Laboratory-Acquired West Nile Virus Infections—United States, 2002

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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Pathology of Fatal West Nile Virus Infections in Native and Exotic Birds during the 1999 Outbreak in New York City, New York

Veterinary Pathology ◽

10.1354/vp.37-3-208 ◽

2000 ◽

Vol 37 (3) ◽

pp. 208-224 ◽

Cited By ~ 307

Author(s):

K. E. Steele ◽

M. J. Linn ◽

R. J. Schoepp ◽

N. Komar ◽

T. W. Geisbert ◽

...

Keyword(s):

United States ◽

New York ◽

New York City ◽

In Situ Hybridization ◽

West Nile Virus ◽

York City ◽

Virus Infections ◽

West Nile ◽

The Brain

West Nile fever caused fatal disease in humans, horses, and birds in the northeastern United States during 1999. We studied birds from two wildlife facilities in New York City, New York, that died or were euthanatized and were suspected to have West Nile virus infections. Using standard histologic and ultrastructural methods, virus isolation, immunohistochemistry, in situ hybridization and reverse-transcriptase polymerase chain reaction, we identified West Nile virus as the cause of clinical disease, severe pathologic changes, and death in 27 birds representing eight orders and 14 species. Virus was detected in 23/26 brains (88%), 24/25 hearts (96%), 15/18 spleens (83%), 14/20 livers (70%), 20/20 kidneys (100%), 10/13 adrenals (77%), 13/14 intestines (93%), 10/12 pancreata (83%), 5/12 lungs (42%), and 4/8 ovaries (50%) by one or more methods. Cellular targets included neurons and glial cells in the brain, spinal cord, and peripheral ganglia; myocardial fibers; macrophages and blood monocytes; renal tubular epithelium; adrenal cortical cells; pancreatic acinar cells and islet cells; intestinal crypt epithelium; oocytes; and fibroblasts and smooth muscle cells. Purkinje cells were especially targeted, except in crows and magpies. Gross hemorrhage of the brain, splenomegaly, menin-goencephalitis, and myocarditis were the most prominent lesions. Immunohistochemistry was an efficient and reliable method for identifying infected cases, but the polyclonal antibody cross-reacted with St. Louis encephalitis virus and other flaviviruses. In contrast, the in situ hybridization probe pWNV-E (WN-USAMRIID99) reacted only with West Nile virus. These methods should aid diagnosticians faced with the emergence of West Nile virus in the United States.

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West Nile virus activity —United States, September 26–October 2, 2002, and investigations of West Nile virus infections in recipients of blood transfusion and organ transplantation

Transfusion Medicine Reviews ◽

10.1016/s0887-7963(03)90008-3 ◽

2003 ◽

Vol 17 (2) ◽

pp. 164

Keyword(s):

United States ◽

West Nile Virus ◽

Blood Transfusion ◽

Organ Transplantation ◽

Virus Infections ◽

West Nile ◽

Virus Activity

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State of Alaska Epidemiology Bulletin: Possible West Nile Virus in an Alaskan traveler to the eastern United States, August 2003

PsycEXTRA Dataset ◽

10.1037/e467122008-001 ◽

2003 ◽

Keyword(s):

United States ◽

West Nile Virus ◽

Eastern United States ◽

West Nile

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338. Analysis of Etiologies of Aseptic Meningitis within a Nation-Wide Hospital Network

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.533 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S239-S239

Author(s):

Arunmozhi S Aravagiri ◽

Scott Kubomoto ◽

Ayutyanont Napatkamon ◽

Sarah Wilson ◽

Sudhakar Mallela

Keyword(s):

United States ◽

West Nile Virus ◽

Aseptic Meningitis ◽

Epidemiologic Study ◽

The United States ◽

Positive Test ◽

Diagnostic Tools ◽

West Nile ◽

Varicella Zoster ◽

The Us

Abstract Background Aseptic meningitis can be caused by an array of microorganisms, both bacterial and non-bacterial, as well as non-infectious conditions. Some etiologies of aseptic meningitis require treatment with antibiotics, antiviral, antifungals, anti-parasitic agents, immunosuppressants, and or chemotherapy. There are limited diagnostic tools for diagnosing certain types of aseptic meningitis, therefore knowing the differential causes of aseptic meningitis, and their relative percentages may assist in diagnosis. Review of the literature reveals that there are no recent studies of etiologies of aseptic meningitis in the United States (US). This is an epidemiologic study to delineate etiologies of aseptic meningitis in a large database of 185 HCA hospitals across the US. Methods Data was collected from January 2016 to December 2019 on all patients diagnosed with meningitis. CSF PCR studies, and CSF antibody tests were then selected for inclusion. Results Total number of encounters were 3,149 hospitalizations. Total number of individual labs analyzed was 10,613, and of these 262 etiologies were identified. 23.6% (62) of cases were due to enterovirus, 18.7% (49) due to HSV-2, 14.5% (38) due to West Nile virus, 13.7% (36) due to Varicella zoster (VZV), 10.5% (27) due to Cryptococcus. Additionally, we analyzed the rate of positive test results by region. Nationally, 9.7% of tests ordered for enterovirus were positive. In contrast, 0.5% of tests ordered for HSV 1 were positive. The southeastern United States had the highest rate of positive tests for HSV 2 (7% of tests ordered for HSV 2 were positive). The central United States had the highest rate of positive test for West Nile virus (11% of tests ordered for West Nile were positive). The northeastern region and the highest rate of positive tests for varicella zoster (18%). Table 1: Percentage of positive CSF tests (positive tests/tests ordered) Table 2: Lists the number of HIV patients and transplant patients that had positive CSF PCR/serologies Figure 1: Percentage of positive CSF tests in each region Conclusion Approximately 40% of aseptic meningitis population had treatable etiologies. A third of the Cryptococcus meningitis population had HIV. Furthermore, enteroviruses had the majority of cases within the US, which are similar to studies done in other parts of the world. Disclosures All Authors: No reported disclosures

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Epidemiology of West Nile Virus Infections in Humans, Italy, 2012–2020: A Summary of Available Evidences

Tropical Medicine and Infectious Disease ◽

10.3390/tropicalmed6020061 ◽

2021 ◽

Vol 6 (2) ◽

pp. 61

Author(s):

Matteo Riccò ◽

Simona Peruzzi ◽

Federica Balzarini

Keyword(s):

West Nile Virus ◽

Age Groups ◽

Invasive Disease ◽

Incidence Rates ◽

Annual Incidence ◽

Virus Infections ◽

West Nile ◽

Po River ◽

Air Temperatures ◽

Sex Risk

In Italy, human cases of West Nile virus (WNV) infection have been recorded since 2008, and seasonal outbreaks have occurred almost annually. In this study, we summarize available evidences on the epidemiology of WNV and West Nile neuro-invasive disease (WNND) in humans reported between 2012 and 2020. In total, 1145 WNV infection cases were diagnosed; of them 487 (42.5%) had WNND. A significant circulation of the pathogen was suggested by studies on blood donors, with annual incidence rates ranging from 1.353 (95% confidence intervals (95% CI) 0.279–3.953) to 19.069 cases per 100,000 specimens (95% CI 13.494–26.174). The annual incidence rates of WNND increased during the study period from 0.047 cases per 100,000 (95% CI 0.031–0.068) in 2012, to 0.074 cases per 100,000 (95% CI 0.054–0.099) in 2020, peaking to 0.377 cases per 100,000 (95% CI 0.330–0.429) in 2018. There were 60 deaths. Cases of WNND were clustered in Northern Italy, particularly in the Po River Valley, during the months of August (56.7%) and September (27.5%). Higher risk for WNND was reported in subjects of male sex (risk ratio (RR) 1.545, 95% CI 1.392–1.673 compared to females), and in older age groups (RR 24.46, 95% CI 15.61–38.32 for 65–74 y.o.; RR 43.7, 95% CI 28.33–67.41 for subjects older than 75 years), while main effectors were identified in average air temperatures (incidence rate ratio (IRR) 1.3219, 95% CI 1.0053–1.7383), population density (IRR 1.0004, 95% CI 1.0001–1.0008), and occurrence of cases in the nearby provinces (IRR 1.0442, 95% CI 1.0340–1.0545). In summary, an enhanced surveillance is vital for the early detection of human cases and the prompt implementation of response measures.

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