Arizona's warm, dry climate has long been a magnet for people with respiratory problems. But a report in today's Morbidity and Mortality Weekly Report (MMWR) indicates that its climate is also fueling the rise of a pulmonary menace: Valley Fever.
The disease is caused by a fungus, Coccidioides immitis, and is named after the San Joaquin River valley of California, where in the 1930s it became a problem for migrant workers. It thrives on a cycle of wet weather, which allows the fungus to proliferate in the soil, and hot, dry, and windy conditions, which kick up the infected soil and allow it to be inhaled. The result is a pneumonia with typical flulike symptoms. In a small number of cases, the fungus can spread in the body and cause serious complications, including meningitis. It is treatable with antifungal medications, but can be especially deadly in elderly people and patients whose immune systems are suppressed.
The number of cases of Valley Fever reported in Arizona has risen by 144% in the past 5 years, to 623 in 1995, according to the report in MMWR, which is published by the Centers for Disease Control and Prevention (CDC) in Atlanta. The disease killed 134 people in the state in 1994. Garry Cole, chair of the College of Ohio's microbiology and immunology department, says that the weather this decade has been ideal for the spread of C. immitis--a cycle of heavy rains and severe droughts. Other factors include a rising number of elderly residents and those with HIV, as well as tourists who have not been previously exposed.
While the fever is spreading more rapidly in Arizona, it is endemic to much of the southwestern United States and is prevalent in the area around Bakersfield, California. A peak of more than a thousand cases a month was recorded in 1992 for the state, according to an earlier CDC report, and the 1994 Northridge earthquake contributed to another spike in the number of cases. "In a severe year, we get three to four thousand cases," says economist Ray Geigle, dean of arts and sciences at California State University, Bakersfield, who says that the construction, agriculture, and oil industries can be severely affected.
Rana Hajjeh, an epidemiologist at the CDC, says that people shouldn't panic about Valley Fever. "But if you're moving to Arizona," she says, "you should know about it."