West Nile Virus

2016 ◽  
Author(s):  
Matthew Finn
Keyword(s):  
West Nile Virus ◽  
Rna Virus ◽  
Immunoglobulin M ◽  
Enzyme Linked Immunosorbent Assay ◽  
Mosquito Vector ◽  
West Nile ◽  
Csf Analysis ◽  
Neuroinvasive Disease ◽  
Breeding Grounds ◽  
Arboviral Disease

West Nile virus (WNV) is a single-stranded RNA virus of the Flavivirus family that is transmitted via a mosquito vector, typically causing fever and capable of causing meningoencephalitis. Although mortality is low, it can lead to debilitating neuroinvasive disease in some patients. WNV is a leading cause of domestically-acquired arboviral disease and most commonly occurs in late August and early September. Consider WNV in otherwise unexplained cases of meningitis or encephalitis. Initial testing should consist of cerebrospinal fluid (CSF) analysis and West Nile immunoglobulin M enzyme-linked immunosorbent assay in serum and/or CSF. WNV is a nationally notifiable disease. Prevention remains the key to controlling this disease. Reducing the breeding grounds of the Culex mosquito and using insect repellant to prevent bites are two important strategies.

scholarly journals Equine seroprevalence of West Nile virus antibodies in the UK in 2019

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Arran J. Folly ◽  
Elisabeth S. L. Waller ◽  
Fiona McCracken ◽  
Lorraine M. McElhinney ◽  
Helen Roberts ◽  
...  
Keyword(s):  
West Nile Virus ◽  
Rna Virus ◽  
Clinical History ◽  
Immunoglobulin M ◽  
Serum Samples ◽  
West Nile ◽  
Recent Infection ◽  
Igm Antibodies ◽  
Epidemiological Surveys ◽  
The Uk

Abstract Background West Nile virus (WNV) is a single-stranded RNA virus that can cause neurological disease in both humans and horses. Due to the movement of competent vectors and viraemic hosts, WNV has repeatedly emerged globally and more recently in western Europe. Within the UK, WNV is a notifiable disease in horses, and vaccines against the virus are commercially available. However, there has been no investigation into the seroprevalence of WNV in the UK equine population to determine the extent of vaccination or to provide evidence of recent infection. Methods Equine serum samples were obtained from the Animal and Plant Health Agency’s equine testing service between August and November 2019. A total of 988 serum samples were selected for horses resident in South East England. WNV seroprevalence was determined using two enzyme-linked immunosorbent assays (ELISAs) to detect total flavivirus antibodies and WNV-specific immunoglobulin M (IgM) antibodies. Positive IgM results were investigated by contacting the submitting veterinarian to establish the clinical history or evidence of prior vaccination of the horses in question. Results Within the cohort, 274 samples tested positive for flavivirus antibodies, of which two subsequently tested positive for WNV-specific IgM antibodies. The follow-up investigation established that both horses had been vaccinated prior to serum samples being drawn, which resulted in an IgM-positive response. All the samples that tested positive by competition ELISA were from horses set to be exported to countries where WNV is endemic. Consequently, the positive results were likely due to previous vaccination. In contrast, 714 samples were seronegative, indicating that the majority of the UK equine population may be susceptible to WNV infection. Conclusions There was no evidence for cryptic WNV infection in a cohort of horses sampled in England in 2019. All IgM-seropositive cases were due to vaccination; this should be noted for future epidemiological surveys in the event of a disease outbreak, as it is not possible to distinguish vaccinated from infected horses without knowledge of their clinical histories.

scholarly journals NS1 Protein Secretion during the Acute Phase of West Nile Virus Infection

2005 ◽  
Vol 79 (22) ◽  
pp. 13924-13933 ◽  
Author(s):  
Joanne Macdonald ◽  
Jessica Tonry ◽  
Roy A. Hall ◽  
Brent Williams ◽  
Gustavo Palacios ◽  
...  
Keyword(s):  
West Nile Virus ◽  
Real Time ◽  
Real Time Pcr ◽  
Diagnostic Marker ◽  
Nonstructural Protein ◽  
Immunoglobulin M ◽  
Enzyme Linked Immunosorbent Assay ◽  
Ns1 Protein ◽  
West Nile ◽  
Time Period

ABSTRACT The West Nile virus (WNV) nonstructural protein NS1 is a protein of unknown function that is found within, associated with, and secreted from infected cells. We systematically investigated the kinetics of NS1 secretion in vitro and in vivo to determine the potential use of this protein as a diagnostic marker and to analyze NS1 secretion in relation to the infection cycle. A sensitive antigen capture enzyme-linked immunosorbent assay (ELISA) for detection of WNV NS1 (polyclonal-ACE) was developed, as well as a capture ELISA for the specific detection of NS1 multimers (4G4-ACE). The 4G4-ACE detected native NS1 antigens at high sensitivity, whereas the polyclonal-ACE had a higher specificity for recombinant forms of the protein. Applying these assays we found that only a small fraction of intracellular NS1 is secreted and that secretion of NS1 in tissue culture is delayed compared to the release of virus particles. In experimentally infected hamsters, NS1 was detected in the serum between days 3 and 8 postinfection, peaking on day 5, the day prior to the onset of clinical disease; immunoglobulin M (IgM) antibodies were detected at low levels on day 5 postinfection. Although real-time PCR gave the earliest indication of infection (day 1), the diagnostic performance of the 4G4-ACE was comparable to that of real-time PCR during the time period when NS1 was secreted. Moreover, the 4G4-ACE was found to be superior in performance to both the IgM and plaque assays during this time period, suggesting that NS1 is a viable early diagnostic marker of WNV infection.

scholarly journals Hospital-based enhanced surveillance for West Nile virus neuroinvasive disease

2016 ◽  
Vol 144 (15) ◽  
pp. 3170-3175 ◽  
Author(s):  
N. P. LINDSEY ◽  
M. FISCHER ◽  
D. NEITZEL ◽  
E. SCHIFFMAN ◽  
M. L. SALAS ◽  
...  
Keyword(s):  
West Nile Virus ◽  
Healthcare Providers ◽  
Public Health Education ◽  
Viral Meningitis ◽  
Immunoglobulin M ◽  
West Nile ◽  
Neuroinvasive Disease ◽  
Optimal Tests ◽  
Attending Physician ◽  
And Control

SUMMARYAccurate data on the incidence of West Nile virus (WNV) disease are important for directing public health education and control activities. The objective of this project was to assess the underdiagnosis of WNV neuroinvasive disease through laboratory testing of patients with suspected viral meningitis or encephalitis at selected hospitals serving WNV-endemic regions in three states. Of the 279 patients with cerebrospinal fluid (CSF) specimens tested for WNV immunoglobulin M (IgM) antibodies, 258 (92%) were negative, 19 (7%) were positive, and two (1%) had equivocal results. Overall, 63% (12/19) of patients with WNV IgM-positive CSF had WNV IgM testing ordered by their attending physician. Seven (37%) cases would not have been identified as probable WNV infections without the further testing conducted through this project. These findings indicate that over a third of WNV infections in patients with clinically compatible neurological illness might be undiagnosed due to either lack of testing or inappropriate testing, leading to substantial underestimates of WNV neuroinvasive disease burden. Efforts should be made to educate healthcare providers and laboratorians about the local epidemiology of arboviral diseases and the optimal tests to be used in different clinical situations.

scholarly journals Performance Characteristics of an In-House Assay System Used To Detect West Nile Virus (WNV)-Specific Immunoglobulin M during the 2001 WNV Season in the United States

2003 ◽  
Vol 10 (1) ◽  
pp. 177-179 ◽  
Author(s):  
Harry E. Prince ◽  
Wayne R. Hogrefe
Keyword(s):  
West Nile Virus ◽  
The United States ◽  
Immunoglobulin M ◽  
Enzyme Linked Immunosorbent Assay ◽  
Screening Assay ◽  
West Nile ◽  
Elisa System ◽  
Igm Elisa ◽  
Specific Immunoglobulin ◽  
Control And Prevention

ABSTRACT During the 2001 U. S. West Nile virus (WNV) season, 163 specimens were reactive in an in-house WNV-specific immunoglobulin M (IgM) screening enzyme-linked immunosorbent assay (ELISA) and were referred to either the Centers for Disease Control and Prevention or the appropriate state public health laboratory (CDC/SPHL) for additional testing. CDC/SPHL supplied results for 124 specimens that could be further evaluated in-house: 70 specimens were nonreactive in the CDC/SPHL WNV-specific IgM screening assay, and 54 specimens were reactive. These specimens were used to evaluate a modified in-house WNV-specific IgM ELISA that incorporated background subtraction to identify nonspecific reactivity and thus improve assay specificity. Of the 70 CDC/SPHL nonreactive samples, 49 (70%) were nonreactive in the modified ELISA; of the 54 CDC/SPHL reactive samples, 51 (94%) were reactive in the modified ELISA. Confirmatory studies performed by CDC/SPHL indicated that 38 CDC/SPHL screen-reactive specimens represented true WNV infection; all 38 specimens were reactive in the modified in-house WNV-specific IgM ELISA. These findings demonstrate that an in-house ELISA system for WNV-specific IgM effectively identifies patients with WNV infection.

West Nile Neuroinvasive Disease With Atypical CSF Findings: A Case Report

2021 ◽  
pp. 194187442199537
Author(s):  
Devin Simon
Keyword(s):  
West Nile Virus ◽  
Virus Infection ◽  
Rare Complication ◽  
Cauda Equina ◽  
Late Summer ◽  
West Nile Virus Infection ◽  
Inpatient Rehabilitation ◽  
West Nile ◽  
Csf Analysis ◽  
Neuroinvasive Disease

West Nile Neuroinvasive Disease (WNND) is a rare complication of West Nile Virus infection with the capability of mimicking other neurologic diseases. This infection should be considered in the differential diagnosis for patients presenting in the late summer months with altered mentation, fever, and focal neurologic deficits without an otherwise clear etiology. A 63-year-old male presented with acute onset fever, confusion, falls, ataxia, vertical nystagmus, and right leg weakness. Although magnetic resonance imaging of the brain and cervical spine were unremarkable, the lumbar spine revealed enhancement of ventral nerve roots in the cauda equina. Cerebrospinal fluid (CSF) analysis was significant for elevated protein without pleocytosis, which was more suggestive of albuminocytologic dissociation. Both serum and CSF IgM labs testing for West Nile Virus were positive. Despite a 5 day course of immunoglobulin therapy, his symptoms did not significantly improve. He eventually was transferred to inpatient rehabilitation for several days prior to returning home. This case highlights the variable presentations of acute West Nile Virus infection in the rare setting of neuroinvasive disease, which can make diagnosis difficult. The CSF analysis may also not always show results consistent with an acute viral infection, which can make determining the underlying etiology more challenging.

scholarly journals Evaluation of a Diagnostic Algorithm Using Immunoglobulin M Enzyme-Linked Immunosorbent Assay To Differentiate Human West Nile Virus and St. Louis Encephalitis Virus Infections during the 2002 West Nile Virus Epidemic in the United States

2004 ◽  
Vol 11 (6) ◽  
pp. 1130-1133 ◽  
Author(s):  
Denise A. Martin ◽  
Amanda Noga ◽  
Olga Kosoy ◽  
Alison J. Johnson ◽  
Lyle R. Petersen ◽  
...  
Keyword(s):  
United States ◽  
West Nile Virus ◽  
Immunosorbent Assay ◽  
Diagnostic Algorithm ◽  
The United States ◽  
Encephalitis Virus ◽  
Immunoglobulin M ◽  
Enzyme Linked Immunosorbent Assay ◽  
Virus Infections ◽  
West Nile

ABSTRACT A diagnostic algorithm was developed to differentiate between human infections of West Nile virus (WNV) and St. Louis encephalitis virus (SLEV) using positive-to-negative (P/N) ratios derived from the immunoglobulin M capture enzyme-linked immunosorbent assay (MAC-ELISA). To validate this algorithm, we tested 1,418 serum and cerebrospinal fluid (CSF) samples from confirmed WNV and SLEV infections collected during the WNV epidemic of 2002 in the United States. WNV P/N-to-SLEV P/N ratios (W/S ratios) were calculated and used to identify the infecting virus. These results were compared to results from the plaque reduction neutralization test (PRNT), which is currently the standard assay used to discriminate between closely related flavivirus infections. If the W/S ratio was ≥1, the predictive value positive (PNP) for WNV was 97.8%, where 95% of flavivirus cases were due to WNV infection and only 3.7% of specimens would require PRNT to differentiate WNV from SLEV infection. Use of the W/S ratio as part of the testing algorithm to interpret MAC-ELISA results generates reportable probable cases quickly, alleviating the need for PRNT in most instances.

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