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Volume 8, Number 7—July 2002

Time-Space Clustering of Human Brucellosis, California, 1973–1992 1

Geoffrey T. Fosgate*, Tim E. Carpenter*, Bruno B. Chomel*, James T. Case†, Emilio E. DeBess‡, and Kevin F. Reilly§
Author affiliations: *University of California, Davis, California, USA; †California Animal Health and Food Safety Laboratory, Davis, California, USA; ‡Department of Human Services, Portland, Oregon, USA; §California Department of Health Services, Sacramento, California, USA;

Main Article

Table 3

Moran’s I procedure for spatial clustering of the four, 5-year cumulative incidences of reported human brucellosis, California, 1973–1992

Crude incidenceb
Race adjustedb
Age-race adjustedb
Yearsa No. of cases z-scorec p value z-scorec p value z-scorec p value
1973–1977 106 2.31 0.02 2.75 0.006 2.84 0.004
1978–1982 97 1.07 0.29 0.05 0.96 -0.34 0.74
1983–1987 98 4.62 <0.001 0.31 0.75 0.27 0.79
1988–1992 115 -0.32 0.75 -0.74 0.46 -0.49 0.63
1973–1992 (mean) 416 1.30 0.19 -0.56 0.57 -0.26 0.79

aCases summed over the specified 5-year period. Incidence over the 20-year period is the mean of incidences for the 5-year periods.
bIncidences are based on the population of the 5-year period’s median year as the denominator. Incidences were adjusted by the direct method with the population distribution of Sacramento County in 1990 as the standard. Data for race were adjusted by using Hispanic and non-Hispanic population totals.
cPositive z-score indicates tendency towards clustering, negative value dispersion.

Main Article

1 Preliminary results of this study were presented at the 9th Symposium of the International Society for Veterinary Epidemiology and Economics, August 6–11, 2000, Breckenridge, Colorado, USA.

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