Pathogenic infection confounds induction of the estrogenic biomarker vitellogenin in rainbow trout

To examine the behavior of the estrogenic biomarker vitellogenin (VTG) under the combined impact of estrogens and pathogens, parasite‐infected or noninfected rainbow trout were exposed to two doses of 17β‐estradiol (E2). Infected and E2‐exposed fish showed significantly lower hepatic VTG mRNA levels than healthy fish. Transcriptome data suggest that this was due to energetic constraints. Reduced responsiveness of the VTG biomarker in parasitized fish might obscure detection of low‐level field exposure. Environ. Toxicol. Chem. © 2012 SETAC