| the ecology of western equine encephalomyelitis virus in the central valley of california, 1945-1985. | reeves' concept of the summer transmission cycle of western equine encephalomyelitis virus in 1945 was that the virus was amplified in a silent transmission cycle involving mosquitoes, domestic chickens, and possibly wild birds, from which it could be transmitted tangentially to and cause disease in human and equine populations. extensive field and laboratory studies done since 1945 in the central valley of california have more clearly defined the specific invertebrate and vertebrate hosts invol ... | 1987 | 3318522 |
| geographic variation among st. louis encephalitis virus strains in the viremic responses of avian hosts. | we studied the capacity of 44 strains of st. louis encephalitis (sle) virus to induce viremia in an epidemiologically important wild avian host, the house sparrow (passer domesticus). selected virus strains were also inoculated at varying doses into 3-week-old chicks. viremic responses were analyzed in terms of the proportion of inoculated nestling and adult birds which became viremic, the mean duration and the mean peak titer of viremia. infectivity of avian sera was determined by plaque assay ... | 1980 | 7446828 |
| role of corvids in epidemiology of west nile virus in southern california. | the invasion of different southern california landscapes by west nile virus (wnv) and its subsequent amplification to epidemic levels during 2004 enabled us to study the impact of differing corvid populations in three biomes: the hot colorado desert with few corvids (coachella valley), the southern san joaquin valley (kern county) with large western scrub-jay but small american crow populations, and the cool maritime coast (los angeles) with a large clustered american crow population. similar su ... | 2006 | 16619622 |
| limited interdecadal variation in mosquito (diptera: culicidae) and avian host competence for western equine encephalomyelitis virus (togaviridae: alphavirus). | 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 isolat ... | 2008 | 18385369 |
| persistent west nile virus transmission and the apparent displacement st. louis encephalitis virus in southeastern california, 2003-2006. | west nile virus (family flaviviridae, genus flavivirus, wnv) invaded the colorado desert biome of southern california during summer 2003 and seemed to displace previously endemic st. louis encephalitis virus (family flaviviridae, genus flavivirus, slev, an antigenically similar flavivirus in the japanese encephalitis virus serocomplex). western equine encephalomyelitis virus (family togaviridae, genus alphavirus, weev), an antigenically distinct alphavirus, was detected during 2005 and 2006, ind ... | 2008 | 18533445 |
| seasonal blood-feeding behavior of culex tarsalis (diptera: culicidae) in weld county, colorado, 2007. | studies on culex tarsalis coquillett in colorado have shown marked seasonal variation in the proportion of blood meals from birds and mammals. however, limitations in the specificity of antibodies used in the precipitin test and lack of vertebrate host availability data warrant revisiting cx. tarsalis blood feeding behavior in the context of west nile virus (wnv) transmission. we characterized the host preference of cx. tarsalis during peak wnv transmission season in eastern colorado and estimat ... | 2009 | 19351092 |
| stone lakes virus (family togaviridae, genus alphavirus), a variant of fort morgan virus isolated from swallow bugs (hemiptera: cimicidae) west of the continental divide. | multiple isolates of an alphaviruses within the western equine encephalomyelitis-serocomplex that were related closely to ft. morgan and its variant buggy creek virus were made from swallow bugs, oeciacus vicarius horvath (hemiptera: cimicidae), collected from cliff swallow (petrochelidon pyrrhonota) nests at the stone lakes national wildlife refuge, sacramento county, ca, during the summers of 2005 and 2006. this virus (hereafter stone lakes virus, family togaviridae, genus alphavirus, stlv) wa ... | 2009 | 19769055 |
| Mosquito host selection varies seasonally with host availability and mosquito density. | Host selection by vector mosquitoes is a critical component of virus proliferation, particularly for viruses such as West Nile (WNV) that are transmitted enzootically to a variety of avian hosts, and tangentially to dead-end hosts such as humans. Culex tarsalis is a principal vector of WNV in rural areas of western North America. Based on previous work, Cx. tarsalis utilizes a variety of avian and mammalian hosts and tends to feed more frequently on mammals in the late summer than during the res ... | 2011 | 22206038 |
| reduced west nile virus transmission around communal roosts of great-tailed grackle (quiscalus mexicanus). | west nile virus has caused several outbreaks among humans in the phoenix metropolitan area (arizona, southwest usa) within the last decade. recent ecologic studies have implicated culex quinquefasciatus and culex tarsalis as the mosquito vectors and identified three abundant passerine birds-great-tailed grackle (quiscalus mexicanus), house sparrow (passer domesticus), and house finch (haemorhous mexicanus)-as key amplifiers among vertebrates. nocturnal congregations of certain species have been ... | 2014 | 25480320 |
| host (avian) biting preference of southern california culex mosquitoes (diptera: culicidae). | the host preference of a vector mosquito species plays a significant role in determining human and animal risk of infection with mosquito-transmitted pathogens. host preferences of common southern california culex species for four bird species, american crow (corvus brachyrhynchos), house sparrow (passer domesticus), house finch (carpodacus mexicanus), and mourning dove (zenaida macroura), were examined by determining the proportion of each mosquito species that successfully engorged on each of ... | 2012 | 22679878 |
| "submergence" of western equine encephalitis virus: evidence of positive selection argues against genetic drift and fitness reductions. | understanding the circumstances under which arboviruses emerge is critical for the development of targeted control and prevention strategies. this is highlighted by the emergence of chikungunya and zika viruses in the new world. however, to comprehensively understand the ways in which viruses emerge and persist, factors influencing reductions in virus activity must also be understood. western equine encephalitis virus (weev), which declined during the late 20th century in apparent enzootic circu ... | 2020 | 32027727 |
| on the fly: interactions between birds, mosquitoes, and environment that have molded west nile virus genomic structure over two decades. | west nile virus (wnv) was first identified in north america almost 20 yr ago. in that time, wnv has crossed the continent and established enzootic transmission cycles, resulting in intermittent outbreaks of human disease that have largely been linked with climatic variables and waning avian seroprevalence. during the transcontinental dissemination of wnv, the original genotype has been displaced by two principal extant genotypes which contain an envelope mutation that has been associated with en ... | 2019 | 31549720 |
| variation in western equine encephalomyelitis viral strain growth in mammalian, avian, and mosquito cells fails to explain temporal changes in enzootic and epidemic activity in california. | the decrease in western equine encephalomyelitis virus (weev; togaviridae, alphavirus) activity in north america over the past 20-30 years has prompted research to determine if there have been concurrent declines in virulence. six (weev) strains isolated from culex tarsalis mosquitoes from california during each of the six preceding decades failed to show a consistent declining temporal trend in virus titer using mosquito (c6/36), avian (duck embryo fibroblast), or mammalian (vero) cells, result ... | 2011 | 21395409 |
| species identification of blood meals from culex tarsalis that had fed on passeriform birds. | blood-engorged culex tarsalis (4,209) collected during 1960 to 1965 in kern county, california and previously shown to have fed on passeriform birds by the precipitin test were further tested by the more sensitive passive hemagglutination inhibition test (phi). it was shown that these mosquitoes fed principally on house finches and house sparrows, the most common passeriform birds found in the collection areas. these data demonstrate the usefulness of the phi test for the identification of arthr ... | 1976 | 961998 |
| spatial variation in host feeding patterns of culex tarsalis and the culex pipiens complex (diptera: culicidae) in california. | west nile virus (family flaviviridae, genus flavivirus, wnv) is now endemic in california across a variety of ecological regions that support a wide diversity of potential avian and mammalian host species. because different avian hosts have varying competence for wnv, determining the blood-feeding patterns of culex (diptera: culicidae) vectors is a key component in understanding the maintenance and amplification of the virus as well as tangential transmission to humans and horses. we investigate ... | 0 | 22897051 |
| avian host and mosquito (diptera: culicidae) vector competence determine the efficiency of west nile and st. louis encephalitis virus transmission. | the ability of the invading ny99 strain of west nile virus (wnv) to elicit an elevated viremia response in california passerine birds was critical for the effective infection of culex mosquitoes. of the bird species tested, western scrub jays, aphelocoma coerulescens, produced the highest viremia response, followed by house finches, carpodacus mexicanus, and house sparrows, passer domesticus. most likely, few mourning, zenaidura macroura, or common ground, columbina passerine, doves and no calif ... | 2005 | 15962789 |
| patterns of avian seroprevalence to western equine encephalomyelitis and saint louis encephalitis viruses in california, usa. | temporal and spatial changes in the enzootic activity of western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses were monitored at representative wetland study sites in the coachella, san joaquin, and sacramento valleys of california from 1996 to 1998 using three methods: (1) virus isolation from pools of 50 host-seeking culex tarsalis coquillett females, (2) seroconversions in flocks of 10 sentinel chickens, and (3) seroprevalence in wild birds collected by mist nets and ... | 2000 | 10916291 |