Myxozoans and Our Dinner Table: Pathogenicity Studies of Myxobolus honghuensis (Myxosporea: Bivalvulida) Using a Suckling Mice Model.

Myxobolus honghuensis parasitizes the pharynx of the allogynogenetic gibel carp Carassius auratus gibelio (Bloch), an economically important food fish with large consumption rates in China. The fact that it is hard to detect the cysts formed by M. honghuensis without euthanizing the fish and the spores can reach the consumers has prompted us to investigate the effect of M. honghuensis on conventional, immunocompetent BALB/c suckling mice, in order to consider the possible pathological effects in general immunocompetent consumers by the ingestion of Myxobolus-infected fish. BALB/c suckling mice were inoculated with serial dilutions of the spore suspension and then hematological and histological studies were performed. Tests of suckling mice showed no statistically difference of fluid accumulation ratio between mice inoculated with 1.65 × 10(6) M. honghuensis spores and negative control after 8-h incubation. Spores did not disrupt intestinal histology, and no abnormal bowel movements were observed within 20 h postinoculation. No anomalous hematology parameters were documented. These results, taken together, reveal that M. honghuensis spores do not cause pathology (diarrhea and elevated fluid accumulation) in BALB/c suckling mice. However, an extrapolation is not currently feasible because of lack of a highly quantifiable risk extrapolation model, inaccessibility to data for the effect of M. honghuensis on humans, and lack of consideration of the immunosuppressed population. Our study extends the results of the effect of myxozoan on suckling mice and serves as baseline for future experiment using the same model in evaluating the myxozoan-caused foodborne disease.