2004 Fiscal Year Final Research Report Summary
Efficacy of beta-ray irradiation in inactivating pathogenic protozoa
| Project/Area Number |
14550549
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Civil and environmental engineering
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| Research Institution | Azabu University |
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Principal Investigator |
MORITA Shigemitsu Azabu University, Health and Environmental Sciences, Assistant Professor, 環境保健学部水環境学研究室, 講師 (50318888)
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| Co-Investigator(Kenkyū-buntansha) |
HIRATA Tsuyoshi Azabu University, Health and Environmental Sciences, Professor, 環境保健学部, 教授 (50005493)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Beta-ray / Inactivation / Protozoa / Cryptosporidium / Repair / Coexisting substances |
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| Research Abstract |
Experimental studies on radioactive rays irradiation were conducted to determine the efficacy of inactivating C.parvum oocysts at various temperatures and intensities. The infectivity decreased exponentially as radiation doses increased. The gamma ray and beta ray doses resulting in a 2 log_<10> reduction in infectivity were 94 Gy and 92 Gy, respectively. Temperature and intensity did not significantly affect the efficacy of radioactive rays irradiation in reducing the infectivity of oocysts. Gamma ray and beta ray doses required for 2 log_<10> reduction in viability as evaluated using in vitro excystation were 13,000 Gy and 12,000 Gy, respectively. Thus, radioactive ray treatment resulted in oocysts that were able to excyst but not infect.
The potential of irradiated oocysts to recover infectivity by photoreactivation and dark repair was investigated.
In the inactivation of C.parvum by beta ray irradiation, high correlation was observed between number of single strand breaks and the dose of beta ray. The yield of single strand breaks formation was calculated to be 0.85/10^3bp per 100 Gy of 500 keV bata ray dose, which is in the same order as that calculated for E.Coli (0.9/10^3bp per 100 Gy of 500 keV bata ray dose).
There was no recovery in infectivity following treatment by fluorescent-light irradiation or storage in darkness.
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Research Products
(13 results)
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[Journal Article] Effect of ultraviolet irradiation on infectivity of Cryptosporidium parvum oocysts2002
Author(s)
Morita, S., Namikoshi, A., Hirata, T., Oguma, K., Katayama, H., Ohgaki, S., Motoyama, N., Fijiwara, M.
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Journal Title
Applied and Environmental Microbiology 68
Pages: 5387-5393
Description
「研究成果報告書概要(和文)」より
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[Journal Article] Effect of ultraviolet irradiation on infectivity of Cryptosporidium parvum oocysts.2002
Author(s)
Morita, S., Namikoshi, A., Hirata, T., Oguma, K., Katayama, H., Ohgaki, S., Motoyama, N., Fijiwara, M.
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Journal Title
Applied and Environmental Microbiology 68, 11
Pages: 5387-5393
Description
「研究成果報告書概要(欧文)」より
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