

OHB improves California worker health and safety through prevention activities. We gather information on job hazards, test new approaches to prevent worker injury and illness, and help make changes at the workplace.

Respiratory Protection is VITAL for prevention of Valley Fever

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