Volume 8, Number 7—July 2002
Research
Time-Space Clustering of Human Brucellosis, California, 1973–1992 1
Table 4
Population-adjusted Moran’s I (Ipop) analysis for spatial clustering of reported human brucellosis cases, California, 1973–1992
Years | No. of cases | z-score | p value | Within %a | Among %a |
---|---|---|---|---|---|
Total population | |||||
1973–1977 | 106 | 7.79 | <0.001 | 75.4 | 24.6 |
1978–1982 | 97 | 9.04 | <0.001 | 62.1 | 37.9 |
1983–1987 | 98 | 4.94 | <0.001 | 56.5 | 43.5 |
1988–1992 | 115 | 4.22 | <0.001 | 93.1 | 6.9 |
1973–1992 | 416 | 18.67 | <0.001 | 58.6 | 41.4 |
Hispanic population | |||||
1973–1977 | 60 | 6.84 | <0.001 | 77.6 | 22.4 |
1978–1982 | 73 | 11.66 | <0.001 | 61.2 | 38.8 |
1983–1987 | 75 | 1.19 | 0.23 | 78.5 | 21.5 |
1988–1992 | 97 | 3.87 | <0.001 | 107.9b | -7.9b |
1973–1992 | 305 | 15.18 | <0.001 | 70.8 | 29.2 |
Non-Hispanic population | |||||
1973–1977 | 46 | 1.52 | 0.13 | 80.7 | 19.3 |
1978–1982 | 24 | 0.15 | 0.88 | 95.0 | 5.0 |
1983–1987 | 23 | 1.47 | 0.14 | 91.0 | 9.0 |
1988–1992 | 18 | 0.49 | 0.62 | 82.9 | 17.1 |
1973–1992 | 111 | 1.41 | 0.16 | 92.3 | 7.7 |
aPercentage of estimated spatial clustering attributed to cases in the same counties and in adjacent counties.
bAll identified clustering attributed to cases in the same counties. Negative value in % demonstrates dispersion of cases in adjacent counties.
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.