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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI:

    Marine leech parasitism of sea turtles varies across host species, seasons, and the tumor disease fibropapillomatosis

    Leah T. Rittenburg, Jake R. Kelley, Kate L. Mansfield, Anna E. Savage*

    *Corresponding author:

    ABSTRACT: Fibropapillomatosis (FP) is a tumorous disease affecting all species of sea turtles and is associated with the pathogen chelonid alphaherpesvirus 5 (ChHV5). Hypothesized ChHV5 vectors include the marine leeches Ozobranchus branchiatus and Ozobranchus margoi, but data on their associations with FP and ChHV5 are minimal. To establish relationships between leech parasitism, turtle hosts, and FP, we compared green and loggerhead turtles from the Indian River Lagoon (IRL), Florida, USA in terms of (1) the presence or absence of ChHV5 within associated leeches, (2) the association between leech parasitism and host FP status, and (3) seasonal variation in leech presence. We identified 55 leeches collected from green turtles as O. branchiatus and 22 leeches collected from loggerhead turtles as O. margoi. Out of 77 sequenced leeches, ten O. branchiatus and five O. margoi were ChHV5-positive. ChHV5-positive O. branchiatus trended towards coming from FP-positive hosts. Using 12 years of turtle capture data from the IRL, we found that leech parasitism was significantly correlated with FP and capture month in green turtles, but not in loggerhead turtles. These results suggest that O. branchiatus and O. margoi may differ in their ability to transmit ChHV5 or to encounter and remain on FP-positive hosts. Alternatively, potential immunological differences between green and loggerhead turtles may explain the observed relationships. This study is the first to provide robust statistical evidence of an association between leeches and FP, as well as seasonal fluctuations in leech presence, in green turtles but not in loggerhead turtles.