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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Parasitic Diseases Laboratory » Research » Publications at this Location » Publication #306766
Title: Using blue mussels (Mytilus spp.) as biosentinels of Cryptosporidium spp. and Toxoplasma gondii contamination in marine aquatic environments

Author
item STAGGS, SARA - Us Environmental Protection Agency (EPA)
item SCOT, KELLY - Us Environmental Protection Agency (EPA)
item WARE, MICHAEL - Us Environmental Protection Agency (EPA)
item SCHABLE, NANCY - Dynamac Corporation
item SEE, MARY - Dynamac Corporation
item GREGORIO, DOMONIC - State Of California
item ZOU, XIAN - University Of Tennessee
item SU, CHUNLEI - University Of Tennessee
item Dubey, Jitender
item VILLEGAS, ERIC - Us Environmental Protection Agency (EPA)

Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2015
Publication Date: 9/11/2015
Citation: Staggs, S., Scot, K., Ware, M., Schable, N., See, M., Gregorio, D., Zou, X., Su, C., Dubey, J.P., Villegas, E. 2015. Using blue mussels (Mytilus spp.) as biosentinels of Cryptosporidium spp. and Toxoplasma gondii contamination in marine aquatic environments. Parasitology Research. 114(12):4655-67.

Interpretive Summary: Toxoplasmosis is a parasitic infection of humans and animals and it continues to be public health and food safety issue. Humans become infected with T. gondii by consuming infected uncooked meat or by the ingestion of food and water contaminated with the environmentally resistant stage of the parasite (oocyst) excreted in cat feces. Epidemiological studies that both fresh and marine waters can be contaminated with oocysts. Mollusks can concentrate oocysts in their body and humans and animals can then become infected if they consume raw mollusks. Bivalves have been proposed as a natural filtration alternative for the detection of oocysts in water as they can and retain parasites, bacteria, and viruses for an extended period of time. In this study,the authors examined the use of indigenous blue mussels (Mytilus spp.) as biosentinels to monitor for the presence of Toxoplasma gondii and Cryptosporidium spp.(another single celled zoonotic parasite) in marine waters. An efficient method to extract oocyst DNA from mussel hemolymph, gill, and digestive gland tissues followed by PCR-based detection of these pathogens was developed. Results revealed that this method could consistently detect as few as 10 oocysts. The results presented here revealed that mussels found in Morro Bay and Point Lobos, CA are contaminated with T. gondii, and at much higher levels than originally reported. The improved methods for detecting shellfish contamination with zoonotic parasites will allow better assessment of environmental contamination as well as the food safety risk posed to people who eat uncooked shellfish. These results will be of interest to biologists, parasitologists, and epidemiologists.

Technical Abstract: Methods to monitor microbial contamination typically involve collecting discrete samples at specific time-points and analyzing for a single contaminant. While informative, many of these methods suffer from poor recovery rates and only provide a snapshot of the microbial load at the time of collection. Bivalves have been proposed as a natural filtration alternative as they are more efficient and can simultaneously concentrate and retain parasites, bacteria, and viruses for an extended period of time. In this study, we examined the use of indigenous blue mussels (Mytilus spp.) as biosentinels to monitor for the presence of Toxoplasma gondii and Cryptosporidium spp. in marine waters. An efficient method to extract oocyst DNA from mussel hemolymph, gill, and digestive gland tissues followed by PCR-based detection of these pathogens was developed. Results revealed that this method could consistently detect as few as 10 oocysts. A limited survey of indigenous mussels from Point Lobos and Morro Bay, California, areas known to have high T. gondii seroprevalence in sea otters, were positive for T. gondii (54% and 33% of total mussels sampled, respectively). Mussels from Point Lobos were also contaminated (26.9%) with Cryptosporidium oocysts. Phylogenetic analysis using the SSU rRNA gene revealed two distinct C. parvum-like genotypes. Overall, this study provides a more refined method for detecting parasites in contaminated mussels and demonstrates the applicability of using indigenous Mytilus spp. as biosentinels for monitoring microbial water quality. More importantly, using this method, T. gondii and Cryptosporidium spp. were found to be prevalent in mussels collected from the California coastline.