This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Brownell, S. A. Articles by Nelson, K. L. Search for Related Content PubMed PubMed Citation Articles by Brownell, S. A. Articles by Nelson, K. L. Agricola Articles by Brownell, S. A. Articles by Nelson, K. L.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, March 2006, p. 2178-2184, Vol. 72, No. 3
0099-2240/06/$08.00+0     doi:10.1128/AEM.72.3.2178-2184.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Inactivation of Single-Celled Ascaris suum Eggs by Low-Pressure UV Radiation

University of California, Berkeley, Berkeley, California 94720

Received 10 August 2005/ Accepted 30 December 2005

Intact and decorticated single-celled Ascaris suum eggs were exposed to UV radiation from low-pressure, germicidal lamps at fluences (doses) ranging from 0 to 8,000 J/m² for intact eggs and from 0 to 500 J/m² for decorticated eggs. With a UV fluence of 500 J/m², 0.44- ± 0.20-log inactivation (mean ± 95% confidence interval) (63.7%) of intact eggs was observed, while a fluence of 4,000 J/m² resulted in 2.23- ± 0.49-log inactivation (99.4%). (The maximum quantifiable inactivation was 2.5 log units.) Thus, according to the methods used here, Ascaris eggs are the most UV-resistant water-related pathogen identified to date. For the range of fluences recommended for disinfecting drinking water and wastewater (200 to 2,000 J/m²), from 0- to 1.5-log inactivation can be expected, although at typical fluences (less than 1,000 J/m²), the inactivation may be less than 1 log. When the eggs were decorticated (the outer egg shell layers were removed with sodium hypochlorite, leaving only the lipoprotein ascaroside layer) before exposure to UV, 1.80- ± 0.32-log reduction (98.4%) was achieved with a fluence of 500 J/m², suggesting that the outer eggshell layers protected A. suum eggs from inactivation by UV radiation. This protection may have been due to UV absorption by proteins in the outer layers of the 3- to 4-µm-thick eggshell. Stirring alone (without UV exposure) also inactivated some of the Ascaris eggs (20% after 75 min), which complicated determination of the inactivation caused by UV radiation alone.

This article has been cited by other articles:

• Pecson, B. M., Barrios, J. A., Johnson, D. R., Nelson, K. L. (2006). A Real-Time PCR Method for Quantifying Viable Ascaris Eggs Using the First Internally Transcribed Spacer Region of Ribosomal DNA. Appl. Environ. Microbiol. 72: 7864-7872 [Abstract] [Full Text]