From 2000 to 2006, cases of valley fever in California increased from 2.4 cases per 100,000 people to eight cases per 100,000 people, according to a study by the California Department of Public Health published in CDC's Morbidity and Mortality Weekly Report, the Los Angeles Times' "Booster Shots" reports.
The study said the jump in infections could be attributed to:
- Construction projects that disrupt soil and release spores into the air;
- An increase in the number of people with chronic conditions that weaken immune systems; and
- An influx of residents who have not been exposed to the fungi previously.
The study found that most illnesses happened in the San Joaquin Valley, particularly Kern County.
Valley fever infections also have increased in Arizona, which reports the most cases in the U.S. (Engel, "Booster Shots," Los Angeles Times, 2/12).