Clams (Corbicula fluminea) as bioindicators of fecal contamination with Cryptosporidium and Giardia spp. in freshwater ecosystems in California

Woutrina A Smith, Edward R Atwill, Ian Gardner, Melissa A. Miller, Heather Fritz, Ronald Hedrick, Ann C. Melli, Nicole M. Barnes, Patricia A Conrad

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

This study evaluated clams as bioindicators of fecal protozoan contamination using three approaches: (i) clam tissue spiking experiments to compare several detection techniques; (ii) clam tank exposure experiments to evaluate clams that had filtered Cryptosporidium oocysts from inoculated water under a range of simulated environmental conditions; (iii) sentinel clam outplanting to assess the distribution and magnitude of fecal contamination in three riverine systems in California. Our spiking and tank experiments showed that direct fluorescent antibody (DFA), immunomagnetic separation (IMS) in combination with DFA, and PCR techniques could be used to detect Cryptosporidium in clam tissues. The most analytically sensitive technique was IMS concentration with DFA detection of oocysts in clam digestive gland tissues, which detected 10 oocysts spiked into a clam digestive gland 83% of the time. In the tank experiment, oocyst dose and clam collection time were significant predictors for detecting Cryptosporidium parvum oocysts in clams. In the wild clam study, Cryptosporidium and Giardia were detected in clams from all three study regions by IMS-DFA analysis of clam digestive glands, with significant variation by sampling year and season. The presence of C. parvum DNA in clams from riverine ecosystems was confirmed with PCR and DNA sequence analysis.

Original languageEnglish (US)
Pages (from-to)673-684
Number of pages12
JournalInternational Journal for Parasitology
Volume35
Issue number6
DOIs
StatePublished - May 2005

Fingerprint

Corbicula
Giardia
Cryptosporidium
Fresh Water
Ecosystem
Oocysts
Bivalvia
Immunomagnetic Separation
Cryptosporidium parvum
Antibodies
Polymerase Chain Reaction
Direct Fluorescent Antibody Technique
DNA Sequence Analysis

Keywords

  • Bivalve
  • Clam
  • Cryptosporidium
  • Fecal pollution
  • Giardia
  • Waterborne pathogens

ASJC Scopus subject areas

  • Parasitology
  • Infectious Diseases

Cite this

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title = "Clams (Corbicula fluminea) as bioindicators of fecal contamination with Cryptosporidium and Giardia spp. in freshwater ecosystems in California",
abstract = "This study evaluated clams as bioindicators of fecal protozoan contamination using three approaches: (i) clam tissue spiking experiments to compare several detection techniques; (ii) clam tank exposure experiments to evaluate clams that had filtered Cryptosporidium oocysts from inoculated water under a range of simulated environmental conditions; (iii) sentinel clam outplanting to assess the distribution and magnitude of fecal contamination in three riverine systems in California. Our spiking and tank experiments showed that direct fluorescent antibody (DFA), immunomagnetic separation (IMS) in combination with DFA, and PCR techniques could be used to detect Cryptosporidium in clam tissues. The most analytically sensitive technique was IMS concentration with DFA detection of oocysts in clam digestive gland tissues, which detected 10 oocysts spiked into a clam digestive gland 83{\%} of the time. In the tank experiment, oocyst dose and clam collection time were significant predictors for detecting Cryptosporidium parvum oocysts in clams. In the wild clam study, Cryptosporidium and Giardia were detected in clams from all three study regions by IMS-DFA analysis of clam digestive glands, with significant variation by sampling year and season. The presence of C. parvum DNA in clams from riverine ecosystems was confirmed with PCR and DNA sequence analysis.",
keywords = "Bivalve, Clam, Cryptosporidium, Fecal pollution, Giardia, Waterborne pathogens",
author = "Smith, {Woutrina A} and Atwill, {Edward R} and Ian Gardner and Miller, {Melissa A.} and Heather Fritz and Ronald Hedrick and Melli, {Ann C.} and Barnes, {Nicole M.} and Conrad, {Patricia A}",
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AU - Smith, Woutrina A

AU - Atwill, Edward R

AU - Gardner, Ian

AU - Miller, Melissa A.

AU - Fritz, Heather

AU - Hedrick, Ronald

AU - Melli, Ann C.

AU - Barnes, Nicole M.

AU - Conrad, Patricia A

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