Dr. Jeff Hersh: Airborne fungus can be harmful
Q: Can someone really breathe in a fungus in the desert in Arizona that can kill them?
A: With the spectrum of possible diseases so vast, it should not be surprising that the short answer is yes. To give a more in-depth answer I will discuss coccidioidomycosis (also called Valley Fever).
Coccidioidomycosis is the infection caused by the fungus Coccidioides, an organism that is found in soil in the southern and western hemispheres, especially in arid areas (including deserts) where it can lay dormant for long periods of time. Areas of California, Arizona and Texas are the places in the U.S. where it is most common.
During dry conditions the spores can be blown into the air and people can breathe them in, so certain professions such as construction or farming which "stir" up dry soil increase the risk of exposure.
Once in the lungs, as little as one spore can cause coccidioidomycosis. In response to this infection, the body mobilizes an immune response that relies on T-cells. Therefore people with immunodeficiencies - especially T-cell deficiencies such as advanced HIV - are at increased risk.
After one to three weeks incubation, there can be sufficient fungi to cause clinical disease. About 60 percent of infected people have symptoms so mild they don't seek medical care; that they were infected is only noted when surveillance antibody tests are done. These patients do not require any treatment and the condition resolves on its own.
About 40 percent of patients infected with Coccidioides develop severe enough symptoms to seek medical care. Since the fungi are usually inhaled, pneumonia symptoms such as fever, cough (sometimes productive of blood tinged sputum), chest pain, weakness and/or flu-like symptoms are the most common clinical presentation.
Some studies note that 25 percent to 50 percent of community-acquired pneumonia in Tucson, Ariz., is due to coccidioidomycosis. Because the symptoms are so similar to community-acquired pneumonia from bacteria, many of these patients are empirically treated with anti-bacterial antibiotics. Over 90 percent of coccidioidomycosis pneumonias resolve on their own, so it may seem the antibiotics helped even though they did not.
Some people with coccidioidomycosis have an immune response that causes rashes/nodules (erythema nordosum), joint stiffness/pain (sometimes called desert rheumatism) and possibly other symptoms. About 5 percent of people with coccidioidomycosis pneumonia develop lung nodules (or, less commonly, cavitations). These nodules can look like lung cancer on X-rays, and sometimes biopsies of these nodules due to suspected cancer is how the condition is diagnosed.
Unfortunately, up to 0.5 percent of all infections have the fungus spread to other parts of the body, causing severe illness (disseminated disease). These patients may have the infection spread to their liver, spleen, blood stream, bone and even the lining around their brain and spinal cord (causing meningitis). Dissemination is more common in immune compromised patients.
Meningitis symptoms can include headache, fever and neck stiffness, and the disease is diagnosed by examination of fluid obtained from a lumbar puncture. This condition is treated with intravenous anti-fungal medications.
Other disseminated disease may present weeks, months or even a year or more after the initial infection as a chronic condition, with symptoms of weight loss, weakness, loss of appetite, shortness of breath, chronic cough and other non-specific symptoms.
I think of this presentation as similar to tuberculosis. In fact, a chest X-ray in these patients can look similar to a tuberculosis X-ray. These patients usually require long duration therapy with anti-fungal medications, oral or intravenous depending on the specific issues for the patient. Unfortunately, some of these patients die from complications of their disease.
Rarely, the fungus can invade an open wound and cause a primary skin infection. These infections are usually diagnosed by clinical inspection and a biopsy, and are treated with anti-fungal medications.
Coccidioidomycosis is common in places where the fungus is endemic, affecting up to 3 percent of people who live in these areas per year (150,000 people), as well as an unknown percentage of visitors. Although over 90 percent of these infections result in self-limited disease (with no treatment required and a full recovery), disseminated disease and/or lung nodules can develop.
It is very important to tell your health care provider if you have traveled to or lived in an area where coccidioidomycosis is endemic so they can consider this diagnosis when it is appropriate.
Jeff Hersh, Ph.D., M.D., F.A.A.P., F.A.C.P., F.A.A.E.P., can be reached at DrHersh@juno.com.