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arbovirus surveillance in six states during 1972.a virus surveillance project was established and maintained during 1972 along 10 major river drainages in six states. mosquitoes, biting flies, and blood specimens from sentinel equines were collected during 83 field trip visits to 141 arthropod collecting sites and 22 sentinel locations from april into december 1972. there were 173,074 mosquitoes tested and 303 arboviruses isolated from 11 of 41 species. from 13,388 biting flies tested, 8 arbovirus isolations were obtained in 1 of 5 species. th ...19767148
host feeding patterns of connecticut mosquitoes (diptera: culicidae).blood-engorged coquillettidia perturbans, psorophora ferox, culex, culiseta, and aedes mosquitoes were collected principally by sweep net from salt marsh and woodland habitats in connecticut. of the 570 mosquitoes tested, precipitin tests identified the origins of 517 blood meals and revealed distinct host feeding patterns. aedes mosquitoes fed chiefly on mammals; a. abserratus, a. cantator, and a. vexans showed selectivity for cattle and (or) horses. a. cantator also obtained blood from avian h ...197717310
occurrence and distribution of western equine encephalomyelitis in florida.research and surveillance programs relating to the occurrence and distribution of western equine encephalomyelitis virus in florida, conducted between 1955 and 1976, suggest that the virus is (1) an endemic arbordae, (2) transmitted in a continuous cycle throughout the year by culiseta melanura mosquitoes, and (3) restricted to fresh water swamps and waterways in central, north, and northwest florida.197823372
a serologic survey of mule deer and elk in utah.sera from mule deer (odocoileus hemionus) and elk (cervus canadensis) in central and northern utah were tested for the prevalence of antibodies to 11 diseases communicable to man or domestic livestock. antibodies to francisella tularensis (at 1:20) were found in 47 of 88 (53.4%) elk and 1 of 89 (1.1%) deer. a screening slide agglutination test for titers to brucella (at 1:20) showed two reactors in elk but none in deer sera. no positive antibody titers were obtained in tests for anaplasmosis, co ...1978105153
arboviruses in new york state: an attempt to determine the role of arboviruses in patients with viral encephalitis and meningitis.in a reveiw of 2,963 patients with signs of infections of the central nervous system in new york state in 1966--1977, arboviruses were found to be the confirmed or presumptive etiologic agents in 60 patients. california encephalitis (ce) virus was the most common (44 patients), followed by powassan (pow) virus (8), st. louis encephalitis virus (7), and eastern equine encephalitis (eee) virus (1). most patients (47) were children. the incidence of encephalitis was higher in patients with arboviru ...1979222159
study of homologous and heterologous antibody response in california horses vaccinated with attenuated venezuelan equine encephalomyelitis vaccine (strain tc-83).of 359 horses vaccinated with attenuated venezuelan equine encephalomyelitis (vee) vaccine (strain tc-83), 87% developed hemagglutination-inhibition (hi) antibodies to vee virus within 1 month. blood from a subsample of 101 of the 359 horses was obtained over a 1-year period. within 1 month after vaccination, 84% of the 101 horses had developed vee hi antibodies, 87% had developed vee-neutralizing (nt) antibodies, and 78% had developed vee complement-fixing (cf) antibodies. one year after vaccin ...1978637386
arbovirus surveillance in florida: wild vertebrate studies 1965-1974.wildlife species from 38 of florida's 67 counties were surveyed over a 10 year period for the presence of antibody to the five major arboviruses circulating in the state. the routine screening of 7891 sera from wild birds and mammals via the hemagglutination-inhibition (h1) test with selected reactors subjected to serum neutralization testing has 1) provided information regarding geographic distribution and seasonality of circulation of these viruses 2) identified enzootic foci of infection and ...19751152173
arboviral disease--united states, 1991.during 1991, state and local health departments reported 122 cases of human arboviral encephalitis to cdc. more than half (69) of the cases resulted from outbreaks of st. louis encephalitis (sle) in arkansas and texas. in addition, an epizootic of eastern equine encephalitis (eee) extending from the atlantic and gulf coasts into the upper midwest caused sporadic human cases and a substantial loss of livestock. this report summarizes the reported cases of arboviral encephalitis in the united stat ...19921321947
mosquito and arbovirus ecology in southeastern california, 1986-1990.mosquito abundance and western equine encephalomyelitis (wee) and st. louis encephalitis (sle) virus activity were monitored in five valleys in southeastern california from june 1986 through april 1990 to study virus overwintering and possible dissemination from south to north along geographically defined corridors. culex tarsalis coquillett predominated in co2 trap collections and was the only species repeatedly infected with wee and sle viruses. abundance peaked during april-may and august-oct ...19921352557
evaluation of domestic pigeons as sentinels for detecting arbovirus activity in southern california.flocks of sentinel domestic pigeons (columbia livia) detected increases in st. louis encephalitis (sle) and western equine encephalomyelitis (wee) virus activity in southern california concurrently with flocks of sentinel chickens. however, occasional low-titered, transient seroconversions to both wee and sle viruses also occurred in pigeons during periods when virus activity was not detected by seroconversions in sentinel chickens, by virus isolation from culex mosquitoes, or by human disease. ...19921536386
an outbreak of equine neonatal salmonellosis.an outbreak of salmonellosis in foals occurred on a large thoroughbred farm in california. only foals less than 8 days of age exhibited clinical signs, which included depression, anorexia, and diarrhea. three foals died from septicemia. the agent responsible was salmonella ohio, which is rarely involved in salmonellosis in horses. during the course of the outbreak, s. ohio was isolated from 27 of 97 mares (27.8%) and 34 of 97 foals (35.1%). mares were the presumed source of infection for foals. ...19911911993
thoracic radiographic features of silicosis in 19 horses.clinical records and thoracic radiographs of 19 horses with a confirmed pathologic diagnosis of silicosis were reviewed. these horses had histories of varying degrees of chronic weight loss, exercise intolerance, and respiratory distress. at the time of presentation, two horses were asymptomatic. ten horses were geldings and nine were female. the mean age of the 19 horses was 10.7 +/- 5.5 years. fourteen horses were identified as being from the monterey-carmel peninsula of midcoastal california. ...19911941758
an assessment of the biological capacity of a sacramento valley population of aedes melanimon to vector arboviruses.daily survivorship, duration of the gonotrophic cycle, absolute abundance and season-long relative abundance were estimated for aedes melanimon in the sacramento valley of california in 1987 and 1988 using mark-release-recapture (mrr) techniques and by monitoring changes in the abundance and parity rate of the native population. one objective of these studies was to determine the extent to which a. melanimon was biologically capable of serving as a horizontal arbovirus vector. daily survivorship ...19912042703
temporal variations in the susceptibility of a semi-isolated population of culex tarsalis to peroral infection with western equine encephalomyelitis and st. louis encephalitis viruses.a semi-isolated population of culex tarsalis in kern county, ca was found to vary significantly in its seasonal and yearly susceptibility to peroral infection with western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses during the breeding seasons of 1975-1981. female cohorts of the population were significantly more resistant to wee virus from 1975 through 1977 than from 1978 through 1981. on the average, females were 40 times more susceptible to wee virus during may tha ...19902160200
diel changes in adult mosquito microhabitat temperatures and their relationship to the extrinsic incubation of arboviruses in mosquitoes in kern county, california.microhabitat temperatures experienced by nocturnally active culex tarsalis coquillett mosquitoes were measured in the southern san joaquin valley of california. temperatures of the diurnal resting shelter and nocturnal activity air space were measured by digital recorder at three cx. tarsalis habitats in kern county. temperatures measured by digital recorders agreed well with temperatures recorded concurrently at nearby california irrigation management and inspection system weather stations. mon ...19902167374
persistence of mosquito-borne viruses in kern county, california, 1983-1988.the persistence of arboviruses was studied from 1983 to 1988 in mixed agriculture, marsh, riparian, and foothill habitats in kern county, ca. western equine encephalomyelitis (wee) virus was isolated frequently during 1983 from culex tarsalis and aedes melanimon and was detected by the seroconversion of sentinel chickens. wee virus then disappeared, even though vector competence studies during 1984-1986 showed that cx. tarsalis was able to transmit wee virus. st. louis encephalitis (sle) virus w ...19902240370
epidemiology of equine protozoal myeloencephalitis in north america based on histologically confirmed cases. a report.following a workshop on equine protozoal myeloencephalitis (epm) convened at the veterinary medical forum of the american college of veterinary internal medicine in 1988, this survey of epm in north america was developed. it is based upon 364 histologically confirmed case records from california, florida, illinois, kentucky, new york, ohio, oklahoma, ontario, pennsylvania, and texas up to 1988. the highest rate of infection was found in young thoroughbred, standardbred, and quarter horses. diffe ...19902342022
the discovery decade of arbovirus research in western north america, 1940-1949. 19872891315
identification of aedes campestris from new mexico: with notes on the isolation of western equine encephalitis and other arboviruses.an arbovirus survey was conducted during august 1985 at white sands missile range in southcentral new mexico following a suspected arboviral disease epizootic among feral horses. a total of 20,566 mosquitoes (18,505 females and 2,061 males) and 8,900 biting gnats were collected and assayed for virus. female mosquitoes were principally aedes campestris (54.8%), aedes dorsalis (30.4%) and culex tarsalis (13.2%). arboviruses were not isolated from biting gnats, but mosquitoes yielded a total of 37 ...19862906989
california serogroup virus infections in wisconsin domestic animals.a serologic survey and experimental virus transmission studies were done to assess the role of domestic animals as amplifier hosts of la crosse (lacv) and jamestown canyon (jcv) viruses. serum from 319 cows, 88 dogs, 122 equines, 47 swine, 10 goats, and 4 cats were tested for neutralizing antibody to lacv, jcv, trivittatus (tvtv), and snowshoe hare (sshv) viruses. antibody prevalences of lacv, tvtv, and sshv were less than 10% in all species. antibody to jcv was detected in all species except ca ...19883189702
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 ...19873318522
air conditioning and television as protective factors in arboviral encephalitis risk.in california, the advent of television and air conditioned housing has coincided with a general decrease in mosquito-borne viral encephalitis cases in humans in the past 25 years. during this same period, levels of vector populations, virus activity in vectors, birds, and horses has been high at times. air conditioning and television encourage persons to remain indoors during summer evenings, the primary time when infected culex tarsalis transmit western equine encephalomyelitis and st. louis e ...19863486605
isolation of cache valley virus and detection of antibody for selected arboviruses in michigan horses in 1980.blood samples collected in september and november 1980 from 87 horses in southwestern michigan were examined for virus isolation and for plaque-reduction neutralizing antibody against selected arboviruses. cache valley virus was isolated from the blood of a clinically normal horse in st joseph county in september. the age-specific antibody prevalence for cache valley virus indicated enzootic transmission in the study area. the high antibody prevalence and the lack of age-specific antibody preval ...19873631684
aerial adulticiding for the suppression of culex tarsalis in kern county, california, using low volume propoxur: 2. impact on natural populations in foothill and valley habitats.a low volume formulation of propoxur wettable powder suspended in larvicidal oil was evaluated on 4 occasions in kern co., california during 1983 using fixed and rotary wing aerial application systems. culex tarsalis abundance was suppressed significantly by all sprays, although reduction below the virus maintenance threshold of 30 females per trap night was achieved only at one foothill site. western equine encephalomyelitis virus minimum infection rates decreased significantly after serial app ...19853880226
leads from the mmwr. arboviral infections of the central nervous system--united states, 1984. 19853999305
experimental infection with western equine encephalomyelitis virus in wild rodents indigenous to kern county, california.six species of rodents from kern county, california, were inoculated subcutaneously with western equine encephalomyelitis (wee) virus to determine their susceptibility to infection and their potential as natural hosts. ammospermophilus nelsoni, citellus beecheyi, dipodomys heermanni, dipodomys nitratoides, peromyscus maniculatus, and sciurus griseus were readily infected. infection was usually fatal in dipodomys species, c. beecheyi, and s. griseus, but was clinically inapparent in other species ...19744426699
california encephalitis studies in iowa during 1969, 1970 and 1971. 19734735659
chronic lead poisoning in horses. 19734735954
a survey for toxoplasma antibodies in northern california livestock and dogs. 19744825778
leptospirosis in california. 19674960757
trinity river serologic survey. a survey of residents of communities along the course of the trinity river between houston and dallas, texas, for antibodies to the viruses of st. louis encephalitis, western equine encephalitis and california encephalitis. 19715120543
occurrence of a cattle eyeworm, thelazia gulosa (nematoda: thelaziidae), in an imported giraffe in california and t. lacrymalis in a native horse in maryland. 19715157171
nigropallidal encephalomalacia in horses in colorado. 19705461699
tick paralysis in california livestock. 19685689541
a review of developments associated with the control of western equine and st. louis encephalitis in california during 1967. 19685730061
arboviruses from western utah, usa, 1967-1976. 19836135808
comparative arboviral susceptibility of female culex tarsalis (diptera: culicidae) collected in co2-baited traps and reared from field-collected pupae. 19836298431
california arbovirus (la crosse) infections. i. clinical and laboratory findings in 66 children with meningoencephalitis. 19734355363
factors influencing the transmission of western equine encephalomyelitis virus between its vertebrate maintenance hosts and from them to humans.a simple model is used to explore the extent to which the uniquely comprehensive studies of western equine encephalomyelitis in kern county, california, by reeves and his colleagues over many years, explain the dynamics and epidemiology of the infection. it is concluded that not only does this series of integrated field and laboratory studies successfully account for these phenomena, to an extent which is unlikely to be substantially improved upon, not least because of the inherent difficulties ...19873688320
equine ehrlichiosis in northern california: 49 cases (1968-1981).case records of horses with equine ehrlichiosis (ehrlichia equi) at the university of california veterinary medical teaching hospital and ackerman creek large animal clinic were analyzed for evaluation of clinical signs, time of onset, hematologic values, response to treatment, and recovery. equine ehrlichiosis was found to be seasonal in horses in the foothills of northern california, with higher incidence than reported previously. the horses developed fever, anorexia, depression, limb edema, i ...19873558086
leads from the mmwr. arboviral encephalitides--united states, 1983. 19836644947
past and present preferred prescribing practices of hormone replacement therapy among los angeles gynecologists: possible implications for public health.usual prescribing strategies of hormone replacement therapy for postmenopausal women by los angeles area gynecologists, both now and 10 years ago, were investigated by a mail survey. of the 330 gynecologists who responded, estrogen therapy is currently used as a routine by nearly all (95 per cent), for women both with and without a uterus. over three-fourths of these physicians favor use of 0.625 mg of conjugated equine estrogen. the estrogen is combined with cyclic progestin therapy, usually 10 ...19883354733
arboviral infections of the central nervous system--united states, 1986. 19873110574
arboviral infections of the central nervous system--united states, 1989. 19902352534
seroepidemiologic survey of antibodies to ehrlichia equi in horses of northern california.the prevalence of antibodies to ehrlichia equi in horses from the foothill regions of northern california and from the sacramento valley (non-foothill area) was determined, using an indirect fluorescent antibody test. horses from foothill regions had a higher prevalence of seropositivity (10.4%) and higher titer (1:10 to 1:80) than did those from non-foothill regions (3.1%; titer less than or equal to 1:10). fifty percent of healthy horses on a foothill farm enzootic for e equi had titer to e eq ...19902195000
distribution of neutralizing antibodies to california and bunyamwera serogroup viruses in horses and rodents in california.neutralization tests were done on sera from 141 horses from high elevation regions of california. antibody prevalences to jamestown canyon, snowshoe hare, and california encephalitis viruses in the california serogroup and northway virus in the bunyamwera serogroup were 55%, 43%, 18%, and 46%, respectively. in 51 horses from rural low elevation regions, seroprevalences were 31%, 35%, 35%, and 37%, respectively. twenty-four horses from a suburban lowland area were seronegative, except for a singl ...19902107770
from the centers for disease control and prevention. arboviral disease--united states, 1994. 19957563474
onchocerciasis in a california dog.a 15-year-old dog that had lived all of its life on ranches and at the wildlife waystation on the western edge of the san gabriel mountains near los angeles, california, developed an extensive granulomatous lesion involving the right eye and associated tissues requiring removal of both the eye and the lesion. microscopic examinations of the tissues revealed the presence of living and dead gravid female worms and male worms belonging to the genus onchocerca. unsheathed microfilariae presumed to b ...19912063954
landscape ecology of arboviruses in southern california: temporal and spatial patterns of vector and virus activity in coachella valley, 1990-1992.consistent temporal and spatial patterns in the activity of culex tarsalis coquillett and western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses were delineated that were useful in developing a stratified surveillance program. vernal increases in cx. tarsalis abundance typically were associated with flooding of saline marshes along the north shore of the salton sea and were followed 6-8 wk later by the onset of wee and sle virus activity. viruses then spread to managed m ...19957616515
landscape ecology of arboviruses in southern california: patterns in the epizootic dissemination of western equine encephalomyelitis and st. louis encephalitis viruses in coachella valley, 1991-1992.temporal and spatial patterns in the initiation and dissemination of western equine encephalomyelitis and st. louis encephalitis virus activity in coachella valley during 1991 and 1992 were detected by testing pools of host-seeking culex tarsalis coquillett for virus infection and sentinel chickens for seroconversions. both viruses repeatedly were detected first at a salt marsh adjacent to the salton sea in the southeastern corner of the study area and then disseminated to the northwest to fresh ...19957616516
bionomics of culex tarsalis (diptera: culicidae) in relation to arbovirus transmission in southeastern california.population dynamics and bionomics of host-seeking culex tarsalis coquillett were studied in the imperial and coachella valleys of california during periods in 1991 and 1992 when western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses were transmitted to sentinel chickens. female abundance was greatest during the spring and fall, before and after most virus transmission occurred and was not correlated with temperature, humidity, or rainfall. parity rates were highest durin ...19957616523
outbreaks of stringhalt in northern california. 19912035250
mosquito and arbovirus surveillance in connecticut, 1991-1992.a surveillance program for mosquito-borne arboviruses was conducted in connecticut following an epizootic of eastern equine encephalitis (eee) in horses and domestic birds during 1990. mosquito trapping was done weekly using co2-baited miniature light traps at 12 freshwater swamp sites that were located mostly in the southeastern portion of the state. trapping was conducted from june 27 to october 11, 1991 and from june 2 to september 30, 1992. totals of 7,435 (1991) and 13,912 (1992) adult fema ...19947707064
arboviral infections in the united states.arboviruses are important considerations in the differential diagnosis of encephalitis and other acute infections. alterations in the environment and in human behaviors contribute to changing patterns of arboviral transmission. these trends, the periodic epidemic resurgence of arboviral diseases such as st. louis encephalitis, and the discovery of new arboviruses present a continued challenge to infectious disease clinicians.19911646839
potential effect of global warming on mosquito-borne arboviruses.if global warming occurs in california, daily mean temperatures may increase by 3 to 5 degrees c, precipitation patterns will change, and sea level may rise 1 m. studies were done on effect of temperature changes on survival of culex tarsalis coquillett, the primary vector of western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses, in two regions where temperatures differed by 5 degrees c. daily mortality of adult vectors increased by 1% for each 1 degree c increase in te ...19948057305
coccidioidomycosis in horses: 15 cases (1975-1984).fifteen confirmed cases of equine coccidioidomycosis that originated in california and arizona were studied retrospectively. age, breed, and sex varied among affected horses. the most common historical problems were chronic weight loss (53% of cases) and persistent cough (33% of cases). the most frequent physical examination abnormalities were related to the respiratory tract (60% of cases). in 27% of cases, horses had signs of musculoskeletal pain. horses consistently had hyperproteinemia, hype ...19921399805
from the centers for disease control. arboviral disease--united states, 1991. 19921324995
trivittatus virus infections in wild mammals and sentinel rabbits in central iowa.a serological survey was conducted in iowa to determine the prevalence rate of california group virus antibodies in sera of several vertebrate species. serum specimens were assayed for infectivity-neutralizing antibody in a microneutralization system with baby hamster kidney cell culture. of 77 sera assayed, 21 (27%) neutralized trivittatus (tvt) virus infectivity. the antibody prevalence rate was highest for eastern cottontail rabbits inasmuch as 46% (10/22) of the serum specimens form this spe ...19751200251
seasonal variation in the vector competence of culex tarsalis (diptera:culicidae) from the coachella valley of california for western equine encephalomyelitis and st. louis encephalitis viruses.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-septe ...19968667391
a field study of persistence of antibodies in california horses vaccinated against western, eastern, and venezuelan equine encephalomyelitis.as a result of the continuing threat of venezuelan equine encephalomyelitis (vee), a study was made to determine if revaccination against vee (tc-83 vaccine) was feasible and if revaccination could be incorporated into other routine vaccination practices. of the horses given annual vaccination with bivalent western equine encephalomyelitis (wee) and eastern equine encephalomyelitis (eee) vaccine, 57% retained detectable serum-neutralizing (sn) antiboyd titers for vee 18 months after the initial ...19751190598
a statistical model of the dynamics of a mosquito vector (culex tarsalis) population.a model of the dynamics of a mosquito culex tarsalis is derived that includes the life states through which the mosquito proceeds. transition probabilities from one state (egg, larva, pupa and adult) to another are derived and they depend on the duration of stay and mortality in each state. a formula is derived for the expected number of mosquitoes alive at any time during the spring or summer. this formula depends on the number of eggs oviposited and the transition probabilities. data are used ...1976953134
diagnosis of oleander poisoning in livestock.since mid-1989, 37 cases of oleander poisoning in livestock have been diagnosed at the california veterinary diagnostic laboratory system. the most frequent source for oleander exposure was plant clippings. sudden death was the most common presenting complaint. other signs reported included diarrhea, pulmonary edema, tachycardia, cardiac arrhythmias, colic, and lethargy. in the past, a presumptive diagnosis of oleander poisoning could be based only on matching clinical signs with evidence of con ...19968844581
high-speed exercise history and catastrophic racing fracture in thoroughbreds.to investigate the relation between several racing speed history characteristics and risk of fatal skeletal injury (fsi) in racing thoroughbreds.19968915427
prevalence of antibodies to mosquito-borne encephalitis viruses in residents of the coachella valley, california.sera from 19 (2.6%) and 118 (16.4%) of 719 outpatients attending clinics in the southeastern coachella valley, california during 1993 and 1994 exhibited igg antibodies to western equine encephalomyelitis and st. louis encephalitis (sle) viruses, respectively, using enzyme immunoassays. however, only seven (1.0%) and 36 (5.0%) outpatients were positive by plaque-reduction neutralization tests (prnts), and seven (1.0%) and 84 (11.7%) outpatients were positive by sera hemagglutination inhibition as ...19969025696
ecology of mosquitoes and lack of arbovirus activity at morro bay, san luis obispo county, california.during 1994-95, totals of 17,656 adult females and 111,104 adults reared from field-collected immatures comprising 19 species in 4 genera of mosquitoes were collected from morro bay estuary and surrounding environs in san luis obispo county, california. aedes dorsalis was the dominant summer mosquito, whereas aedes squamiger and ae. washinoi were abundant during winter and early spring. host-seeking culex tarsalis were collected infrequently, even though immatures were collected frequently from ...19969046476
the prevalence of shedding of cryptosporidium and giardia spp. based on a single fecal sample collection from each of 91 horses used for backcountry recreation.cryptosporidium parvum and giardia duodenalis are now recognized as primary enteric pathogens in animals and humans. regulatory agencies, such as the environmental protection agency are under increasing pressure to reduce the concentration of these protozoa in surface waters. given the popularity of recreational riding of horses on public land in california backcountry, concerns have been raised by various regulatory agencies as to whether horses used for backcountry recreation are a significant ...19979087926
landscape ecology of arboviruses in southeastern california: temporal and spatial patterns of enzootic activity in imperial valley, 1991-1994.western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses were detected in the imperial valley during the summers of 1991-1994 by isolation from the primary vector, culex tarsalis coquillett, and by the seroconversion of sentinel chickens. enzootic transmission consistently was not detected first each year at sampling sites near specific landscape features such as a heron rookery and other riparian habitats along the new river, sites along the mexican border, or saline and ...19979103761
time of host-seeking by culex tarsalis (diptera:culicidae) in california.factors altering the pattern of culex tarsalis coquillett host-seeking activity were studied in kern and riverside counties of california using an automatic time-segregated sampler baited with bottled co2 gas released at 0.5 or 1.0 liters/min. host-seeking always commenced shortly after sunset and usually peaked during the succeeding 1-3 h, the hottest and driest time of the night. the time of maximal activity varied over time and space, because of increased mosquito abundance (presumably reduce ...19979220677
correlation of culex tarsalis population indices with the incidence of st. louis encephalitis and western equine encephalomyelitis in california.mosquito population indices from california for the period 1953-1973 were analyzed to determine their association with activity of st. louis encephalitis (sle) and western equine encephalomyelitis (wee) viruses. culex tarsalis female populations, as measured by new jersey light trap indices (lti), correlated positively with the incidence rates of encephalitis in humans, and were a reliable means of forecasting the years of highest incidence. the critical level of c. tarsalis in urban areas below ...1979453436
mouse and baby chicken virulence of enzootic strains of western equine encephalomyelitis virus from california.eight enzootic strains of western equine encephalomyelitis (wee) virus isolated from culex tarsalis or aedes melanimon collected in several geographic areas of california were evaluated for their virulence in suckling mice, adult mice, and one-day-old baby chickens. the epidemic fleming strain and the cloned b628(cl 15) variant were used as virulent and avirulent control viruses, respectively, in adult mice. enzootic strains of wee virus were grouped into three phenotypes on the basis of their n ...19979288823
caecal disease in equids.to review the breed, age, gender, clinical and laboratory findings, treatment and outcome of horses with caecal disease presented to a referral centre.19979293333
experimental infection of turkey poults with western equine encephalitis virus.the pathogenicity of a field isolate of western equine encephalitis (wee) virus, which was recovered from a breeder hen during investigations of egg production drops in california turkey flocks, was tested in 2-wk-old turkey poults. no symptoms or mortality were observed in poults inoculated intramuscularly with 4.2 log10 50% embryo lethal doses of virus; however, the infection did result in mild to moderate lymphoid necrosis in the bursa of fabricius and thymus glands beginning on the first day ...19979356702
arboviral disease surveillance and control in california. 1979427296
prevalence of antibodies to western equine encephalomyelitis and st. louis encephalitis viruses in residents of california exposed to sporadic and consistent enzootic transmission.sera from outpatients attending county health department clinics in areas of california with consistent (imperial valley) and sporadic (sacramento valley) enzootic transmission of western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses exhibited neutralizing antibody prevalence rates of 1.3% (n = 690) and 0.5% (n = 1,066) for wee and 11.0% and 0.8% for sle, respectively. seroprevalence for sle virus in imperial county increased as a function of both age and years of resid ...19979392590
mosquito-borne arboviruses in arctic america.mosquito-borne arboviruses are prevalent throughout subarctic regions of canada and alaska, principally in the boreal forest extending between latitudes 53 and 66 degrees n, but they have been identified in tundra regions as far north as 70 degrees n. all mosquito-borne agents have been bunyaviruses, comprising principally the snowshoe hare subtype of california encephalitis (ce) virus, but also northway virus. mosquito vectors comprise several aedes species and culiseta inornata, all of which h ...19751602
risk analysis of quarantine station performance: a case study of the importation of equine infectious anemia virus-infected horses into california.we examined the risk of importing and mistakenly releasing equine infectious anemia virus (eiav)-infected horses into california. a computer simulation model was constructed to evaluate current and alternative quarantine station procedures; 150,000 iterations were performed to simulate 15 different scenarios of 10,000 horses imported into the state over a 14-year period. simulation results showed that under current conditions of low eiav prevalence in exporting countries, increasing the quaranti ...19989526854
ocular onchocerciasis in the horse. 19714949805
condylar fractures of the third metacarpal bone and third metatarsal bone in 75 horses: radiographic features, treatments, and outcome. 19836604048
arboviral encephalitis: the need for clinical suspicion in connecticut. 19846723298
epidemiological and bacteriological studies of corynebacterium equi isolates from californian farms.soil samples were collected from 6 horse breeding establishments in california and cultured for corynebacterium equi. only 3 of the farms had a history of the occurrence of pneumonia caused by c. equi. one farm had experienced an outbreak in 5 out of 6 foals just before soil sampling. soil isolates were identified as c. equi on the basis of physical and biochemical characteristics found to be consistent with isolates of equine origin. c. equi was found in many soil samples within endemic areas w ...19826962887
[surveillance and control of diseases caused by arboviruses in california]. 19806444822
comparative molecular characterization of corynebacterium pseudotuberculosis of different origin.ribotyping and susceptibility to 17 antimicrobial agents were used to compare 37 isolates of corynebacterium pseudotuberculosis (28 from horses, 1 from cattle, 3 from sheep and 5 from goats) derived from various types of lesions, and different geographic locations. according to the presence of nitrate reductase, all but one isolate from horses reduced nitrate (nitrate-positive), whereas all isolates from sheep and goats were unable to reduce nitrate (nitrate-negative). the ribotype of the nitrat ...19989695286
ecology of aedes dorsalis (diptera: culicidae) in relation to western equine encephalomyelitis virus in the coachella valley of california.the ecology of western equine encephalomyelitis virus (wee) was studies during 1994-1996 along a portion of the north shore of the salton sea in coachella valley, california, known to support a focal aedes dorsalis (meigen) population. wee was detected during 1995 by the seroconversion of sentinel chickens concurrently at sites within and outside of the area supporting ae. dorsalis. wee was not detected during 1994 or 1996; neither was wee detected by seroconversion of sentinel rabbits nor by is ...19989701945
venezuelan equine encephalomyelitis: report of an outbreak associated with jungle exposure. 19846438552
protozoal myeloencephalitis in horses in california.three cases of equine protozoal myeloencephalitis were diagnosed over a 12-month period in horses that had never left the state of california. these cases suggest that the disease is enzootic in california.19846436215
arboviral encephalitides--united states, 1983. 19836415386
perinatal arbovirus encephalitis and its sequelae. 19685732127
egg production drops in breeder turkeys associated with western equine encephalitis virus infection.egg production drops associated with western equine encephalitis (wee) virus infection occurred in three turkey breeder flocks in california during summer 1993 and again in one flock the following year. egg production losses totaled 8.76%, 9.57%, 9.71%, and 10.12% and were accompanied by an increase in small white-shelled and shell-less eggs. the outbreaks coincided with peak wee virus activity in the state on the basis of statistics compiled by the california department of health services on se ...199910216771
genetic variation among isolates of western equine encephalomyelitis virus from california.the mechanism for long-term maintenance of western equine encephalomyelitis (wee) virus in california was investigated by studying genetic variation in the e2 portion of the genome of 55 strains of wee virus isolated since 1938 from different locations in california. four major lineages were evident: virus strains isolated from the central valley since 1993 and los angeles in 1991 formed lineage a; southern california strains isolated since 1978 and isolates from the central valley from 1978 to ...199910348252
case-control study of risk factors associated with isolation of salmonella saintpaul in hospitalized horses.in an investigation of a 1981-1982 outbreak of nosocomial salmonella saintpaul infection in hospitalized horses at the university of california veterinary medical teaching hospital in davis, california, a case-control study was performed using data gathered from the records of 33 cases and 132 controls. multiple logistic regression risk analysis was used to identify factors associated with isolation of the organism, controlling for the effects of other, possibly confounding variables. horses rec ...19846507427
detection of ehrlichia risticii, the agent of potomac horse fever, in freshwater stream snails (pleuroceridae: juga spp.) from northern california.ehrlichia dna was identified by nested pcr in operculate snails (pleuroceridae: juga spp.) collected from stream water in a northern california pasture in which potomac horse fever (phf) is enzootic. sequencing of pcr-amplified dna from a suite of genes (the 16s rrna, groesl heat shock operon, 51-kda major antigen genes) indicated that the source organism closely resembled ehrlichia risticii, the causative agent of phf. the minimum percentage of juga spp. harboring the organism in the population ...19989687446
role of peridomestic birds in the transmission of st. louis encephalitis virus in southern california.in response to the 1984 st. louis encephalitis (sle) epidemic in the los angeles basin of southern california (usa), an investigative program was initiated to evaluate the interactive components of the sle virus transmission cycle. from 1987 through 1996 (10 yr), 52,589 birds were bled and their sera tested for sle and western equine encephalomyelitis (wee) virus antibodies by the hemagglutination inhibition (hai) test. eighty-three percent of the birds tested were house finches (carpodacus mexi ...200010682741
risk factors associated with corynebacterium pseudotuberculosis infection in california horses.a case-control study was designed using equine medical records from the uc davis veterinary medical teaching hospital (vmth) and data derived through a mailed survey. the objective was to evaluate the associations between horse demographics, horse-management factors, and equine corynebacterium pseudotuberculosis infection in california. horses admitted to the vmth between july 1 1992 and june 30 1994 served as the study base for case identification and simple random sampling of 800 controls. a q ...19989689656
response of house finches to infection with sympatric and allopatric strains of western equine encephalomyelitis and st. louis encephalitis viruses from california.adult house finches from kern county were inoculated subcutaneously with recent sympatric and allopatric isolates of western equine encephalomyelitis and st. louis encephalitis (sle) viruses made from culex tarsalis coquillett collected in kern county and coachella valley, ca, respectively. virulence, as measured by the amplitude of the viremia response during days 1 and 2 postinfection, varied significantly among strains, but independently of geographic origin. the intensity of the immune respo ...200010730497
application and evaluation of a mailed questionnaire for an epidemiologic study of corynebacterium pseudotuberculosis infection in horses.the objective of this study is to describe the design, application and validity of a self-administered (mailed) questionnaire to collect data on potential risk factors for corynebacterium pseudotuberculosis infection in california horses. horses admitted to the uc davis veterinary medical teaching hospital (vmth) between 1 july 1992 and 30 june 1994 served as the study base for case identification and simple random sampling of 800 control horses. a questionnaire was mailed to owners of the study ...19989689657
relationships among weather, mosquito abundance, and encephalitis virus activity in california: kern county 1990-98.the summer abundance of culex tarsalis in kern county, california, during 1990-98 was related quantitatively to rainfall, snow depth and water content, and runoff of the kern river. total monthly rain that fell during winter, lagged by 4-6 months, explained only 13% of the variability in the number of host-seeking females collected per trap night per month during summer. in contrast, regression analysis showed that river runoff 1 month earlier explained 67% of the variability in mosquito abundan ...200010757487
detection of anti-arboviral immunoglobulin g by using a monoclonal antibody-based capture enzyme-linked immunosorbent assay.monoclonal antibody (mab)-based capture enzyme-linked immunosorbent assays (elisas) for the detection of anti-arboviral immunoglobulin g (igg elisas) were developed for a comprehensive array of medically important arboviruses from the alphavirus, flavivirus, and bunyavirus genera. tests were optimized and standardized so that maximum homology could be maintained among working parameters for the different viral agents, enabling a wide range of viruses to be easily tested for at one time. mabs wer ...200010790108
ehrlichia equi infection of horses from minnesota and wisconsin: detection of seroconversion and acute disease investigation.equine granulocytic ehrlichiosis (ege) is caused by infection with ehrlichia equi. ege has been reported primarily in northern california, where e equi is transmitted by the tick ixodes pacificus. reports of ege and the emergence of human granulocytic ehrlichia in minnesota prompted a seroprevalence study of e equi in horses of minnesota and wisconsin. tick (ixodes scapularis) endemic areas of minnesota and wisconsin were compared to nonendemic regions of minnesota. indirect fluorescent antibody ...200010830537
cross-sectional study of faecal shedding of giardia duodenalis and cryptosporidium parvum among packstock in the sierra nevada range.faecal specimens from 305 horses and mules used as packstock at one of 17 commercial or governmental (national park service, us forest service) operations were examined for giardia duodenalis and cryptosporidium parvum using immunofluorescent microscopy. fourteen packstock (4.6%) were shedding g. duodenalis cysts, with herd-level prevalences ranging 0-22%. number of packstock in the corral, size of corral and density of packstock in the corral were associated with the odds of shedding g. duodena ...200010836481
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 ...200010916291
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