Batch solar disinfection inactivates oocysts of Cryptosporidium parvum and cysts of Giardia muris in drinking water

J Appl Microbiol. 2006 Aug;101(2):453-63. doi: 10.1111/j.1365-2672.2006.02935.x.


Aim: 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.

Methods and 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.

Significance and impact of the study: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cryptosporidiosis / prevention & control
  • Cryptosporidium parvum / radiation effects*
  • Disinfection
  • Female
  • Giardia / radiation effects*
  • Giardiasis / prevention & control
  • Mice
  • Mice, Inbred Strains
  • Microscopy, Electron
  • Oocysts / radiation effects
  • Oocysts / ultrastructure
  • Sunlight*
  • Water Microbiology*
  • Water Purification*
  • Water Supply