Screening for West Nile virus infections of susceptible animal species in Austria

Avian mortality and encephalomyelitis in equines are considered good indicators for West Nile virus (WNV) activity. We retrospectively tested 385 horse sera for WNV antibodies and looked for WNV nucleic acid and/or WNV antigen in paraffin embedded tissues from 12 horses with aetiologically unresolved encephalomyelitis and 102 free-living birds of different species which had been found dead. With the exception of four horses originating from eastern European countries investigated on the occasion of transit through Austria, all horse sera were negative. Nested RT-PCR of the horse tissues yielded no amplification of WNV-RNA. Also, all bird samples, examined by immunohistochemistry, in situ hybridization and nested RT-PCR were negative for WNV. These results indicate that currently WNV cannot be considered a significant pathogen in Austria.

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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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Pathology of fatal lineage 1 and 2 West Nile virus infections in horses in South Africa

Journal of the South African Veterinary Association ◽

10.4102/jsava.v85i1.1105 ◽

2014 ◽

Vol 85 (1) ◽

Cited By ~ 3

Author(s):

June H. Williams ◽

Stephanie Van Niekerk ◽

Stacey Human ◽

Erna Van Wilpe ◽

Marietjie Venter

Keyword(s):

West Nile Virus ◽

South African ◽

Viral Entry ◽

Plasma Cells ◽

Ventral Horn ◽

Virus Infections ◽

Rt Pcr ◽

West Nile ◽

Lineage 2 ◽

The One

Since 2007, West Nile virus (WNV) has been reported in South African horses, causing severe neurological signs. All cases were of lineage 2, except for one case that clustered with lineage 1 viruses. In the present study, gross and microscopic lesions of six South African lineage 2-infected horses and the one lineage 1 case are described. Diagnoses were confirmed by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) of central nervous system (CNS) tissue and one by RT-PCR of a brain virus isolate. The CNS of all cases was negative by RT-PCR or immunohistochemistry (IHC) for African horse sickness (AHS), equine encephalosis virus, equine herpes viruses 1 and 4, other zoonotic flaviviruses, alphaviruses, and shunivirus, and either by immunofluorescence or IHC for rabies. Gross visceral lesions were nonspecific but often mimicked those of AHS. The CNS histopathology of WNV lineage 2 cases resembled the nonsuppurative polioencephalomyelitis reported in the Northern Hemisphere lineage 1 and recent Hungarian lineage 2 cases. Occasional meningitis, focal spinal ventral horn poliomalacia, dorsal and lateral horn poliomyelitis, leucomyelitis, asymmetrical ventral motor spinal neuritis and frequent olfactory region involvement were also seen. Lineage 2 cases displayed marked variations in CNS lesion severity, type and distribution, and suggested various viral entry routes into the CNS, based on findings in experimental mice and hamsters. Lineage 1 lesions were comparable to the milder lineage 2 cases. West Nile virus IHC on CNS sections with marked lesions from all cases elicited only two antigen-positive cells in the olfactory cortex of one case. The presence in the CNS of T-lymphocytes, B-lymphocytes, plasma cells and macrophage-monocytes was confirmed by cluster of differentiation (CD) 3, CD20, multiple myeloma oncogene 1 (MUM1) and macrophage (MAC) 387 IHC.

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Screening of Mosquitoes for West Nile Virus and Usutu Virus in Croatia, 2015–2020

Tropical Medicine and Infectious Disease ◽

10.3390/tropicalmed6020045 ◽

2021 ◽

Vol 6 (2) ◽

pp. 45

Author(s):

Ana Klobucar ◽

Vladimir Savic ◽

Marcela Curman Posavec ◽

Suncica Petrinic ◽

Urska Kuhar ◽

...

Keyword(s):

West Nile Virus ◽

Culex Pipiens ◽

Rt Pcr ◽

West Nile ◽

Usutu Virus ◽

Culex Pipiens Complex ◽

Mammalian Origin ◽

Mosquito Pool ◽

The City ◽

Generation Sequencing

In the period from 2015 to 2020, an entomological survey for the presence of West Nile virus (WNV) and Usutu virus (USUV) in mosquitoes was performed in northwestern Croatia. A total of 20,363 mosquitoes were sampled in the City of Zagreb and Međimurje county, grouped in 899 pools and tested by real-time RT-PCR for WNV and USUV RNA. All pools were negative for WNV while one pool each from 2016 (Aedes albopictus), 2017 (Culex pipiens complex), 2018 (Cx. pipiens complex), and 2019 (Cx. pipiens complex), respectively, was positive for USUV. The 2018 and 2019 positive pools shared 99.31% nucleotide homology within the USUV NS5 gene and both clustered within USUV Europe 2 lineage. The next-generation sequencing of one mosquito pool (Cx. pipiens complex) collected in 2018 in Zagreb confirmed the presence of USUV and revealed several dsDNA and ssRNA viruses of insect, bacterial and mammalian origin.

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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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Environmental Predictors of Human West Nile Virus Infections, Colorado

Emerging Infectious Diseases ◽

10.3201/eid1311.070506 ◽

2007 ◽

Vol 13 (11) ◽

pp. 1788-1790 ◽

Cited By ~ 20

Author(s):

Jennifer L. Patnaik ◽

Lara Juliusson ◽

Richard L. Vogt

Keyword(s):

West Nile Virus ◽

Virus Infections ◽

Environmental Predictors ◽

West Nile ◽

Human West Nile Virus

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The survey of wild birds for West Nile virus in Poland

Polish Journal of Veterinary Sciences ◽

10.2478/v10181-011-0085-9 ◽

2011 ◽

Vol 14 (4) ◽

pp. 573-577 ◽

Cited By ~ 2

Author(s):

J. Niczyporuk ◽

E. Samorek-Salamonowicz ◽

W. Kozdruń ◽

Z. Mizak

Keyword(s):

West Nile Virus ◽

Genetic Material ◽

Early Spring ◽

Wild Birds ◽

Rt Pcr ◽

West Nile ◽

Late Autumn ◽

The Brain

The survey of wild birds for West Nile virus in PolandTwo thousand one hundred and forty birds belonging to 39 different species from different locations in Poland were examined. The study has taken place from the early spring till late autumn 2007-2010 when the activity of the mosquitoes was the highest. The brain samples were taken from the birds and whole cellular RNA was isolated, then the RT-PCR and NRT-PCR were performed to detect the presence of West Nile virus (WNV). The obtained results were confirmed by the commercial WNV Kit. No genetic material of WNV was found in the examined samples.

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Increase in human West Nile and Usutu virus infections, Austria, 2018

Eurosurveillance ◽

10.2807/1560-7917.es.2018.23.43.1800545 ◽

2018 ◽

Vol 23 (43) ◽

Cited By ~ 40

Author(s):

Stephan W. Aberle ◽

Jolanta Kolodziejek ◽

Christof Jungbauer ◽

Karin Stiasny ◽

Judith H. Aberle ◽

...

Keyword(s):

West Nile Virus ◽

Blood Donors ◽

Blood Donation ◽

Virus Infections ◽

West Nile Fever ◽

West Nile ◽

Usutu Virus ◽

Neuroinvasive Disease ◽

Human West Nile Virus ◽

Imported Cases

Between 28 June and 17 September 2018, 27 cases of human West Nile virus infections were recorded in Austria; four cases of West Nile neuroinvasive disease, 11 cases of West Nile fever, six infections detected by blood donation screening and six imported cases. In addition, 18 cases of human Usutu virus infections (all blood donors) were recorded. This is the highest number of annual infections recorded in Austria since the introduction of both viruses.

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Emergence of West Nile virus infections in humans in Turkey, 2010 to 2011

Eurosurveillance ◽

10.2807/ese.17.21.20182-en ◽

2012 ◽

Vol 17 (21) ◽

Cited By ~ 3

Author(s):

H Kalaycioglu ◽

G Korukluoglu ◽

A Ozkul ◽

O Oncul ◽

S Tosun ◽

...

Keyword(s):

West Nile Virus ◽

Mosquito Control ◽

Epidemiological Studies ◽

Control Measures ◽

Lower Activity ◽

Virus Infections ◽

West Nile ◽

Notifiable Diseases ◽

Routine Surveillance

In 2010, 47 human cases of West Nile virus (WNV) infection, including 12 laboratory-confirmed and 35 probable cases, were identified in Turkey. These were the first cases detected during routine surveillance. The patients were from 15 provinces, mainly located in the western part of the country. Incidence was 0.19/100,000 with a maximum of 1.39 in Sakarya province. Forty of the total 47 cases showed neuroinvasive manifestation. Median age was 58 years with a range of four to 86. Ten of the patients died. Enhanced surveillance in humans and animals and mosquito control measures were implemented. The WNV infections were included in the national notifiable diseases list as of April 2011. In 2011, three probable and two confirmed cases of WNV infection were diagnosed in provinces where infections had been detected in the previous year, supporting a lower activity than 2010. However, detection of WNV infections in humans in 2010 and 2011 consecutively, may indicate that WNV has become endemic in the western part of Turkey. Field epidemiological studies were undertaken to understand more about the nature of infection in Turkey.

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