In the boomtowns of Southern California and the American Southwest, where houses go up faster than the land can be cleared, the air is filled with dust churned up by bulldozers and held aloft by the hot wind. But dust isn't the only problem in these overheated regions. Another is the lung disease, valley fever, known medically as coccidioidomycosis, or cocci.
The soil-borne fungus that causes valley fever is stirred into the air by farming, construction and wind, and then breathed into the lungs. Valley fever can cause fever, chest pain and coughing, among other symptoms. Most people who inhale the valley fever fungus have few, if any, problems. But some, especially pregnant women, people with weakened immune systems, and those of Asian, Hispanic and African descent, may develop a serious or even fatal illness from valley fever.
Mild cases of valley fever usually go away on their own. When valley fever is more serious, doctors prescribe antifungal medications that can treat the underlying infection.
The fungus that causes valley fever, Coccidioides immitis, thrives in the alkaline desert soils of southern Arizona, northern Mexico and California's San Joaquin Valley. It's also endemic to Utah, Nevada, New Mexico, Texas and parts of Central and South America — areas with mild winters and arid summers.
Like many other fungi, Coccidioides immitis has a complex life cycle. In the soil, it grows as a mold with long filaments that break off into airborne spores when the soil is disturbed. The spores are extremely small, can be carried hundreds of miles by the wind and are highly contagious. Once inside the lungs, the spores reproduce, perpetuating the cycle of the disease.
For more than half of infected people, this poses no problem. Their immune system effectively "walls off" the fungus, and they never develop symptoms, although they may have lingering patches of infection in their lungs. Others have varying degrees of chest pain, weakness, fever, chills, night sweats, joint aches and sometimes a rash or swollen lymph nodes — symptoms that usually go away on their own or with treatment. In a few people, the illness progresses to severe pneumonia or spreads beyond the lungs and may ultimately prove fatal.
How global warming, snowbirds, the real estate boom and AIDS contribute to valley fever
The first case of valley fever was recognized more than a century ago. Since then, doctors have diagnosed upward of 100,000 cases a year in endemic areas. But starting in the 1990s, the incidence of valley fever increased significantly, especially in California and Arizona. A number of factors seem to have contributed to the rise in reported cases — up more than threefold between 1993 and 2003 in Arizona alone.
Valley fever isn't limited to humans; dogs, horses, cattle, bats, snakes, coyotes and most other animals also are susceptible to the disease. Even house cats can catch valley fever when dust seeps in around windows and doors during storms.
- Climate change. In desert regions, changing rainfall patterns and extended periods of drought seem to be closely associated with the upsurge in valley fever. Coccidioides, dormant during long dry spells, "blooms" when it rains and is swept into the air by anything that disturbs the soil: earthquakes, storms, farming, construction. In Arizona, most outbreaks occur in June, July, August, October and November. In California, the risk of infection is highest during the summer months, usually June through August.
- Population growth. During the past few decades, the Southwest has seen unprecedented growth, with a great increase in both permanent residents and winter visitors. That means large numbers of people with no natural immunity to valley fever are exposed to the fungus. The influx of people into California during the Dust Bowl of the 1930s sparked a similar rise in valley fever outbreaks.
- Building boom. Unchecked growth has been one of the most troublesome consequences of the mass migration to the Sun Belt states. This has led to rampant land clearing and construction, which spew thousands of tons of fungus-laden dust into the air every year.
- HIV/AIDS. People with severely compromised immune systems, especially those with advanced AIDS, are at great risk of disseminated valley fever. As people live longer with AIDS, and as they relocate or travel to endemic areas, the risk of serious infection increases.
When to seek medical advice:
- Environmental exposure. Anyone who inhales the spores that cause valley fever is at risk of infection. Some experts estimate that up to half of the people living in areas where valley fever is common have had the disease. People who have jobs that expose them to dust are most at risk — construction, road and agricultural workers, ranchers, archeologists, and military personnel on field exercises.
- Smoking. Smokers, especially those with scarring and thickening of lung tissue (pulmonary fibrosis), are at higher risk of valley fever than nonsmokers are.
- Race. For reasons that aren't well understood, people of color are more susceptible to valley fever and several times more likely to develop serious illness than whites are. Filipinos, Hispanics and blacks have the highest risk.
- Pregnancy. Pregnant women are vulnerable to valley fever in the third trimester and right after their babies are born.
- Diabetes. The rate of valley fever infection is higher among people with diabetes.
- Weakened immune system. Anyone with a weakened immune system — including people living with AIDS or those treated with steroids, chemotherapy or anti-rejection drugs after transplant surgery — is at high risk of valley fever as well as of serious complications of the disease. People with cancer and Hodgkin's disease also have an increased risk.
- Age. Older adults are more likely to develop valley fever than younger people are, possibly because their immune systems are less robust or because they have other medical conditions that affect their overall health.
Valley fever, even when it's symptomatic, often clears on its own. Yet for older adults and others at high risk, recovery can be slow and the risk of disseminated disease high. For that reason, it's important to seek medical care if you develop the signs and symptoms of valley fever, especially if you live in or have recently traveled to an area where this disease is common.
Be sure to tell your doctor if you've traveled to a place where valley fever is endemic and have symptoms. More and more often, people who spend a few days golfing or hiking in Arizona return home with valley fever but are never tested for the disease.
Valley fever occurs in three forms: acute, chronic and disseminated.
Acute valley fever
The acute form is often mild, with few, if any, symptoms. When symptoms do occur, they tend to resemble those of the flu, and can range from minor to severe:
- Chest pain, which can vary from a mild feeling of constriction to intense pressure resembling a heart attack.
- Night sweats.
- Shortness of breath.
- Joint aches.
- Rash. Some people develop painful red bumps that may later turn brown — mainly on the lower legs but sometimes on the chest, arms and back. Others may have a raised red rash with blisters or eruptions that look like pimples.
If you don't become ill from valley fever, you may only learn that you've been infected when you later have a positive skin or blood test or when small areas of residual infection (nodules) show up on a routine chest X-ray. Although they don't cause problems in and of themselves, nodules can look like cancer on X-ray, leading to unnecessary biopsies.
If you do develop symptoms, especially severe ones, the course of the disease is uncertain. It can take from six months to a year to fully recover, and fatigue and joint aches can last even longer. The severity of the disease depends on several factors, including your overall health and the number of fungus spores you inhale.
Chronic valley fever
Appearing as many as 20 years after the initial infection, chronic valley fever is most common in people with diabetes or a weakened immune system. You're likely to have periods of worsening symptoms alternating with periods of recovery. Signs and symptoms are similar to those of tuberculosis:
Disseminated valley fever
- Low-grade fever
- Weight loss
- Chest pain
- Blood-tinged sputum
- Nodules in the lungs
The most serious form of the disease, disseminated valley fever occurs when the infection spreads beyond the lungs to other parts of the body, most often the skin, bones, liver, brain, heart and the membranes that protect the brain and spinal cord (meninges).
The signs and symptoms of disseminated disease depend on which parts of your body are affected and may include:
- Nodules, ulcers and skin lesions that are more serious than the rash that sometimes occurs with other forms of the disease
- Painful lesions in the skull, spine or other bones
- Painful, swollen joints, especially in the knees or ankles
- Meningitis — an infection of the membranes and fluid surrounding the brain and spinal cord and the most deadly complication of valley fever
Valley fever isn't diagnosed on the basis of signs and symptoms, which are usually vague and nonspecific, or on a chest X-ray, which can't distinguish valley fever from other lung diseases. Instead, a definitive diagnosis depends on finding Coccidioides spherules in infected tissue, blood or other body secretions. For that reason, you're likely to have one or more of the following tests:
- Sputum smear or culture. These tests check a sample of your sputum for the presence of the valley fever fungus.
- Blood tests. Through a blood test, your doctor can check for antibodies against the fungus that causes valley fever and determine how serious your infection is.
Valley fever can cause a number of serious complications, especially in people living with HIV/AIDS. These complications include:
- Severe pneumonia. Most people recover from valley fever pneumonia with only residual scarring in their lungs. Others, mainly people of color and those with weakened immune systems, may become seriously ill.
- Lung nodules. A small percentage of people develop thin-walled nodules (cavities) in their lungs. Many of these eventually disappear without causing any problems, but some may rupture, causing chest pain and difficulty breathing. A ruptured lung nodule requires the placement of a tube into the space around the lungs to remove the air, or surgery to repair the damage.
- Disseminated disease. This is by far the most serious complication of valley fever. If the fungus spreads throughout the body, it can leave a trail of devastation, ranging from skin ulcers and abscesses to bone lesions, severe joint pain, heart inflammation, urinary tract problems and meningitis — an infection of the membranes and fluid covering the brain and spinal cord.
Most people with acute valley fever don't require treatment. Even when symptoms are fairly serious, the best therapy for otherwise healthy adults is usually bed rest and fluids — the same approach used for colds and the flu. Still, doctors carefully monitor people with valley fever, and if symptoms don't improve or become worse, they may prescribe antifungal medications such as fluconazole.
Antifungal medications are also used for high-risk people or for those with chronic or disseminated disease.
In general, the antifungal drugs fluconazole and itraconazole are used for all but the most serious cases. All antifungals can have serious side effects, however, they usually go away once the medication is stopped. The most common side effects of fluconazole and itraconazole are nausea, vomiting, abdominal pain and diarrhea.
These medications control the fungus but don't destroy it, and relapses are common. For many people, a single bout of valley fever bestows lifelong immunity, but the disease can be reactivated or you can be reinfected if your immune system is weakened for any reason.
The few ways of preventing valley fever — wearing a mask, staying inside during dust storms, wetting the soil before digging, keeping doors and windows tightly closed — aren't particularly effective. Still, if you live in or visit areas where valley fever is common — especially Phoenix or Tucson, Arizona, and Bakersfield, California — take commonsense precautions, especially during the summer months, when the chance of infection is highest.
|Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.