New genotypes and factors associated with Cryptosporidium detection in mussels (Mytilus spp.) along the California coast

Woutrina A Smith, M. A. Miller, Ian Gardner, Edward R Atwill, M. Harris, J. Ames, D. Jessup, A. Melli, D. Paradies, K. Worcester, P. Olin, N. Barnes, Patricia A Conrad

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


A 3 year study was conducted to evaluate mussels as bioindicators of faecal contamination in coastal ecosystems of California. Haemolymph samples from 4680 mussels (Mytilus spp.) were tested for Cryptosporidium genotypes using PCR amplification and DNA sequence analysis. Our hypotheses were that mussels collected from sites near livestock runoff or human sewage outflow would be more likely to contain the faecal pathogen Cryptosporidium than mussels collected distant to these sites, and that the prevalence would be greatest during the wet season when runoff into the nearshore marine environment was highest. To test these hypotheses, 156 batches of sentinel mussels were collected quarterly at nearshore marine sites considered at higher risk for exposure to livestock runoff, higher risk for exposure to human sewage, or lower risk for exposure to both faecal sources. Cryptosporidium genotypes detected in Haemolymph samples from individual mussels included Cryptosporidium parvum, Cryptosporidium felis, Cryptosporidium andersoni, and two novel Cryptosporidium spp. Factors significantly associated with detection of Cryptosporidium spp. in mussel batches were exposure to freshwater outflow and mussel collection within a week following a precipitation event. Detection of Cryptosporidium spp. was not associated with higher or lower risk status for exposure to livestock faeces or human sewage sources. This study showed that mussels can be used to monitor water quality in California and suggests that humans and animals ingesting faecal-contaminated water and shellfish may be exposed to both host-specific and anthropozoonotic Cryptosporidium genotypes of public health significance.

Original languageEnglish (US)
Pages (from-to)1103-1113
Number of pages11
JournalInternational Journal for Parasitology
Issue number10
StatePublished - Sep 2005


  • Bivalve
  • Cryptosporidium
  • Faecal pollution
  • Mussel
  • Shellfish
  • Waterborne pathogen

ASJC Scopus subject areas

  • Parasitology
  • Infectious Diseases


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