Pro-inflammatory cytokines in the serum of silver catfish (Rhamdia quelen) naturally infected by Clinostomum complanatum: a preliminary study.

Clinostomum complanatum is a zoonotic parasite of birds, and its larval form (metacercariae) may cause disease in fish. The immune response of fish infected by C. complanatum is unknown, and therefore the objective of this study was to evaluate serum levels of pro-inflammatory cytokines in silver catfish (Rhamdia quelen) infected by this parasite. The analysis showed that fish infected with metacercariae presented significantly (P < 0.05) higher levels of tumor necrosis factor alpha (TNF-α), interleukin 1 (IL-1), and interleukin 6 (IL-6) when compared to those not infected. These data suggest that C. complanatum larvae activate the host immune response.