Identification of Cryptosporidium parvum and Blastocystis hominis subtype ST3 in Cholga mussel and treated sewage: Preliminary evidence of fecal contamination in harvesting area

P Suarez; A Vallejos-Almirall; I Fernández; I Gonzalez-Chavarria; J L Alonso; G Vidal

doi:10.1016/j.fawpar.2023.e00214

Identification of Cryptosporidium parvum and Blastocystis hominis subtype ST3 in Cholga mussel and treated sewage: Preliminary evidence of fecal contamination in harvesting area

Food Waterborne Parasitol. 2023 Dec 9:34:e00214. doi: 10.1016/j.fawpar.2023.e00214. eCollection 2024 Mar.

Authors

P Suarez^{1

2

3}, A Vallejos-Almirall⁴, I Fernández³, I Gonzalez-Chavarria⁵, J L Alonso⁶, G Vidal^{1

2}

Affiliations

¹ Environmental Engineering & Biotechnology Group (GIBA-UDEC), Environmental Science Faculty & EULA-CHILE Center, Universidad de Concepción, Concepción 4030000, Chile.
² Water Research Center for Agriculture and Mining (CRHIAM), ANID Fondap Center, Victoria 1295, Concepción, Chile.
³ Laboratorio de Parasitología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
⁴ Grupo Interdisciplinario de Biotecnología Marina (GIBMAR), Centro de Biotecnología, Universidad de Concepción, Concepción, Chile.
⁵ Laboratorio de Lipoproteínas y Cáncer, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
⁶ Instituto de Ingeniería del Agua y Medio Ambiente, Universitat Politècnica de València, Valencia, Spain.

Abstract

Cryptosporidium parvum and Blastocystis hominis are foodborne parasites known for causing diarrhea. They accumulate in mussels grown on contaminated water bodies, due to the discharge of treated sewage from sewage treatment plants (STP). Despite this, some countries like Chile do not include these parasites in the control or monitoring of sewage water. The objective of this research was to evaluate the contamination of C. parvum. and B. hominis from treated sewage (disinfected by chlorination) and Cholga mussels in a touristic rural cove from the bay of Concepción. Cholga mussels from commercial stores and a treated sewage sample were analyzed. Cryptosporidium spp. was identified by Ziehl-Neelsen-Staining (ZNS) and C. parvum by direct-immunofluorescence assay (IFA) from ZNS-positive samples. Blastocystis hominis was identified by PCR using locus SSU rDNA. C. parvum and B. hominis subtype ST3 were found in 40% and 45% of Cholga mussel samples, respectively, and both parasites were identified in the treated sewage. Blastocystis hominis SSU rDNA gene alignment from Cholga mussels and treated sewage showed 89% of similarity, indicating that could be the same parasite in both samples. We describe the first evidence of possible contamination with these parasites from treated sewage to Cholga mussel suggesting an environmental contamination with high human risk. Based on these results, further studies will consider all the rural coves and STP from the bay to prevent possible contamination of these parasites.

Keywords: Fecal contamination; Foodborne; Parasite; Sewage treatment plant; Waterborne.