A confirmed case of Murray Valley encephalitis acquired at Channel Point, NT

Abstract

A 83 year old non-indigenous male was admitted to Royal Darwin Hospital on 8/5/09 with suspected MVE (suspected onset date 4/5/09). A RDH doctor informed Medical Entomology (ME) of the suspected case on 11/5/09 but advised that test results were still pending. The first tests were conducted on 9/5/09, showing a weakly positive MVE IgM in CSF (negative for Kunjin and West Nile), a positive PCR, and a weak positive arbovirus serology HI result for MVE (titre 40). Further tests were conducted on 11/5/09 and 15/5/09, but the MVE HI titre did not rise. Tests were also conducted for other viruses including Dengue, Stratford, Kokobera, Edge Hill and Alfuy, but the test results were negative. MVE was confirmed on 19/5/09. The patient remained in ICU showing symptoms of encephalitis, including confusion, fever and fitting, until he passed away on 23/5/09. ME received the Flavivirus Disease Case Investigation Form from CDC on 20/5/09. The patient’s fishing partner reported that the patient had been fishing at Wranglers Creek and other areas at Channel Point for three and a half weeks since Easter, experiencing moderate mosquito numbers at dawn and dusk only. The patient has not been to any other areas, and there was anecdotal evidence that the patient did not usually practice personal protection, such as using insect repellent.