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  Vol. 290 No. 4, July 23, 2003 TABLE OF CONTENTS
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Neurologic Manifestations and Outcome of West Nile Virus Infection

James J. Sejvar, MD; Maryam B. Haddad, MSN, MPH, FNP; Bruce C. Tierney, MD; Grant L. Campbell, MD, PhD; Anthony A. Marfin, MD, MPH; Jay A. Van Gerpen, MD; Aaron Fleischauer, PhD; A. Arturo Leis, MD; Dobrivoje S. Stokic, MD; Lyle R. Petersen, MD, MPH

JAMA. 2003;290:511-515.

ABSTRACT

Context  The neurologic manifestations, laboratory findings, and outcome of patients with West Nile virus (WNV) infection have not been prospectively characterized.

Objective  To describe prospectively the clinical and laboratory features and long-term outcome of patients with neurologic manifestations of WNV infection.

Design, Setting, and Participants  From August 1 to September 2, 2002, a community-based, prospective case series was conducted in St Tammany Parish, La. Standardized clinical data were collected on patients with suspected WNV infection. Confirmed WNV-seropositive patients were reassessed at 8 months.

Main Outcome Measures  Clinical, neurologic, and laboratory features at initial presentation, and long-term neurologic outcome.

Results  Sixteen (37%) of 39 suspected cases had antibodies against WNV; 5 had meningitis, 8 had encephalitis, and 3 had poliomyelitis-like acute flaccid paralysis. Movement disorders, including tremor (15 [94%]), myoclonus (5 [31%]), and parkinsonism (11 [69%]), were common among WNV-seropositive patients. One patient died. At 8-month follow-up, fatigue, headache, and myalgias were persistent symptoms; gait and movement disorders persisted in 6 patients. Patients with WNV meningitis or encephalitis had favorable outcomes, although patients with acute flaccid paralysis did not recover limb strength.

Conclusions  Movement disorders, including tremor, myoclonus, and parkinsonism, may be present during acute illness with WNV infection. Some patients with WNV infection and meningitis or encephalitis ultimately may have good long-term outcome, although an irreversible poliomyelitis-like syndrome may result.



INTRODUCTION
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Most human infections with West Nile virus (WNV) are subclinical or manifest as a mild febrile illness, but a small proportion of patients (<1%) develop acute neurologic illness.1-4 Although recent WNV outbreaks have been associated with severe neurologic disease,1-5 retrospective studies have failed to identify clinical features that distinguish WNV from other viral encephalitides.1, 5-9 The US outbreak of WNV in 200210 presented an opportunity to assess neurologic manifestations, laboratory and neurodiagnostic findings, and outcome associated with WNV infection.1, 7, 11


METHODS
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From August 1 to September 2, 2002, patients from St Tammany Parish, La, with suspected WNV infection were identified through state-based surveillance at local hospitals and regional medical centers. Suspected WNV infection was defined as illness with evidence of an acute infectious process (eg, temperature >=39°C; elevated white blood cell count; or cerebrospinal fluid [CSF] pleocytosis) along with clinical evidence of meningitis, encephalitis, or acute focal weakness (Box). Infection with WNV was confirmed if WNV-specific antibodies were detected in acute-phase serum or CSF samples by IgM antibody-capture enzyme-linked immunosorbent assay (MAC-ELISA)12 and were confirmed by plaque-reduction neutralization assay.13


Box. Diagnostic Criteria

West Nile Meningitis

A. Clinical signs of meningeal inflammation, including nuchal rigidity, Kernig or Brudzinski sign, or photophobia or phonophobia
B. Additional evidence of acute infection, including 1 or more of the following: fever (>38°C) or hypothermia (<35°C); cerebrospinal fluid pleocytosis (>=5 leukocytes/mm3); peripheral leukocyte count >10 000/mm3; neuroimaging findings consistent with acute meningeal inflammation

West Nile Encephalitis

A. Encephalopathy (depressed or altered level of consciousness, lethargy, or personality change lasting >=24 hours)
B. Additional evidence of central nervous system inflammation, including 2 or more of the following: fever (>=38°C) or hypothermia (<=35°C); cerebrospinal fluid pleocytosis (>=5 leukocytes/mm3); peripheral leukocyte count >10 000/mm3; neuroimaging findings consistent with acute inflammation (with or without involvement of the meninges) or acute demyelination; presence of focal neurologic deficit; meningismus (as defined in A); electroencephalography findings consistent with encephalitis; seizures, either new onset or exacerbation of previously controlled

Acute Flaccid Paralysis

A. Acute onset of limb weakness with marked progression over 48 hours
B. At least 2 of the following: asymmetry to weakness; areflexia/hyporeflexia of affected limb(s); absence of pain, paresthesia, or numbness in affected limb(s); cerebrospinal fluid pleocytosis (>=5 leukocytes/mm3) and elevated protein levels (>=45 mg/dL); electrodiagnostic studies consistent with an anterior horn cell process; spinal cord magnetic resonance imaging documenting abnormal increased signal in the anterior gray matter

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Eligible enrollees were assessed on presentation to medical care. Patients were approached under the auspices of a public health event; oral consent was obtained. Standardized case histories and initial symptoms and signs were collected. One neurologist (J.J.S.) examined each patient; a second neurologist verified findings for 7 patients. Laboratory results, neuroimaging and electrophysiologic findings were recorded and updated 1 week following initial assessment, during repeat neurologic evaluation.

Approximately 8 months later (March 15-April 4, 2003), patients with confirmed WNV infection were reexamined. The Centers for Disease Control and Prevention institutional review board approved the follow-up protocol. Using a standardized questionnaire, patients were queried about symptoms, functional status, and ability to perform daily activities. The neurologic assessment was repeated (J.J.S.).

Exact Wilcoxon rank-sum test was used for comparison of medians. Statistical analyses were performed using SAS, version 8.1 (SAS Institute, Cary, NC).


RESULTS
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Clinical Features

Of 39 patients evaluated, WNV infection was confirmed in 16 patients. Discharge diagnoses of the 23 patients without WNV infection included viral meningitis (n = 6), headache (n = 5), viral encephalitis (n = 4), unspecified viral illness (n = 4), and encephalopathy (n = 1). Final diagnoses were unavailable for 3 patients.

Eleven (69%) of the 16 WNV-seropositive patients were white (population of St Tammany Parish is 74% white), and 9 were male. Of the 16 patients, 5 were classified as having West Nile meningitis (WNM), 8 as having West Nile encephalitis (WNE), and 3 as having acute flaccid paralysis (AFP) (Table 1). One patient classified with AFP also had encephalitis. Information regarding the initial presentation of 3 patients with AFP had been reported previously.14-15 Patients with WNM (median age, 35 years) were younger than those with WNE (median, 70 years) (P = .003). One patient with severe WNE had systemic lupus erythematosis and was treated with corticosteroids. No other WNV-seropositive patient had a clear condition indicating immunocompromise.


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Table. Clinical Features


The 16 WNV-seropositive patients were hospitalized a median of 2.5 days after symptom onset; the median hospital stay was 12 days (Table 1). Five patients spent a median of 10 days (range, 3-19 days) in intensive care.

Self-reported symptoms were similar among all patients presenting with possible WNV infection (Table 1). Eleven of the 15 WNV-seropositive patients with headache described it as frontal/retro-orbital, and 5 of the 16 WNV-seropositive patients reported a rash. Fifteen WNV-seropositive patients reported "shakiness" or "twitching," with 5 describing it as notable in the evening prior to sleep. Among patients with WNE, the most common complaints were behavioral or personality changes, manifested as irritability, confusion, or disorientation. Two patients with WNM and 1 patient with WNE reported difficulty with balance and gait. Five patients reported weakness, which was focal in the 3 patients developing AFP and was generalized in 2 patients.

The 8 patients with WNE had a mean admission Glasgow Coma Scale score of 11 (range, 4T [intubated] to 15). A median of 3 days passed between symptom onset and changes in mental status. Cranial nerve and bulbar abnormalities were observed in several patients with WNE. Results of formal strength testing displayed mild-to-moderate diffuse weakness in 4 patients and focal weakness in the 3 patients with AFP. New sensory abnormalities were not observed. Four patients with WNE and 1 patient with WNM displayed abnormal hyperreflexia; the 3 patients with AFP all had areflexia or hyporeflexia of the affected limbs.

Dyskinesias (ie, movements including tremor, myoclonus, and features of parkinsonism) were observed in 15 of the 16 WNV-seropositive patients (Table 1). Tremor was observed in 15 patients; 9 had onset of tremor after day 5 of illness. Tremor in all 15 patients was static or kinetic, asymmetric, and involved the upper extremities. Two patients additionally displayed intentional movement dysmetria. Myoclonus was directly observed in 10 patients. Parkinsonism was observed in all 3 patients with AFP, 6 of 8 patients with WNE, and 2 of 5 patients with WNM. Resting tremor was not observed. Seizures were documented using electroencephalography in 1 patient with WNE.

All 3 patients with AFP had asymmetric limb weakness within 48 hours of initial symptom onset. Pain, paresthesias, or acute sensory loss were not observed. All 3 patients experienced bowel and bladder dysfunction.

Neuroimaging and Electrophysiologic Studies

None of the WNV-seropositive patients showed acute abnormalities on computed tomography. Magnetic resonance imaging of the brain was performed on 10 of the 16 patients: the findings showed nonacute abnormalities in 8 patients and bilateral, focal lesions in the basal ganglia, thalamus, and pons on T2- and diffusion-weighted sequences in 2 severely ill patients with WNE (Figure 1). Findings of magnetic resonance imaging of the cervical, thoracic, and lumbosacral spine for the 2 patients with AFP with lower extremity involvement showed enhancement of the cauda equina and nerve root clumping consistent with meningitis. Findings of magnetic resonance images of the cervical and thoracic spine in a patient with AFP with right arm involvement showed diffuse degenerative changes without spinal cord abnormalities.



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Figure. T2-Weighted Axial Magnetic Resonance Image From a Patient With West Nile Virus Encephalitis

The image displays bilateral increased signal in the posterior thalami (lower 2 arrowheads) and focal areas of striatum (upper 2 arrowheads).


Electroencephalograms were obtained for 7 patients with WNE. Abnormal findings included electrographic seizures in 1 patient, focal sharp waves in 1 patient, and diffuse irregular slow waves in 6 patients. No correlation between electroencephalographic findings and the presence of myoclonus or tremor was observed.

Electromyographs and nerve conduction studies were performed on the 3 WNV-seropositive patients and 1 WNV-seronegative patient with asymmetric weakness from 3 to 42 days after onset of weakness. All WNV-seropositive patients demonstrated findings consistent with a severe, asymmetric process affecting anterior horn cells. The WNV-seronegative patient displayed overall findings consistent with a combined axonal and demyelinating neuropathy (ie, Guillain-Barré syndrome).

Outcome and 8-Month Follow-up

One patient with WNE remained comatose and ventilator-dependent until death, which occurred 2.5 months after onset of illness. All surviving patients eventually were discharged home. However, 3 patients with AFP and 2 patients with WNE were initially discharged to long-term rehabilitation facilities. At 8 months, 11 patients were home and functioning independently; 3 were home, but dependent; and 1 was undergoing rehabilitation.

At 8 months, 10 WNV-seropositive patients reported persistent fatigue, 3 persistent myalagias, and 2 persistent headache. Four patients with WNE reported persistent cognitive deficits, including difficulties with memory, short-term recall, and slowness of thought. One patient had mental status scores significantly below baseline levels.

Follow-up neurologic examination of the 15 WNV-seropositive patients who survived revealed no neurologic deficits in the 5 patients with WNM. Among patients with WNE and AFP, tremor was present in 5 patients and parkinsonism in 5. A postural and/or kinetic tremor was observed in 5 patients following recovery from WNE, and in 1 patient, it was severe enough to interfere with grooming and eating. Parkinsonism persisted in 5 of the 11 patients. In all but 1 patient (the patient with underlying systemic lupus erythematosis), parkinsonism was mild and did not interfere with daily activities. One patient with WNE with severe initial parkinsonism and postural instability was ambulatory with a walker for 4 months following illness onset, but by 6 months was able to climb ladders at work. Eight-month follow-up examination demonstrated only minimal postural instability and bradykinesia. The 8-month follow-up examination revealed 2 patients who demonstrated myoclonus of the upper extremities and face.

Five of 7 patients with severe encephalitis, as characterized by an initial Glascow Coma Scale score of 12 or less or an initial mental status score of 2 SDs below normal for age, had favorable outcomes, defined as achieving or exceeding their level of functioning before illness. Two patients with particularly guarded prognoses during acute illness were functioning at baseline level by 6 months, with no residual symptoms. Recovery to normal or near-normal functioning occurred within 4 months in all cases of improvement.

Patients with AFP showed no improvement in limb weakness. Bladder symptoms in the patients with AFP had resolved. Electromyographs and nerve conduction studies performed at the 8-month follow-up examination revealed chronic denervervation and motor axon loss in affected limbs. One patient with AFP experienced continued severe dyspnea. Chest and diaphragmatic fluoroscopy performed 3 months after illness onset revealed right hemidiaphragmatic paralysis consistent with central nervous system etiologic findings.

Patients with AFP reported the lowest overall functioning scores and had the lowest scores on both Barthel and modified Rankin scoring systems (data not shown). Five of 7 patients who survived WNE and 4 of 5 patients who survived WNM reported normal functional scores (data not shown). Seven of the 10 patients who were employed before WNV infection returned to work within 4 months following hospital discharge. Five patients, including all 3 with AFP, described continuing difficulties with daily activities, such as grooming, housekeeping, and mobility. All patients with AFP required use of a wheelchair for ambulation, and 2 patients who had been independently mobile before infection required walkers following recovery from WNE.


COMMENT
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Movement disorders, in particular tremor, myoclonus, and parkinsonism, were prominent among WNV-seropositive patients, but uncommon among WNV-seronegative patients. While tremor and myoclonus have been documented prospectively in patients with St Louis encephalitis virus 16-18 or other viral infections,19-20 they have not been described in contemporary WNV studies.1-3,5-6,9, 21 Documentation of these findings in 15 of 16 WNV-seropositive patients suggests that these findings have diagnostic relevance.

Previous immunohistological assessments have detected WNV in the basal ganglia, thalamus, and pons in patients with severe encephalitis,22 suggesting the possibility of viral involvement of these structures with resultant parkinsonism and tremor. Magnetic resonance imaging findings in 2 patients correlated clinically with the findings of parkinsonism and tremor; however, in 8 patients, parkinsonian features were present without abnormal findings on magnetic resonance imaging. Parkinsonism has been observed with Japanese encephalitis virus infection,23-26 a related flavivirus. Some prior studies have suggested long-term persistence of signs,23-25 while others have reported parkinsonism as a more transient feature.27 In our study, the patient with severe persistent parkinsonism at 8-month follow-up had shown persistence of abnormalities in the basal ganglia, thalamus, and substantia nigra on magnetic resonance imaging.

All patients with WNM had favorable outcome; all returned to work and reported normal or near-normal functioning at 8-month follow-up. In addition, 5 patients with severe WNE had excellent outcomes, achieving premorbid levels of functioning without residual disability within 4 months of illness. Severe encephalitis caused by other viral agents28-30 may often be associated with severe persistent cognitive and neurologic deficits; by comparison, this group of patients with WNE displayed a low incidence of persistent sequelae. Severity of initial encephalopathy does not necessarily portend poor long-term outcome in all patients.

Two of the 3 patients with AFP developed AFP without associated encephalopathy or meningismus. Clinical findings and electrodiagnostic data suggested involvement of anterior horn cells of the spinal cord, resulting in a poliomyelitis-like syndrome.14-15,31-32 At 8 months, none of the patients had improvement in weakness, and electromyographic data suggested permanent motor neuron loss, indicating that significant recovery in weakness is unlikely. Persistent dyspnea in 1 patient with AFP is most likely due to poliomyelitis-like diaphragmatic and intercostal muscle weakness with respiratory failure.33-35

We conclude that movement disorders, particularly tremor, myoclonus, and parkinsonism, may be underrecognized manifestations of acute WNV illness and have a generally favorable prognosis. However, complaints of persistent fatigue, headache, and myalgia are common. Long-term outcome of patients with WNE is variable, and severe initial encephalopathy did not necessarily portend poor prognosis. A poliomyelitis-like syndrome can occur without associated meningitis or encephalitis and has poor long-term outcome.


AUTHOR INFORMATION
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Corresponding Author and Reprints: James J. Sejvar, MD, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, MS A-39, Atlanta, GA 30333 (e-mail: zea3{at}cdc.gov).

Author Contributions: Study concept and design: Sejvar, Haddad, Tierney, Campbell, Marfin, Petersen.

Acquisition of data: Sejvar, Haddad, Tierney, Campbell, Van Gerpen, Leis, Stokic.

Analysis and interpretation of data: Sejvar, Haddad, Marfin, Van Gerpen, Fleischauer, Stokic, Petersen.

Drafting of the manuscript: Sejvar, Haddad, Tierney, Petersen.

Critical revision of the manuscript for important intellectual content: Sejvar, Campbell, Marfin, Van Gerpen, Fleischauer, Leis, Stokic, Petersen.

Statistical expertise: Sejvar, Haddad, Fleischauer.

Obtained funding: Marfin.

Administrative, technical, or material support: Sejvar, Haddad, Campbell, Marfin, Van Gerpen, Petersen.

Study supervision: Petersen.

Funding/Support: The study was supported by program funds for West Nile virus through the Department of Health and Human Services, Centers for Disease Control and Prevention.

Acknowledgment: We wish to acknowledge the contributions of the following individuals and institutions, whose assistance made this project possible: Case-series participants and their families; R. Ratard, MD, state epidemiologist, A. Vacari, DVM, E. Brewer, MD, J. Hand, MPH; R. Essien, MSHCN, Louisiana Office of Public Health; M. Bunning, DVM, P. Collins, MS, S. Montgomery, DVM, MPH, A. Kipp, MPH, C. Chow, MD, D. Martin, PhD, Division of Vector-Borne Infectious Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention; D. Cashen, RN, Lakeview Regional Medical Center, Covington, La; K. Moise, RN, St. Tammany Parish Hospital, Covington, La; P. Vaccaro, RN, North Oaks Regional Medical Center, Hammond, La; B. Meiche, RN, North Shore Regional Medical Center, Slidell, La; T. Croney, RN, Slidell Memorial Hospital, Slidell, La; J. Maffei, MD, D. Friloux, RN, Charity Hospital, New Orleans, La; D. Baumgarten, MD; C. Bitar, MD; M. Culasso, MD; R. Duffour, MD; J. Fitzpatrick, MD; S. Ganji, MD; T. Hall, MD; R. Houser, MD; S. Kemmerly, MD; J. LeFran, MD; R. Millet, MD; C. Nine-Montanez, MD; R. Peltier, MD, S. Raina, MD, G. Reddi, MD, R. Saguiguit, MD.

Author Affiliations: Division of Viral and Rickettsial Diseases (Dr Sejvar) and Division of Vector-Borne Infectious Diseases (Drs Campbell, Marfin, and Petersen), National Center for Infectious Diseases, and Epidemic Intelligence Service, Epidemiology Program Office (Drs Tierney and Fleischauer and Ms Haddad), Centers for Disease Control and Prevention, Atlanta, Ga; Department of Neurology, Ochsner Clinic, New Orleans, La (Dr Van Gerpen); Center for Neuroscience and Neurological Recovery, Methodist Rehabilitation Center, Jackson, Miss (Drs Leis and Stokic).


REFERENCES
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Neurology 2006;66:361-365.
ABSTRACT | FULL TEXT  

Alpha/Beta Interferon Protects against Lethal West Nile Virus Infection by Restricting Cellular Tropism and Enhancing Neuronal Survival
Samuel and Diamond
J. Virol. 2005;79:13350-13361.
ABSTRACT | FULL TEXT  

Neurologic, Neuropsychologic, and Electroencephalographic Findings After European Tick-borne Encephalitis in Children
Schmolck et al.
J Child Neurol 2005;20:500-508.
ABSTRACT  

Neurologic, Neuropsychologic, and Electroencephalographic Findings After European Tick-borne Encephalitis in Children
Schmolck et al.
J Child Neurol 2005;20:500-508.
ABSTRACT  

THE EMERGENCE OF WEST NILE VIRUS DURING A LARGE OUTBREAK IN ILLINOIS IN 2002
HUHN et al.
Am J Trop Med Hyg 2005;72:768-776.
ABSTRACT | FULL TEXT  

Characterization of an In Vitro Model of Alphavirus Infection of Immature and Mature Neurons
Vernon and Griffin
J. Virol. 2005;79:3438-3447.
ABSTRACT | FULL TEXT  

West Nile Virus Infection
Zak et al.
Am. J. Roentgenol. 2005;184:957-961.
ABSTRACT | FULL TEXT  

West Nile Virus Infection: MR Imaging Findings in the Nervous System
Ali et al.
Am. J. Neuroradiol. 2005;26:289-297.
ABSTRACT | FULL TEXT  

Update in Neurology
Samuels
ANN INTERN MED 2005;142:28-36.
FULL TEXT  

West Nile Virus: A Case Report with Flaccid Paralysis and Cervical Spinal Cord: MR Imaging Findings
Kraushaar et al.
Am. J. Neuroradiol. 2005;26:26-29.
ABSTRACT | FULL TEXT  

Post-infectious encephalomyelitis associated with St. Louis encephalitis virus infection
Sejvar et al.
Neurology 2004;63:1719-1721.
ABSTRACT | FULL TEXT  

Cerebrospinal Fluid Neutrophilic Pleocytosis in Hospitalized West Nile virus Patients
Crichlow et al.
J Am Board Fam Med 2004;17:470-472.
ABSTRACT | FULL TEXT  

Clinical Characteristics and Functional Outcomes of West Nile Fever
Watson et al.
ANN INTERN MED 2004;141:360-365.
ABSTRACT | FULL TEXT  

West Nile Virus Encephalomyelitis in Transplant Recipients
Rosenberg
JAMA 2004;292:859-860.
FULL TEXT  

West Nile Virus Infection in the United States
Tyler
Arch Neurol 2004;61:1190-1195.
FULL TEXT  

Naturally Acquired West Nile Virus Encephalomyelitis in Transplant Recipients: Clinical, Laboratory, Diagnostic, and Neuropathological Features
Kleinschmidt-DeMasters et al.
Arch Neurol 2004;61:1210-1220.
ABSTRACT | FULL TEXT  

Flavivirus Encephalitis
Solomon
NEJM 2004;351:370-378.
FULL TEXT  

The aetiology of flaccid paralysis in West Nile virus infection * Authors' reply
Leis et al.
J. Neurol. Neurosurg. Psychiatry 2004;75:940-941.
FULL TEXT  

Stiff-Person Syndrome Following West Nile Fever
Hassin-Baer et al.
Arch Neurol 2004;61:938-941.
ABSTRACT | FULL TEXT  

Additional articles abstracted in ACP Journal Club
Evid. Based Med. 2004;9:67-67.
FULL TEXT  

West Nile Virus Infection: A Pediatric Perspective
Hayes and O'Leary
Pediatrics 2004;113:1375-1381.
ABSTRACT | FULL TEXT  

Other articles noted: 25 Jul 03 to 7 Nov 03
Evid. Based Nurs. 2004;7:e1-1.
FULL TEXT  

Clinical and Laboratory Features of West Nile Virus Infection
JWatch Neurology 2003;2003:1-1.
FULL TEXT  

Spectrum of Neurologic Findings in West Nile Virus Infection
JWatch General 2003;2003:6-6.
FULL TEXT  

Spectrum of Neurologic Findings in West Nile Virus Infection
JWatch Infect. Diseases 2003;2003:1-1.
FULL TEXT  

West Nile Virus
Petersen et al.
JAMA 2003;290:524-528.
FULL TEXT  





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