Evaluation of Cryptosporidium parvum oocyst inactivation following exposure to ultraviolet light-emitting diodes by in vitro excystation and dye staining assays

Makoto Matsubayashi; Isao Teramoto; Itsuo Urakami; Jun Naohara; Kazumi Sasai; Yasutoshi Kido; Akira Kaneko

doi:10.1016/j.parint.2022.102557

Evaluation of Cryptosporidium parvum oocyst inactivation following exposure to ultraviolet light-emitting diodes by in vitro excystation and dye staining assays

Parasitol Int. 2022 Jun:88:102557. doi: 10.1016/j.parint.2022.102557. Epub 2022 Feb 5.

Authors

Makoto Matsubayashi¹, Isao Teramoto², Itsuo Urakami³, Jun Naohara⁴, Kazumi Sasai⁵, Yasutoshi Kido⁶, Akira Kaneko⁶

Affiliations

¹ Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka 598-8531, Japan; Department of Parasitology, Graduate School of Medicine, Osaka City University, Osaka 545-8585, Japan; Asian Health Science Research Institute, Osaka Prefecture University, Osaka 598-8531, Japan; Department of Veterinary Parasitology, Faculty of Veterinary Medicine, Airlangga University, Surabaya 60115, Indonesia. Electronic address: matsubayashi@vet.osakafu-u.ac.jp.
² Department of Parasitology, Graduate School of Medicine, Osaka City University, Osaka 545-8585, Japan.
³ Chiyoda Kohan Co., Ltd., Tokyo 104-8115, Japan.
⁴ Department of Biomedical Engineering, Faculty of Engineering, Okayama University of Science, Okayama 700-0005, Japan.
⁵ Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka 598-8531, Japan; Asian Health Science Research Institute, Osaka Prefecture University, Osaka 598-8531, Japan.
⁶ Department of Parasitology, Graduate School of Medicine, Osaka City University, Osaka 545-8585, Japan; Department of Parasitology and Research Centre for Infectious Disease Sciences, Graduate School of Medicine, Osaka City University, Osaka 545-8585, Japan.

PMID: 35134539
DOI: 10.1016/j.parint.2022.102557

Abstract

Cryptosporidium spp. are protozoan parasites that are transmitted via fecal-oral routes and can exhibit chemical resistance. Chlorine resistance makes it very difficult to eliminate parasites present in contaminated drinking water. While the efficacy of ultraviolet light-emitting diodes (UV-LEDs) against microorganisms has been reported, the efficacy of UV-LEDs against Cryptosporidium spp. has not been fully evaluated. Here, we assessed the efficacy of UV-LEDs with peak wavelengths of 268, 275, 284, and 289 nm against Cryptosporidium parvum at various exposure times, with a fixed exposure distance, using two in vitro methods. Consequently, the time required for 2 log₁₀ inactivation through the excystation method by UV-LEDs of 268, 275, 284, and 289 nm was estimated as 115.5, 104.1, 37.4, and 30.7 min, respectively. The propidium iodide (PI) and 4',6-diamidino-2-phenylindole (DAPI) staining assays estimated the inactivation time as 311.3, 275.2, 60.6, and 39.1 min, respectively. Our results showed that UV-LED irradiation at longer wavelengths produced higher inactivation activity against C. parvum, which corroborates our previously reported in vivo assay results, although further study is needed to clarify the mechanism.

Keywords: Cryptosporidium parvum; In vitro; Inactivation assay; Oocyst; UV lamp; UV-LED.

MeSH terms

Animals
Cryptosporidiosis* / parasitology
Cryptosporidium parvum* / physiology
Cryptosporidium*
Oocysts / physiology
Staining and Labeling
Ultraviolet Rays