Reactivation of Giardia lamblia cysts after exposure to polychromatic UV light
Article first published online: 24 JUL 2010
© 2010 The Authors. Journal compilation © 2010 The Society for Applied Microbiology
Letters in Applied Microbiology
Volume 51, Issue 4, pages 395–399, October 2010
How to Cite
Shin, G., Linden, K.G. and Faubert, G. (2010), Reactivation of Giardia lamblia cysts after exposure to polychromatic UV light. Letters in Applied Microbiology, 51: 395–399. doi: 10.1111/j.1472-765X.2010.02908.x
- Issue published online: 14 SEP 2010
- Article first published online: 24 JUL 2010
- 2010/0748: received 3 May 2010, revised 22 June 2010 and accepted 14 July 2010
- drinking water disinfection;
- Giardia lamblia;
- medium-pressure UV;
- Mongolian gerbils;
- UV disinfection
Aims: In this study, we determined the ability of a promising alternative UV technology – a polychromatic emission from a medium-pressure UV (MP UV) technology – to inhibit the reactivation of UV-irradiated Giardia lamblia cysts.
Methods and Results: A UV-collimated beam apparatus was used to expose shallow suspensions of purified G. lamblia cysts in PBS (pH 7·2) or filtered drinking water to a low dose (1 mJ cm−2) of MP UV irradiation. After UV irradiation, samples were exposed to two repair conditions (light or dark) and two temperature conditions (25°C or 37°C for 2–4 h). The inactivation of G. lamblia cysts by MP UV was very extensive, and c. 3 log10 inactivation was achieved with a dose of 1 mJ cm−2. Meanwhile, there was no apparent reactivation (neither in vivo nor in vitro) of UV-irradiated G. lamblia under the conditions tested.
Conclusion: The results of this study indicated that, unlike the traditional low-pressure (LP) UV technology, an alternative UV technology (MP UV) could inhibit the reactivation of UV-irradiated G. lamblia cysts even when the cysts were exposed to low UV doses.
Significance and Impact of the Study: It appears that alternative UV technology has some advantages over the traditional LP UV technology in drinking water disinfection because of their high level of inactivation against G. lamblia cysts and also effective inhibition of reactivation in UV-irradiated G. lamblia cysts.