Mosquito-borne diseases in horses encompass a range of illnesses transmitted by mosquito vectors, impacting equine health worldwide. These diseases include West Nile Virus (WNV), Eastern Equine Encephalitis (EEE), Western Equine Encephalitis (WEE), and Venezuelan Equine Encephalitis (VEE). Each disease is caused by distinct viral pathogens, leading to varying clinical presentations, such as fever, neurological symptoms, and in severe cases, death. Understanding the epidemiology, transmission dynamics, and pathogenesis of these diseases is essential for effective prevention and control strategies. This page compiles peer-reviewed research studies and scholarly articles that explore the transmission, clinical manifestations, and management of mosquito-borne diseases in horses.
Morita K, Nabeshima T, Buerano CC.Japanese encephalitis (JE) is an inflammation of the central nervous system in humans and animals, specifically horses and cattle. The disease, which can sometimes be fatal, is caused by the flavivirus Japanese encephalitis virus (JEV), of which there are five genotypes (genotypes 1, 2, 3, 4 and 5). The transmission cycle of the virus involves pigs and wild birds as virus amplifiers and mosquitoes as vectors for transferring the virus between amplifying hosts and to dead- end hosts, i.e. humans, horses and cattle. In horses and cattle the disease is usually asymptomatic, but when clinical sign...
Downs JA, Hyzer G, Marion E, Smith ZJ, Kelen PV, Unnasch TR.Eastern equine encephalitis (EEE) is a mosquito-borne viral disease that is often fatal to humans and horses. Some species including white-tailed deer and passerine birds can survive infection with the EEE virus (EEEV) and develop antibodies that can be detected using laboratory techniques. In this way, collected serum samples from free ranging white-tailed deer can be used to monitor the presence of the virus in ecosystems. This study developed and tested a risk index model designed to predict EEEV activity in white-tailed deer in a three-county area of Michigan. The model evaluates EEEV risk...
Molaei G, Armstrong PM, Abadam CF, Akaratovic KI, Kiser JP, Andreadis TG.Eastern equine encephalitis virus (EEEV) causes a highly pathogenic mosquito-borne zoonosis that is responsible for sporadic outbreaks of severe illness in humans and equines in the eastern USA. Culiseta (Cs.) melanura is the primary vector of EEEV in most geographic regions but its feeding patterns on specific avian and mammalian hosts are largely unknown in the mid-Atlantic region. The objectives of our study were to: 1) identify avian hosts of Cs. melanura and evaluate their potential role in enzootic amplification of EEEV, 2) assess spatial and temporal patterns of virus activity during a ...
Diarra M, Fall M, Lancelot R, Diop A, Fall AG, Dicko A, Seck MT, Garros C, Allène X, Rakotoarivony I, Bakhoum MT, Bouyer J, Guis H.In Senegal, considerable mortality in the equine population and hence major economic losses were caused by the African horse sickness (AHS) epizootic in 2007. Culicoides oxystoma and Culicoides imicola, known or suspected of being vectors of bluetongue and AHS viruses are two predominant species in the vicinity of horses and are present all year-round in Niayes area, Senegal. The aim of this study was to better understand the environmental and climatic drivers of the dynamics of these two species. Culicoides collections were obtained using OVI (Onderstepoort Veterinary Institute) light traps a...
Kulkarni MA, Berrang-Ford L, Buck PA, Drebot MA, Lindsay LR, Ogden NH.In Canada, the emergence of vector-borne diseases may occur via international movement and subsequent establishment of vectors and pathogens, or via northward spread from endemic areas in the USA. Re-emergence of endemic vector-borne diseases may occur due to climate-driven changes to their geographic range and ecology. Lyme disease, West Nile virus (WNV), and other vector-borne diseases were identified as priority emerging non-enteric zoonoses in Canada in a prioritization exercise conducted by public health stakeholders in 2013. We review and present the state of knowledge on the public heal...
Dhama K, Kapoor S, Pawaiya RV, Chakraborty S, Tiwari R, Verma AK.A fascinating and important arbovirus is Ross River Virus (RRV) which is endemic and epizootic in nature in certain parts of the world. RRV is a member of the genus Alphavirus within the Semliki Forest complex of the family Togaviridae, which also includes the Getah virus. The virus is responsible for causing disease both in humans as well as horses. Mosquito species (Aedes camptorhynchus and Aedes vigilax; Culex annulirostris) are the most important vector for this virus. In places of low temperature as well as low rainfall or where there is lack of habitat of mosquito there is also limitatio...
Fall M, Fall AG, Seck MT, Bouyer J, Diarra M, Balenghien T, Garros C, Bakhoum MT, Faye O, Baldet T, Gimonneau G.Culicoides biting midges (Diptera: Ceratopogonidae) are important vectors of arboviruses in Africa. Culicoides oxystoma has been recently recorded in the Niayes region of Senegal (West Africa) and its high abundance on horses suggests a potential implication in the transmission of the African horse sickness virus in this region. This species is also suspected to transmit bluetongue virus to imported breeds of sheep. Little information is available on the biology and ecology of Culicoides in Africa. Therefore, understanding the circadian host-seeking activity of this putative vector is of prima...
López RH, Soto SU, Gallego-Gómez JC.West Nile virus (WNV) is a member of the genus Flavivirus, and it is transmitted between Culex sp. mosquitoes and avian hosts. Equids and humans are commonly infected with WNV as dead-end hosts, and the signs and symptoms of infection range from mild illness to neurologic symptoms as encephalitis, meningitis and sometimes death. Previous phylogenetic studies have classified WNV into six genetically distinct lineages and provided valuable insight on WNV dispersal patterns within the Americas and its emergence in different geographic areas. In this study, we isolated, sequenced and genetically c...
Hale D.West Nile Virus is the most frequent cause of arboviral disease in the United States. It was first identified in the United States in 1999. Since that time, each of the 48 contiguous states in the United States has seen the disease, and it has been found in 96% of the U.S. counties in infected humans, mosquitoes, birds, horses, or other mammals. Although most often the disease resolves on its own, patients can develop serious and life-threatening complications, and may need further monitoring and treatment. This article reviews the prevalence, transmission, signs and symptoms, complications, t...
Amaya M, Keck F, Lindquist M, Voss K, Scavone L, Kehn-Hall K, Roberts B, Bailey C, Schmaljohn C, Narayanan A.Many viruses have been implicated in utilizing or modulating the Ubiquitin Proteasome System (UPS) to enhance viral multiplication and/or to sustain a persistent infection. The mosquito-borne Venezuelan equine encephalitis virus (VEEV) belongs to the Togaviridae family and is an important biodefense pathogen and select agent. There are currently no approved vaccines or therapies for VEEV infections; therefore, it is imperative to identify novel targets for therapeutic development. We hypothesized that a functional UPS is required for efficient VEEV multiplication. We have shown that at non-tox...
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...
Page PC, Labuschagne K, Venter GJ, Schoeman JP, Guthrie AJ.The efficacy of alphacypermethrin-treated high density polyethylene (HDPE) mesh applied to jet stalls against Culicoides biting midges (Diptera: Ceratopogonidae) was determined by mechanical aspiration of midges from horses and using Onderstepoort 220 V downdraught black light traps in four blocks of a 3 × 2 randomised design under South African field conditions. The alphacypermethrin-treated HDPE mesh applied to the stall significantly (P = 0.008) reduced the number of Culicoides midges, predominantly Culicoides (Avaritia) imicola Kieffer, mechanically aspirated from horses housed in the sta...
Baig B, Mehta T, Khalid N, Chhabra L.We present the case of a 40-year-old man with rapidly deteriorating acute meningoencephalitis, finally diagnosed as eastern equine encephalitis (EEE). The course and timing in this patient are quite characteristic. EEE is an arthropod borneviral illness in which the mosquito serves as the vector. It is amongst the most severe of the arbovirus encephalitides and has a high mortality and morbidity. In nonfatal cases, residual neurological deficits are often severe and permanent. North American lineage of EEE is mainly found in the northeast especially along the coastal areas. EEE is primarily fo...
Gutiérrez S, Thébaud G, Smith DR, Kenney JL, Weaver SC.The within-host diversity of virus populations can be drastically limited during between-host transmission, with primary infection of hosts representing a major constraint to diversity maintenance. However, there is an extreme paucity of quantitative data on the demographic changes experienced by virus populations during primary infection. Here, the multiplicity of cellular infection (MOI) and population bottlenecks were quantified during primary mosquito infection by Venezuelan equine encephalitis virus, an arbovirus causing neurological disease in humans and equids.
Gale P, Kelly L, Snary EL.The emergence of bluetongue virus and Schmallenberg virus in Great Britain (GB) during the last decade has highlighted the need for understanding the relative importance of the various pathways of the entry of livestock arboviruses so as to help focus surveillance and mitigation. This study summarizes what is known for the main routes of entry and assesses the strength of the current evidence for and against. Entry through infected arthropod vectors is considered at the level of each life cycle stage for tick-, biting midge- and mosquito-borne viruses, and while there is evidence that this cou...
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 ...
Sedlák K, Zelená H, Křivda V, Šatrán P.The West Nile virus (WNV) is an important mosquito-borne flavivirus occurring around the world. Occasionally found in Central Europe, the virus spread massively through whole Hungary between 2008 and 2009. The aim of our study was to determine the recent prevalence of the WNV infection in horses in the Czech Republic. Methods: Overall, 2349 serum samples, collected from healthy unvaccinated adult horses in the Czech Republic between 2011 and 2013, were tested. A commercially available competitive ELISA kit (cELISA) was used for this purpose and positive samples were confirmed by virus neutrali...
van den Hurk AF, Hall-Mendelin S, Webb CE, Tan CS, Frentiu FD, Prow NA, Hall RA.In 2011, a variant of West Nile virus Kunjin strain (WNVKUN) caused an unprecedented epidemic of neurological disease in horses in southeast Australia, resulting in almost 1,000 cases and a 9% fatality rate. We investigated whether increased fitness of the virus in the primary vector, Culex annulirostris, and another potential vector, Culex australicus, contributed to the widespread nature of the outbreak. Methods: Mosquitoes were exposed to infectious blood meals containing either the virus strain responsible for the outbreak, designated WNVKUN2011, or WNVKUN2009, a strain of low virulence th...
Aharonson-Raz K, Lichter-Peled A, Tal S, Gelman B, Cohen D, Klement E, Steinman A.With the rapid global spread of West Nile virus (WNV) and the endemic state it has acquired in new geographical areas, we hereby bring a thorough serological investigation of WNV in horses in a longstanding endemic region, such as Israel. This study evaluates the environmental and demographic risk factors for WNV infection in horses and suggests possible factors associated with the transition from endemic to epidemic state. West Nile virus seroprevalence in horses in Israel was determined throughout a period of more than a decade, before (1997) and after (2002 and 2013) the massive West Nile f...
Long MT.Mosquito-borne diseases affect horses worldwide. Mosquito-borne diseases generally cause encephalomyelitis in the horse and can be difficult to diagnose antemortem. In addition to general disease, and diagnostic and treatment aspects, this review article summarizes the latest information on these diseases, covering approximately the past 5 years, with a focus on new equine disease encroachments, diagnostic and vaccination aspects, and possible therapeutics on the horizon.
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...
Silva JR, Romeiro MF, Souza WM, Munhoz TD, Borges GP, Soares OA, Campos CH, Machado RZ, Silva ML, Faria JL, Chávez JH, Figueiredo LT.Arboviruses are an important public health problem in Brazil, in especially flaviviruses, including the Saint Louis encephalitis virus (SLEV) and the Rocio virus (ROCV), are especially problematic. These viruses are transmitted to humans or other vertebrates through arthropod bites and may cause diseases with clinical manifestations that range from asymptomatic infection, viral hemorrhagic fever to encephalitis. Methods: A serological survey of horses from various regions of Brazil using an enzyme-linked immunosorbent assay (ELISA) with recombinant SLEV domain III peptides and ROCV E protein a...
Prow NA, Hewlett EK, Faddy HM, Coiacetto F, Wang W, Cox T, Hall RA, Bielefeldt-Ohmann H.The mosquito-borne West Nile virus (WNV) is responsible for outbreaks of viral encephalitis in humans and horses with particularly virulent strains causing recent outbreaks in Eastern Europe, the Middle East, and North America. In Australia, a strain of WNV, Kunjin (WNVKUN), is endemic in the north and infection with this virus is generally asymptomatic. However, in early 2011, following extensive flooding, an unprecedented outbreak of WNVKUN encephalitis in horses occurred in South-Eastern Australia, resulting in more than 1,000 cases and a mortality of 10-15%. Despite widespread evidence of ...
Di Sabatino D, Bruno R, Sauro F, Danzetta ML, Cito F, Iannetti S, Narcisi V, De Massis F, Calistri P.West Nile virus (WNV) transmission has been confirmed in the last four years in Europe and in the Mediterranean Basin. An increasing concern towards West Nile disease (WND) has been observed due to the high number of human and animal cases reported in these areas confirming the importance of this zoonosis. A new epidemiological scenario is currently emerging: although new introductions of the virus from abroad are always possible, confirming the epidemiological role played by migratory birds, the infection endemisation in some European territories today is a reality supported by the constant r...
Williams JH, van Niekerk S, Human S, van Wilpe E, Venter M.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 Afr...
Reed DS, Glass PJ, Bakken RR, Barth JF, Lind CM, da Silva L, Hart MK, Rayner J, Alterson K, Custer M, Dudek J, Owens G, Kamrud KI, Parker MD, Smith J.Alphavirus replicons were evaluated as potential vaccine candidates for Venezuelan equine encephalitis virus (VEEV), western equine encephalitis virus (WEEV), or eastern equine encephalitis virus (EEEV) when given individually or in combination (V/W/E) to mice or cynomolgus macaques. Individual replicon vaccines or the combination V/W/E replicon vaccine elicited strong neutralizing antibodies in mice to their respective alphavirus. Protection from either subcutaneous or aerosol challenge with VEEV, WEEV, or EEEV was demonstrated out to 12 months after vaccination in mice. Individual replicon v...
Pradier S, Sandoz A, Paul MC, Lefebvre G, Tran A, Maingault J, Lecollinet S, Leblond A.To assess environmental and horse-level risk factors associated with West Nile Virus (WNV) circulation in Camargue, Southern France, a serosurvey was conducted on non-vaccinated horses (n = 1159 from 134 stables) in 2007 and 2008. Fifteen Landsat images were examined to quantify areas with open water and flooded vegetation around sampled horses. Mean percentages of areas of open water and flooded vegetation, as well as variations in these percentages between 3 periods (November to February = NOT, March to July = END and August to October = EPI), were calculated for buffers of 2 km radius aroun...
Bingham AM, Burkett-Cadena ND, Hassan HK, McClure CJ, Unnasch TR.Studies investigating winter transmission of Eastern equine encephalitis virus (EEEV) were conducted in Hillsborough County, Florida. The virus was detected in Culiseta melanura and Anopheles quadrimaculatus in February 2012 and 2013, respectively. During the winter months, herons were the most important avian hosts for all mosquito species encountered. In collections carried out in the summer of 2011, blood meals taken from herons were still common, but less frequently encountered than in winter, with an increased frequency of mammalian- and reptile-derived meals observed in the summer. Four ...
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...
López-Ruiz N, Montaño-Remacha MDC, Durán-Pla E, Pérez-Ruiz M, Navarro-Marí JM, Salamanca-Rivera C, Miranda B, Oyonarte-Gómez S....In Andalusia, Spain, West Nile virus (WNV) surveillance takes place from April to November, during the active vector period. Within this area seroconversion to this virus was evidenced in wild birds in 2004, affecting horses and two humans for the first time in 2010. Since 2010, the virus has been isolated every year in horses, and national and regional surveillance plans have been updated with the epidemiological changes found. WNV is spreading rapidly throughout southern Europe and has caused outbreaks in humans. Here we describe the second WNV outbreak in humans in Andalusia, with three con...
Epp T, Waldner C, West K, Townsend H.In 2003, the occurrence and location of horses with clinical signs of West Nile virus infection were identified in the southern portion of Saskatchewan with the help of veterinarians, owners, and the regional laboratory. A total of 133 clinical cases were reported between July 30 and September 19, 2003; however, postseason surveillance suggests that the number of cases was underestimated. The case fatality rate was 43.8% (95% CI 35.2, 52.4). Factors associated with fatality in clinical cases included sex, week of onset of clinical signs, and coat color. Reported clinical cases clustered within...
Ganzenberg S, Sieg M, Ziegler U, Pfeffer M, Vahlenkamp TW, Hörügel U, Groschup MH, Lohmann KL.West Nile virus (WNV) infections were first detected in Germany in 2018, but information about WNV seroprevalence in horses is limited. The study's overall goal was to gather information that would help veterinarians, horse owners, and veterinary-, and public health- authorities understand the spread of WNV in Germany and direct protective measures. For this purpose, WNV seroprevalence was determined in counties with and without previously registered WNV infections in horses, and risk factors for seropositivity were estimated. The cohort consisted of privately owned horses from nine counties i...
Skaff NK, Armstrong PM, Andreadis TG, Cheruvelil KS.Eastern equine encephalitis virus (EEEV) is an expanding mosquito-borne threat to humans and domestic animal populations in the northeastern United States. Outbreaks of EEEV are challenging to predict due to spatial and temporal uncertainty in the abundance and viral infection of Cs. melanura, the principal enzootic vector. EEEV activity may be closely linked to wetlands because they provide essential habitat for mosquito vectors and avian reservoir hosts. However, wetlands are not homogeneous and can vary by vegetation, connectivity, size, and inundation patterns. Wetlands may also have diffe...
Chevalier V, Dupressoir A, Tran A, Diop OM, Gottland C, Diallo M, Etter E, Ndiaye M, Grosbois V, Dia M, Gaidet N, Sall AA, Soti V, Niang M.In 2005, a serological study was carried out on horses in five ecologically contrasted zones of the Senegal River basin (Senegal) to assess West Nile virus (WNV) transmission and investigate underlying environmental risk factors. In each study zone, horses were randomly selected and blood samples taken. A land-cover map of the five study areas was built using two satellite ETM+ images. Blood samples were screened by ELISA for anti-WNV IgM and IgG and positive samples were confirmed by seroneutralization. Environmental data were analysed using a principal components analysis. The overall IgG se...
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...
Grady GF, Maxfield HK, Hildreth SW, Timperi RJ, Gilfillan RF, Rosenau BJ, Francy DB, Calisher CH, Marcus LC, Madoff MA.Reappearance of eastern equine encephalitis (EEE) in Massachusetts residents in the 1970's provided an opportunity to assess the predictive value of data on rainfall, EEE in horses, and carriage of EEE virus (EEEV) by mosquitoes, factors which had been studied annually since the last EEE outbreak in 1955-1956. The cycle of multiple cases during 1973-1975 started in a second consecutive year of rainfall that exceeded the annual mean by more than 20 cm, conditions recapitulating the 1955-1956 experience. In 1973, widespread EEE fatalities in horses presaged human cases, another recapitulation of...
Pupo M, Guzmán MG, Fernández R, Llop A, Dickinson FO, Pérez D, Cruz R, González T, Estévez G, González H, Santos P, Kourí G, Andonova M....A surveillance system to detect West Nile virus (WNV) was established in Cuba in 2002. WNV infection was confirmed by serologic assays in 4 asymptomatic horses and 3 humans with encephalitis in 2003 and 2004. These results are the first reported evidence of WNV activity in Cuba.
Weese JS, Baird JD, DeLay J, Kenney DG, Staempfli HR, Viel L, Parent J, Smith-Maxie L, Poma R.West Nile virus encephalomyelitis was diagnosed in 28 horses presented to the Ontario Veterinary College Veterinary Teaching Hospital between August 20 and October 15, 2002. The age range of affected horses was 5 months to 20 years (mean 6.9 years, median 6 years). Clinical signs were highly variable. Duration of hospitalization ranged from < 1 to 12 days (mean 5 days, median 5.4 days). Overall, 16 of the 28 (57%) horses were discharged and, of the 14 from which follow-up information was available, 13 (93%) were reported to be clinically normal 4 to 6 weeks following discharge, while the other...
Abutarbush SM, Al-Majali AM.The objectives of this study are to report clinical WNV infection in horses and to determine the seroprevalence of and risk factors for WNV infection in horses in Jordan. In late summer and early fall of 2012, two mares were presented for evaluation of neurological signs. The first mare had hind-limb ataxia. The second mare was slightly depressed and lethargic. She had ataxia in her four limbs and cranial nerves deficits. Both horses were found positive for WNV IgM antibodies using commercial IgM-capture ELISA test. Both horses were treated symptomatically and recovered uneventfully. The occur...
Mattar S, Komar N, Young G, Alvarez J, Gonzalez M.We prospectively sampled flavivirus-naïve horses in northern Colombia to detect West Nile virus (WNV) and St. Louis encephalitis virus (SLEV) seroconversion events, which would indicate the current circulation of these viruses. Overall, 331 (34.1%) of the 971 horses screened were positive for past infection with flaviviruses upon initial sampling in July 2006. During the 12-month study from July 2006-June 2007, 33 WNV seroconversions and 14 SLEV seroconversions were detected, most of which occurred in the department of Bolivar. The seroconversion rates of horses in Bolivar for the period of M...
Mands V, Kline DL, Blackwell A.Examples of the commercial trap Mosquito Magnet Pro (MMP emitting attractant 1-octen-3-ol in carbon dioxide 500 mL/min generated from propane fuel), were run 24 h/day on the Isle of Skye, Scotland, during June-August 2001 and evaluated for catching Culicoides biting midges (Diptera: Ceratopogonidae). From 30 days trapping, the catch averaged 2626 +/- 1358 Culicoides females/trap/day (mean +/- SE, range 558 +/- 139 to 6088 +/- 3597, for five sets of six consecutive nights), predominantly the pest Culicoides impunctatus Goetghebuer (68% overall), plus C. vexans (Staeger) > C. delta Edwards &g...
Badenhorst M, de Heus P, Auer A, Rümenapf T, Tegtmeyer B, Kolodziejek J, Nowotny N, Steinmann E, Cavalleri JV.Prevalence studies have demonstrated a global distribution of equine hepacivirus (EqHV), a member of the family Flaviviridae. However, apart from a single case of vertical transmission, natural routes of EqHV transmission remain elusive. Many known flaviviruses are horizontally transmitted between hematophagous arthropods and vertebrate hosts. This study represents the first investigation of potential EqHV transmission by mosquitoes. More than 5000 mosquitoes were collected across Austria and analyzed for EqHV ribonucleic acid (RNA) by reverse transcription quantitative polymerase chain reacti...
Prow NA, Hewlett EK, Faddy HM, Coiacetto F, Wang W, Cox T, Hall RA, Bielefeldt-Ohmann H.The mosquito-borne West Nile virus (WNV) is responsible for outbreaks of viral encephalitis in humans and horses with particularly virulent strains causing recent outbreaks in Eastern Europe, the Middle East, and North America. In Australia, a strain of WNV, Kunjin (WNVKUN), is endemic in the north and infection with this virus is generally asymptomatic. However, in early 2011, following extensive flooding, an unprecedented outbreak of WNVKUN encephalitis in horses occurred in South-Eastern Australia, resulting in more than 1,000 cases and a mortality of 10-15%. Despite widespread evidence of ...
Alonso-Padilla J, Loza-Rubio E, Escribano-Romero E, Córdoba L, Cuevas S, Mejía F, Calderón R, Milián F, Travassos Da Rosa A, Weaver SC....West Nile virus (WNV) was probably introduced in southern and northern Mexico from the USA in two independent events. Since then, WNV activity has been reported in several Mexican states bordering the USA and the Gulf of Mexico, but disease manifestations seen there in humans and equids are quite different to those observed in the USA. We have analysed WNV seroprevalence in asymptomatic, unvaccinated equids from two Mexican states where no data had been previously recorded. WNV IgG antibodies were detected in 31.6% (91/288) of equine sera from Chiapas and Puebla states (53.3% and 8.0%, respect...
West Nile virus (WNV) is one of the most widely distributed (re-)emerging arboviruses. In Croatia, acute WNV infections as well as seropositivity were detected in humans, horses, birds and poultry. Although serologic evidence of WNV human infections dates back to the 1970s, no clinical cases were reported until 2012. WNV outbreaks, as well as sporadic infections, were continuously recorded in continental Croatian counties from 2012 to 2018. In addition, acute asymptomatic infections (IgM antibodies) in horses have been regularly notified in continental regions since 2012, while seropositive ho...
Mulatti P, Bonfanti L, Capelli G, Capello K, Lorenzetto M, Terregino C, Monaco F, Ferri G, Marangon S.Since 2008, West Nile Virus (WNV) has expanded its range in several Italian regions, and its yearly recurrence suggests the virus may have become endemic in some areas. In 2011, a new plan based also on the detection of IgM antibodies was implemented in the north-eastern Italian regions of Veneto and Friuli Venezia Giulia, aiming to early detect WNV infections in areas where the virus had already circulated during the previous summers, and in adjacent zones. From July to November 2011, 1880 sera from 521 equine premises were screened by a commercial IgM capture ELISA. Mosquitoes were captured ...
Franklin RP, Kinde H, Jay MT, Kramer LD, Green EG, Chiles RE, Ostlund E, Husted S, Smith J, Parker MD.A yearling quarter horse, which was raised in southern California, received routine vaccinations for prevention of infection by Eastern equine encephalomyelitis virus (EEEV). One week later, severe neurologic signs developed, and the horse was humanely destroyed. A vaccine-related encephalomyelitis was later suspected. A final diagnosis of EEEV infection was established on the basis of acute onset of the neurologic signs, histopathologic and serologic testing, and isolation and molecular characterization of EEEV from brain tissue. The vaccine was extensively tested for viral inactivation. Nucl...
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...
Ruiz-López MJ, Muñoz-Chimeno M, Figuerola J, Gavilán AM, Varona S, Cuesta I, Martínez-de la Puente J, Zaballos Á, Molero F, Soriguer RC....Emerging infectious diseases are one of the most important global health challenges because of their impact on human and animal health. The vector-borne West Nile virus (WNV) is transmitted between birds by mosquitos, but it can also infect humans and horses causing disease. The local circulation of WNV in Spain has been known for decades, and since 2010, there have been regular outbreaks in horses, although only six cases were reported in humans until 2019. In 2020, Spain experienced a major outbreak with 77 human cases, which was followed by 6 additional cases in 2021, most of them in the An...
Yuen KY, Bielefeldt-Ohmann H.Ross River virus (RRV) has recently been suggested to be a potential emerging infectious disease worldwide. RRV infection remains the most common human arboviral disease in Australia, with a yearly estimated economic cost of $4.3 billion. Infection in humans and horses can cause chronic, long-term debilitating arthritogenic illnesses. However, current knowledge of immunopathogenesis remains to be elucidated and is mainly inferred from a murine model that only partially resembles clinical signs and pathology in human and horses. The epidemiology of RRV transmission is complex and multifactorial...
López RH, Soto SU, Gallego-Gómez JC.West Nile virus (WNV) is a member of the genus Flavivirus, and it is transmitted between Culex sp. mosquitoes and avian hosts. Equids and humans are commonly infected with WNV as dead-end hosts, and the signs and symptoms of infection range from mild illness to neurologic symptoms as encephalitis, meningitis and sometimes death. Previous phylogenetic studies have classified WNV into six genetically distinct lineages and provided valuable insight on WNV dispersal patterns within the Americas and its emergence in different geographic areas. In this study, we isolated, sequenced and genetically c...
Nielsen CF, Reisen WK, Armijos MV, Maclachlan NJ, Scott TW.Although horse cases frequently are reported during West Nile virus (WNV) outbreaks, few investigations have focused on the epidemiology of this transmission. From April to October 2003 to 2005, mosquito abundance and infection were monitored 3 days per week at an equine research facility at the University of California, Davis. Thirty-two nonvaccinated horses enrolled as controls in a vaccine study were bled monthly, and their serum was tested for evidence of WNV infection by plaque reduction neutralization test (PRNT). In 2004, one positive Culex pipiens pool was associated with a single hors...
Samina I, Havenga M, Koudstaal W, Khinich Y, Koldijk M, Malkinson M, Simanov M, Perl S, Gijsbers L, Weverling GJ, Uytdehaag F, Goudsmit J.Studies were performed with an inactivated vaccine against the mosquito-borne flavivirus, West Nile virus (WNV). The mammalian cell line, PER.C6, was selected as the platform for WNV growth since both the neurovirulent strains NY99 and ISR98 that cause epidemics in humans and high mortality in geese, respectively, could be propagated to high titers (10(9) to 10(10)TCID(50)/ml) on these cells. Based on the high DNA homology of the WNV envelope (E) protein and non-structural protein 5 (NS5), and identical neurovirulence in mice and geese, we concluded that NY99 and ISR98 viruses are closely rela...
