Volume 8, Number 7—July 2002
Research
Time-Space Clustering of Human Brucellosis, California, 1973–1992 1
Table 5
Population-adjusted Moran’s I (Ipop) analysis for spatial clustering of reported human brucellosis cases due to Brucella abortus and B. melitensis in Hispanic populations, California, 1973–1992.
Years | No. of cases | z-score | p value | Within %a | Among % |
---|---|---|---|---|---|
B. abortusb | |||||
1973–1977 | 12 | -0.01 | 0.99 | 96.7 | 3.3 |
1978–1982 | 12 | 4.28 | <0.001 | 74.8 | 25.2 |
1983–1987 | 9 | -0.47 | 0.64 | 125.4c | -25.4c |
1988–1992 | 23 | 0.15 | 0.88 | 108.8c | -8.8c |
B. melitensis | |||||
1973–1977 | 17 | 6.47 | <0.001 | 62.4 | 37.6 |
1978–1982 | 48 | 8.77 | <0.001 | 70.8 | 29.2 |
1983–1987 | 56 | 1.18 | 0.24 | 83.2 | 16.8 |
1988–1992 | 50 | 3.15 | 0.002 | 104.6c | -4.6c |
aPercentage of estimated spatial clustering attributed to cases in same counties and in adjacent counties.
bCases are reported as B. abortus or B. melitensis based on bacterial isolation or reported animal contact as cattle or goats, respectively, when bacterial isolation was not performed or species not determined.
cAll identified clustering due to cases in the same counties. Negative value for 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.