Detection of toxoplasma antibodies in sera of Salmonidae by ELISA

Toxoplasma gondii is a protozoan parasite with a worldwide distribution. It is capable of infecting all warm-blooded animals. Toxoplasmosis was not considered a waterborne zoonoses, but recently, it has been reported in many marine mammals. Coastal pollution by sewage from humans and pets has been suggested as a source for toxoplasma infection in these animals. Recent reports of toxoplasmosis in marine mammals raise concern that cold-blooded marine animals are potential sources of T. gondii infection. Conversely, the increasing proclivity for eating fish, crabs, shrimp, and mollusks—raw, undercooked, smoked, or dried—facilitates zoonoses infections caused by protozoan microorganisms; and one of them is toxoplasma. Detection of antibodies against T. gondii can be achieved by different serological tests such as enzyme-linked immunosorbent assay (ELISA). To determine whether toxoplasmosis has a role in Salmonidae infection, which is the most common seafood in Shahrekord district, this research was carried out on 50 Salmonidae aged 4 months (weight 700 ± 200 g). ELISA was performed on serum samples for detecting T. gondii-specific immunoglobulin M (IgM) and immunoglobulin G (IgG). As a result, toxoplasmic IgM antibody was detected in five of 50 samples (cut-off value of ≥0.183). Based on these findings, we believe that Salmonidae may be susceptible to primary T. gondii infection. While there is still no evidence of T. gondii transmission from cold-blooded sea animals to human via consuming their meat or other products, further research can be done to prove the possibility of this hypothesis.