Presumptive West Nile Virus infection in a Komodo Dragon (Varanus komodoensis)

Abstract

Abstract A 3-yr-old, male Komodo dragon (Varanus komodoensis) presented acutely in early October 2021 with an abnormal posture and asymmetric tetraparesis. The subadult lizard had spent the previous 4 months either in an outdoor space or in an indoor space with open windows. Physical examination, radiographs, and complete blood count and chemistry panel failed to reveal the cause of the neurologic signs. West Nile virus (WNV) plaque reduction serum neutralization on presentation was negative (1:20), as was WNV polymerase chain reaction (PCR) testing and viral isolation on whole blood. Empirical treatment with a daily corticosteroid, course of antibiotics, and encouragement of mild exercise was initiated. Magnetic resonance imaging of the brain and spinal cord was unremarkable, and a lumbar cerebrospinal fluid (CSF) tap revealed a mononuclear pleocytosis and protein elevation. Follow-up WNV serology revealed rising titer and seroconversion 13 days after presentation (1:80) and 32 days after presentation (1:640); however, WNV PCR testing of CSF fluid was negative. Thi Komodo dragon gradually improved over six weeks before being put back on public display 74 days after presentation. The WNV titer remained high (1:640) through the winter of 2021-22, and an anamnestic response was observed following a vaccination series with a killed equine vaccine in the spring of 2022. There is a previous brief report of WNV infection in a captive crocodile monitor (Varanus salvadorii), and an unpublished case in the same species at the first author’s institution. This is the first report of neurologic disease from presumptive WNV infection in a Komodo dragon. We recommend that WNV infection be a differential diagnosis if a varanid lizard present with acute neurologic signs with a history of arthropod vector exposure, particularly in the summer or fall.