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|
Research
Sporadic Cryptosporidiosis
Decline after Membrane Filtration of Public Water Supplies, England, 1996–2002
Stella Goh,* Mark Reacher,†
David P. Casemore,‡ Neville Q. Verlander,§ André Charlett,§ Rachel M.
Chalmers,¶ Margaret Knowles,# Anthony Pennington,* Joy Williams,* Keith
Osborn,** and Sarah Richards††
*Carlisle and District Primary Care Trust, Carlisle, United Kingdom; †Health
Protection Agency, Cambridge, United Kingdom; ‡University of Wales, Aberystwyth,
Ceredigion, Wales, United Kingdom; §Health Protection Agency Centre for
Infections, Colindale, London, United Kingdom; ¶Singleton Hospital, Swansea,
Wales, United Kingdom; #Cumberland Infirmary, Carlisle, United Kingdom;
**United Utilities, Great Sankey, Warrington, United Kingdom; and ††West
Cumberland Hospital, Whitehaven, United Kingdom
Appendix
| Appendix
Table 1. Water sources, water distribution zones, filtration,
and populations served, Copeland and Allerdale Local Authorities,
1996–2002 |
|
|
Water sources
|
Water zones
|
Filtration of water supplies
|
Average population
|
|
|
Crummock Lake
|
Crummock North
Crummock South
|
Unfiltered March 1, 1996–February
29, 2000;
membrane filtration from March 1, 2000, to August 31, 2002
|
58,295
|
|
Ennerdale Lake
|
Ennerdale North
Ennerdale South
|
Unfiltered March 1, 1996–February
29, 2000;
membrane filtration from March 1, 2000, to August 31, 2002
|
47,780
|
|
"Other*"
|
Millom
Quarry Hill
Hausegill
Hayknott
Underscar
Bridgend
Fellside
Multiple sources
Private
|
Conventionally filtered* throughout
the study
period (March 1, 1996–August 31, 2002)
|
59,699
|
|
| *A variety of conventionally
treated and unfiltered water, and private supplies. |
| Appendix
Table 2. Symptoms and duration of symptoms in case-patients |
|
|
Characteristics
|
n (%)
|
|
|
Before membrane filtration
|
After membrane filtration
|
Before and after membrane filtration
|
|
|
|
|
March 1, 1996–February 29, 2000
|
March 1, 2000–August 31, 2002
|
March 1, 1996–August 31, 2002
|
|
|
Symptoms
|
|
Diarrhea
|
153 (100)
|
22 (100)
|
175 (100)
|
|
Vomiting
|
94 (61.4)
|
10 (45.5)
|
104 (59.4)
|
|
Abdominal pain
|
110 (71.9)
|
18 (81.8)
|
128 (73.1)
|
|
Fever
|
69 (45.1)
|
9 (40.9)
|
78 (44.6)
|
|
Loss of appetite
|
68 (44.4)
|
18 (81.8)
|
86 (49.1)
|
|
Weight loss
|
56 (36.6)
|
17 (77.3)
|
73 (41.7)
|
|
Symptoms at interview
|
38 (24.8)
|
4 (18.2)
|
42 (24.0)
|
|
No symptoms at interview
|
115 (75.2)
|
18 (81.8)
|
133 (76.0)
|
|
Median days* symptomatic
|
9
|
10
|
9
|
|
Range
|
2–21
|
3–20
|
2–21
|
|
| *Of patients without symptoms
at interview. |
| Appendix
Table 3. Admissions to hospital by age and sex |
|
|
Characteristics
|
Before membrane filtration
|
After membrane filtration
|
Before and after membrane filtration
|
|
|
|
|
March 1, 1996–February 29, 2000
|
March 1, 2000–August 31, 2002
|
March 1, 1996–August 31, 2002
|
|
|
|
|
Total
|
Admitted
|
%
|
Total
|
Admitted
|
%
|
Total
|
Admitted
|
%
|
|
|
Female
|
|
<1–5 y
|
34
|
5
|
15
|
7
|
1
|
14
|
41
|
6
|
15
|
|
6–15 y
|
22
|
2
|
9
|
4
|
1
|
25
|
26
|
3
|
12
|
|
Total >1–15 y
|
56
|
7
|
13
|
11
|
2
|
18
|
67
|
9
|
13
|
|
Male
|
|
<1–5 y
|
53
|
14
|
26
|
2
|
0
|
0
|
55
|
14
|
25
|
|
6–15 y
|
25
|
2
|
8
|
3
|
1
|
33
|
28
|
3
|
11
|
|
Total <1–15 y
|
78
|
16
|
21
|
5
|
1
|
20
|
83
|
17
|
20
|
|
F and M
|
|
<1–5 y
|
87
|
19
|
22
|
9
|
1
|
11
|
96
|
20
|
21
|
|
6–15 y
|
47
|
4
|
9
|
7
|
2
|
29
|
54
|
6
|
11
|
|
Total <1–15 y
|
134
|
23
|
17
|
16
|
3
|
19
|
150
|
26
|
17
|
|
| Appendix
Table 4. Speciation of Cryptosporidium isolates |
|
|
Isolates
|
n (%)
|
|
|
Before membrane filtration
|
After membrane filtration
|
Before and after membrane filtration
|
|
|
|
|
January 1, 1998–February 29, 2000
|
March 1, 2000–August 31, 2002
|
January 1, 1998–August 31, 2002
|
|
|
Total speciated
|
68 (100)
|
16 (100)
|
84 (100)
|
|
C. hominis
|
1 (1.5)
|
3 (18.8)
|
4 (4.8)
|
|
C. parvum
|
57 (83.8)
|
13 (81.2)
|
70 (83.3)
|
|
Not determined
|
10 (14.7)
|
0 (0)
|
10 (11.9)
|
|
|
