Volume 5, Number 4—August 1999
Dispatch
Chlorine Disinfection of Recreational Water for Cryptosporidium parvum
Colleen Carpenter*, Ronald Fayer*
, James Trout*, and Michael J. Beach†
, James Trout*, and Michael J. Beach†
Table 2
Contact times and infectivity for purified Crytosporidium parvum oocysts subjected to chlorination (Experiments 1 and 2)a
| 2 ppm |
10 ppm |
||||||
|---|---|---|---|---|---|---|---|
| Infectivity |
Infectivity |
||||||
| Expt. | Days (min.) | Ctb value | 20ºC | 30ºC | Ctb value | 20ºC | 30ºC |
| 2 | (360) | 720 | 4/4 | 4/4 | 3,600 | 4/4 | 0/4 |
| 2 | (720) | 1,440 | 4/4 | 3/4 | 7,200 | 0/4 | 0/4 |
| 1 | 1 (1440) | 2,880 | 4/4c | 0/4 | 14,400 | 0/4 | 0/4 |
| 2 | 1 (1440) | 2,880 | 4/4 | 0/4 | 14,400 | 0/4 | 0/4 |
| 1 | 2 (2880) | 5,760 | 0/4 | 0/4 | 28,800 | 0/4 | 0/4 |
| 2 | 2 (2880) | 5,760 | 0/4 | 0/4 | 28,800 | 0/4 | 0/4 |
| 1 | 3 (4320) | 8,640 | 4/4 | 0/4 | 43,200 | 0/4 | 0/4 |
| 2 | 3 (4320) | 8,640 | 0/4 | 0/4 | 43,200 | 0/4 | 3/4 |
| 1 | 4 (5760) | 11,520 | 0/4 | 0/4 | 57,600 | 0/4 | 0/4 |
| 1 | 5 (7200) | 14,400 | 0/4 | 0/4 | 72,000 | 0/4 | 0/4 |
| 1 | 6 (8640) | 17,280 | 0/4 | 0/4 | 86,400 | 0/4 | 0/4 |
| 1 | 7 (10,080) | 20,160 | 0/4 | 0/4 | 100,800 | 0/4 | 0/4 |
aTreatments in which mice were found infected are shown in bold
bHypothetical Ct value calculated by assuming constant chlorine concentration.
cFraction represents number of mice showing developmental stages of C. parvum in the intestinal epithelium over the total number of mice inoculated, e.g., 4/4 indicates 4 mice were found infected out of 4 mice inoculated.
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