Topic:Arboviruses
Arboviruses are a group of viruses transmitted by arthropods, such as mosquitoes and ticks, that can infect horses, leading to various diseases. These viruses include the West Nile virus, Eastern equine encephalitis virus, and Western equine encephalitis virus, among others. Infection with arboviruses can result in neurological symptoms in horses, including ataxia, fever, and in severe cases, encephalitis. The transmission dynamics, pathogenesis, and clinical outcomes of arboviral infections in horses are subjects of ongoing research. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, clinical manifestations, diagnostic methods, and preventive measures related to arboviral infections in equine populations.
Animal viral diseases and global change: bluetongue and West Nile fever as paradigms. Environmental changes have an undoubted influence on the appearance, distribution, and evolution of infectious diseases, and notably on those transmitted by vectors. Global change refers to environmental changes arising from human activities affecting the fundamental mechanisms operating in the biosphere. This paper discusses the changes observed in recent times with regard to some important arboviral (arthropod-borne viral) diseases of animals, and the role global change could have played in these variations. Two of the most important arboviral diseases of animals, bluetongue (BT) and West Ni...
Eastern equine encephalitis in Tennessee: 2002-2008. Human and equine outbreaks caused by eastern equine encephalomyelitis virus (EEEV) typically occur in North America adjacent to coastal wetlands associated with the presence of Culiseta melanura (Coquillet) mosquitoes. Eastern equine encephalomyelitis (EEE) is an emerging disease in Tennessee, as the first records of equine disease began in 2002. In 2006 we trapped and tested mosquitoes for EEEV at hardwood swamps in western Tennessee that were at the epicenter of a multi-equine outbreak in fall of 2005. Additionally, the Tennessee Valley Authority tested mosquito pools collected in Tennessee ...
Serological detection of St. Louis encephalitis virus and West Nile virus in equines from Santa Fe, Argentina. St. Louis encephalitis virus (SLEV) and West Nile virus (WNV) present ecological and antigenic similarities and are responsible for serious human diseases. In addition, WNV is a significant pathogen in terms of equine health. The purpose of our study was to analyse the seroprevalence of SLEV and WNV in equine sera collected in Santa Fe Province, Argentina. The seroprevalence determined using the plaque reduction neutralisation test was 12.2% for SLEV, 16.2% for WNV and 48.6% for a combination of both viruses. These results provide evidence of the co-circulation of SLEV and WNV in equines in Sa...
[West Nile virus infection]. West Nile virus (WNV) is an arbovirus usually transmitted by mosquitoes. The main reservoirs are birds, although the virus may infect several vertebrate species, such as horses and humans. Up to 80% of human infections are asymptomatic. The most frequent clinical presentation is febrile illness, and neuroinvasive disease can occur in less than 1% of cases. Spain is considered a high-risk area for the emergence of WNV due to its climate and the passage of migratory birds from Africa (where the virus is endemic). These birds nest surrounding wetlands where populations of possible vectors for the...
Epizootic heamorragic disease. Epizootic haemorrhagic disease (EHD) is an infectious non-contagious viral disease transmitted by insects of the genus Culicoides which affects wild and domestic ruminants. The causative agent, the epizootic haemorrhagic disease virus (EHDV), belongs to the family Reoviridae, genus Orbivirus and shares many morphological and structural characteristics with the other members of the genus such as bluetongue, African horse sickness and equine encephalosis viruses. In recent years EHD outbreaks have been reported in countries bordering the European Union. They caused disease in cattle and severe r...
A competitive ELISA for the detection of group-specific antibody to equine encephalosis virus. A polyclonal antibody-based, group-specific, competitive ELISA (C-ELISA) for the detection of antibodies to equine encephalosis virus (EEV) was developed. The assay measures the competition between a specific guinea pig antiserum and a test serum, for a pre-titrated EEV antigen. The C-ELISA detected antibodies to the seven known EEV serotypes. Reference antisera raised against other arboviruses did not cross react with EEV antigen. Negative sera from horses in the United Kingdom were used to establish the baseline for a negative population. Negative and positive populations of South African ho...
Eastern equine encephalitis: an emerging arboviral disease threat, Maine, 2009. Eastern equine encephalitis (EEE) is one of the most severe arboviral encephalitides in North America. Before 2009, limited nonhuman EEE virus activity had been reported in Maine, all from the southernmost area of the state. No human case has been reported in a Maine resident. Methods: We review all EEE virus activity reported to Maine Centers for Disease Control in 2009 and describe current testing practices for possible human EEE cases. Results: In 2009, fatal cases of EEE were identified in 15 horses, 1 llama, and 3 flocks of pheasants in Maine, with activity extending into the central part...
Simulation of the seasonal cycles of bird, equine and human West Nile virus cases. The West Nile virus (WNV) is an arthropod-borne virus (arbovirus) circulating in a natural transmission cycle between mosquitoes (enzootic vectors) and birds (amplifying hosts). Additionally, mainly horses and humans (dead-end hosts) may be infected by blood-feeding mosquitoes (bridge vectors). We developed an epidemic model for the simulation of the WNV dynamics of birds, horses and humans in the U.S., which we apply to the Minneapolis metropolitan area (Minnesota). The SEIR-type model comprises a total of 19 compartments, that are 4 compartments for mosquitoes and 5 compartments or health st...
Serologic evidence of the recent circulation of Saint Louis encephalitis virus and high prevalence of equine encephalitis viruses in horses in the Nhecolândia sub-region in South Pantanal, Central-West Brazil. As in humans, sub-clinical infection by arboviruses in domestic animals is common; however, its detection only occurs during epizootics and the silent circulation of some arboviruses may remain undetected. The objective of the present paper was to assess the current circulation of arboviruses in the Nhecolândia sub-region of South Pantanal, Brazil. Sera from a total of 135 horses, of which 75 were immunized with bivalent vaccine composed of inactive Eastern equine encephalitis virus (EEEV) and Western equine encephalitis virus(WEEV) and 60 were unvaccinated, were submitted to thorough viral i...
Cotton rats and house sparrows as hosts for North and South American strains of eastern equine encephalitis virus. Eastern equine encephalitis virus (EEEV; family Togaviridae, genus Alphavirus) is an arbovirus that causes severe disease in humans in North America and in equids throughout the Americas. The enzootic transmission cycle of EEEV in North America involves passerine birds and the ornithophilic mosquito vector, Culiseta melanura, in freshwater swamp habitats. However, the ecology of EEEV in South America is not well understood. Culex (Melanoconion) spp. mosquitoes are considered the principal vectors in Central and South America; however, a primary vertebrate host for EEEV in South America has not...
Re-emergence of bluetongue, African horse sickness, and other orbivirus diseases. Arthropod-transmitted viruses (Arboviruses) are important causes of disease in humans and animals, and it is proposed that climate change will increase the distribution and severity of arboviral diseases. Orbiviruses are the cause of important and apparently emerging arboviral diseases of livestock, including bluetongue virus (BTV), African horse sickness virus (AHSV), equine encephalosis virus (EEV), and epizootic hemorrhagic disease virus (EHDV) that are all transmitted by haematophagous Culicoides insects. Recent changes in the global distribution and nature of BTV infection have been espec...
Serosurveillance for Japanese encephalitis, Akabane, and Aino viruses for Thoroughbred horses in Korea. Recent global warming trends may have a significant impact on vector-borne viral diseases, possibly affecting vector population dynamics and disease transmission. This study measured levels of hemagglutination-inhibition (HI) antibodies against Japanese encephalitis virus (JEV) and neutralizing antibodies against Akabane virus (AKAV) and Aino virus (AINV) for Thoroughbred horses in Korea. Blood samples were collected from 989 racehorses in several provinces, between October 2005 and March 2007. Sera were tested using either an HI assay or a virus neutralization test. Approximately half (49.7%;...
North American encephalitic arboviruses. 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.
Hematophagous Diptera collected from a horse and paired carbon dioxide-baited suction trap in southern California: relevance to West Nile virus epizootiology. Hematophagous Diptera landing on a horse were removed by vacuum, and their numbers were related to a paired carbon dioxide-baited suction trap at three locations in southern California where West Nile virus activity was high during the preceding year. Insects collected from the horse included mosquitoes (nine species), biting midges (Culicoides sonorensis Wirth & Jones), and black flies (Simulium bivittatum Malloch). Mosquitoes were predominantly collected from the head, crest, withers, neck, chest, and shoulders of the horse, whereas biting midges and black flies were predominantly collected ...
Serological assessment of West Nile fever virus activity in the pastoral system of Ferlo, Senegal. 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...
Control of arbovirus infections by a coordinated response: West Nile Virus in England and Wales. Although there is no recognized transmission of human arboviral infections in the UK, concerns about the possible spread of West Nile virus (WNV) have precipitated coordinated activities around both surveillance and response. The Department of Health has chaired a UK WNV task force since the end of 2000. This is a multidisciplinary group of senior representatives from Agencies and Government Departments involved in human and animal health, entomology and academic departments. Activities include surveillance for WNV infections in humans, and in dead birds, mosquitoes and horses. All have been n...
Five-year surveillance of West Nile and eastern equine encephalitis viruses in Southeastern Virginia. To investigate the occurrence of West Nile virus (WNV) and Eastern equine encephalitis virus (EEE) in southeastern Virginia, the Bureau of Laboratories at the Norfolk Department of Public Health (NDPH) analyzed mosquito pools and the sera of sentinel chickens from the southeastern Virginia area each year from 2000 to 2004. Mosquito pool supernatants were screened for the presence of viral RNA by conventional reverse transcription polymerase chain reaction (RT-PCR) and Taqman RT-PCR with the i-Cycler. Mosquito pools were also tested for virus activity by Vero cell culture. The primary enzootic ...
Envelope glycoprotein mutations mediate equine amplification and virulence of epizootic venezuelan equine encephalitis virus. Epidemics of Venezuelan equine encephalitis (VEE) result from high-titer equine viremia of IAB and IC subtype viruses that mediate increased mosquito transmission and spillover to humans. Previous genetic studies suggest that mutations in the E2 envelope glycoprotein allow relatively viremia-incompetent, enzootic subtype ID strains to adapt for equine replication, leading to VEE emergence. To test this hypothesis directly, chimeric VEEV strains containing the genetic backbone of enzootic subtype ID strains and the partial envelope glycoprotein genes of epizootic subtype IC and IAB strains, as ...
Culicoides and other biting flies on the Palos Verdes Peninsula of Southern California, and their possible relationship to equine dermatitis. Biting insects were sampled to investigate the cause(s) of dermatitis (putative Culicoides hypersensitivity [CHS]) on horses on the Palos Verdes Peninsula, Los Angeles County, California. Suction traps baited with CO2 were operated at 5 sites from April 2002 to August 2003, supplemented by sampling from horses. Six species of Culicoides, 7 species of mosquitoes, and occasional Simulium and Stomoxys were collected in traps. Culicoides sonorensis was the most common midge trapped, although C. obsoletus and C. freeborni also were collected repeatedly. Insects from the belly region of horses in sp...
[West Nile virus: in France again, in humans and horses]. West Nile virus (WNV) is a common arbovirosis, transmitted by mosquitoes mainly Culex. WNV is commonly responsible for equine epizootics and epidemics in humans in sub-Saharan Africa. It has been occasionally described in Southern Europe and in some Mediterranean countries. Since 1994, WNV clinical aspects seem to change with an increase of central neurological involvement and a higher mortality, especially among people older than 50 years. In 1999, WNV reached New York, being responsible for severe clinical manifestations. It spread all over North America in less than four years Four (only fo...
Isolation of Ross River virus from mosquitoes and from horses with signs of musculo-skeletal disease. To report clinical and clinicopathological findings in horses naturally infected with Ross River virus (RRV) and identify likely mosquito arbovirus vector species. Methods: Veterinarians submitted serum samples from 750 horses because they suspected Ross River virus (RRV) infection. The samples were tested for the presence of IgM and IgG antibody to RRV and for the presence of virus. Mosquitoes were trapped, differentiated to species level and tested for the presence of RRV by virus isolation. Results: RRV was isolated from six species of mosquitoes (Ochlerotatus camptorhyncus, Culex globocoxi...
Avian host preference by vectors of eastern equine encephalomyelitis virus. An important variable in the amplification and escape from the enzootic cycle of the arboviral encephalitides is the degree of contact between avian hosts and mosquito vectors. To analyze this interaction in detail, blood-fed mosquitoes that were confirmed vectors of eastern equine encephalomyelitis (EEE) virus were collected in 2002 from an enzootic site in central Alabama during the time this virus was actively transmitted. Avian-derived blood meals were identified to the species level of the host, and the proportion derived from each species was compared with the overall composition of the ...
Transmission of eastern equine encephalomyelitis virus in central Alabama. A site near Tuskegee, Alabama was examined for vector activity of eastern equine encephalomyelitis (EEE) virus in 2001. More than 23,000 mosquitoes representing 8 genera and 34 species were collected during a 21-week period, and five species, Culiseta melanura, Aedes vexans, Coquillettidia perturbans, Culex erraticus, and Uranotaenia sapphirina, were examined for the presence of virus using a nested reverse transcriptase-polymerase chain reaction for EEE virus. Each species was infected at various times of the mosquito season (May-September) with different minimum infection rates (MIRs). Culis...
California state Mosquito-Borne Virus Surveillance and Response Plan: a retrospective evaluation using conditional simulations. The California Mosquito-Borne Virus Surveillance and Response Plan recently was developed to provide a semi-quantitative means for assessing risk for western equine encephalomyelitis (WEE) or St. Louis encephalitis (SLE) viruses and to provide intervention guidelines for mosquito control and public health agencies during periods of heightened risk for human infection. West Nile virus recently has arrived in California, and the response plan also will provide a baseline for assessing the risk for human and equine infection with this virus. In the response plan, overall risk is calculated by ave...
Serologic survey of domestic animals for zoonotic arbovirus infections in the Lacandón Forest region of Chiapas, Mexico. 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 ...
Initiating arbovirus surveillance in Arkansas, 2001. Migratory birds could introduce West Nile (WN) virus to Arkansas. The purpose of this study was to establish a cooperative arbovirus surveillance program to monitor mosquitoes and birds in Arkansas for arboviruses. Our objectives were to: 1) perform routine, multicounty collections of mosquitoes and test them for eastern equine encephalitis, St. Louis encephalitis, and WN viruses; and 2) conduct passive surveillance by testing dead wild birds for WN virus. Arbovirus surveillance was organized by the Arkansas Department of Health, University of Arkansas, and Vector Disease Control Incorporated....
Limited potential for mosquito transmission of genetically engineered, live-attenuated western equine encephalitis virus vaccine candidates. Specific mutations associated with attenuation of Venezuelan equine encephalitis (VEE) virus in rodent models were identified during efforts to develop an improved VEE vaccine. Analogous mutations were produced in full-length cDNA clones of the Cba 87 strain of western equine encephalitis (WEE) virus by site-directed mutagenesis in an attempt to develop an improved WEE vaccine. Isogenic viral strains with these mutations were recovered after transfection of baby hamster kidney cells with infectious RNA. We evaluated two of these strains (WE2102 and WE2130) for their ability to replicate in and...
Isolation of eastern equine encephalitis virus and West Nile virus from crows during increased arbovirus surveillance in Connecticut, 2000. The emergence of the West Nile virus (WNV) in the northeastern United States has drawn emphasis to the need for expanded arbovirus surveillance in Connecticut. Although the state of Connecticut began a comprehensive mosquito-screening program in 1997, only since 1999 have there been efforts to determine the prevalence of arboviruses in bird populations in this state. Herein, we report on our results of an arbovirus survey of 1,704 bird brains. Included in this report are the first known isolations of eastern equine encephalitis virus (EEEV) from crows and data on the geographic and temporal di...