West Nile Virus (WNV) is a mosquito-borne virus that affects horses, causing neurological disease. It is transmitted primarily through the bite of infected mosquitoes, which acquire the virus from feeding on infected birds. Horses are considered a dead-end host, meaning they do not contribute to the transmission cycle of the virus. Clinical signs in horses can range from mild fever and lethargy to severe neurological symptoms such as ataxia, weakness, and paralysis. Diagnosis is typically confirmed through serological testing or detection of the virus in tissues. Vaccination is available and serves as a preventive measure to reduce the incidence of the disease. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, pathogenesis, clinical presentation, and management of West Nile Virus in equine populations.
Ahlers LRH, Goodman AG.Vector-borne diseases, including arboviruses, pose a serious threat to public health worldwide. Arboviruses of the flavivirus genus, such as Zika virus (ZIKV), dengue virus, yellow fever virus (YFV), and West Nile virus (WNV), are transmitted to humans from insect vectors and can cause serious disease. In 2017, over 2,000 reported cases of WNV virus infection occurred in the United States, with two-thirds of cases classified as neuroinvasive. WNV transmission cycles through two different animal populations: birds and mosquitoes. Mammals, particularly humans and horses, can become infected thro...
Bażanów B, Jansen van Vuren P, Szymański P, Stygar D, Frącka A, Twardoń J, Kozdrowski R, Pawęska JT.West Nile virus (WNV) and Usutu virus (USUV) are members of the family Flaviviridae which, natural life cycles involve mosquito-bird-mosquito transmission. Both represent emerging viruses in Europe with potential to cause neuroinvasive disease in humans. This study investigates the seroprevalence of serum neutralizing antibodies to WNV and to USUV in birds and in horses in Poland. Antibodies against WNV and USUV were detected in 5 (35.7%) and in 1 (7.14%) of 14 birds and in 62 (15.08%) and in 115 (27.98%) of 411 horses, respectively. Twenty-one WNV serologically positive horses (33.87%) and 67...
Csank T, Drzewnioková P, Korytár Ľ, Major P, Gyuranecz M, Pistl J, Bakonyi T.In central Europe, at least three flaviviruses circulate among vectors and vertebrate hosts. West Nile virus (WNV) and Usutu virus (USUV) are mosquito-borne viruses maintained in the nature by enzootic cycle between mosquitoes and birds. Tick-borne encephalitis virus (TBEV) is a flavivirus causing annual human cases in Slovakia. The aim of this study is the prevalence assessment of flavivirus infections in horses (n = 145) and birds (n = 109) by enzyme-linked immunosorbent assay (ELISA) and confirmation by neutralization test (VNT). WNV antibodies have been detected in 11.7% of tested ...
Kumar R, Patil RD.The importance of horse (Equus caballus) to equine practitioners and researchers cannot be ignored. An unevenly distributed population of equids harbors numerous diseases, which can affect horses of any age and breed. Among these, the affections of nervous system are potent reason for death and euthanasia in equids. Many episodes associated with the emergence of equine encephalitic conditions have also pose a threat to human population as well, which signifies their pathogenic zoonotic potential. Intensification of most of the arboviruses is associated with sophisticated interaction between ve...
Venter M, Pretorius M, Fuller JA, Botha E, Rakgotho M, Stivaktas V, Weyer C, Romito M, Williams J.During 2008-2015 in South Africa, we conducted West Nile virus surveillance in 1,407 animals with neurologic disease and identified mostly lineage 2 cases in horses (7.4%, 79/1,069), livestock (1.5%, 2/132), and wildlife (0.5%, 1/206); 35% were fatal. Geographic correlation of horse cases with seropositive veterinarians suggests disease in horses can predict risk in humans.
Barros SC, Ramos F, Fagulha T, Duarte M, Henriques AM, Waap H, Luís T, Costa T, Amador R, Quintans S, Fevereiro M.West Nile fever (WNF) is an emergent disease in Europe, under surveillance in the European Union. Following a 5-year period of apparent silence (autumn 2010 to summer 2015), West Nile virus (WNV) reemerged in the South of Portugal, in July 2015. Here we present data from the onset, geographic location within mainland Portugal, and outcome of clinical cases of WNV infection in horses in 2015 and 2016. During the transmission seasons of 2015 and 2016, twenty-seven horses, most symptomatic (n=20) were found positive to IgM, pr-E immunoglobulins and VNT, leading to the subsequent report to Animal ...
Piyasena TBH, Setoh YX, Hobson-Peters J, Prow NA, Bielefeldt-Ohmann H, Khromykh AA, Perera D, Cardosa MJ, Kirkland PD, Hall RA.In Australia, infection of horses with the West Nile virus (WNV) or Murray Valley encephalitis virus (MVEV) occasionally results in severe neurological disease that cannot be clinically differentiated. Confirmatory serological tests to detect antibody specific for MVEV or WNV in horses are often hampered by cross-reactive antibodies induced to conserved epitopes on the envelope (E) protein. This study utilized bacterially expressed recombinant antigens derived from domain III of the E protein (rE-DIII) of MVEV and WNV, respectively, to determine whether these subunit antigens provided specific...
García-Bocanegra I, Belkhiria J, Napp S, Cano-Terriza D, Jiménez-Ruiz S, Martínez-López B.During the last decade, West Nile virus (WNV) outbreaks have increased sharply in both horses and human in Europe. The aims of this study were to evaluate characteristics and spatio-temporal distribution of WNV outbreaks in horses in Spain between 2010 and 2016 in order to identify the environmental variables most associated with WNV occurrence and to generate high-resolution WNV suitability maps to inform risk-based surveillance strategies in this country. Between August 2010 and November 2016, a total of 403 WNV suspected cases were investigated, of which, 177 (43.9%) were laboratory confirm...
Rocheleau JP, Michel P, Lindsay LR, Drebot M, Dibernardo A, Ogden NH, Fortin A, Arsenault J.Periodic outbreaks of West Nile virus (WNV), Eastern equine encephalitis virus (EEEV) and to a lesser extent, California serogroup viruses (CSGV), have been reported in parts of Canada in the last decade. This study was designed to provide a broad assessment of arboviral activity in Quebec, Canada, by conducting serological surveys for these arboviruses in 196 horses, 1442 dogs and 485 humans. Sera were screened by a competitive enzyme linked immunosorbent assay and positive samples confirmed by plaque reduction neutralisation tests. The percentage of seropositive samples was 83·7%, 16·5%, 7...
Beck C, Lowenski S, Durand B, Bahuon C, Zientara S, Lecollinet S.West Nile Fever is a zoonotic disease caused by a mosquito-borne flavivirus, WNV. By its clinical sensitivity to the disease, the horse is a useful sentinel of infection. Because of the virus' low-level, short-term viraemia in horses, the primary tools used to diagnose WNV are serological tests. Inter-laboratory proficiency tests (ILPTs) were held in 2010 and 2013 to evaluate WNV serological diagnostic tools suited for the European network of National Reference Laboratories (NRLs) for equine diseases. These ILPTs were designed to evaluate the laboratories' and methods' performances in detectin...
Benjelloun A, El Harrak M, Calistri P, Loutfi C, Kabbaj H, Conte A, Ippoliti C, Danzetta ML, Belkadi B.West Nile virus-associated disease is one of the most widespread vector-borne diseases in the world. In Morocco, the first cases were reported in horses in 1996 and the disease re-emerged in 2003 and in 2010. The objective of this work was to study the epidemiological situation of WNV-associated infection in Morocco, by quantifying the seroprevalence of anti-WNV IgM and IgG antibodies in horses in different bioclimatic regions-zones of Morocco in 2011. During the months of May, June and July 2011, 840 serum samples were collected from horses in four regions characterized by different environme...
Pauvolid-Corrêa A, Komar N.Current methods for detecting Flavivirus antibodies are enzyme-linked immunosorbent assays (ELISAs) and neutralization tests, both of which require laboratories and trained staff. We evaluated the VectorTest™ West Nile Virus Antigen Assay in an inhibition platform (VecTest-inhibition assay [VIA]) as a simpler screening method for detecting antibodies for a variety of flaviviruses among a population of equines from Brazil. We found that the VIA is a field-deployable rapid method with 100% sensitivity and 64% specificity compared with blocking ELISA for the detection of group-specific Flavivir...
Cardinale E, Bernard C, Lecollinet S, Rakotoharinome VM, Ravaomanana J, Roger M, Olive MM, Meenowa D, Jaumally MR, Melanie J, Héraud JM, Zientara S....The circulation of West Nile virus (WNV) in horses was investigated in the Southwest Indian ocean. In 2010, blood samples were collected from a total of 303 horses originating from Madagascar, Mauritius, Reunion and the Seychelles and tested for WNV-specific antibodies. An overall seroprevalence of 27.39% was detected in the Indian Ocean with the highest WNV antibody prevalence of 46.22% (95% CI: [37.4-55.2%]) in Madagascar. The age and origin of the horses were found to be associated with the WNV infection risk. This paper presents the first seroprevalence study investigating WN fever in hors...
Bolfa P, Jeon I, Loftis A, Leslie T, Marchi S, Sithole F, Beck C, Lecollinet S, Zientara S, Hans A, Issel CJ.Equines in the West Indies are used for recreational purposes, tourism industry, racing and agriculture or can be found in feral populations. Little is known in the Caribbean basin about the prevalence of some major equine infectious diseases, some with zoonotic potential, listed as reportable by the OIE. Our objective was to study the prevalence of antibodies for West Nile Virus (WNV), Equine Herpes Virus-1 and 4 (EHV-1 and EHV-4), Equine Influenza (EI), Equine Viral Arteritis (EVA) and Equine Infectious Anemia Virus (EIAV) using a retrospective serological convenience study. We used 180 equi...
Azmi K, Tirosh-Levy S, Manasrah M, Mizrahi R, Nasereddin A, Al-Jawabreh A, Ereqat S, Abdeen Z, Lustig Y, Gelman B, Schvartz G, Steinman A.West Nile virus (WNV) epidemiological situation in Israel and Palestine, due to their unique location, draws attention following to the global spread of West Nile fever (WNF). Although much information is available from Israel on clinical cases and prevalence of WNV, clinical cases are rarely reported in Palestine, and prevalence is not known. The objectives of this study were to determine WNV seroprevalence in various domestic animals in Palestine and to reevaluate current seroprevalence, force of infection, and risk factors for WNV exposure in horses in Israel. Sera samples were collected fr...
Torgeman A, Mador N, Dorozko M, Lifshitz A, Eschar N, White MD, Wolf DG, Epstein E.Assuring viral safety of horse plasma-derived products is fundamental for ethical and regulatory reasons. We previously demonstrated the ability of pepsin digestion at low pH to inactivate West Nile and Sindbis viruses in horse plasma. The present study further examined the efficiency of pepsin digestion to inactivate four additional viruses: HSV-1 and BVDV (lipid-enveloped), BPV and Reo-3 (nonenveloped). These viruses were spiked into hyperimmunized horse plasma against botulinum toxin and subjected to low pH (3.2) alone or combined with pepsin digestion (1200 units/ml). Peptic digestion inac...
Delcambre GH, Liu J, Streit WJ, Shaw GPJ, Vallario K, Herrington J, Wenzlow N, Barr KL, Long MT.West Nile virus (WNV), a mosquito borne member of the Flaviviridae, is one of the most commonly diagnosed agents of viral encephalitis in horses and people worldwide. Objective: A cassette of markers for formalin-fixed paraffin-embedded tissue and an archive of tissues from experimental infections in the horse were used to investigate the equine neuroimmune response to WNV meningoencephalomyelitis to phenotype the early response to WNV infection in the horse. Methods: Quantitative analysis using archived tissue from experimentally infected horses. Methods: The thalamus and hindbrain from 2 gro...
Vanhomwegen J, Beck C, Desprès P, Figuerola A, García R, Lecollinet S, López-Roig M, Manuguerra JC, Serra-Cobo J.The presence of major arbovirus vector species, climate change that promotes the expansion and increase of their populations, and potential animal reservoirs mean that vector-borne diseases represent a significant health risk for Mallorca's inhabitants. Microbiological monitoring of circulating arboviruses, particularly flaviviruses causing encephalitis, was initiated using domestic horses from localities near wetlands as "sentinel" hosts. A total of 291 blood samples were taken from 172 horses between 2011 and 2012, using paired samples to highlight seroconversion events. A multiplex immunoas...
Pintore MD, Cerutti F, D'Angelo A, Corona C, Gazzuola P, Masoero L, Colombo C, Bona R, Cantile C, Peletto S, Casalone C, Iulini B.A fatal case of meningoencephalitis was reported in a 13-year-old Koninklijk Warmbloed Paard Nederland stallion, suspected of West Nile virus (WNV) infection, in the Piedmont region of Italy. Clinical signs included right head tilt and circling, depression alternated with excitability, fever and lateral strabismus. Combined treatment consisting of dimethylsulfoxide, dexamethasone, sulphonamides and sedative was administered, but because of the poor conditions the horse was euthanatized and submitted for necropsy. At post-mortem examination no skin lesions were observed, all organs appeared nor...
Maquart M, Dahmani M, Marié JL, Gravier P, Leparc-Goffart I, Davoust B.West Nile virus (WNV) is widely distributed over the world, including Europe, Africa, and Asia and spread over the past two decades to North and South America. In the south of France, sporadic cases are frequently described and the virus is endemic in Italy with frequent cases and outbreaks. The aim of this study was to identify a possible WNV circulation in Corsica (French island in the Mediterranean Sea) in sheep, horses, and dogs as sentinel animals for the virus surveillance. In 2014, 386 blood samples were collected from 219 sheep, 96 horses, and 71 dogs, in 12 localities in Corsica, in t...
Bielefeldt-Ohmann H, Bosco-Lauth A, Hartwig AE, Uddin MJ, Barcelon J, Suen WW, Wang W, Hall RA, Bowen RA.Most natural West Nile virus (WNV) infections in humans and horses are subclinical or sub-lethal and non-encephalitic. Yet, the main focus of WNV research remains on the pathogenesis of encephalitic disease, mainly conducted in mouse models. We characterized host responses during subclinical WNV infection in horses and compared outcomes with those obtained in a novel rabbit model of subclinical WNV infection (Suen et al. 2015. Pathogens, 4: 529). Experimental infection of 10 horses with the newly emerging WNV-strain, WNVNSW2011, did not result in neurological disease in any animal but transcr...
Cui J, Zhao Y, Wang H, Qiu B, Cao Z, Li Q, Zhang Y, Yan F, Jin H, Wang T, Sun W, Feng N, Gao Y, Sun J, Wang Y, Perlman S, Zhao J, Yang S, Xia X.West Nile virus (WNV) is prevalent in Africa, Europe, the Middle East, West Asia, and North America, and causes epidemic encephalitis. To date, no effective therapy for WNV infection has been developed; therefore, there is urgent need to find an efficient method to prevent WNV disease. In this study, we prepared and evaluated the protective efficacy of immune serum IgG and pepsin-digested F(ab')₂ fragments from horses immunized with the WNV virus-like particles (VLP) expressing the WNV M and E proteins. Immune equine F(ab')₂ fragments and immune horse sera efficiently neutralized WNV infec...
Faverjon C, Vial F, Andersson MG, Lecollinet S, Leblond A.West Nile virus (WNV) is a growing public health concern in Europe and there is a need to develop more efficient early detection systems. Nervous signs in horses are considered to be an early indicator of WNV and, using them in a syndromic surveillance system, might be relevant. In our study, we assessed whether or not data collected by the passive French surveillance system for the surveillance of equine diseases can be used routinely for the detection of WNV. We tested several pre-processing methods and detection algorithms based on regression. We evaluated system performances using simulate...
Liu SA, Haque M, Stanfield B, Andrews FM, Roy AA, Kousoulas KG.West Nile Virus (WNV) is endemic in the US and causes severe neurologic disease in horses since its introduction in 1999. There is no effective pharmaceutical treatment for WNV infection rendering vaccination as the only approach to prevention and control of disease. The purpose of this study was to evaluate a recombinant vaccine containing domain III (DIII) of the WNV envelope glycoprotein with and without a natural adjuvant equine (CD40L) in producing virus neutralizing antibodies in horses. Serum IgG1 concentration in the groups of horses vaccinated with the DIII-CD40L+TiterMax and DIII-CD4...
West Nile fever (WNF) is a viral disease of wild birds transmitted by mosquitoes. Humans and equids can also be affected and suffer from meningoencephalitis. In Algeria, since the 1994 epidemic, no data on WNV circulation was available until 2012. In September 2012, a fatal human case of WNV neuro-invasive infection occurred in Jijel province. This study describes the first seroprevalence study of West Nile virus (WNV) antibodies conducted in the equine population in Algeria. During 2014, serum samples were collected from 293 equids (222 donkeys and 71 horses) asymptomatic and unvaccinated for...
Joó K, Bakonyi T, Szenci O, Sárdi S, Ferenczi E, Barna M, Malik P, Hubalek Z, Fehér O, Kutasi O.West Nile virus (WNV) mainly infects birds, horses and humans. Outcomes of the infection range from mild uncharacteristic signs to fatal neurologic disease. The main objectives of the present study were to measure serum IgG and IgM antibodies in naturally exposed and vaccinated horses and to compare results of haemagglutination inhibition test (HIT), enzyme-linked immunosorbent assay (ELISA) and plaque reduction neutralisation test (PRNT). Altogether 224 animals were tested by HIT for WNV antibodies and 41 horses were simultaneously examined by ELISA and PRNT. After primary screening for WNV a...
Efforts to detect West Nile virus (WNV) in the Vojvodina province, northern Serbia, commenced with human and mosquito surveillance in 2005, followed by horse (2009) and wild bird (2012) surveillance. The knowledge obtained regarding WNV circulation, combined with the need for timely detection of virus activity and risk assessment resulted in the implementation of a national surveillance programme integrating mosquito, horse and bird surveillance in 2014. From 2013, the system showed highly satisfactory results in terms of area specificity (the capacity to indicate the spatial distribution of t...
Rizzo C, Napoli C, Venturi G, Pupella S, Lombardini L, Calistri P, Monaco F, Cagarelli R, Angelini P, Bellini R, Tamba M, Piatti A, Russo F, Palù G....In Italy a national Plan for the surveillance of imported and autochthonous human vector-borne diseases (chikungunya, dengue, Zika virus disease and West Nile virus (WNV) disease) that integrates human and veterinary (animals and vectors) surveillance, is issued and revised annually according with the observed epidemiological changes. Here we describe results of the WNV integrated veterinary and human surveillance systems in Italy from 2008 to 2015. A real time data exchange protocol is in place between the surveillance systems to rapidly identify occurrence of human and animal cases and to de...
Cleton NB, van Maanen K, Bergervoet SA, Bon N, Beck C, Godeke GJ, Lecollinet S, Bowen R, Lelli D, Nowotny N, Koopmans MPG, Reusken CBEM.The genus Flavivirus in the family Flaviviridae includes some of the most important examples of emerging zoonotic arboviruses that are rapidly spreading across the globe. Japanese encephalitis virus (JEV), West Nile virus (WNV), St. Louis encephalitis virus (SLEV) and Usutu virus (USUV) are mosquito-borne members of the JEV serological group. Although most infections in humans are asymptomatic or present with mild flu-like symptoms, clinical manifestations of JEV, WNV, SLEV, USUV and tick-borne encephalitis virus (TBEV) can include severe neurological disease and death. In horses, infection wi...
Humblet MF, Vandeputte S, Fecher-Bourgeois F, Léonard P, Gosset C, Balenghien T, Durand B, Saegerman C.This study aimed at estimating, in a prospective scenario, the potential economic impact of a possible epidemic of WNV infection in Belgium, based on 2012 values for the equine and human health sectors, in order to increase preparedness and help decision-makers. Modelling of risk areas, based on the habitat suitable for Culex pipiens, the main vector of the virus, allowed us to determine equine and human populations at risk. Characteristics of the different clinical forms of the disease based on past epidemics in Europe allowed morbidity among horses and humans to be estimated. The main costs ...
Johnson DJ, Ostlund EN, Pedersen DD, Schmitt BJ.A traditional single-stage reverse transcription-polymerase chain reaction (RT-PCR) procedure is effective in determining West Nile (WN) virus in avian tissue and infected cell cultures. However, the procedure lacks the sensitivity to detect WN virus in equine tissue. We describe an RT-nested PCR (RT-nPCR) procedure that identifies the North American strain of WN virus directly in equine and avian tissues.
Davis LE, Beckham JD, Tyler KL.Arboviruses continue to be a major cause of encephalitis in North America, and West Nile virus neuroinvasive disease is now the dominant cause of encephalitis. Transmission to humans of North American arboviruses occurs by infected mosquitoes or ticks. Most infections are asymptomatic or produce a flulike illness. Rapid serum or cerebrospinal fluid IgM antibody capture ELISA assays are available to diagnosis the acute infection for all North American arboviruses. Unfortunately, no antiviral drugs are approved for the treatment of arbovirus infection and current therapy is supportive.
Quirin R, Salas M, Zientara S, Zeller H, Labie J, Murri S, Lefrançois T, Petitclerc M, Martinez D.To determine whether West Nile virus (WNV) had reached the archipelago of Guadeloupe, a serologic study in horses and birds was conducted in 2002. Immunoglobulin (Ig) G, IgM, enzyme-linked immunosorbent assay, and seroneutralization tests identified WNV infection in horses and chickens. Six months later, a high rate of seroconversion was observed in horses.
Steinman A, Banet C, Sutton GA, Yadin H, Hadar S, Brill A.Between August and October 2000, 76 horses were reported by veterinary practitioners as having signs of a neurological disorder, varying from an involvement of the spinal cord alone to the entire central nervous system; 15 of the horses died or were euthanased as a result of their grave prognosis or secondary complications. At the same time, an outbreak of West Nile virus infection affected people and birds, principally domestic geese. West Nile virus was isolated from four of the horses with encephalomyelitis and five other horses seroconverted, indicating that the virus was the probable caus...
Ozkul A, Ergunay K, Koysuren A, Alkan F, Arsava EM, Tezcan S, Emekdas G, Hacioglu S, Turan M, Us D.West Nile fever is an important zoonotic infection caused by West Nile virus (WNV), a member of the Flaviviridae. Previous serological data from Turkey suggest widespread WNV circulation. This report includes cases of human and equine WNV infections occurring concurrently, and manifesting as central nervous system infections, in two neighboring provinces of Central Anatolia, Turkey. A partial phylogenetic analysis of the causative virus is given for the first time. Methods: The cases were reported in February (horses) and March (human). Symptoms of the disease were similar in the two species, ...
Yeh JY, Lee JH, Park JY, Seo HJ, Moon JS, Cho IS, Kim HP, Yang YJ, Ahn KM, Kyung SG, Choi IS, Lee JB.The detection of West Nile virus (WNV) in areas endemic for Japanese encephalitis virus (JEV) is complicated by the extensive serological cross-reactivity between the two viruses. A testing algorithm was developed and employed for the detection of anti-WNV antibody in areas endemic for JEV. Using this differentiation algorithm, a serological survey of poultry (2004 through 2009) and horses (2007 through 2009) was performed. Among 2681 poultry sera, 125 samples were interpreted as being positive for antibodies against JEV, and 14 were suspected to be positive for antibodies against undetermined...
Ahlers LRH, Goodman AG.Vector-borne diseases, including arboviruses, pose a serious threat to public health worldwide. Arboviruses of the flavivirus genus, such as Zika virus (ZIKV), dengue virus, yellow fever virus (YFV), and West Nile virus (WNV), are transmitted to humans from insect vectors and can cause serious disease. In 2017, over 2,000 reported cases of WNV virus infection occurred in the United States, with two-thirds of cases classified as neuroinvasive. WNV transmission cycles through two different animal populations: birds and mosquitoes. Mammals, particularly humans and horses, can become infected thro...
Bielefeldt-Ohmann H, Prow NA, Wang W, Tan CS, Coyle M, Douma A, Hobson-Peters J, Kidd L, Hall RA, Petrovsky N.In 2011, following severe flooding in Eastern Australia, an unprecedented epidemic of equine encephalitis occurred in South-Eastern Australia, caused by Murray Valley encephalitis virus (MVEV) and a new variant strain of Kunjin virus, a subtype of West Nile virus (WNVKUN). This prompted us to assess whether a delta inulin-adjuvanted, inactivated cell culture-derived Japanese encephalitis virus (JEV) vaccine (JE-ADVAX™) could be used in horses, including pregnant mares and foals, to not only induce immunity to JEV, but also elicit cross-protective antibodies against MVEV and WNVKUN. Foals, 74...
Rockstroh A, Moges B, Berneck BS, Sattler T, Revilla-Fernández S, Schmoll F, Pacenti M, Sinigaglia A, Barzon L, Schmidt-Chanasit J, Nowotny N....Tick-borne encephalitis virus (TBEV) and West Nile virus (WNV) are important arthropod-borne zoonotic flaviviruses. Due to the emergence of WNV in TBEV-endemic regions co-circulation of both viruses is increasing. Flaviviruses are structurally highly similar, which leads to cross-reacting antibodies upon infection. Currently available serological assays for TBEV and WNV infections are therefore compromised by false-positive results, especially in IgG measurements. In order to discriminate both infections novel diagnostic methods are needed. We describe an ELISA to measure IgG antibodies specif...
Silva JR, Medeiros LC, Reis VP, Chavez JH, Munhoz TD, Borges GP, Soares OA, Campos CH, Machado RZ, Baldani CD, Silva ML, Faria JL, Silva EE....Since the emergence of West Nile virus (WNV) in North America in 1999, there have been several reports of WNV activity in Central and South American countries. To detect WNV in Brazil, we performed a serological survey of horses from different regions of Brazil using recombinant peptides from domain III of WNV. Positive samples were validated with the neutralisation test. Our results showed that of 79 ELISA-positive horses, nine expressed WNV-specific neutralising antibodies. Eight of the infected horses were from the state of Mato Grosso do Sul and one was from the state of Paraíba. Our resu...
Zohaib A, Saqib M, Beck C, Hussain MH, Lowenski S, Lecollinet S, Sial A, Asi MN, Mansoor MK, Saqalein M, Sajid MS, Ashfaq K, Muhammad G, Cao S.This study describes the first large-scale serosurvey on West Nile virus (WNV) conducted in the equine population in Pakistan. Sera were collected from 449 equids from two provinces of Pakistan during 2012-2013. Equine serum samples were screened using a commercial ELISA kit detecting antibodies against WNV and related flaviviruses. ELISA-positive samples were further investigated using virus-specific microneutralization tests (MNTs) to identify infections with Japanese encephalitis virus (JEV), WNV and tick-borne encephalitis virus (TBEV). Anti-WNV antibodies were detected in 292 samples by E...
Chapman GE, Baylis M, Archer D, Daly JM.Equine populations worldwide are at increasing risk of infection by viruses transmitted by biting arthropods, including mosquitoes, biting midges (Culicoides), sandflies and ticks. These include the flaviviruses (Japanese encephalitis, West Nile and Murray Valley encephalitis), alphaviruses (eastern, western and Venezuelan encephalitis) and the orbiviruses (African horse sickness and equine encephalosis). This review provides an overview of the challenges faced in the surveillance, prevention and control of the major equine arboviruses, particularly in the context of these viruses emerging in ...
Ward MP, Schuermann JA, Highfield LD, Murray KO.Equine West Nile virus (WNV) encephalomyelitis cases - based on clinical signs and ELISA serology test results - reported to Texas disease control authorities during 2002 were analyzed to provide insights into the epidemiology of the disease within a previously disease-free population. The epidemic occurred between June 27 and December 17 (peaking in early October) and 1,698 cases were reported. Three distinct epidemic phases were identified, occurring mostly in southeast, northwest and then central Texas. Significant (P<0.05) disease clusters were identified in northwest and northern Texas. M...
Maquart M, Dahmani M, Marié JL, Gravier P, Leparc-Goffart I, Davoust B.West Nile virus (WNV) is widely distributed over the world, including Europe, Africa, and Asia and spread over the past two decades to North and South America. In the south of France, sporadic cases are frequently described and the virus is endemic in Italy with frequent cases and outbreaks. The aim of this study was to identify a possible WNV circulation in Corsica (French island in the Mediterranean Sea) in sheep, horses, and dogs as sentinel animals for the virus surveillance. In 2014, 386 blood samples were collected from 219 sheep, 96 horses, and 71 dogs, in 12 localities in Corsica, in t...
Thompson NN, Auguste AJ, Coombs D, Blitvich BJ, Carrington CV, da Rosa AP, Wang E, Chadee DD, Drebot MA, Tesh RB, Weaver SC, Adesiyun AA.Seroprevalence rates of selected arboviruses in animal populations in Trinidad were determined using serum samples collected between 2006 and 2009 from horses (n=506), cattle (n=163), sheep (n=198), goats (n=82), pigs (n=184), birds (n=140), rodents (n=116), and other vertebrates (n=23). The sera were screened for antibodies to West Nile virus (WNV), St. Louis encephalitis virus (SLEV), Ilheus virus (ILHV), Bussuquara virus (BSQV), Venezuelan equine encephalitis virus (VEEV), eastern equine encephalitis virus (EEEV), and western equine encephalitis virus (WEEV), using hemagglutination inhibiti...
Young JJ, Coulombier D, Domanović D, Zeller H, Gossner CM.West Nile virus (WNV) infection is notifiable in humans and equids in the European Union (EU). An area where a human case is detected is considered affected until the end of the mosquito transmission season (week 48) and blood safety measures have to be implemented. We used human and equine case notifications between 2013 and 2017 to define the WNV distribution in the EU and to investigate the relevance of using equine cases as a complementary trigger for blood safety measures. Adding areas with equine cases to the definition of an affected area would have a major impact on blood safety measur...
Vanhomwegen J, Beck C, Desprès P, Figuerola A, García R, Lecollinet S, López-Roig M, Manuguerra JC, Serra-Cobo J.The presence of major arbovirus vector species, climate change that promotes the expansion and increase of their populations, and potential animal reservoirs mean that vector-borne diseases represent a significant health risk for Mallorca's inhabitants. Microbiological monitoring of circulating arboviruses, particularly flaviviruses causing encephalitis, was initiated using domestic horses from localities near wetlands as "sentinel" hosts. A total of 291 blood samples were taken from 172 horses between 2011 and 2012, using paired samples to highlight seroconversion events. A multiplex immunoas...
García-Carrasco JM, Muñoz AR, Olivero J, Segura M, Real R.West Nile virus is a widely spread arthropod-born virus, which has mosquitoes as vectors and birds as reservoirs. Humans, as dead-end hosts of the virus, may suffer West Nile Fever (WNF), which sometimes leads to death. In Europe, the first large-scale epidemic of WNF occurred in 1996 in Romania. Since then, human cases have increased in the continent, where the highest number of cases occurred in 2018. Using the location of WNF cases in 2017 and favorability models, we developed two risk models, one environmental and the other spatio-environmental, and tested their capacity to predict in 2018...
Barbić L, Listeš E, Katić S, Stevanović V, Madić J, Starešina V, Labrović A, Di Gennaro A, Savini G.West Nile virus (WNV) is an emerging zoonotic pathogen with rapid global expansion. The virus circulation is confirmed in many countries of Mediterranean Basin and Southern and Central Europe. In our study detection of specific WNV antibodies was performed in horses and cattle sera samples collected from October 2010 to April 2011. Serum samples were randomly taken from different parts of Croatia and tested by IgG and IgM ELISA. Positive serological results were confirmed by virus neutralization assay (VN-assay) and plaque reduction neutralization test (PRNT). Results showed that WNV antibodie...
Snyder RE, Feiszli T, Foss L, Messenger S, Fang Y, Barker CM, Reisen WK, Vugia DJ, Padgett KA, Kramer VL.The California Arbovirus Surveillance Program was initiated over 50 years ago to track endemic encephalitides and was enhanced in 2000 to include West Nile virus (WNV) infections in humans, mosquitoes, sentinel chickens, dead birds and horses. This comprehensive statewide program is a function of strong partnerships among the California Department of Public Health (CDPH), the University of California, and local vector control and public health agencies. This manuscript summarizes WNV surveillance data in California since WNV was first detected in 2003 in southern California. From 2003 through ...
Khatibzadeh SM, Gold CB, Keggan AE, Perkins GA, Glaser AL, Dubovi EJ, Wagner B.To compare antibody responses of horses naturally infected with West Nile virus (WNV) and those vaccinated against WNV, to identify whether vaccination interferes with the ability to diagnose WNV infection, and to determine the duration of antibody responses after vaccination. Methods: Sera from horses naturally infected with WNV (n = 10) and adult WNV-naïve horses before and after vaccination with a live canarypox virus-vectored vaccine (7) or a killed virus vaccine (8). Methods: An established WNV IgM capture ELISA was used to measure IgM responses. Newly developed capture ELISAs were used ...
Ulloa A, Langevin SA, Mendez-Sanchez JD, Arredondo-Jimenez JI, Raetz JL, Powers AM, Villarreal-Treviño C, Gubler DJ, Komar N.A serologic survey in domestic animals (birds and mammals) was conducted in four communities located in the Lacandón Forest region of northeastern Chiapas, Mexico, during June 29 to July 1, 2001, with the objective to identify zoonotic arboviruses circulating in this area. We collected 202 serum samples from healthy domestic chickens, geese, ducks, turkeys, horses and cattle. The samples were tested by plaque-reduction neutralization test for antibodies to selected mosquito-borne flaviviruses (family Flaviviridae), including St. Louis encephalitis (SLE), Rocio (ROC), Ilheus (ILH), Bussuquara ...
Guthrie AJ, Howell PG, Gardner IA, Swanepoel RE, Nurton JP, Harper CK, Pardini A, Groenewald D, Visage CW, Hedges JF, Balasuriya UB, Cornel AJ....West Nile virus (WNV) infection is endemic in southern Africa. With the recent emergence of WNV infection of horses in Europe and the USA the present study was performed to estimate the risk of seroconversion to WNV in a cohort of 488 young Thoroughbred (TB) horses. Objective: To estimate the risk of seroconversion to WNV among a cohort of South African TB yearlings sold at the 2001 National Yearling Sales (NYS) and to determine whether the risk varied geographically. Two horses were also infected with a recent South African isolate of WNV to evaluate its virulence in horses. Methods: Serum sa...
Sule WF, Oluwayelu DO, Adedokun RA, Rufai N, McCracken F, Mansfield KL, Johnson N.To investigate exposure of Nigerian horses to West Nile virus (WNV), we determined the seroprevalence rate of anti-WNV antibody in a cohort of 145 horses. Serum samples were collected from three locations in southwestern Nigeria between October, 2011, and July, 2012. The horses were asymptomatic and unvaccinated against WNV at the time of sampling. All sera were tested using a competition enzyme-linked immmunosorbent assay (ELISA) and by an immunoglobulin M (IgM)-specific ELISA. High rates of anti-WNV antibody prevalence were observed in all locations with a mean level of 90.3% (95% confidence...
Niczyporuk JS, Samorek-Salamonowicz E, Lecollinet S, Pancewicz SA, Kozdruń W, Czekaj H.Serum samples of 474 wild birds, 378 horses, and 42 humans with meningitis and lymphocytic meningitis were collected between 2010 and 2014 from different areas of Poland. West Nile virus (WNV) antibodies were detected using competition enzyme linked immunosorbent assays: ELISA-1 ID Screen West Nile Competition, IDvet, ELISA-2 ID Screen West Nile IgM Capture, and ELISA-3 Ingezim West Nile Compac. The antibodies were found in 63 (13.29%) out of 474 wild bird serum samples and in one (0.26%) out of 378 horse serum samples. Fourteen (33.33%) out of 42 sera from patients were positive against WNV a...
Azmi K, Tirosh-Levy S, Manasrah M, Mizrahi R, Nasereddin A, Al-Jawabreh A, Ereqat S, Abdeen Z, Lustig Y, Gelman B, Schvartz G, Steinman A.West Nile virus (WNV) epidemiological situation in Israel and Palestine, due to their unique location, draws attention following to the global spread of West Nile fever (WNF). Although much information is available from Israel on clinical cases and prevalence of WNV, clinical cases are rarely reported in Palestine, and prevalence is not known. The objectives of this study were to determine WNV seroprevalence in various domestic animals in Palestine and to reevaluate current seroprevalence, force of infection, and risk factors for WNV exposure in horses in Israel. Sera samples were collected fr...
Chevalier V, Lancelot R, Diaité A, Mondet B, Sall B, De Lamballerie X.The Ferlo area (north-central Senegal) is characterized by a system of temporary ponds favorable to arboviruses among which West Nile fever (WNF) was already identified. During the rainy season in 2003, a serological study was undertaken on horses to assess the activity of the WNF virus (WNFV) in Barkedji (Ferlo). The observed serological prevalence rate was 78.3% for neutralizing antibodies, with a 95% confidence interval (CI) of [64.0, 92.7]. This prevalence rate significantly increased with age (P = 10(-5)). This study confirmed that WNF was endemic in the Ferlo. The transmission risks depe...
Long MT, Jeter W, Hernandez J, Sellon DC, Gosche D, Gillis K, Bille E, Gibbs EP.The objectives of these studies were to assess the diagnostic performance (sensitivity and specificity) of the IgM capture enzyme-linked immunosorbent assay (ELISA; MAC) for diagnosis of West Nile (WN) virus in horses and to examine the performance of this test by using different criteria for seropositivity. A total of 36 horses classified as WN virus infected (group 1) and 383 horses from 4 subpopulations of hoses classified as noninfected (groups 2, 3, 4, and 5) were used in the study. The sensitivity (proportion of infected horses that tested positive for WN virus IgM antibodies) and specif...
