Coccidioidmycosis Outbreak

An Outbreak of Coccidioidomycosis (Valley Fever) Caused by Landslides Triggered by the 1994 Northridge, California Earthquake

In:

A Paradox of Power: Voices of Warning and Reason in the Geosciences: Geological Society of America, Reviews in Engineering Geology; Welby, C.W., and Gowan, M.E., editors. 1998.

By:

U.S. Geological Survey
Golden, Colorado
Centers for Disease Control and Prevention
Atlanta, Georgia

Randall W. Jibson

Edwin L. Harp

Eileen Schneider

Rana A. Hajjeh

Richard A. Spiegel

Abstract

Following the 17 January 1994 Northridge, California earthquake (M=6.7), Ventura County, California experienced a major outbreak of coccidioidomycosis (valley fever), a respiratory disease contracted by inhaling airborne fungal spores. In the 8 weeks following the earthquake (24 January through 15 March), 203 outbreak-associated cases were reported, which is about an order of mangitude more that the expected number of cases, and three of these cases were fatal. Simi Valley, in easternmost Ventura County, had the highest attack rate in the county, and the attack rate decreased westward across the county. The temporal and spatial distribution of coccidioidomycosis cases indicates that the outbreak resulted from inhalation of spore-contaminated dust generated by earthquake-triggered landslides. Canyons northeast of Simi Valley produced many highly disrupted, dust-generating landslides during the earthquake and its aftershocks. Prevailing winds after the earthquake were from the northeast, which transported dust into Simi Valley and beyond to communities to the west. The three fatalities from the coccidioidomycosis epidemic accounted for 4 percent of the total earthquake-related fatalities.

A Coccidioidmycosis Outbreak Following the Northridge, California, Earthquake

In:

The Journal of the American Medical Association, March 19, 1997, vol. 277, American Medical Association

By:

Eileen Schneider, MD

Rana A. Hajjeh, MD

Richard A. Speigel, DVM

Randall W. Jibson, PhD

Edwin L. Harp, PhD

Grant A. Marshall, MS

Robert A. Gunn, MD

Micahel M. McNeil, MBBS

Robert W. Pinner, MD

Roy C. Baron, MD

Ronald C. Burger

Lori C. Hutwagner, MS

Casey Crump

Leo Kaufman, PhD

Susan E. Reef, MD

Gary M. Feldman, MD

Demosthenes Pappagianis, MD

S. Benson Werner, MD

Abstract

Objective—To describe a coccidioidomycosis outbreak in Ventura County following the January 1994 earthquake, centered in Northridge, Calif., and to identify factors that increased the risk for acquiring acute coccidioidomycosis infection.

Design—Epidemic investigation, population-based skin test survey, and case-control study.

Setting—Ventura County, California

Results—In Ventura County, between January 24 and March 15, 1994, 203 outbreak-associated coccidioidomycosis cases, including 3 fatalities, were identified (attack rate [AR], 30 cases per 100,000 population). The majority of cases (56%) and the highest AR (114 per 100,000 population) occurred in the town of Simi Valley, a community located at the base of a mountain range that experienced numerous LANDSLIDES associated with the earthquake. Disease onset for cases peaked 2 weeks after the earthquake. The AR was 2.8 times greater for persons 40 years of age and older than younger persons (relative risk, 2.8; 95% confidence interval [CI], 2.1 - 3.7; P<.001). Environmental data indicated that large dust clouds, generated by LANDSLIDES following the earthquake and strong aftershocks in the Santa Susana Mountains north of Simi Valley, were dispersed into nearby valleys by northeast winds. Simi Valley case-control study data indicated that physically being in a dust cloud (odds ratio, 3.0; 95% CI, 1.6 - 5.4; P<.001) and time spent in a dust cloud (P<.001) significantly increased the risk for being diagnosed with acute coccidioidomycosis.

Conclusions—Both the location and timing of cases strongly suggest that the coccidioidomycosis outbreak in Ventura County was caused when arthrospores were spread in dust clouds generated by the earthquake. This is the first report of a coccidioidomycosis outbreak following an earthqukae. Public and physician awareness, especially in endemic areas following similar dust cloud-generating events, may result in prevention and early recognition of acute coccidioidomycosis.

Randy Jibson
U.S. Geological Survey
Geologic Hazards team
email: jibson@usgs.gov
P.O. Box 25046, MS 966
Lakewood, CO 80225
Edwin L. Harp
U.S. Geological Survey
Geologic Hazards team
email: harp@usgs.gov
P.O. Box 25046, MS 966
Lakewood, CO 80225