Valley Fever Outbreak Blamed on Quake’s Dust Cloud : Health: Researchers say the Ventura County cases are the first known to be related to a temblor. An L.A. County official disputes the findings.


A cloud of dust rising from the Santa Susana Mountains after the Jan. 17 earthquake may have been responsible for the unprecedented outbreak of valley fever that struck Simi Valley and much of eastern Ventura County this spring, scientists say.

After five months of interviews and analysis, scientists at the federal Centers for Disease Control have concluded that residents caught in the dust cloud were most likely to contract the flu-like ailment.

Researchers believe that disease-bearing spores were stirred up by landslides caused by the quake and its aftershocks, then swept with the wind across the county.

“The spores are often in the ground, but they’re pretty much just sitting there,” said Richard Spiegel, a researcher with the Atlanta-based CDC. “Basically from all the ground shaking, that unleashed significantly more dust than you might normally have.”


Altogether, 203 cases of valley fever were diagnosed among Ventura County residents in the weeks after the quake. That compares to 52 cases for all of 1993. A 71-year-old Simi Valley man died in the 1994 outbreak.

The CDC team will declare the Simi Valley outbreak the first known to be related to an earthquake when it presents its conclusions at a Stanford University conference Thursday.

But Dr. Shirley Fannin, director of disease control programs for Los Angeles County, disputed the findings.

‘Piddle paddle,” Fannin said. “I have to tell you I disagree.”


The San Fernando Valley, hardest hit by the magnitude 6.8 quake, saw little change in its rate of disease, she said. Only 46 cases have been reported this year.

The disease, a fungal infection known to scientists as coccidioidomycosis, manifests no real symptoms in about 60% of cases. Other victims experience flu-like exhaustion, coughing, even high fever and pneumonia. Older people are usually more severely affected.

Fannin believes that Ventura County and the CDC overreacted to the valley fever scare.

“They called everything with a positive lab test for antibodies a case of valley fever,” she said. She explained that tests would have been positive if a patient had contracted the illness any time in the last several years.


Los Angeles County health officials do not count a case as valley fever until further tests or active symptoms confirm the disease, Fannin said.

CDC researchers defended their findings, saying all of the Ventura County cases were confirmed with blood tests. The direction of the wind or the amount of fungus found in the paved-over San Fernando Valley could account for the low incidence there, said Eileen Schneider, a CDC epidemiologist in San Diego.

Also, she said the San Gabriel Mountains northeast of the Valley did not experience the same landslide activity that occurred in the Santa Susana range near Simi Valley. Although the northern edge of the Valley also borders the Santa Susanas, winds were blowing toward Simi Valley after the quake, Schneider said.

The quake and each of its aftershocks brought up a cloud of ocher dust from the canyons around Simi Valley. The highest concentrations of valley fever cases occurred in the neighborhoods near the base of the mountains north of the city, she said.


A map hanging in Ventura County’s Public Health Services Department shows graphically how valley fever spores may have spread. Dozens of pushpins are clustered in Simi Valley.

The pins fan out on a southwest course, with several cases in Thousand Oaks, and thin out farther from the mountains on the Oxnard Plain.

Ventura County and CDC officials believed from the start that the earthquake had kicked off the valley fever outbreak, but conducted tests this spring aimed at proving their theory.

They asked valley fever victims if they had been in a dust cloud, and more than a third responded that they had.


They tested a random sample of the Simi Valley population for overall exposure to the fungus causing valley fever and found fewer than 6% had been exposed. They tracked the cases and found that the incidence of the disease returned to normal levels about two months after the quake.

Finally, they studied the age, race and other demographic factors for victims and found nothing to suggest another reason for the outbreak, Schneider said.

The disease takes it name from the San Joaquin Valley, where it is most commonly found.