Natural History of West Nile Virus Infection

2014-08-27 03:54:54 | BioPortfolio


This study will examine how West Nile virus (WNV) infection affects the body. Some people infected with WNV have no symptoms. In others, symptoms may vary from fever and headache to a polio-like syndrome with paralysis, to coma and brain changes like those of a stroke. Many patients recover with no lasting effects, while a few can have long-lasting neurological damage or may die. This study will collect clinical, laboratory, diagnostic, and radiographic information on people thought to have WNV to better understand the disease.

Patients 18 years of age and older diagnosed with or suspected of having West Nile virus infection may be eligible for this study. Patients will be hospitalized until they are well enough to go home and will undergo the following tests and procedures:

- Medical history and physical examination: A thorough history and physical examination will be done on the first day of the study. Then, brief physical exams, including measures of blood pressure, heart rate, breathing rate, and temperature, will be done during each day of hospitalization and at every follow-up clinic visit (at 2 weeks and at 1, 3, and 6 months).

- Blood tests: Blood samples will be collected on the first day of the study, at day 7, at hospital discharge, and at follow-up visits to determine if virus remains in the blood and how it is affecting the body.

- Magnetic resonance imaging (MRI): MRI scans will be done within 72 hours of beginning the study and 1 month after that. This test uses a strong magnetic field and radio waves to produce images of the brain that might show abnormalities in the brains of patients with WNV and reveal whether the abnormalities can predict how an individual will recover. For the procedure, the patient lies on a table that is moved into the narrow tunnel-like scanner. During the procedure, a contrast agent that brightens the images is injected through a catheter placed in an arm vein.

- Neurological examination and neurological function tests: Participants will be tested to see if the West Nile virus has affected their thinking and ability to perform normal daily activities. These tests will be done at the start of the study, on days 3 and 7 (also days 2, 4, 5, and 6 if patients are still in the hospital), at discharge, and at follow-up visits. The tests involve answering a number of questions and performing simple tasks, such as squeezing a hand or lifting a foot.

- Patients who develop weakness in their arms or legs will also have the following studies:

1. Electromyography (EMG) to study the electrical activity of the muscle. For this test, needles are placed into a muscle to record the electrical activity at that site.

2. Nerve conduction studies to measure how well the nerves are working. A small charge of electricity is delivered to a nerve in the affected limb, triggering a muscle to tighten or bend. Small wire electrodes are attached to the skin to measure the time is takes for the nerve to move the electrical current from one part of the limb to another.

3. Spinal MRI to see if the virus is affecting the spinal cord.

Results of other tests done by the patient's local doctor (such as lumbar puncture, electroencephalogram, x-rays, etc.) will be requested. If a lumbar puncture is done, a small amount of cerebrospinal fluid will be requested for testing for WNV.


Investigation of the Natural History of West Nile Virus Infection in Patients with Recently Acquired West Nile Fever or Neuroinvasive Disease is a descriptive natural history study. Since the first reports of WNV disease in North America in 1999, geographic range has expanded, a trend that is expected to continue for the near future. There are few sequentially collected clinical, radiologic and laboratory data from patients with WNV disease. Standardized data collection tools to measure neurologic outcome have not been developed. Prospectively collected data on laboratory and clinical events associated with WNV infection are needed to bridge gaps in current knowledge of this disease and to assist with the design of better treatments. The objectives of this study are to identify and describe the mortality and morbidity, specifically the neurologic and functional outcomes of patients with confirmed WNV disease in order to characterize the clinical course and diverse manifestations, and to assess kinetics of humoral immune responses to WNV infection, correlating these responses with clinical outcomes. Eligible patients fall into two categories: those with neuroinvasive disease caused by WNV infection, and those with WNV fever who received medical attention for their illness. All subjects must have had illness onset within four months prior to enrollment and must have laboratory confirmation of the diagnosis. There will be study visits at Days 1, 14, 30, 90, 180, and 365. Evaluations will include serum and cerebrospinal fluid for determination of WNV IgM/IgG levels and PCR for WNV, urine PCR for WNV, physical examination, serial neurologic examinations, a baseline MRI scan, and four functional and cognitive assessments that have been validated in neurologic illness in adults: the Barthel Index (BI), the Modified Rankin Scale (MRS), the Glasgow Outcome Score (GOS) and the modified Mini-Mental Status Examination (3MS). The subset of study participants who develop motor weakness of an extremity (ies) will have electromyograms, nerve conduction studies and spinal MRI performed. Results from selected clinically indicated tests (done by study participants' physicians, not mandated for the study) will be recorded in the Case Record Forms (CRFs).

Study Design



West Nile Virus


National Institutes of Health Clinical Center, 9000 Rockville Pike
United States




National Institutes of Health Clinical Center (CC)

Results (where available)

View Results


Published on BioPortfolio: 2014-08-27T03:54:54-0400

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Vaccines or candidate vaccines used to prevent infection with WEST NILE VIRUS.

A species of FLAVIVIRUS, one of the Japanese encephalitis virus group (ENCEPHALITIS VIRUSES, JAPANESE). It can infect birds and mammals. In humans, it is seen most frequently in Africa, Asia, and Europe presenting as a silent infection or undifferentiated fever (WEST NILE FEVER). The virus appeared in North America for the first time in 1999. It is transmitted mainly by CULEX spp mosquitoes which feed primarily on birds, but it can also be carried by the Asian Tiger mosquito, AEDES albopictus, which feeds mainly on mammals.

A mosquito-borne viral illness caused by the WEST NILE VIRUS, a FLAVIVIRUS and endemic to regions of Africa, Asia, and Europe. Common clinical features include HEADACHE; FEVER; maculopapular rash; gastrointestinal symptoms; and lymphadenopathy. MENINGITIS; ENCEPHALITIS; and MYELITIS may also occur. The disease may occasionally be fatal or leave survivors with residual neurologic deficits. (From Joynt, Clinical Neurology, 1996, Ch26, p13; Lancet 1998 Sep 5;352(9130):767-71)

A subgroup of the genus FLAVIVIRUS which comprises a number of viral species that are the etiologic agents of human encephalitis in many different geographical regions. These include Japanese encephalitis virus (ENCEPHALITIS VIRUS, JAPANESE), St. Louis encephalitis virus (ENCEPHALITIS VIRUS, ST. LOUIS), Murray Valley encephalitis virus (ENCEPHALITIS VIRUS, MURRAY VALLEY), and WEST NILE VIRUS.

A state bounded on the north by Pennsylvania, on the east by Delaware and the Atlantic Ocean, on the south by Virginia and West Virginia, and on the west by West Virginia.

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