| A Live Attenuated West Nile Virus Strain as a Potential Veterinary Vaccine | LUSTIG, SHLOMO | 2000 |
KeywordsWNV AbstractThis article reviews the development of two attenuated West Nile virus (WNV) variants, WNI-25 and WNI-25A. These variants have lost the neuroinvasion trait of the parental virus. Attenuation was achieved through serial passages in mosquito cells and neutralization escape from WNV-specific monoclonal antibody. Genetic analysis reveals amino acid changes between the parental and each of the variants. The attenuated variants preserve the ability to replicate in mice and geese and to induce a protective immune response. WNI-25A was found to be a genetically stable virus. This variant was successfully used as a live vaccine to protect geese against a wild-type virulent WNV field isolate that closely resembles the WNV isolated during the 1999 New York epidemic. AuthorsLUSTIG, SHLOMO, OLSHEVSKY, UDY, BEN-NATHAN, DAVID, LACHMI, BAT-EL, MALKINSON, MERTYN, KOBILER, DAVID and HALEVY, MENACHEM Year Published2000 PublicationViral Immunology LocationsDOI10.1089/vim.2000.13.401 |
| West Nile Virus in the New World: Appearance, Persistence, and Adaptation to a New Econiche—An Opportunity Taken | CALISHER, CHARLES H. | 2000 |
KeywordsNo keywords available AbstractNo abstract available AuthorsCALISHER, CHARLES H. Year Published2000 PublicationViral Immunology LocationsDOI10.1089/vim.2000.13.411 |
|
Mosquito Surveillance for West Nile Virus in Connecticut, 2000: Isolation from
Culex pipiens
,
Cx. restuans
,
Cx. salinarius
, and
Cul | Andreadis, Theodore G. | 2001 |
KeywordsWNV AbstractFourteen isolations of West Nile (WN) virus were obtained from four mosquito species (Culex pipiens [5], Cx. restuans [4], Cx. salinarius [2], and Culiseta melanura [3]) in statewide surveillance conducted from June through October 2000. Most isolates were obtained from mosquitoes collected in densely populated residential locales in Fairfield and New Haven counties, where the highest rates of dead crow sightings were reported and where WN virus was detected in 1999. Minimum field infection rates per 1,000 mosquitoes ranged from 0.5 to 1.8 (county based) and from 1.3 to 76.9 (site specific). Cx. restuans appears to be important in initiating WN virus transmission among birds in early summer; Cx. pipiens appears to play a greater role in amplifying virus later in the season. Cs. melanura could be important in the circulation of WN virus among birds in sylvan environments; Cx. salinarius is a suspected vector of WN virus to humans and horses. AuthorsAndreadis, Theodore G., Anderson, John F. and Vossbrinck, Charles R. Year Published2001 PublicationEmerging Infectious Diseases LocationsDOI10.3201/eid0704.010413 |
| Discovery, Distribution, and Abundance of the Newly Introduced Mosquito Ochlerotatus japonicus (Diptera: Culicidae) in Connecticut, USA | Andreadis, Theodore G. | 2001 |
KeywordsWNV AbstractThe earliest documented specimen of an exotic east Asian mosquito Ochlerotatus (Finlaya) japonicis japonicus (Theobald) in the Western Hemisphere is reported along with the results of a state wide survey to determine the distribution and abundance of this mosquito in Connecticut. Ochlerotatus japonicus was collected from 87 locations in eight counties. It is established throughout the state and occurs in a variety of natural and artificial container habitats including discarded tire casings, bird baths, wooden barrels, porcelain bath tubs (used for watering animals), plastic milk cartons, toys, vinyl tarpaulins (covering wood piles and swimming pools), exposed rock holes in stream beds, tree holes, subterranean catch basins, surface water rain pools, and spring-fed depressions. Larvae were particularly common in containers with water, decaying leaves, and algae, in shaded and sunlit areas and, in rock-pool habitats along streambeds, in association with Ochlerotatus atropalpus (Coquillett). Adult females were collected in sod grass-infused gravid and CO2- baited light traps, from early June through October, with peak collections in September. Biting females were collected by human bait method augmented with CO2, verifying its capacity to feed on humans. The ovitraps used in this study were not effective for recovering this species. Our results suggest that Oc. japonicus was introduced into Connecticut between 1992 and 1998. Because of the ability of Oc. japonicus to transmit West Nile virus, and because of the recent detection of this virus in field-collected specimens, the introduction of Oc. japonicus is considered a significant public health development. AuthorsAndreadis, Theodore G., Anderson, John F., Munstermann, Leonard E., Wolfe, Roger J. and Florin, David A. Year Published2001 PublicationJournal of Medical Entomology LocationsDOI10.1603/0022-2585-38.6.774 |
|
Fatal Encephalitis and Myocarditis in Young Domestic Geese (
Anser anser domesticus
) Caused by West Nile Virus
| Swayne, David E. | 2001 |
KeywordsWNV AbstractDuring 1999 and 2000, a disease outbreak of West Nile (WN) virus occurred in humans, horses, and wild and zoological birds in the northeastern USA. In our experiments, WN virus infection of young domestic geese (Anser anser domesticus) caused depression, weight loss, torticollis, opisthotonus, and death with accompanying encephalitis and myocarditis. Based on this experimental study and a field outbreak in Israel, WN virus is a disease threat to young goslings and viremia levels are potentially sufficient to infect mosquitoes and transmit WN virus to other animal species. AuthorsSwayne, David E., Beck, Joan R., Smith, Calandra S., Shieh, Wun-Ju and Zaki, Sharif R. Year Published2001 PublicationEmerging Infectious Diseases LocationsDOI10.3201/eid0704.010429 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/11585545 |
| Vector Surveillance for West Nile Virus | WHITE, DENNIS J. | 2001 |
KeywordsWNV AbstractWest Nile virus (WNV) was detected in the metropolitan New York City (NYC) area during the summer and fall of 1999. Sixty-two human cases, including seven fatalities, were documented. The New York State Department of Health (NYSDOH) initiated and implemented a statewide mosquito and WNV surveillance system. We developed a WNV response plan designed to provide local health departments (LHD) a standardized means to begin to assess basic mosquito population data and to detect WNV circulation in mosquito populations. During the 2000 arbovirus surveillance season, local health agencies collected 317,676 mosquitoes and submitted 9,952 pools for virus testing. NYSDOH polymerase chain reaction (PCR) testing detected 363 WNV-positive pools. Eight species of mosquitoes were found to be infected. Of the 26 counties conducting mosquito surveillance, WNV-positive mosquitoes were detected only in NYC, on Long Island, and in four counties in the lower Hudson River valley region. LHD larval surveillance provided initial or enhanced mosquito habitat location and characterization and mosquito species documentation. Adult mosquito surveillance provided LHD information on species' presence, density, seasonal fluctuations, virus infection, minimum infection ratios (MIR) and indirect data on mosquito control efficacy after larval or adult control interventions. Collective surveillance activities conducted during 1999 and 2000 suggest that WNV has dispersed throughout the state and may affect local health jurisdictions within NYS, adjacent states, and Canada in future years. Vector surveillance will remain a critical component of LHD programs addressing public health concerns related to WNV. AuthorsWHITE, DENNIS J. Year Published2001 PublicationAnnals of the New York Academy of Sciences LocationsDOI10.1111/j.1749-6632.2001.tb02686.x Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/11797806 |
|
West Nile Virus in Overwintering
Culex
Mosquitoes, New York City, 2000
| Nasci, Roger S. | 2001 |
KeywordsWNV AbstractAfter 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. AuthorsMiller, James R., WHITE, DENNIS J., Nasci, Roger S., Savage, Harry M., Cropp, Bruce C., Godsey, Marvin S., Kerst, Amy J., Bennett, Paul, Gottfried, Kristy and Lanciotti, Robert S. Year Published2001 PublicationEmerging Infectious Diseases LocationsDOI10.3201/eid0704.010426 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/11585542 |
| Simulation Studies of St. Louis Encephalitis and West Nile Viruses: The Impact of Bird Mortality | Lord, Cynthia C. | 2001 |
KeywordsWNV AbstractWest Nile virus (WNv) has spread through much of the eastern United States following its introduction in 1999, and arrived in Florida in 2001. Prior to its arrival, we anticipated that its transmission cycle was likely to be similar to that of St. Louis encephalitis virus (SLEv). However, high levels of avian mortality have been reported for WNv in the northeastern United States, and it was unknown how this would impact the transmission dynamics of WNv. Simulation models were used to compare the two viruses by considering the impact of bird mortality on the transmission dynamics of arboviruses in south Florida. Transmission models without disease-induced mortality (SLEv) were compared with models including disease-induced mortality (WNv). Disease-induced mortality depressed transmission, eliminating epizootics in two of 14 simulations that were epizootic without the additional mortality. In both models, the most important factor in the likelihood of epizootics was mosquito population size; the mosquito mortality rate was also important. The additional avian mortality altered the factors most important in the size and timing of epizootics, although it did not always directly affect the outcome of the simulations. In some cases, low-level transmission occurred prior to the epizootic peak. When disease-induced avian mortality was included in the simulations, appreciable numbers of dead birds occurred prior to high levels of infection in mosquitoes. This has implications for the use of dead birds as a surveillance tool monitoring the spread and transmission of WNv. AuthorsLord, Cynthia C. and Day, Jonathan F. Year Published2001 PublicationVector-Borne and Zoonotic Diseases LocationsDOI10.1089/15303660160025930 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/12653130 |
| Effect of Incubation at Overwintering Temperatures on the Replication of West Nile Virus in New York Culex pipiens (Diptera: Culicidae) | Dohm, David J. | 2001 |
KeywordsWNV AbstractWe examined the effect of simulated overwintering temperatures on West Nile (WN) virus replication in Culex pipiens L. derived from mosquitoes collected during the autumn 1999 WN epizootic in New York. The WN virus was a strain isolated from a dead crow also collected during this outbreak. Virus was recovered from most mosquitoes held exclusively at 26 degres C. In contrast, none of the mosquitoes held exclusively at the lower temperatures had detectable infections. When mosquitoes were transferred to 26 degrees C after being held at 10 degrees C for 21-42 d, infection and dissemination rates increased with increased incubation at 26 degrees C. Future studies involving the attempted isolation of WN virus from overwintering mosquitoes may benefit from holding the mosquitoes at 26 degrees C before testing for infectious virus. AuthorsDohm, David J. and Turell, Michael J. Year Published2001 PublicationJournal of Medical Entomology LocationsDOI10.1603/0022-2585-38.3.462 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/11372976 |
| Effect of Holding Conditions on the Detection of West Nile Viral RNA by Reverse Transcriptase-Polymerase Chain Reaction from Mosquito (Diptera: Culicidae) Pools | Turell, Michael J. | 2002 |
KeywordsWNV AbstractWe evaluated the effect of holding temperature and time between mosquito death and processing mosquito pools for virus detection on our ability to detect West Nile (WN) viral RNA from pools of mosquitoes by reverse transcriptase-polymerase chain reaction (RT-PCR). Pools of 24 uninfected Culex pipiens L. mosquitoes were "spiked" with either a single Cx. pipiens that had been inoculated previously with WN virus or with an uninfected mosquito. These pools were held dry at 20, 4, -20, or -70 degrees C for selected time intervals before all mosquito pools were triturated in TRIzol LS reagent and processed for detection of WN viral RNA. While infectious virus virtually disappeared from pools maintained at 20 degrees C by 48 h after mosquito death, neither holding temperature (20 to -70 degrees C) nor holding period (up to 2 wk) affected detection of WN viral RNA by real-time RT-PCR. These findings suggest that we need not keep mosquitoes chilled to be able to detect WN viral RNA effectively by RT-PCR. This should enhance the feasibility of field-based WN virus surveillance programs where only detection of WN viral RNA is the objective and maintenance of a cold chain may not be possible. AuthorsTurell, Michael J., Spring, Alexandra R., Miller, Melissa K. and Cannon, Charles E. Year Published2002 PublicationJournal of Medical Entomology LocationsDOI10.1603/0022-2585-39.1.1 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/11931239 |
