AUTHOR=Milne Gregory , Fujimoto Chelsea , Bean Theodor , Peters Harry J. , Hemmington Martin , Taylor Charly , Fowkes Robert C. , Martineau Henny M. , Hamilton Clare M. , Walker Martin , Mitchell Judy A. , Léger Elsa , Priestnall Simon L. , Webster Joanne P. 

TITLE=Infectious Causation of Abnormal Host Behavior: Toxoplasma gondii and Its Potential Association With Dopey Fox Syndrome

JOURNAL=Frontiers in Psychiatry

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2020.513536

DOI=10.3389/fpsyt.2020.513536

ISSN=1664-0640

ABSTRACT=<p>The apicomplexan parasite <italic>Toxoplasma gondii</italic>, the causative agent of toxoplasmosis, can infect all warm-blooded animals. <italic>T. gondii</italic> can subtly alter host behaviors—either through manipulation to enhance transmission to the feline definitive host or as a side-effect, or “constraint,” of infection. In humans, <italic>T. gondii</italic> infection, either alone or in association with other co-infecting neurotropic agents, has been reliably associated with both subtle behavioral changes and, in some cases, severe neuropsychiatric disorders, including schizophrenia. Research on the potential impact of <italic>T. gondii</italic> on the behavior of other long-lived naturally infected hosts is lacking. Recent studies reported a large number of wild red foxes exhibiting a range of aberrant behavioral traits, subsequently classified as Dopey Fox Syndrome (DFS). Here we assessed the potential association between <italic>T. gondii</italic> and/or other neurotropic agents with DFS. Live, captive foxes within welfare centers were serologically tested for <italic>T. gondii</italic> and, if they died naturally, PCR-tested for vulpine circovirus (FoxCV). Post-mortem pseudo-control wild foxes, obtained from pest management companies, were PCR-tested for <italic>T. gondii</italic>, FoxCV, canine distemper virus (CDV), canine adenovirus type (CAV)-1 and CAV-2. We also assessed, using non-invasive assays, whether <italic>T. gondii</italic>–infected foxes showed subtle behavioral alterations as observed among infected rodent (and other) hosts, including altered activity, risk, and stress levels. All foxes tested negative for CAV, CDV, CHV, and DogCV. DFS was found to be associated with singular <italic>T. gondii</italic> infection (captives vs. pseudo-controls, 33.3% (3/9) vs. 6.8% (5/74)) and singular FoxCV infection (66.7% (6/9) vs. 11.1% (1/9)) and with <italic>T. gondii</italic>/FoxCV co-infection (33.3% (3/9) vs. 11.1% (1/9)). Overall, a higher proportion of captive foxes had signs of neuroinflammation compared to pseudo-controls (66.7% (4/6) vs. 11.1% (1/9)). Consistent with behavioral changes seen in infected rodents, <italic>T. gondii</italic>–infected foxes displayed increased attraction toward feline odor (n=6 foxes). These preliminary results suggest that wild foxes with DFS are infected with <italic>T. gondii</italic> and likely co-infected with FoxCV and/or another co-infecting neurotropic agent. Our findings using this novel system have important implications for our understanding of both the impact of parasites on mammalian host behavior in general and, potentially, of the infectious causation of certain neuropsychiatric disorders.</p>