RESUMEN
Eastern equine encephalitis and Venezuelan equine encephalitis are endemic neglected tropical diseases in the Americas, causing encephalitis in both horses and humans. In 2013, a cross-sectional study was performed in 243 horses located in the highlands and lowlands throughout Costa Rica. Serum samples were analyzed with an IgG ELISA and confirmed by the plaque-reduction neutralization test (PRNT80). Venezuelan equine encephalitis virus (VEEV) and Eastern equine encephalitis virus (EEEV) overall seroprevalences by the PRNT80 were 36% (95% confidence interval [CI]: 29.9-42.5; 78/217 horses) and 3% (95% CI: 1.3-5.9; 6/217 horses), respectively. Both the viruses occurred in the lowlands and highlands. Rainfall and altitude were associated with VEEV seropositivity in the univariate analysis, but only altitude <100 meters above sea level was considered a risk factor in the multivariate analysis. No risk factors could be identified for the EEEV in the multivariate analysis. This is the first study that estimates the seroprevalence of the EEEV and VEEV in Costa Rican horses. The VEEV is widely distributed, whereas the EEEV occurs at a much lower frequency and only in specific areas. Clinical cases and occasional outbreaks of both viruses are to be expected.
Asunto(s)
Encefalomielitis Equina Oriental , Encefalomielitis Equina Venezolana , Enfermedades de los Caballos , Animales , Costa Rica/epidemiología , Estudios Transversales , Encefalomielitis Equina Oriental/veterinaria , Encefalomielitis Equina Venezolana/veterinaria , Enfermedades de los Caballos/epidemiología , Caballos , Factores de Riesgo , Estudios SeroepidemiológicosRESUMEN
The Pantanal hosts diverse wildlife species and therefore is a hotspot for arbovirus studies in South America. A serosurvey for Mayaro virus (MAYV), eastern (EEEV), western (WEEV) and Venezuelan (VEEV) equine encephalitis viruses was conducted with 237 sheep, 87 free-ranging caimans and 748 equids, including 37 collected from a ranch where a neurologic disorder outbreak had been recently reported. Sera were tested for specific viral antibodies using plaque-reduction neutralisation test. From a total of 748 equids, of which 264 were immunised with vaccine composed of EEEV and WEEV and 484 had no history of immunisation, 10 (1.3%) were seropositive for MAYV and two (0.3%) for VEEV using criteria of a ≥ 4-fold antibody titre difference. Among the 484 equids without history of immunisation, 48 (9.9%) were seropositive for EEEV and four (0.8%) for WEEV using the same criteria. Among the sheep, five were sero- positive for equine encephalitis alphaviruses, with one (0.4%) for EEEV, one (0.4%) for WEEV and three (1.3%) for VEEV. Regarding free-ranging caimans, one (1.1%) and three (3.4%), respectively, had low titres for neutralising antibodies to VEEV and undetermined alphaviruses. The neurological disorder outbreak could not be linked to the alphaviruses tested. Our findings represent strong evidence that MAYV and all equine encephalitis alphaviruses circulated in the Pantanal.
Asunto(s)
Caimanes y Cocodrilos/inmunología , Alphavirus/inmunología , Anticuerpos Neutralizantes/sangre , Anticuerpos Antivirales/sangre , Enfermedades de los Caballos/inmunología , Ovinos/inmunología , Factores de Edad , Caimanes y Cocodrilos/sangre , Animales , Brasil/epidemiología , Virus de la Encefalitis Equina del Este/inmunología , Virus de la Encefalitis Equina Venezolana/inmunología , Virus de la Encefalitis Equina del Oeste/inmunología , Encefalomielitis Equina Oriental/epidemiología , Encefalomielitis Equina Oriental/veterinaria , Encefalomielitis Equina Venezolana/epidemiología , Encefalomielitis Equina Venezolana/veterinaria , Encefalomielitis Equina del Oeste/epidemiología , Encefalomielitis Equina del Oeste/veterinaria , Enfermedades de los Caballos/sangre , Enfermedades de los Caballos/prevención & control , Caballos/sangre , Caballos/inmunología , Pruebas de Neutralización , Estudios Seroepidemiológicos , Ovinos/sangre , HumedalesRESUMEN
Eastern equine encephalitis is a viral zoonosis that exhibits complex distribution and epidemiology, and greater importance should be given to this disease by the public-health authorities. In Brazil, although eastern equine encephalitis virus (EEEV) has been identified in vectors and antibodies are sometimes detected in horses and humans, there have been no records of equine encephalitis in horses caused by this virus during the last 24 years. This study describes eighteen cases of eastern equine encephalomyelitis that occurred in six Brazilian states between 2005 and 2009. Viral RNA was identified using semi-nested RT-PCR to detect members of the genus Alphavirus, and by genetic sequencing. The gene encoding NSP1 was partially amplified, and after genetic sequencing, eighteen sequences were generated. All eighteen strains were classified as belonging to lineage III of American EEEV. These findings could be an indication of the importance of this virus in animal and human public health.
Asunto(s)
Virus de la Encefalitis Equina del Este/patogenicidad , Encefalomielitis Equina Oriental/epidemiología , Enfermedades de los Caballos/epidemiología , Animales , Secuencia de Bases , Tronco Encefálico/virología , Brasil/epidemiología , Cerebelo/virología , Virus de la Encefalitis Equina del Este/clasificación , Virus de la Encefalitis Equina del Este/genética , Encefalomielitis Equina Oriental/veterinaria , Encefalomielitis Equina Oriental/virología , Enfermedades de los Caballos/virología , Caballos/virología , Ratones , ARN Viral/aislamiento & purificación , Análisis de Secuencia de ADNRESUMEN
BACKGROUND: The eastern equine encephalitis (EEE) and Venezuelan equine encephalitis (VEE) viruses are pathogens that infect humans and horses in the Americas. Outbreaks of neurologic disease in humans and horses were reported in Panama from May through early August 2010. METHODS: We performed antibody assays and tests to detect viral RNA and isolate the viruses in serum samples from hospitalized patients. Additional cases were identified with enhanced surveillance. RESULTS: A total of 19 patients were hospitalized for encephalitis. Among them, 7 had confirmed EEE, 3 had VEE, and 1 was infected with both viruses; 3 patients died, 1 of whom had confirmed VEE. The clinical findings for patients with EEE included brain lesions, seizures that evolved to status epilepticus, and neurologic sequelae. An additional 99 suspected or probable cases of alphavirus infection were detected during active surveillance. In total, 13 cases were confirmed as EEE, along with 11 cases of VEE and 1 case of dual infection. A total of 50 cases in horses were confirmed as EEE and 8 as VEE; mixed etiologic factors were associated with 11 cases in horses. Phylogenetic analyses of isolates from 2 cases of equine infection with the EEE virus and 1 case of human infection with the VEE virus indicated that the viruses were of enzootic lineages previously identified in Panama rather than new introductions. CONCLUSIONS: Cases of EEE in humans in Latin America may be the result of ecologic changes that increased human contact with enzootic transmission cycles, genetic changes in EEE viral strains that resulted in increased human virulence, or an altered host range. (Funded by the National Institutes of Health and the Secretaría Nacional de Ciencia, Tecnología e Innovación, Panama.).
Asunto(s)
Brotes de Enfermedades , Virus de la Encefalitis Equina del Este , Virus de la Encefalitis Equina Venezolana , Encefalomielitis Equina Oriental , Encefalomielitis Equina Venezolana , Adolescente , Animales , Anticuerpos Antivirales/sangre , Niño , Preescolar , Virus de la Encefalitis Equina del Este/genética , Virus de la Encefalitis Equina del Este/inmunología , Virus de la Encefalitis Equina del Este/aislamiento & purificación , Virus de la Encefalitis Equina Venezolana/genética , Virus de la Encefalitis Equina Venezolana/inmunología , Virus de la Encefalitis Equina Venezolana/aislamiento & purificación , Encefalomielitis Equina Oriental/epidemiología , Encefalomielitis Equina Oriental/veterinaria , Encefalomielitis Equina Venezolana/epidemiología , Encefalomielitis Equina Venezolana/veterinaria , Resultado Fatal , Femenino , Enfermedades de los Caballos/epidemiología , Caballos , Humanos , Lactante , Masculino , Panamá/epidemiología , Filogenia , ARN Viral/sangreRESUMEN
Outbreaks of eastern equine encephalitis observed from May 2008 to August 2009 in the Brazilian states of Pernambuco, Ceará, and Paraíba are reported. The disease occurred in 93 farms affecting 229 equids with a case fatality rate of 72.92%. Main clinical signs were circling, depression or hyperexcitability, ataxia, and progressive paralysis with a clinical manifestation period of 3-15 days. Main histologic lesions were a diffuse lymphocytic encephalomyelitis with neuronal death, satellitosis, neuronophagia, and hemorrhages being more severe in the cerebral gray matter of the telencephalon, diencephalon, and mesencephalon. Some animals also had areas of malacia in the telencephalon, thalamus, and basal nuclei. From 1 case, the virus was isolated by mice inoculation, and in other 13 cases was identified as Eastern equine encephalitis virus by semi-nested reverse transcription polymerase chain reaction. After DNA sequencing, all samples were identified as eastern equine encephalitis through the BLASTn analysis, but samples from the Ceará and Paraíba states corresponded to the same cluster, while the sample from the state of Pernambuco corresponded to a different cluster.
Asunto(s)
Brotes de Enfermedades/veterinaria , Virus de la Encefalitis Equina del Este , Encefalomielitis Equina Oriental/veterinaria , Enfermedades de los Caballos/epidemiología , Animales , Encéfalo/patología , Brasil/epidemiología , Virus de la Encefalitis Equina del Este/genética , Encefalomielitis Equina Oriental/diagnóstico , Encefalomielitis Equina Oriental/epidemiología , Encefalomielitis Equina Oriental/patología , Técnica del Anticuerpo Fluorescente Directa/veterinaria , Enfermedades de los Caballos/diagnóstico , Enfermedades de los Caballos/patología , Enfermedades de los Caballos/virología , Caballos/virología , Reacción en Cadena de la Polimerasa/veterinaria , Estaciones del AñoRESUMEN
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 yet been identified. Therefore, to further assess the reservoir host potential of wild rodents and wild birds, we compared the infection dynamics of North American and South American EEEV in cotton rats (Sigmodon hispidus) and house sparrows (Passer domesticus). Our findings suggested that each species has the potential to serve as amplification hosts for North and South America EEEVs.
Asunto(s)
Vectores de Enfermedades , Virus de la Encefalitis Equina del Este , Encefalomielitis Equina Oriental/veterinaria , Enfermedades de los Caballos/transmisión , Sigmodontinae/virología , Gorriones/virología , Animales , Anticuerpos Antivirales/sangre , Enfermedades Transmisibles Emergentes/transmisión , Enfermedades Transmisibles Emergentes/veterinaria , Enfermedades Transmisibles Emergentes/virología , Virus de la Encefalitis Equina del Este/clasificación , Virus de la Encefalitis Equina del Este/inmunología , Virus de la Encefalitis Equina del Este/aislamiento & purificación , Encefalomielitis Equina Oriental/transmisión , Encefalomielitis Equina Oriental/virología , Enfermedades de los Caballos/virología , Caballos , América del Norte , América del Sur , Especificidad de la EspecieRESUMEN
Mosquitoes were collected in the Amazon Basin, near Iquitos, Peru, and used in experimental studies to evaluate their susceptibility to strains of eastern equine encephalitis virus (EEEV) that were isolated from mosquitoes captured within 20 km of Iquitos. When fed on hamsters or chickens with a viremia of 4105 plaque-forming units (PFU) of EEEV/ml, Culex pedroi Sirivanakarn and Belkin, Aedesfulvus (Wiedemann), Psorophora albigenu (Peryassu), and Psorophoraferox (Von Humboldt) were susceptible to infection, whereas none of the Aedes serratus (Theobald), Culex vomerifer Komp, Culex gnomatos Sallum, Huchings, and Ferreira, Culex portesi Senevet and Abonnenc, or Culex coronator Dyar and Knab became infected, even though they fed on the same viremic blood sources. When these mosquito species fed on animals with viremias of approximately 10(8) PFU/ml, Cx. pedroi, Ae.II (Brazil-Peru) and a lineage III (Argentina-Panama) isolate of EEEV. This study, combined with the repeated isolation of strains of EEEV from Cx. pedroi captured in the Amazon Basin region of Peru, suggests that Cx. pedroi may be the primary enzootic vector of EEEV in this region.