Batch solar disinfection inactivates oocysts of Cryptosporidium parvum and cysts of Giardia muris in drinking water.
OBJECTIVE
To determine whether batch solar disinfection (SODIS) can be used to inactivate oocysts of Cryptosporidium parvum and cysts of Giardia muris in experimentally contaminated water.


RESULTS
Suspensions of oocysts and cysts were exposed to simulated global solar irradiation of 830 W m(-2) for different exposure times at a constant temperature of 40 degrees C. Infectivity tests were carried out using CD-1 suckling mice in the Cryptosporidium experiments and newly weaned CD-1 mice in the Giardia experiments. Exposure times of > or =10 h (total optical dose c. 30 kJ) rendered C. parvum oocysts noninfective. Giardia muris cysts were rendered completely noninfective within 4 h (total optical dose >12 kJ). Scanning electron microscopy and viability (4',6-diamidino-2-phenylindole/propidium iodide fluorogenic dyes and excystation) studies on oocysts of C. parvum suggest that inactivation is caused by damage to the oocyst wall.


CONCLUSIONS
Results show that cysts of G. muris and oocysts of C. parvum are rendered completely noninfective after batch SODIS exposures of 4 and 10 h (respectively) and is also likely to be effective against waterborne cysts of Giardia lamblia.


CONCLUSIONS
These results demonstrate that SODIS is an appropriate household water treatment technology for use as an emergency intervention in aftermath of natural or man-made disasters against not only bacterial but also protozoan pathogens.
McGuigan
K G
KG
Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland. kmcguigan@rcsi.ie
Méndez-Hermida
F
F
Castro-Hermida
J A
JA
Ares-Mazás
E
E
Kehoe
S C
SC
Boyle
M
M
Sichel
C
C
Fernández-Ibáñez
P
P
Meyer
B P
BP
Ramalingham
S
S
Meyer
E A
EA
D000818:Animals; D003457:Cryptosporidiosis / Q000517:prevention & control; D016785:Cryptosporidium parvum / Q000528:radiation effects*; D004203:Disinfection; D005260:Female; D005872:Giardia / Q000528:radiation effects*; D005873:Giardiasis / Q000517:prevention & control; D051379:Mice; D008815:Mice, Inbred Strains; D008854:Microscopy, Electron; D033661:Oocysts / Q000528:radiation effects / Q000648:ultrastructure; D013472:Sunlight; D014871:Water Microbiology; D018508:Water Purification; D014881:Water Supply