Persistent Infection with West Nile Virus Years after Initial Infection

Persistent Infection with West Nile Virus Years after Initial Infection

from Tom Kindlon, posted on CO-CURE Dec 19 09

[TK: It was previously noted on Co-Cure that after being infected with West Nile Virus, some patients went on to develop a CFS-like condition. Tom]

The Journal of Infectious Diseases 2010;201:2-4

C 2010 by the Infectious Diseases Society of America. All rights reserved.
DOI: 10.1086/648731

Persistent Infection with West Nile Virus Years after Initial Infection

Kristy Murray,1
Christopher Walker,1
Emily Herrington,1
Jessica A. Lewis,2
Joseph McCormick,1
David W. C. Beasley,2
Robert B. Tesh,2 and
Susan Fisher-Hoch1

1School of Public Health, University of Texas Health Science Center at
Houston, Houston and Brownsville, and 2University of Texas Medical Branch,

West Nile virus (WNV) RNA was demonstrated in 5 (20%) of 25 urine samples
collected from convalescent patients 573-2452 days (1.6-6.7 years) after WNV
infection. Four of the 5 amplicons sequenced showed >99% homology to the WNV
NY99 strain. These findings show that individuals with chronic symptoms
after WNV infection may have persistent renal infection over several years.

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"When WNV reached Houston in 2002, we established a longitudinal
study to follow hospitalized WNV-infected patients
to determine risk factors for encephalitis and to understand
long-term clinical sequelae. Methods for WNV confirmation
and study inclusion criteria have been described elsewhere [11].
Written informed consent was obtained upon recruitment. This
cohort now numbers 112 patients who are evaluated every 6
months, at which time blood is collected and a questionnaire
ascertaining subjective and objective measurements of clinical
sequelae is completed. At 1 year after infection, ~60% of patients
remain symptomatic, particularly those who were encephalitic.
Resolution of symptoms plateaued ~2 years after
infection, and after 5 years 60% of patients who presented with
encephalitis continued to report clinical symptoms. Chronic
symptoms were significantly associated with the persistence of
detectable anti-WNV serum immunoglobulin M (P=.026)
and also with a history of hypertension. Cytokine studies
showed that many of the chronically symptomatic patients also
had significantly elevated plasma levels of interferon g-inducing
protein, a marker of active viral infection (K.M., unpublished
data). There was also evidence of suppression of the type 2 T
helper pathway, which might be an indicator of immunosilencing
processes facilitating viral persistence. Finally, the deaths of
5 participants were attributed to chronic renal failure. Collectively,
these observations led us to hypothesize that some members
of the cohort were persistently infected with WNV and
that the kidney could be a preferred site of continued replication
and source of shedding. Accordingly, we developed protocols
for the collection and processing of urine for the detection of
viral nucleic acid by RT-PCR."


"Of the 5 positive patients, 4 reported chronic symptoms,
including weakness, fatigue, memory loss, and ataxia. All had
a clinical presentation of encephalitis, were male, and had a
history of hypertension. One patient developed kidney failure
following his illness. Three patients were 16 years past their
initial infection."