Emerging Cases of Powassan Virus Encephalitis in New England: Clinical Presentation, Imaging, and Review of the Literature.
Clin Infect Dis. 2015 Dec 13;
Authors: Piantadosi A, Rubin DB, McQuillen DP, Hsu L, Lederer PA, Ashbaugh CD, Duffalo C, Duncan R, Thon J, Bhattacharyya S, Basgoz N, Feske SK, Lyons JL
Abstract
BACKGROUND: Powassan virus is a rarely diagnosed cause of encephalitis in the United States. In the Northeast, it is transmitted by Ixodes scapularis, the same vector that transmits the causative agent of Lyme disease, and the prevalence of Powassan virus among animal hosts and vectors has been increasing. Here we present eight cases of Powassan virus encephalitis from Massachusetts and New Hampshire in 2013-2015.
METHODS: We abstracted clinical and epidemiological information for patients with Powassan virus encephalitis diagnosed at two hospitals in Massachusetts from 2013-2015. We evaluated their brain imaging in comparison to published findings from Powassan and other viral encephalitides.
RESULTS: The patients ranged in age from 21 to 82, were mostly previously healthy, and presented with syndromes of fever, headache, and altered consciousness. Infections occurred from May to September and were often associated with known tick exposures. In all patients, CSF analyses showed pleocytosis with elevated protein. In seven of eight patients, brain MRI demonstrated deep foci of increased T2/FLAIR signal intensity.
CONCLUSIONS: We describe eight cases of Powassan virus encephalitis in Massachusetts and New Hampshire in 2013-2015. Prior to this, there had been only two cases of Powassan virus encephalitis identified in Massachusetts. The cases described here may represent emergence of this virus in a region where its vector, Ixodes scapularis, is known to be prevalent; or may represent the emerging diagnosis of an under-appreciated pathogen. We recommend testing for Powassan virus in patients who present with encephalitis in the spring to fall in New England.
PMID: 26668338 [PubMed - as supplied by publisher]