Table 1.
Distribution of cases of cryptosporidiosis in Greater Glasgow & Clyde NHS Board area by drinking-water source, before and after the introduction of filtration on Loch Katrine water, Scotland
| Relation to enhanced water filtration* | Water source, no.† | ||
|---|---|---|---|
| Loch Katrine | Other | All | |
| Before | 89 (78) | 118 (129) | 207 |
| After | 60 (71) | 128 (117) | 188 |
| All | 149 | 246 | 395 |
*
Coagulation and rapid gravity filtration, introduced in September 2007.
†
Numbers in parentheses are cases expected under the null hypothesis (i.e. no association between water supply and filtration).