Infectivity of Giardia duodenalis Cysts from UV Light-Disinfected Wastewater Effluent Using a Nude BALB/c Mouse Model

Luciana Urbano Dos Santos; Delma Pegolo Alves; Ana Maria Aparecida Guaraldo; Romeu Cantusio Neto; Mauricio Durigan; Regina Maura Bueno Franco

doi:10.5402/2013/713958

Infectivity of Giardia duodenalis Cysts from UV Light-Disinfected Wastewater Effluent Using a Nude BALB/c Mouse Model

ISRN Parasitol. 2013 Jan 14:2013:713958. doi: 10.5402/2013/713958. eCollection 2013.

Authors

Luciana Urbano Dos Santos¹, Delma Pegolo Alves², Ana Maria Aparecida Guaraldo³, Romeu Cantusio Neto⁴, Mauricio Durigan⁵, Regina Maura Bueno Franco⁶

Affiliations

¹ Laboratory of Oxidation Processes, Department of Sanitation and Environment, School of Civil Engineering, Architecture and Urbanism, University of Campinas (UNICAMP), C.P. Box 6021, 13083-852 Campinas, SP, Brazil.
² CEMIB Multidisciplinary Centre for Biological Investigation, University of Campinas (UNICAMP), C.P. Box 6095, 13083-877 Campinas, SP, Brazil.
³ Laboratory of Helminthology, Department of Parasitology, Institute of Biology, University of Campinas (UNICAMP), C.P. Box 6109, 13083-970 Campinas, SP, Brazil.
⁴ Laboratory of Microbiology, Society for Water Supply and Sanitation (SANASA), Street Abolição 2.375, 13045-750 Campinas, SP, Brazil.
⁵ Laboratory of Genetic and Molecular Analysis, Center of Molecular Biology and Genetic Engineering (CBMEG), Institute of Biology, University of Campinas (UNICAMP), C.P. Box 6109, 13083-875 Campinas, SP, Brazil.
⁶ Laboratory of Protozoology, Department of Animal Biology, Institute of Biology, University of Campinas (UNICAMP), C.P. Box 6109, 13083-970 Campinas, SP, Brazil.

Abstract

Giardia duodenalis is a protozoan of public health interest that causes gastroenteritis in humans and other animals. In the city of Campinas in southeast Brazil, giardiasis is endemic, and this pathogen is detected at high concentrations in wastewater effluents, which are potential reservoirs for transmission. The Samambaia wastewater treatment plant (WWTP) in the city of Campinas employs an activated sludge system for sewage treatment and ultraviolet (UV) light for disinfection of effluents. To evaluate this disinfection process with respect to inactivating G. duodenalis cysts, two sample types were investigated: (i) effluent without UV disinfection (EFL) and (ii) effluent with UV disinfection (EFL+UV). Nude immunodeficient BALB/c mice were intragastrically inoculated with a mean dose of 14 cysts of G. duodenalis recovered from effluent from this WWTP, EFL, or EFL+UV. All animals inoculated with G. duodenalis cysts developed the infection, but animals inoculated with UV-exposed cysts released a lower average concentration of cysts in their faeces than animals inoculated with cysts that were not UV disinfected. Trophozoites were also observed in both groups of animals. These findings suggest that G. duodenalis cysts exposed to UV light were damaged but were still able to cause infection.