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.
FEEMSTER RF.This research focuses on the first recognized human infection of equine encephalomyelitis, a disease mostly found in horses, which occurred in Massachusetts in the summer of 1938. The study dives […]
HOLLISTER AC, LONGSHORE WA, DEAN BH, STEVENS IM.For the most part, epidemiologic phenomena observed in the outbreak of encephalitis in 1952 accorded with patterns that had been apparent in previous years. Ninety-seven per cent of the 414 laboratory-confirmed cases of western equine and St. Louis encephalitis in humans occurred in the 20 Central Valley counties. The cases of western equine encephalomyelitis in horses were generally scattered over the state. In the Central Valley most of the cases in horses were in animals less than two years of age; elsewhere the incidence was higher in older horses.There were no laboratory-confirmed cases o...
HAMMON WM, REEVES WC.In three cases of encephalitis in humans that occurred in the area where the newly described California virus was isolated from mosquitoes, serological evidence seemed to indict the California virus as the etiological agent. In the case of an infant with very severe disease, the serological evidence was convincing; the evidence was almost as strong in the case of a seven-year-old boy; the results in an adult were equivocal. Inapparent infection in man is quite common as indicated by neutralization tests on the sera of nearly 600 residents of California, but encephalitic manifestations of infec...
Tenbroeck C, Hurst EW, Traub E.Equine encephalomyelitis of the eastern type is a disease of the late summer and fall and cases are found in greatest numbers near salt marshes. The epidemiological findings are against its transmission by contact and favor the view that it is insect borne. Although virus can be demonstrated in the blood of infected horses it is present for a relatively short time, and the possibility that the disease is not primarily an infection of horses but that it is transmitted to them from another host is considered.
The results of integrated human and veterinary surveillance for West Nile virus (WNV) infections in Austria during the transmission seasons 2015 and 2016 are shown. Altogether WNV nucleic acid was detected in 21 humans, horses, wild birds and mosquito pools. In detail: in four human clinical cases [two cases of West Nile fever (WNF) and two cases of West Nile neuroinvasive disease (WNND)]; eight blood donors [among 145,541 tested donations], of which three remained asymptomatic and five subsequently developed mild WNF; two horses with WNND, of which one recovered and one had to be euthanized; ...
Hasan SS, Dey D, Singh S, Martin M.Alphaviruses are arboviruses that cause arthritis and encephalitis in humans. Eastern Equine Encephalitis Virus (EEEV) is a mosquito-transmitted alphavirus that is implicated in severe encephalitis in humans with high mortality. However, limited insights are available into the fundamental biology of EEEV and residue-level details of its interactions with host proteins. In recent years, outbreaks of EEEV have been reported mainly in the United States, raising concerns about public safety. This review article summarizes recent advances in the structural biology of EEEV based mainly on single-par...
Mellor PS, Boorman J.African horse sickness virus (AHSV) and bluetongue virus (BTV) are dsRNA viruses within the genus Orbivirus. Both are able to cause non-contagious, infectious arthropod-borne diseases in their respective vertebrate hosts. AHSV infects equines and occasionally dogs, whereas BTV replicates in ruminants. The disease caused by AHSV is usually at its most severe in horses, whereas certain breeds of sheep are particularly sensitive to BTV infection. AHSV is endemic in sub-Saharan Africa but periodically makes brief excursions beyond this area. BTV occurs much more widely and can be found in a band a...
Reisen WK, Fang Y, Brault AC.Historically, western equine encephalomyelitis virus (WEEV) caused large equine and human epidemics in the Americas from Canada into Argentina. Despite recent enhanced surveillance for West Nile virus, there have been few reports of equine or human cases and little documented enzootic activity of WEEV. During the past three years, WEEV has been active again in California, but without human or equine cases. In the current study, we compared host and vector competence of representative WEEV isolates made during each decade over the past 60 years using white-crowned sparrows, house sparrows, and ...
Arthropod-borne viruses (arboviruses) cause morbidity and mortality in humans and domestic animals worldwide. The percentage of population immunity or susceptibility to these viruses in Ecuador is unknown. To investigate the proportion of Ecuadorian populations with IgG antibodies (Abs) (past exposure/immunity) and IgM Abs (current exposure) against flaviviruses and alphaviruses and to study the activity of these viruses in Ecuador. During 2009-2011, we conducted a serosurvey for selected arboviruses in humans (n=1,842), equines (n=149), and sentinel hamsters (n=84) at two coastal locations an...
Deardorff ER, Weaver SC.The mosquito Culex (Melanoconion) taeniopus is a proven vector of enzootic Venezuelan equine encephalitis virus (VEEV) subtype IE in Central America. It has been shown to be highly susceptible to infection by this subtype, and conversely to be highly refractory to infection by other VEEV subtypes. During the 1990s in southern coastal Mexico, two VEE epizootics in horses were attributed to subtype IE VEEV. These outbreaks were associated with VEEV strains with an altered infection phenotype for the epizootic mosquito vector, Aedes (Ochlerotatus) taeniorhynchus. To determine the infectivity for ...
Arthropodborne viruses (arboviruses) are transmitted to humans primarily through the bites of infected mosquitoes and ticks. Symptomatic infections most often manifest as a systemic febrile illness and, less commonly, as neuroinvasive disease (e.g., meningitis, encephalitis, or acute flaccid paralysis). West Nile virus (WNV) is the leading cause of domestically acquired arboviral disease in the United States. However, several other arboviruses also cause seasonal outbreaks and sporadic cases. In 2011, CDC received reports of 871 cases of nationally notifiable arboviral diseases (excluding deng...
Reisen WK, Hardy JL, Presser SB, Chiles RE.The vector competence of Culex tarsalis Coquillett from the Coachella Valley of California for western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses was monitored monthly from February to November 1993. The concentration of WEE virus required to infect 50% of the females increased during summer coincidentally with ambient temperature and was highest during July. Transmission rates of WEE virus were high during March, low during May-June, and high again during July-September. Females expressed both mesenteronal escape and salivary gland barriers limiting WEE virus diss...
Mughini-Gras L, Mulatti P, Severini F, Boccolini D, Romi R, Bongiorno G, Khoury C, Bianchi R, Montarsi F, Patregnani T, Bonfanti L, Rezza G....In Italy, West Nile virus (WNV) equine outbreaks have occurred annually since 2008. Characterizing WNV vector habitat requirements allows for the identification of areas at risk of viral amplification and transmission. Maxent-based ecological niche models were developed using literature records of 13 potential WNV Italian vector mosquito species to predict their habitat suitability range and to investigate possible geographical associations with WNV equine outbreak occurrence in Italy from 2008 to 2010. The contribution of different environmental variables to the niche models was also assessed...
Rossi SL, Guerbois M, Gorchakov R, Plante KS, Forrester NL, Weaver SC.Venezuelan equine encephalitis virus (VEEV) is an arbovirus that causes periodic outbreaks that impact equine and human populations in the Americas. One of the VEEV subtypes located in Mexico and Central America (IE) has recently been recognized as an important cause of equine disease and death, and human exposure also appears to be widespread. Here, we describe the use of an Internal Ribosome Entry Site (IRES) from encephalomyocarditis virus to stably attenuate VEEV, creating a vaccine candidate independent of unstable point mutations. Mice infected with this virus produced antibodies and wer...
Reisen WK, Meyer RP, Presser SB, Hardy JL.The extrinsic incubation rate (inverse of the time in days from infection to median transmission) of western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses by laboratory strains of Culex tarsalis Coquillett increased as a linear function of incubation temperatures from 10 to 30 degrees C. The estimated temperatures for zero transmission thresholds (intercept of the X axis) were 10.9 and 14.9 degrees C, and the number of degree days above these thresholds required for median transmission (inverse of the slope) was 67.6 and 115.2, respectively. Although the bodies of mos...
Petrucciani A, Yu G, Ventresca M.Eastern Equine Encephalitis (EEE) is an arbovirus that, while it has been known to exist since the 1930's, recently had a spike in cases. This increased prevalence is particularly concerning due to the severity of the disease with 1 in 3 symptomatic patients dying. The cause of this peak is currently unknown but could be due to changes in climate, the virus itself, or host behavior. In this paper we propose a novel multi-season deterministic model of EEE spread and its stochastic counterpart. Models were parameterized using a dataset from the Florida Department of Health with sixteen years of ...
Valerio L, Marini F, Bongiorno G, Facchinelli L, Pombi M, Caputo B, Maroli M, Della Torre A.Knowledge of the frequency of contact between a mosquito species and its different hosts is essential to understand the role of each vector species in the transmission of diseases to humans and/or animals. However, no data are so far available on the feeding habits of Aedes albopictus in Italy or in other recently colonized temperate regions of Europe, due to difficulties in collecting blood-fed females of this diurnal and exophilic species. We analyzed Ae. albopictus host-feeding patterns in two urban and two rural sites within the area of Rome (Italy). Ae. albopictus was collected using stic...
Cardo MV, Vezzani D.Targeted vector surveillance informed by data on mosquito biting patterns can help limit arboviral zoonotic diseases. To characterise host-biting networks in rural and urban equestrian facilities from temperate Argentina, adult resting mosquitoes were collected (December 2018-April 2019) with a battery-powered aspirator. Engorged females were sorted to species, and their blood source was identified using molecular techniques. Bipartite network analysis was performed for rural and urban matrices. A total of 177 bloodmeals from 11 mosquito species of Aedes and Culex were identified, with seven m...
Romi R, Pontuale G, CIufolini MG, Fiorentini G, Marchi A, Nicoletti L, Cocchi M, Tamburro A.In the late summer of 1998, an outbreak of equine encephalomyelitis due to West Nile virus (WNV) occurred in the Tuscany region of central Italy. The disease was detected in 14 race horses from nine localities in four Provinces: Firenze, Lucca, Pisa and Pistoia. The outbreak area included Fucecchio wetlands (1800 ha), the largest inland marsh in Italy, and the adjacent hilly Cerbaie woodlands with farms breeding horses. To detect potential vectors of WNV, entomological surveys of Fucecchio and Cerbaie were undertaken during 1999-2002 by collecting mosquito larvae from breeding sites and adult ...
Yoshida S, Matsuda A, Iwata E, Ono T, Hisaeda K, Ohzawa E, Hiasa Y, Kitagawa H.Noma horses are native Japanese horses. Health checkups revealed that many Noma horses developed dermatitis during summer, which subsided in winter. Seasonal development and signs of itching, suggestive of allergic dermatitis, were observed. In this study, allergen-specific IgE was measured using blood samples collected from 15 Noma horses in summer and winter to identify allergens highly associated with dermatitis. The presence of dermatitis in the subject individuals was recorded during blood sample collection. White blood cell and eosinophil counts, serum total IgE concentration, and serum ...
Zhong D, Zheng J, Ma Z, Wang Y, Wei J.The prevalence and impact of Getah virus (GETV) are significant concerns in China. GETV can infect a wide range of animals, including horses, pigs, sheep, cattle, birds, and humans, resulting in substantial losses in the livestock and agricultural industries. GETV infection can cause the development of ulcers and inflammation in the mouth and gums of horses, which result in pain and discomfort and lead to symptoms such as reduced appetite, drooling, and difficulty chewing. As a result, there is a pressing need for efficient and rapid disease diagnosis methods. However, the currently available ...
Carrasco L, Utrilla MJ, Fuentes-Romero B, Fernandez-Novo A, Martin-Maldonado B.West Nile Virus (WNV) is a zoonotic, vector-borne pathogen affecting humans and animals, particularly in Europe. The virus is primarily transmitted through mosquitoes that infect birds, which serve as the main reservoirs. Humans and horses are incidental hosts. This review focuses on the epidemiology of WNV in southern Europe, particularly its increasing prevalence. Methods included an extensive literature review and analysis of recent outbreaks. WNV is largely asymptomatic in humans, but a small percentage can develop West Nile neuroinvasive disease (WNND), leading to severe neurological symp...
Kordowitzki P.Eastern equine encephalitis virus (EEEV) is a mosquito-transmitted alphavirus that, among humans, can cause a severe and often fatal illness. The zoonotic EEEV enzootic cycle involves a cycle of transmission between and avian hosts, frequently resulting in spillover to dead-end vertebrate hosts such as humans and horses. Interestingly, it has been described that the W132G mutation of the very low-density lipoprotein receptor (VLDLR), the receptor of EEEV, significantly enhanced the VLDLR-mediated cell attachment of EEEV. The patient's metabolism plays a pivotal role in shaping the complex lan...
Vaccination is one of the most important measures for preventing infectious diseases. Vaccinations against tetanus and West-Nile-Virus are essential to protect the individual horse. These infections are not contagious and are not transmitted from animal to animal. By contrast, Equine Influenza and Equine-Herpes-Virus infections are highly contagious, transmissible diseases. In addition to protecting the vaccinated individual, vaccinating as many horses as possible aims at inducing a broad herd immunity, which interrupts infection chains and thus additionally protects the individual. Vaccinatio...
Keven JB, Walker ED.Eastern equine encephalomyelitis virus (EEEV) is endemic in Michigan, showing an upsurge in human cases and in infections of white-tailed deer, horses, and other animals in the past decade (2010-2020). However, blood-host associations of the enzootic mosquito vector Culiseta melanura in the Great Lakes region are poorly known compared with other better-studied regions. Vertebrate sources of blood meals of Cs. melanura collected from resting boxes were determined through sequencing of the mitochondrial cytochrome B gene generated from polymerase chain reaction. Thirty-six unique avian species w...
Kuhn KG, Shelton K, Sanchez G, Zamor R, Bohanan K, Nichols M, Morris L, Robert J, Austin A, Dart B, Bolding B, Maytubby P, Vogel J, Stevenson B.West Nile Virus (WNV) is the most widespread and frequently reported mosquito-borne disease in the US, with a high risk of outbreaks. Accurate surveillance of WNV is complicated by many mild or asymptomatic infections, resulting in human cases being under-reported and disease distribution and transmission not being well understood. In this study, we investigated how wastewater surveillance can be used for monitoring WNV in Oklahoma. We analyzed samples collected from wastewater treatment facilities in 16 counties during July 1 to September 31, 2023, for the presence of WNV genetic material and...
Suvanto MT, Truong Nguyen PT, Vauhkonen H, Olander V, Joensuu R, Culverwell CL, Kaansalo K, Hepojoki J, Vapalahti O, Korhonen EM, Smura T, Huhtamo E.The genus (, ) comprises several globally important vector-borne animal viruses, such as borne bluetongue virus, African horse sickness virus and epizootic haemorrhagic disease virus (EHDV). Orbiviruses that are associated with mosquitoes are a diverse group including established mosquito-borne animal pathogens such as the Peruvian horse sickness virus and phylogenetically related less well-characterized viruses isolated mostly from mammals. Although reported from various geographic regions, these viruses have not previously been detected in northern Europe. Using next-generation sequencing a...
Abbas I, Ahmed F, Muqaddas H, Alberti A, Varcasia A, Sedda L.Climate change can cause spatio-temporal shifts in the epidemiology of various vector borne pathogens, especially in vulnerable areas such as the Mediterranean Basin (MB). Among these pathogens, the West Nile virus (WNV) became endemic in the region. This systematic review and meta-analysis study summarizes WNV epidemiology, molecular characteristics, and surveillance in various MB countries, relying on data and scientific articles on WNV published during 2010-2023. The number of published articles varied across the three MB subregions: Southern Europe (n = 153), North Africa (n = 33), and...
Akinniyi OO, Lawal TR, Rufai N, Jolayemi KO, Amaje J.African horse sickness (AHS) is endemic in Nigeria. Despite this, little is known about the perspective of horse handlers in Nigeria regarding AHS. The study aimed to evaluate the knowledge, attitudes, and perceptions (KAP) of horse handlers in Southwest Nigeria regarding AHS. A cross-sectional survey study was conducted, which involved convenient sampling of 131 horse handlers in Lagos and Oyo States by February - April 2024. The pre-validated questionnaires were administered via face-to-face interviews, covering demographics, knowledge of AHS transmission, clinical signs, prevention and cont...
Hoxha I, Xhekaj B, Muja-Bajraktari N, Sekulin K, Unterköfler MS, Schlamadinger L, Situmorang T, Fuehrer HP, Obwaller AG, Camp JV, Walochnik J....West Nile virus (WNV, family Flaviviridae) is the most geographically widespread arbovirus affecting humans. It circulates between wild birds and mosquitoes, while humans and horses are dead-end hosts. In recent years, several outbreaks have been reported from European countries, including the Balkan Peninsula. In the Republic of Kosovo, a southern Balkan country, data on WNV are scarce, and neither mosquito monitoring nor WNV surveillance is established. To address this gap, we aimed to assess a first monitoring approach that should set the basis and support future large-scale activities in t...
Arshad A, Reif AH, Cavalleri JV, Desvars-Larrive A.Equids serve diverse roles in contemporary society. Their use as companion animals, in sports, transportation, and food production brings them into close contact with humans, creating potential zoonotic risks. This review had two objectives: (i) to catalogue zoonotic pathogens detected in equids across Central Europe, and (ii) to analyse research trends and collaborations in equid zoonosis studies within the region. We conducted a systematic literature search following PRISMA guidelines to identify publications on naturally occurring zoonotic pathogens in equids from nine countries: Austria, t...
Diptera-borne diseases pose a major threat to global health, and their distribution is constantly changing due to climate change, globalization, and environmental changes. To improve the knowledge of dipteran species and their distribution in equine facilities, CDC-UV and oviposition traps were placed, and the dipping technique was performed in 16 equestrian centers of Northwest (NW) Spain (Galicia and Castilla y León Autonomous Communities) between July and November 2023. A questionnaire was distributed among the horse owners to obtain additional information. Four genera of culicids, (51.8%...
Busquets N, Gardela J, José-Cunilleras E, Solé A, Salvador MJ, Obón E, Molina-López R, Aranda C, Montalvo T, Corbella I, Bou-Monclús MA....West Nile virus (WNV), mainly transmitted by mosquitoes, poses significant health risks to humans and horses, particularly in endemic regions. The first detection of WNV lineage 2 in Spain was in 2017 in Catalonia (northeastern Spain). In 2023, WNV was confirmed in a young yellow-legged gull and a probable human case was notified within the urban settings. We aimed to define the zone of WNV circulation in the Barcelona Metropolitan Area where these infections occurred and the effectiveness of the One Health approach for early WNV detection. The Catalan WNV surveillance and control programs in...
Schwarzer A, Ziegler U, Fertey J, Kreuz M, Vahlenkamp TW, Groschup MH, Ulbert S.West Nile virus (WNV), Usutu virus (USUV) and tick-borne encephalitis virus (TBEV) are worldwide endemic zoonotic orthoflaviviruses, often co-circulating in the same areas. Serological studies in animals, mostly birds and horses, are important means to monitor the spread of these viruses and the infection risks for humans. However, cross-reactive antibodies to these structurally similar flaviviruses frequently impact serological differentiation in enzyme-linked immunosorbent assays (ELISAs), hence time-consuming virus neutralization tests (VNTs) have to be employed in laboratories with high bi...
