Asunto(s)
Culex/virología , Brotes de Enfermedades , Insectos Vectores/virología , Fiebre del Nilo Occidental/epidemiología , Animales , Culex/genética , Culex/fisiología , Europa (Continente)/epidemiología , Conducta Alimentaria , Humanos , Insectos Vectores/genética , Insectos Vectores/fisiología , América del Norte/epidemiología , Fiebre del Nilo Occidental/transmisión , Fiebre del Nilo Occidental/virología , Virus del Nilo Occidental/patogenicidadAsunto(s)
Fiebre del Nilo Occidental/epidemiología , Animales , Enfermedades de las Aves/epidemiología , Aves/virología , Culicidae/virología , Humanos , Vigilancia de la Población , Estados Unidos/epidemiología , Fiebre del Nilo Occidental/prevención & control , Fiebre del Nilo Occidental/transmisión , Fiebre del Nilo Occidental/veterinaria , Virus del Nilo Occidental/aislamiento & purificaciónRESUMEN
La Crosse (LAC) virus, a California serogroup bunyavirus, is the leading cause of pediatric arboviral encephalitis in the United States and an emerging disease in Tennessee, West Virginia, and North Carolina. Human cases of LAC encephalitis in Tennessee and North Carolina have increased above endemic levels during 1997 to 1999 and may represent an expansion of a new southeastern endemic focus. This report describes the isolation of LAC virus from the exotic mosquito Aedes albopictus. The discovery of LAC virus in wild populations of Ae. albopictus coupled with its expanding distribution in the southeastern United States, suggests that this mosquito may become an important accessory vector, potentially increasing the number of human cases in endemic foci or expanding the range of the disease.
Asunto(s)
Aedes/virología , Encefalitis de California/virología , Virus La Crosse/clasificación , Virus La Crosse/aislamiento & purificación , Aedes/fisiología , Animales , ADN Viral/análisis , Humanos , Insectos Vectores/virología , Virus La Crosse/genética , North Carolina , Reacción en Cadena de la Polimerasa , Vigilancia de la Población , TennesseeRESUMEN
An outbreak of encephalitis due to West Nile (WN) virus occurred in New York City and the surrounding areas during 1999. Mosquitoes were collected as part of a comprehensive surveillance program implemented to monitor the outbreak. More than 32,000 mosquitoes representing 24 species were tested, and 15 WN virus isolates were obtained. Molecular techniques were used to identify the species represented in the WN virus-positive mosquito pools. Most isolates were from pools containing Culex pipiens mosquitoes, but several pools contained two or more Culex species.
Asunto(s)
Culex/virología , Brotes de Enfermedades , Insectos Vectores/virología , Virus del Nilo Occidental/aislamiento & purificación , Aedes/clasificación , Aedes/virología , Animales , Anopheles/clasificación , Anopheles/virología , Chlorocebus aethiops , Culex/clasificación , Culicidae/clasificación , Culicidae/virología , ADN Viral/análisis , Insectos Vectores/clasificación , New Jersey/epidemiología , New York/epidemiología , Células Vero , Fiebre del Nilo Occidental/epidemiología , Fiebre del Nilo Occidental/virología , Virus del Nilo Occidental/genéticaRESUMEN
After the 1999 West Nile (WN) encephalitis outbreak in New York, 2,300 overwintering adult mosquitoes were tested for WN virus by cell culture and reverse transcriptase-polymerase chain reaction. WN viral RNA and live virus were found in pools of Culex mosquitoes. Persistence in overwintering Cx. pipiens may be important in the maintenance of WN virus in the northeastern United States.
Asunto(s)
Culex/virología , Brotes de Enfermedades , Insectos Vectores/virología , Virus del Nilo Occidental/aislamiento & purificación , Aedes/citología , Animales , Línea Celular , Chlorocebus aethiops , Ciudad de Nueva York/epidemiología , ARN Viral/análisis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Estaciones del Año , Células Vero , Virus del Nilo Occidental/genéticaRESUMEN
West Nile (WN) virus transmission in the United States during 2000 was most intense on Staten Island, New York, where 10 neurologic illnesses among humans and 2 among horses occurred. WN virus was isolated from Aedes vexans, Culex pipiens, Cx. salinarius, Ochlerotatus triseriatus, and Psorophora ferox, and WN viral RNA was detected in Anopheles punctipennis. An elevated weekly minimum infection rate (MIR) for Cx. pipiens and increased dead bird density were present for 2 weeks before the first human illness occurred. Increasing mosquito MIRs and dead bird densities in an area may be indicators of an increasing risk for human infections. A transmission model is proposed involving Cx. pipiens and Cx. restuans as the primary enzootic and epizootic vectors among birds, Cx. salinarius as the primary bridge vector for humans, and Aedes/Ochlerotatus spp. as bridge vectors for equine infection.
Asunto(s)
Enfermedades de las Aves/virología , Culicidae/virología , Reservorios de Enfermedades/veterinaria , Enfermedades de los Caballos/virología , Insectos Vectores/virología , Fiebre del Nilo Occidental/virología , Virus del Nilo Occidental , Animales , Enfermedades de las Aves/mortalidad , Aves/virología , Caballos/virología , Humanos , Ciudad de Nueva York/epidemiología , Fiebre del Nilo Occidental/epidemiología , Fiebre del Nilo Occidental/veterinaria , Virus del Nilo Occidental/aislamiento & purificaciónRESUMEN
Surveillance of mosquito populations for virus activity is not often performed by small, vector-control districts because they do not have the financial resources to use virus isolation, or newer methods such as the polymerase chain reaction. Consequently, development and refinements of rapid, sensitive, and simple enzyme-linked immunosorbent assays (ELISAs) applicable to a wide variety of public health settings are justified. We have developed an antigen-capture ELISA for the detection of eastern equine encephalitis (EEE) virus in mosquitoes that uses both monoclonal capture and detector antibodies. The sensitivity of this assay is 4.0-5.0 log10 plaque-forming units/ml, which is comparable to previously published EEE antigen-capture assays developed with polyclonal antibody reagents. This test identifies only North American strains of EEE virus and does not react with either western equine encephalitis or Highlands J viruses. Test sensitivity was enhanced by sonicating mosquito pools, treating them with Triton X-100, and increasing the time and temperature of antigen incubation. The conversion of this ELISA to a monoclonal antibody-based format should result in a readily standardizable and transferable assay that will permit laboratories lacking virus isolation facilities to conduct EEE virus surveillance.
Asunto(s)
Aedes/virología , Virus de la Encefalitis Equina del Este/aislamiento & purificación , Encefalomielitis Equina Oriental/diagnóstico , Ensayo de Inmunoadsorción Enzimática/métodos , Animales , Anticuerpos Monoclonales/inmunología , Especificidad de Anticuerpos , Antígenos Virales/análisis , Antígenos Virales/inmunología , Chlorocebus aethiops , Virus de la Encefalitis Equina del Este/crecimiento & desarrollo , Femenino , Glicoproteínas/inmunología , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Células Vero , Proteínas Virales/inmunologíaRESUMEN
The authors report on the development and application of a rapid TaqMan assay for the detection of West Nile (WN) virus in a variety of human clinical specimens and field-collected specimens. Oligonucleotide primers and FAM- and TAMRA-labeled WN virus-specific probes were designed by using the nucleotide sequence of the New York 1999 WN virus isolate. The TaqMan assay was compared to a traditional reverse transcriptase (RT)-PCR assay and to virus isolation in Vero cells with a large number ( approximately 500) of specimens obtained from humans (serum, cerebrospinal fluid, and brain tissue), field-collected mosquitoes, and avian tissue samples. The TaqMan assay was specific for WN virus and demonstrated a greater sensitivity than the traditional RT-PCR method and correctly identified WN virus in 100% of the culture-positive mosquito pools and 98% of the culture-positive avian tissue samples. The assay should be of utility in the diagnostic laboratory to complement existing human diagnostic testing and as a tool to conduct WN virus surveillance in the United States.
Asunto(s)
Enfermedades de las Aves/diagnóstico , Culicidae/virología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Polimerasa Taq/metabolismo , Fiebre del Nilo Occidental/diagnóstico , Virus del Nilo Occidental/aislamiento & purificación , Animales , Enfermedades de las Aves/virología , Aves/virología , Encéfalo/virología , Chlorocebus aethiops , Humanos , ARN Viral/sangre , ARN Viral/líquido cefalorraquídeo , Sensibilidad y Especificidad , Células Vero , Cultivo de Virus , Fiebre del Nilo Occidental/veterinaria , Fiebre del Nilo Occidental/virología , Virus del Nilo Occidental/genéticaRESUMEN
Aedes triseriatus (Say) population density patterns and La Crosse encephalitis virus infection rates were evaluated in relation to a variety of habitat parameters over a 14-wk period. Ovitraps and landing collections were used in a La Crosse virus-enzootic area in Nicholas County, WV. Study sites were divided into categories by habitat type and by proximity to the residences of known La Crosse encephalitis cases. Results demonstrated that Ae. triseriatus population densities were higher in sugar maple/red maple habitats than in hemlock/mixed hardwood habitats or in a site characterized by a large number of small red maple trees. Sites containing artificial containers had higher population densities than those without. La Crosse virus minimum infection rates in mosquitoes collected as eggs ranged from 0.4/1,000 to 7.5/1,000 in the 12 study sites, but did not differ significantly among sites regardless of habitat type or proximity to human case residences. La Crosse virus infection rates in landing Ae. triseriatus mosquitoes ranged from 0.0/1,000 to 27.0/1,000. La Crosse virus was also isolated from host-seeking Ae. canadensis (Theobald) in two study sites, at rates similar to those found in the Ae. triseriatus populations. The Ae. triseriatus oviposition patterns and La Crosse virus infection rates suggest that this mosquito species disperses readily in the large woodlands of central West Virginia. The La Crosse enzootic habitats in Nicholas County, WV, are contrasted with those studied in other geographic regions where La Crosse virus is found.
Asunto(s)
Aedes/virología , Insectos Vectores/virología , Virus La Crosse/aislamiento & purificación , Animales , Conducta Animal , Femenino , Humanos , Tiempo (Meteorología) , West VirginiaRESUMEN
West Nile virus is a mosquito borne flavivirus endemic over a large geographic area including Africa, Asia, and the Middle East. Although the virus generally causes a mild, self-limiting febrile illness in humans, it has sporadically caused central nervous system infections during epidemics. An isolate of West Nile virus was obtained from a pool of four male Culex univittatus complex mosquitoes while we were conducting an investigation of Rift Valley fever along the Kenya-Uganda border in February-March 1998. This represents the first field isolation of West Nile virus from male mosquitoes and strongly suggests that vertical transmission of the virus occurs in the primary maintenance mosquito vector in Kenya. A phylogenetic analysis of the complete amino acid sequence of the viral envelope glycoprotein demonstrated a sister relationship with a Culex pipiens mosquito isolate from Romania made in 1996. This unexpected finding probably reflects the role of migratory birds in disseminating West Nile virus between Africa and Europe.
Asunto(s)
Culex/virología , Transmisión Vertical de Enfermedad Infecciosa , Insectos Vectores/virología , Fiebre del Nilo Occidental/transmisión , Virus del Nilo Occidental/inmunología , Secuencia de Aminoácidos , Animales , Antígenos Virales/análisis , Secuencia de Bases , Chlorocebus aethiops , Cartilla de ADN/química , ADN Viral/química , Electroforesis en Gel de Agar , Femenino , Técnica del Anticuerpo Fluorescente Indirecta , Humanos , Kenia/epidemiología , Datos de Secuencia Molecular , Filogenia , ARN Viral/química , ARN Viral/aislamiento & purificación , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Alineación de Secuencia , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Células Vero , Proteínas del Envoltorio Viral/química , Proteínas del Envoltorio Viral/genética , Fiebre del Nilo Occidental/epidemiología , Fiebre del Nilo Occidental/inmunología , Fiebre del Nilo Occidental/virología , Virus del Nilo Occidental/clasificación , Virus del Nilo Occidental/genéticaRESUMEN
La Crosse virus is a mosquito-borne arbovirus that causes encephalitis in children. Only nine cases were reported in Tennessee during the 33-year period from 1964-1996. We investigated a cluster of La Crosse encephalitis cases in eastern Tennessee in 1997. Medical records of all suspected cases of La Crosse virus infection at a pediatric referral hospital were reviewed, and surveillance was enhanced in the region. Previous unreported cases were identified by surveying 20 hospitals in the surrounding 16 counties. Mosquito eggs were collected from five sites. Ten cases of La Crosse encephalitis were serologically confirmed. None of the patients had been discharged from hospitals in the region with diagnosed La Crosse encephalitis in the preceding 5 years. Aedes triseriatus and Aedes albopictus were collected at the case sites; none of the mosquitos had detectable La Crosse virus. This cluster may represent an extension of a recently identified endemic focus of La Crosse virus infection in West Virginia.
Asunto(s)
Encefalitis de California/epidemiología , Virus La Crosse/aislamiento & purificación , Adolescente , Aedes/fisiología , Aedes/virología , Animales , Niño , Preescolar , Análisis por Conglomerados , Encefalitis de California/diagnóstico , Encefalitis de California/patología , Femenino , Humanos , Lactante , Masculino , Vigilancia de la Población , Tennessee/epidemiologíaRESUMEN
In October 1995, epidemic "hemorrhagic fever," without jaundice or renal manifestations, was reported in rural Nicaragua following heavy flooding; 2259 residents were evaluated for nonmalarial febrile illnesses (cumulative incidence, 6.1%) and 15 (0.7%) died with pulmonary hemorrhage. A case-control study found that case-patients were more likely than controls to have ever walked in creeks (matched odds ratio [MOR], 15.0; 95% confidence interval [CI], 1.7-132.3), have household rodents (MOR, 10.4; 95% CI, 1.1-97.1), or own dogs with titers >/=400 to Leptospira species (MOR, 23.4; 95% CI, 3.6-infinity). Twenty-six of 51 case-patients had serologic or postmortem evidence of acute leptospirosis. Leptospira species were isolated from case-patients and potential animal reservoirs. This leptospirosis epidemic likely resulted from exposure to flood waters contaminated by urine from infected animals, particularly dogs. Leptospirosis should be included in the differential diagnosis for nonmalarial febrile illness, particularly during periods of flooding or when pulmonary hemorrhage occurs.
Asunto(s)
Hemorragia/complicaciones , Leptospirosis/epidemiología , Enfermedades Pulmonares/complicaciones , Adolescente , Adulto , Animales , Estudios de Casos y Controles , Bovinos , Niño , Preescolar , Desastres , Brotes de Enfermedades , Vectores de Enfermedades , Perros , Hemorragia/microbiología , Caballos , Humanos , Incidencia , Lactante , Leptospira/clasificación , Leptospira/aislamiento & purificación , Leptospirosis/complicaciones , Leptospirosis/microbiología , Enfermedades Pulmonares/microbiología , Nicaragua/epidemiología , Roedores , Porcinos , Microbiología del AguaAsunto(s)
Infecciones por Arbovirus/epidemiología , Culicidae , Desastres , Insectos Vectores , Animales , Infecciones por Arbovirus/transmisión , Culicidae/virología , Virus de la Encefalitis Equina del Este , Virus de la Encefalitis Equina del Oeste , Encefalitis de San Luis/epidemiología , Encefalitis de San Luis/transmisión , Encefalomielitis Equina/epidemiología , Encefalomielitis Equina/transmisión , Humanos , Insectos Vectores/virología , Vigilancia de la Población , Estados Unidos/epidemiologíaRESUMEN
Patterns in the distribution of titers in arbovirus-positive mosquito pools were examined. Virus isolation records from the Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention, from 1974 through 1993 were used to estimate virus titers in field-collected pools. Pools were classified as either low titer (< or = 3.0 log10 plaque-forming units [PFU]/ml) or high titer (> 3.0 log10 PFU/ml). The proportion of virus-positive pools that had high titers varied among the different domestic arboviruses, within viruses among field sites and years, and within viruses among mosquito species tested. Alphaviruses produced a greater proportion of pools with high titers than did the flaviviruses. Variation in the proportion of pools with high titers among sites and years suggested variation in mosquito and/or virus strains. Variation in the proportion of pools with high titers among mosquito species indicated species-specific differences in vectorial capacity. The results show that information about the titer of virus in mosquito pools can complement other parameters, such as the minimum infection rate, currently used in mosquito-based arbovirus surveillance programs.
Asunto(s)
Culicidae/virología , Virus de la Encefalitis Equina del Este/aislamiento & purificación , Virus de la Encefalitis de San Luis/aislamiento & purificación , Virus de la Encefalitis Equina del Oeste/aislamiento & purificación , Virus La Crosse/aislamiento & purificación , Animales , Arbovirus , Chlorocebus aethiops , Células VeroRESUMEN
Potosi (POT) virus, a recently characterized Bunyamwera serogroup virus, was discovered when it was isolated from Aedes albopictus collected at a waste-tire site in Potosi, Washington County, Missouri, during 1989. During the following year, POT virus was not isolated from 39,048 mosquitoes, including 17,519 Ae. albopictus, collected in Washington County. In 1991, mosquito collections from South Carolina, Ohio, and Michigan yielded 8 strains of POT virus: 6 from Coquillettidia perturbans and one each from Culex restuans and Psorophora columbiae. Additional collections of Ae. albopictus from several states during 1990-93 failed to yield further isolates of POT virus. In 1994, POT virus was isolated from Ae. albopictus and Anopheles punctipennis in North Carolina and from Ae. albopictus in Illinois. These represent the first virus isolations of any type for Ae. albopictus in those states. Thus far, POT virus has been isolated from 5 mosquito species in different genera in 6 states. The known geographic range of POT virus, based on virus isolations, has been extended from Missouri to the upper Midwest and the Atlantic seaboard. Potential vector relationships and possible transmission cycles of POT virus are discussed.
Asunto(s)
Virus Bunyamwera/aislamiento & purificación , Culicidae/virología , Animales , Femenino , Masculino , Estados UnidosRESUMEN
Adult female density, parity status, and wing length were determined weekly for a population of Coquillettidia perturbans in an area enzootic for eastern equine encephalitis virus in central Ohio. Samples were collected in CO2-baited CDC miniature light traps from the first week in June through the 2nd week of September 1992. Population density indicated a single emergence peak during the 2nd week in July. However, parity rates showed 2 peaks, occurring in the first week of August (70.9% parous) and the 2nd week of September (55.3% parous), which suggested that there was a relatively small 2nd generation. Average wing length declined significantly over the season. The decline in size was negatively correlated with average air temperature occurring at least 6 wk before the time of emergence. Despite the seasonal decline in wing length, the low coefficient of variation for the average wing length (5.5) indicated relatively little variation in size. Comparison of parous and nulliparous female wing lengths each week suggested that there was no association between size and survival in this species.
Asunto(s)
Culicidae , Encefalomielitis Equina/veterinaria , Animales , Culicidae/anatomía & histología , Culicidae/virología , Virus de la Encefalitis Equina del Este/aislamiento & purificación , Encefalomielitis Equina/epidemiología , Encefalomielitis Equina/virología , Femenino , Caballos , Ohio/epidemiología , Densidad de Población , Alas de AnimalesRESUMEN
Aedes albopictus is a serious nuisance species and a potential vector of domestic arboviruses in the U.S. Public health and mosquito control agencies have taken numerous actions to address the problems posed by this species. Federally mandated programs of disinsection and inspection of tire casings imported into the U.S. are aimed at preventing additional introductions of this and other exotic mosquito species. Control programs, including the use of traditional chemical larvicides and adulticides, as well as the introduction of predatory copepods into larval habitats, have been developed and tested for population management. A few of the established populations in the northern areas of Ae. albopictus distribution in the continental U.S. have been successfully eradicated through source reduction and insecticide application.
Asunto(s)
Aedes , Vectores de Enfermedades , Control de Mosquitos/métodos , Animales , Comercio/legislación & jurisprudencia , Reservorios de Enfermedades , Insecticidas , Control de Mosquitos/organización & administración , América del NorteRESUMEN
Bloodfed Aedes albopictus were collected during 1989-91 by vacuum aspirator from rural and urban study sites in Missouri, Florida, Indiana, Illinois, and Louisiana. Blood hosts identified by ELISA and precipitin tests were rabbit (n = 91), Rattus sp. (n = 69), dog (n = 14), unidentified mammal (n = 14), cow (n = 13), human (n = 10), deer (n = 10), sciurid (n = 7), turtle (n = 5), murid other than Rattus sp. (n = 4), raccoon (n = 3), passeriform bird (n = 3), and cat (n = 2). As an opportunistic bloodfeeder, Ae. albopictus may be a potential vector of domestic arboviruses and a nuisance pest where infestations occur.
Asunto(s)
Aedes/fisiología , Aves/parasitología , Mamíferos/parasitología , Tortugas/parasitología , Animales , Aves/sangre , Gatos , Bovinos , Ciervos/parasitología , Perros , Ecosistema , Ensayo de Inmunoadsorción Enzimática , Conducta Alimentaria , Interacciones Huésped-Parásitos , Humanos , Mamíferos/sangre , Conejos , Mapaches/parasitología , Ratas , Sciuridae/parasitología , Estados UnidosRESUMEN
Pupal density, wing length at emergence, host-seeking female abundance, and host-seeking female wing length and parity were determined monthly for a population of Aedes albopictus (Skuse) in a southwestern Louisiana tire dump from January 1988 through January 1989. Pupae and host-seeking females were first collected in April. Pupal densities were consistently high from June through September. Host-seeking female abundance was highest during July and August. Average female wing length was longest during spring, declined in midsummer, and increased slightly during fall. Average wing length was negatively correlated with average pupal density during the month of collection and with average air temperature recorded the previous month. Host-seeking females had consistently longer wings than emerging females, and parous host-seeking females had longer wings than nulliparous host-seeking females. Average wing length of the parous host-seeking females was consistently long throughout the season. Parity of host-seeking females parity was highest during July when approximately 21 parous host-seeking females were collected per hour. These results indicate that seasonal patterns in immature population density influence average body size and parity structure in Ae. albopictus.