Investigation of clusters of giardiasis using GIS and a spatial scan statistic

Table 2 Significant low rate giardiasis spatial clusters in southern Ontario, 1990–98

Cluster^a	No. of Cases in cluster	Expected No. of cases	Annual cases per 100,000 person-yrs	Cluster RR^b	No. of CSDs^c	P-value
1	102	587	0.3	0.17	15	0.001
2	297	704	0.8	0.42	4	0.001
3	257	542	0.9	0.47	5	0.001
4	275	541	1	0.51	19	0.001
5	494	722	1.3	0.68	6	0.001
6	339	457	1.4	0.742	1	0.001
7	2	20	0.2	0.1	6	0.019
8	105	166	1.2	0.63	14	0.065

^a See Figure 4 for the spatial distribution of the geographically large clusters ^b Rate ratio ^c Census Sub-divisions

ISSN: 1476-072X