Table 4. Incidence of sporadic cryptosporidiosis by water source, March 1, 1996–August 31, 2002.

Water source and time intervals*	Membrane filtration (MF)	Cases (n)	Person-years	Rate per 100,000 person-years	95% CI†
Crummock Lake
Before MF interval	No	56	233,623	23.97	(18.11, 31.13)
After MF interval
Commissioning MF	Yes	1	25,726	3.89	(0.10, 21.66)
Established MF pre-FMDE	Yes	1	33,970	2.94	(0.07, 16.40)
Established MF and FMDE	Yes	1	54,902	1.82	(0.05, 10.15)
Established MF and post-FMDE	Yes	3	31,490	9.53	(1.96, 27.84)
Total after MF	Yes	6	146,088	4.11	(1.51, 8.91)
Ennerdale Lake
Before MF interval	No	43	191,053	22.51	(16.29, 30.32)
After MF interval
Commissioning MF	Yes	0	20,258	0	(0, 18.21)
Established MF pre-FMDE	Yes	1	27,223	3.67	(0.09, 20.47)
Established MF and FMDE	Yes	2	46,387	4.31	(0.52, 15.57)
Established MF and post-FMDE	Yes	0	26,606	0	(0, 13.86)
Total after MF	yes	3	120,474	2.49	(0.51, 7.28)
Other sources
Before MF interval	No	54	238,265	22.66	(17.03, 29.57)
After MF interval
Commissioning MF	No	3	24,449	12.27	(2.53, 35.86)
Established MF pre-FMDE	No	4	32,257	12.4	(3.38 , 31.75 )
Established MF and FMDE	No	3	51,997	5.77	(1.19, 16.86)
Established MF and post-FMDE	No	3	29,824	10.06	(2.07, 29.40)
Total after MF	No	13	138,527	9.38	(5.00,16.05)

*Time intervals. pre-MF (membrane filtration) March 1, 1996–February 29, 2000; post-MF March 1, 2000–August 31, 2002. Post-MF comprises the following: commissioning MF, March 1, 2000–July 31, 2000; established MF before foot and mouth disease epidemic (FMDE), August 1, 2000–February 20, 2001; established MF and FMDE, February 21, 2001–January 20, 2002; established MF and post-FMDE, January 21, 2002–August31, 2002.
†CI, confidence intervals.