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rift valley fever in chad.to evaluate the importance of human exposure to rift valley fever virus in chad, investigations were carried out to determine specific antibody prevalence in domestic ruminants during the 2002 rainy season. results highlighted recent, substantial, active transmission of this virus.200415200839
nss protein of rift valley fever virus blocks interferon production by inhibiting host gene transcription.rift valley fever virus (rvfv) is an important cause of epizootics and epidemics in africa and a potential agent of bioterrorism. a better understanding of the factors that govern rvfv virulence and pathogenicity is required, given the urgent need for antiviral therapies and safe vaccines. we have previously shown that rvfv strains with mutations in the nss gene are excellent inducers of alpha/beta interferon (ifn-alpha/beta) and are highly attenuated in mice. here, we demonstrate that nss is su ...200415331713
exposure of sheep to mosquito bites: possible consequences for the transmission risk of rift valley fever in senegal.rift valley fever (rvf) is a growing health problem in west africa. in northern senegal, the candidate vectors of this arbovirosis are aedes (aedimorphus) vexans meigen and culex (culex) poicilipes theobald (diptera: culicidae). domestic ruminants are the reservoirs of the virus. a study was undertaken during the 2002 rainy season to assess spatial and temporal variations in exposure to mosquito bites in sheep herds, and to evaluate the possible consequences on the risk of rvf transmission to sh ...200415347392
laboratory transmission of rift valley fever virus by phlebotomus duboscqi, phlebotomus papatasi, phlebotomus sergenti, and sergentomyia schwetzi (diptera: psychodidae).we examined the potential for phlebotomus papatasi (scopoli), phlebotomus duboscqi (neveu-lemarie), phlebotomus sergenti (parrot), and sergentomyia schwetzi (adler, theodor, & parrot) to transmit rift valley fever (rvf) virus. after feeding on hamsters that had been inoculated with rvf virus, p. papatasi, p. sergenti, and s. schwetzi became infected and developed disseminated infections. all p. papatasi and p. duboscqi inoculated with rvf virus developed high-titer infections. in contrast, only ...200015535589
experimental detection of rift valley fever virus by reverse transcription-polymerase chain reaction assay in large samples of mosquitoes.a reverse transcription-polymerase chain reaction (rt-pcr) was assessed in laboratory tests to detect the presence of single aedes aegypti (l.) or eretmapodites quinquevittatus theobald mosquitoes infected with rift valley fever virus in pools of mosquitoes, 50-600 in size, from laboratory colonies or mixed field collections. the viral rna was detected in all pools containing infected mosquitoes and was shown to be as sensitive as infant mice but more sensitive than vero cell cultures for virus ...200015535594
validation of igg-sandwich and igm-capture elisa for the detection of antibody to rift valley fever virus in humans.rift valley fever (rvf) virus is an important zoonotic and a potential biothreat agent. this paper describes validation of sandwich and capture enzyme-linked immunoassays (elisa) based on gamma-irradiated antigens for the detection of rvfv-specific igg and igm antibody in humans. validation data sets derived from testing field-collected sera from africa (n=2400) were dichotomised according to the results of a virus neutralisation test. in addition, sera from laboratory workers immunized with ina ...200515664066
bichat guidelines for the clinical management of haemorrhagic fever viruses and bioterrorism-related haemorrhagic fever viruses.haemorrhagic fever viruses (hfvs) are a diverse group of viruses that cause a clinical disease associated with fever and bleeding disorder. hfvs that are associated with a potential biological threat are ebola and marburg viruses (filoviridae), lassa fever and new world arenaviruses (machupo, junin, guanarito and sabia viruses) (arenaviridae), rift valley fever (bunyaviridae) and yellow fever, omsk haemorrhagic fever, and kyanasur forest disease (flaviviridae). in terms of biological warfare con ...200415677844
rift valley fever.rift valley fever (rvf) is an arthropod-borne viral disease of ruminants, camels and humans. it is also a significant zoonosis which may be encountered as an uncomplicated influenza-like illness, but may also present as a haemorrhagic disease with liver involvement; there may also be ocular or neurological lesions. in animals, rvf may be inapparent in non-pregnant adults, but outbreaks are characterised by the onset of abortions and high neonatal mortality. jaundice hepatitis and death are seen ...200415702723
the production and evaluation of a standard diagnostic peste des petits ruminants (ppr) hyperimmune serum prepared from the egyptian antigen (egypt 87).the aim of this study was to produce a specific hyperimmune serum for diagnosis of peste des petits ruminants (ppr). based on good laboratory practices and standard operating procedures, we produced this reagent in goats using attenuated local strain of pprv. the quality was assured to meet the internationally required levels of potency and sterility. the titer of the product was 1024 as evaluated by virus neutralization (vn) and agar gel immunodiffusion (agid) tests. in its final form, it is a ...200415724381
isolation of bovine viral diarrhea virus 1, a pestivirus from autopsied lamb specimen from tamil nadu, india.an epizootic of febrile illness among the madras red breed of sheep had occurred in 1994 in verrapuram, chennai, india. the epizootic was suspected as rift valley fever (rvf)-like sickness based on clinical features. however, its etiological agent could neither be isolated nor implicated conclusively. during the post-epizootic period a male lamb died of similar clinical features and the spleen was immediately collected. inoculation of spleen suspension in infant mouse brain yielded a virus that ...200415745045
[rift valley fever virus].rift valley fever virus (rvfv) causes massive mosquito-borne epidemics among humans and decimates ruminants in which the mortality rate is about 1% and 10-30%, respectively. morbidity in rvfv-infected humans is high largely due to the effects of hemorrhagic fever and encephalitis. this virus is native to sub-saharan africa; yet if this virus is introduced into the environment, virus transmission appears to occur whenever sheep and cattle are present with abundant mosquito populations. rvfv is a ...200415745161
immune responses to recombinants of the south african vaccine strain of lumpy skin disease virus generated by using thymidine kinase gene insertion.the south african vaccine strain of lumpy skin disease virus (type sa-neethling) is currently being developed as a vector for recombinant vaccines of economically important livestock diseases throughout africa. in this study, the feasibility of using the viral thymidine kinase gene as the site of insertion was investigated and recombinant viruses were evaluated in animal trials. two separate recombinants were generated and selected for homogeneity expressing either the structural glycoprotein ge ...200515811653
rift valley fever virus nonstructural protein nss promotes viral rna replication and transcription in a minigenome system.rift valley fever virus (rvfv), which belongs to the genus phlebovirus, family bunyaviridae, has a tripartite negative-strand genome (s, m, and l segments) and is an important mosquito-borne pathogen for domestic animals and humans. we established an rvfv t7 rna polymerase-driven minigenome system in which t7 rna polymerase from an expression plasmid drove expression of rna transcripts for viral proteins and minigenome rna transcripts carrying a reporter gene between both termini of the m rna se ...200515827175
an inhibition enzyme-linked immunosorbent assay for the detection of antibody to rift valley fever virus in humans, domestic and wild ruminants.this paper describes the development and validation of an inhibition elisa based on gamma-irradiated tissue culture-derived antigen for the detection of antibody to rift valley fever virus (rvfv) in humans, domestic and wild ruminants. validation data sets derived from field-collected sera in africa (humans=1367, cattle=649, goats=806, sheep=493, buffalo=258, camels=156) were categorized according to the results of a virus neutralisation test. in addition, individual sera from 93 laboratory work ...200515893560
mosquito vectors of the 1998-1999 outbreak of rift valley fever and other arboviruses (bagaza, sanar, wesselsbron and west nile) in mauritania and senegal.following an outbreak of rift valley fever (rvf) in south-eastern mauritania during 1998, entomological investigations were conducted for 2 years in the affected parts of senegal and mauritania, spanning the sénégal river basin. a total of 92 787 mosquitoes (diptera: culicidae), belonging to 10 genera and 41 species, were captured in light traps. in senegal, culex poicilipes (41%) and mansonia uniformis (39%) were the most abundant species caught, whereas aedes vexans (77%) and cx. poicilipes (1 ...200515958020
imiquimod 5% cream (aldara).imiquimod is a novel synthetic molecule with potent immune-modifying activities. formulated in a 5% vanishing cream as aldara, this self-applied therapy has shown good efficacy and safety in the treatment of external genital and perianal warts caused by human papillomavirus (hpv) infection (condyloma acuminata). the molecule does not demonstrate direct antiviral activity, but through induction of cytokines results in immune-based resolution of wart tissue and reduction of viral burden. phase iii ...199815991984
rainfall patterns and population dynamics of aedes (aedimorphus) vexans arabiensis, patton 1905 (diptera: culicidae), a potential vector of rift valley fever virus in senegal.the importance of rainfall for the development of aedes vexans arabiensis populations, one of the potential vectors of rift valley fever in west africa, was demonstrated in a two-year follow-up study conducted in the ferlo region of senegal. in 2003, the rainy season began with heavy rains and, as a result, temporary ponds, the breeding places for mosquitoes, were flooded at their maximum level immediately. in such conditions, aedes vexans arabiensis populations are abundant at the very beginnin ...200516007962
alkhumra virus infection, a new viral hemorrhagic fever in saudi arabia.four patients with typical acute viral hemorrhagic fever were identified in the holy city of makkah, saudi arabia, between 8 and 23 february 2001, the hajj (pilgrimage) period of that year. tests for rift valley fever (rvf), crimean-congo hemorrhagic fever (cchf), and dengue were negative. blood specimens were sent to the centres for disease control and prevention (cdc), atlanta for viral culture and testing for other hemorrhagic fever viruses. a new flavivirus closely related to the tick-borne ...200516038757
production of monoclonal antibodies against rift valley fever virus application for rapid diagnosis tests (virus detection and elisa) in human sera.this paper describes the production and characterization of rvfv monoclonal antibodies. the characteristics of 32 out of 55 elisa and/or ifa positive monoclonal antibodies were determined, including the rvfv components against which they are directed. one monoclonal antibody recognized the nucleoprotein, 15 the gc and 16 the gn. among the latter ones, five monoclonal antibodies possess another specificity and recognized both gn and either the nucleoprotein (four of them) or the nss protein (one) ...200616102851
the n terminus of rift valley fever virus nucleoprotein is essential for dimerization.rift valley fever virus (rvfv) is a phlebovirus in the bunyaviridae family. the nucleoprotein n is the most abundant component of the virion; numerous copies of n associate with the viral rna genome and form pseudohelicoidal ribonucleoproteins (rnps) circularized by a panhandle structure formed by the base-paired rna sequences at the 3' and 5' termini. these structures play a central role in transcription and replication. we investigated the intermolecular interactions of the rvfv n protein and ...200516140773
rift valley fever virus nss mrna is transcribed from an incoming anti-viral-sense s rna segment.analysis of purified rift valley fever virus (rvfv) particles demonstrated the presence of three negative-sense rna genomes, plus three anti-viral-sense rna segments. the virion-associated anti-viral-sense s segment served as a template for the synthesis of nss mrna immediately after infection. nss protein synthesis also occurred early in infection, suggesting that nss protein produced early in infection probably has biologically significant roles in virus replication and/or survival in the host ...200516140788
immunogenicity of combination dna vaccines for rift valley fever virus, tick-borne encephalitis virus, hantaan virus, and crimean congo hemorrhagic fever virus.dna vaccines for rift valley fever virus (rvfv), crimean congo hemorrhagic fever virus (cchfv), tick-borne encephalitis virus (tbev), and hantaan virus (htnv), were tested in mice alone or in various combinations. the bunyavirus vaccines (rvfv, cchfv, and htnv) expressed gn and gc genes, and the flavivirus vaccine (tbev) expressed the prem and e genes. all vaccines were delivered by gene gun. the tbev dna vaccine and the rvfv dna vaccine elicited similar levels of antibodies and protected mice f ...200616174542
apoptosis of hepatocytes caused by punta toro virus (bunyaviridae: phlebovirus) and its implication for phlebovirus pathogenesis.experimental infection of hamsters with punta toro virus (ptv) produces a disease with clinical and pathological similarities to the severe human hemorrhagic fever caused by rift valley fever virus (rvfv), thus providing an animal model for rvfv pathogenesis. in this model, hepatocytic apoptosis is the main pathological component of liver injuries that are responsible for severe hemorrhagic manifestations. to further elucidate whether viral replication in hepatocytes directly causes apoptosis, w ...200516192639
rift valley fever in small ruminants, senegal, 2003.during the 2003 rainy season, the clinical and serologic incidence of rift valley fever was assessed in small ruminant herds living around temporary ponds located in the semi-arid region of the ferlo, senegal. no outbreak was detected by the surveillance system. serologic incidence was estimated at 2.9% (95% confidence interval 1.0-8.7) and occurred in 5 of 7 ponds with large variations in the observed incidence rate (0%-20.3%). the location of ponds in the ferlo valley and small ponds were corr ...200516318720
pathogenesis of rift valley fever virus in mosquitoes--tracheal conduits & the basal lamina as an extra-cellular barrier.knowledge of the fate of an arbovirus in a mosquito is fundamental to understanding the mosquito's competence to transmit the virus. when a competent mosquito ingests viremic vertebrate blood, virus infects midgut epithelial cells and replicates, then disseminates to other tissues, including salivary glands and/or ovaries. the virus is then transmitted to the next vertebrate host horizontally via bite and/or vertically to the mosquito's offspring. not all mosquitoes that ingest virus become infe ...200516355869
aspects of bioecology of two rift valley fever virus vectors in senegal (west africa): aedes vexans and culex poicilipes (diptera: culicidae).the dispersal, population dynamics, and age structure of two rift valley fever virus (phlebovirus: bunyaviridae) (rvfv) vectors, aedes vexans meigen and culex poicilipes theobald, were investigated in northern senegal. the main objective was to investigate possible factors that mediate rvfv emergence and propagation at a site where humans and livestock live in proximity to temporary surface pools. in mark-release-recapture studies, recapture rates of 0.18% (156/85,500) and 3.46% (201/5,800) were ...200516363157
rift valley fever virus.rift valley fever is considered to be one of the most important viral zoonoses in africa. in 2000, the rift valley fever virus spread to the arabian peninsula and caused two simultaneous outbreaks in yemen and saudi arabia. it is transmitted to ruminants and to humans by mosquitoes. the viral agent is an arbovirus, which belongs to the phlebovirus genus in the bunyaviridae family. this family of viruses comprises more than 300 members grouped into five genera: orthobunyavirus, phlebovirus, hanta ...200516375716
rescue of infectious rift valley fever virus entirely from cdna, analysis of virus lacking the nss gene, and expression of a foreign gene.rift valley fever virus (rvfv) (genus phlebovirus, family bunyaviridae) has a tripartite negative-strand genome, causes a mosquito-borne disease that is endemic in sub-saharan african countries and that also causes large epidemics among humans and livestock. furthermore, it is a bioterrorist threat and poses a risk for introduction to other areas. in spite of its danger, neither veterinary nor human vaccines are available. we established a t7 rna polymerase-driven reverse genetics system to resc ...200616501102
[the mammals of guinea as reservoirs and carriers of arboviruses].a great body of data on the fauna and ecology of wild mammals and their participation in the circulation of arboviruses were collected when the ecology of the latter of the republic of guinea was studied in 1978 to 1989. a hundred and eighteen species belonging to 10 orders were identified. over 2,000 biological specimens were virologically and serologically examined. six arboviruses were isolated. these included dugbe virus (from the hussar monkey cercopithecus (erythrocebus patas) and 5 viruse ...200616562748
domestic transmission of rift valley fever virus in diawara (senegal) in 1998.in 1998, circulation of the rift valley fever (rvf) virus was revealed in diawara by detection of igm antibodies in sheep and isolation of the virus from mosquitoes caught outside a village. a seroprevalence study was carried out. finger-prick blood samples, individual and collective details were obtained. one thousand five hundred twenty people (6 months - 83 years) were included. overall prevalence in this group was approximately 5.2%. the prevalence in infants (6 months - 2 years) was 8.5%. a ...200516610651
adverse response of non-indigenous cattle of european breeds to live attenuated smithburn rift valley fever vaccine.three hundred eighteen european cows and 115 buffaloes were vaccinated with locally prepared smithburn vaccine, of which, 100 cows and 20 buffaloes were pregnant. twenty-eight cows aborted within 72 days post-vaccination, buffaloes did not abort. blood samples collected 77 days post-vaccination from aborted cows, 17 pregnant cows, 5 pregnant buffaloes, and 32 non-pregnant cows. sera were tested by elisa for anti-rvf igm and igg. all aborted cows were strongly positive for igg. five of 17 cows an ...200616628582
rift valley fever virus noncoding regions of l, m and s segments regulate rna synthesis.rift valley fever virus (rvfv) (phlebovirus, bunyaviridae) possesses a genome composed of three negative-stranded rna molecules. each segment contains 3' and 5' noncoding regions with terminal complementary sequences forming a panhandle structure. we showed that transcription-replication of the l, m and s segments is regulated, and we established a minigenome rescue system expressing a cat reporter to investigate the role of the noncoding regions in this process. the l, m and s segment-based min ...200616630639
midzonal lesions in yellow fever: a specific pattern of liver injury caused by direct virus action and in situ inflammatory response.yellow fever is an acute infectious, non-contagious disease characterized by intense vasculopathy and lesions in different organs. in the liver, one of the main targets of the virus, the infection induces a characteristic midzonal injury characterized by hepatocyte necrosis, apoptosis and steatosis. this characteristics pattern of liver injury in yellow fever is also observed in conditions of low-flow hypoxia and other infections such as dengue and rift valley fever. there are no reports in the ...200616650626
potential arbovirus emergence and implications for the united kingdom.arboviruses have evolved a number of strategies to survive environmental challenges. this review examines the factors that may determine arbovirus emergence, provides examples of arboviruses that have emerged into new habitats, reviews the arbovirus situation in western europe in detail, discusses potential arthropod vectors, and attempts to predict the risk for arbovirus emergence in the united kingdom. we conclude that climate change is probably the most important requirement for the emergence ...200616704800
risk of a rift valley fever epidemic at the haj in mecca, saudi arabia.rift valley fever (rvf) is a zoonotic disease that affects both humans and domestic animals. in humans, it can cause a fatal haemorrhagic fever disease. when domestic animals such as sheep, goats, camels and cattle are infected, the infection may or may not be accompanied by clinical signs of disease. both sub-clinical and clinically affected animals present a hazard as a source of infection for humans. the risk of infection is greatest at the time of killing, when aerosols of infected blood may ...200616796043
protective immune responses induced by different recombinant vaccine regimes to rift valley fever.the glycoprotein (gp) and nucleocapsid (nc) genes of rift valley fever virus (rvfv) were expressed in different expression systems and were evaluated for their ability to protect mice from virulent challenge using a prime-boost regime. mice vaccinated with a lumpy skin disease virus-vectored recombinant vaccine (rlsdv-rvfv) expressing the two rvfv glycoproteins (g1 and g2) developed neutralising antibodies and were fully protected when challenged, as were those vaccinated with a crude extract of ...200616870311
nsm and 78-kilodalton proteins of rift valley fever virus are nonessential for viral replication in cell culture.rift valley fever viruses carrying mutations of the m gene preglycoprotein region, one lacking nsm protein expression, one lacking 78-kda protein expression, and one lacking expression of both proteins, were compared in cell culture. all of the mutants and their parent virus produced plaques with similar sizes and morphologies in vero e6 cells and had similar growth kinetics in vero, c6/36, and mrc5 cells, demonstrating that the nsm and 78-kda proteins were not needed for the virus to replicate ...200616873285
development and characterization of a rift valley fever virus cell-cell fusion assay using alphavirus replicon vectors.rift valley fever virus (rvfv), a member of the phlebovirus genus in the bunyaviridae family, is transmitted by mosquitoes and infects both humans and domestic animals, particularly cattle and sheep. since primary rvfv strains must be handled in bsl-3+ or bsl-4 facilities, a rvfv cell-cell fusion assay will facilitate the investigation of rvfv glycoprotein function under bsl-2 conditions. as for other members of the bunyaviridae family, rvfv glycoproteins are targeted to the golgi, where the vir ...200616945399
synthesis, proteolytic processing and complex formation of n-terminally nested precursor proteins of the rift valley fever virus glycoproteins.the genomic m rna segment of rift valley fever virus is transcribed to produce a single mrna with multiple translation initiation sites. the products of translation are an n-terminal nested series of polyproteins. these polyproteins enter the secretory system of the host cell and are proteolytically processed to yield the mature virion glycoproteins, gn and gc, and two non-structural glycoproteins. by means of pulse-chase immune precipitation experiments we identify the gn and gc precursor molec ...200716963099
the s segment of punta toro virus (bunyaviridae, phlebovirus) is a major determinant of lethality in the syrian hamster and codes for a type i interferon antagonist.two strains of punta toro virus (ptv), isolated from febrile humans in panama, cause a differential pathogenesis in syrian hamsters, which could be a useful model for understanding the virulence characteristics and differential outcomes in other phleboviral infections such as rift valley fever virus. genetic reassortants produced between the lethal adames (a/a/a) and nonlethal balliet (b/b/b) strains were used in this study to investigate viral genetic determinants for pathogenesis and lethality ...200717050607
tlr3 deletion limits mortality and disease severity due to phlebovirus infection.tlr3 was the first member of the tlr family of pattern recognition receptors found to detect a conserved viral molecular pattern, dsrna, yet supporting evidence for a major role in host defense against viral pathogens is limited. punta toro virus (ptv) has been shown to produce severe infection in mice, modeling disease caused by the related highly pathogenic rift valley fever phlebovirus in humans and domesticated ungulates. using tlr3-deficient mice, we investigated the involvement of tlr3 in ...200617056560
tlr3 deletion limits mortality and disease severity due to phlebovirus infection.tlr3 was the first member of the tlr family of pattern recognition receptors found to detect a conserved viral molecular pattern, dsrna, yet supporting evidence for a major role in host defense against viral pathogens is limited. punta toro virus (ptv) has been shown to produce severe infection in mice, modeling disease caused by the related highly pathogenic rift valley fever phlebovirus in humans and domesticated ungulates. using tlr3-deficient mice, we investigated the involvement of tlr3 in ...200617056560
the nsm proteins of rift valley fever virus are dispensable for maturation, replication and infection.rift valley fever (rvf) virus belongs to the bunyaviridae family of segmented negative-strand rna viruses and causes mosquito-borne disease in sub-saharan africa. we report the development of a t7 rna polymerase-driven plasmid-based genetic system for the virulent egyptian isolate, zh501. we have used this system to rescue a virus that has a 387 nucleotide deletion on the genomic m segment that eliminates the coding region for two non-structural proteins known as nsm. this virus, deltansm rzh501 ...200717070883
[feeding pattern of rift valley fever virus vectors in senegal. implications in the disease epidemiology].during the rainy season 2003, an entomological survey was undertaken in the sahelian bioclimatic zone of the ferlo area in northern senegal, in order to evaluate the degree of interaction between rift valley fever (rvf) virus vectors and domestic animals and to determine the role of natural vertebrate hosts in the transmission and maintenance cycle. the study of vector-host contact was carried out under bed net traps using man, cow, sheep, chicken as bait whereas the rvfv vectors-vertebrate host ...200617111980
regional and international approaches on prevention and control of animal transboundary and emerging diseases.transboundary animal diseases pose a serious risk to the world animal agriculture and food security and jeopardize international trade. the world has been facing devastating economic losses from major outbreaks of transboundary animal diseases (tads) such as foot-and-mouth disease, classical swine fever, rinderpest, peste des petits ruminants (ppr), and rift valley fever. lately the highly pathogenic avian influenza (hpai) due to h5n1 virus, has become an international crisis as all regions arou ...200617135498
descriptive and spatial epidemiology of rift valley fever outbreak in yemen 2000-2001.rift valley fever (rvf) is an arboviral disease produced by a bunyavirus belonging to the genus phlebovirus. several species of aedes and culex are the vectors of this virus that affects sheep, goats, buffalos, cattle, camels and human beings. the human disease is well known, especially during periods of intense epizootic activity. the initial description of the disease dates back to 1930, when animals and human outbreaks appeared on a farm in lake naivasha, in the great rift valley of kenya. un ...200617135517
preparation and evaluation of a recombinant rift valley fever virus n protein for the detection of igg and igm antibodies in humans and animals by indirect elisa.this paper describes the cloning, sequencing and bacterial expression of the n protein of the rift valley fever virus (rvfv) zim688/78 isolate and its evaluation in indirect elisas (i-elisa) for the detection of igm and igg antibodies in human and sheep sera. sera used for the evaluation were from 106 laboratory workers immunised with an inactivated rvf vaccine, 16 rvf patients, 168 serial bleeds from 8 sheep experimentally infected with wild type rvfv and 210 serial bleeds from 10 sheep vaccina ...200717174410
cloning and expression of rift valley fever virus nucleocapsid (n) protein and evaluation of a n-protein based indirect elisa for the detection of specific igg and igm antibodies in domestic ruminants.serodiagnosis of rift valley fever (rvf) currently relies on the use of live or inactivated whole virus as antigens. the recombinant nucleocapsid (n) protein of rvf virus was tested for diagnostic applicability in an indirect enzyme-linked immunosorbent assay (i-elisa), using sera from experimentally infected sheep (n=128), vaccinated sheep (n=240), and field-collected sera from sheep (n=251), goats (n=362) and cattle (n=100). the n-protein based i-elisa performed at least as good as vn and hi t ...200717187944
complete genome analysis of 33 ecologically and biologically diverse rift valley fever virus strains reveals widespread virus movement and low genetic diversity due to recent common ancestry.rift valley fever (rvf) virus is a mosquito-borne rna virus responsible for large explosive outbreaks of acute febrile disease in humans and livestock in africa with significant mortality and economic impact. the successful high-throughput generation of the complete genome sequence was achieved for 33 diverse rvf virus strains collected from throughout africa and saudi arabia from 1944 to 2000, including strains differing in pathogenicity in disease models. while several distinct virus genetic l ...200717192303
developing global climate anomalies suggest potential disease risks for 2006-2007.el niño/southern oscillation (enso) related climate anomalies have been shown to have an impact on infectious disease outbreaks. the climate prediction center of the national oceanic and atmospheric administration (noaa/cpc) has recently issued an unscheduled el niño advisory, indicating that warmer than normal sea surface temperatures across the equatorial eastern pacific may have pronounced impacts on global tropical precipitation patterns extending into the northern hemisphere particularly ov ...200617194307
the potential role of rattus rattus in enzootic cycle of rift valley fever in egypt. 1-detection of rvf antibodies in r. rattus blood samples by both enzyme linked immuno sorbent assay (elisa) and immuno-diffusion technique (id).three hundreds of rattus rattus (r. rattus) were trapped from 3 different governorates of egypt (one hundred each), blood samples were withdrawal and subjected for detection of anti-rvf antibodies by both elisa and id techniques. the prevalence rate of antibodies by elisa were 88 (29.33%) positive out of 300 tested blood samples, the highest rate was in behira governorate 36 (36%) and the lowest one was in alexandria governorate 22 (22%) while it was 30 (30%) in minia governorate. but when id te ...200117216936
application of reverse transcriptase-polymerase chain reaction for detection of rift valley fever viral antigen from mosquito.a reverse transcriptase polymerase chain reaction (rt-pcr) was applied to detect rift valley fever virus (rvfv) in culex pipiens mosquito pools collected from alexandria and behira governorates of egypt (50 pools each). all mosquito pools were subjected to double sandwich enzyme linked immunosorbent assay (elisa) technique to detect rvf viral antigen. out of all 100 mosquito pools, only 18(18%) were positive by elisa, 10(20%) out of 50 pools were positive in behira governorate and 8(16%) were po ...200117216948
the potential role of rattus rattus in enzootic cycle of rift valley fever in egypt 2-application of reverse transcriptase polymerase chain reaction (rt-pcr) in blood samples of rattus rattus.a reverse transcriptase -polymerase chain reaction (rt-pcr) was applied to detect rift valley fever virus (rvf-v) in blood samples of rattus rattus (r. rattus) collected from 3 different governorates of egypt, alexandria, behira and minia governorates (one hundred each). out of 300 blood samples 29(9.67%) were positive for rvf-virus by rt-pcr with higher percent in behira governorate rural areas (16%), followed by minia governorate rural areas (13.85%) while the lowest percent was in alexandria ...200217219894
screening for rift valley fever infection in northern somalia: a gis based survey method to overcome the lack of sampling frame.following repeated import bans imposed by saudi arabia on livestock originated from somalia due to suspicion of rift valley fever (rvf) presence and the severe socio-economic consequences of this, it was imperative for the somaliland government to carry out surveillance activities in order to determine the status of transboundary diseases in its territory. a gis computer software (arcview) was used to overcome the lack of lists of sampling sites due to the high mobility of pastoral nomadic herds ...200717257783
rift valley fever outbreak--kenya, november 2006-january 2007.in mid-december 2006, several unexplained fatalities associated with fever and generalized bleeding were reported to the kenya ministry of health (kmoh) from garissa district in north eastern province (nep). by december 20, a total of 11 deaths had been reported. of serum samples collected from the first 19 patients, rift valley fever (rvf) virus rna or immunoglobulin m (igm) antibodies against rvf virus were found in samples from 10 patients; all serum specimens were negative for yellow fever, ...200717268404
a shared transcription termination signal on negative and ambisense rna genome segments of rift valley fever, sandfly fever sicilian, and toscana viruses.the phlebovirus genus (family bunyaviridae) is composed of a diverse group of arboviruses that cause disease syndromes ranging from mild febrile illness to hemorrhagic fever with high fatality. although antigenically similar, these viruses differ by approximately 25% at the genome level, and their ecologies, including geographic ranges, preferred vector species, and hosts, vary considerably. in contrast to other ambisense viruses, where rna hairpin structures which serve as transcription termina ...200717329326
the persistence of rift valley fever in the jazan region of saudi arabia.a survey was conducted in the jazan region of saudi arabia to investigate the presence of rift valley fever (rvf) in sheep and goats, by clinical identification of suspected herds and detection of immunoglobulin m (igm) antibodies to rvf virus. the level of herd immunity was identified by detecting immunoglobulin g (igg) antibodies. rift valley fever was diagnosed in six out of eight districts included in the survey. twenty-two animals from 17 herds tested positive for the presence of igm antibo ...200617361776
factors associated with rift valley fever in south-west saudi arabia.the authors undertook a study of environmental and animal risk factors associated with rift valley fever (rvf) in south-west saudi arabia. an enzyme-linked immunosorbent assay was used to detect the presence of immunoglobulin m (igm) and immunoglobulin g (igg) antibodies against the rvf virus in serum samples from sentinel animals. in addition, a further 32 known igm-positive serum samples were tested using the reverse transcription polymerase chain reaction (rt-pcr) to detect the rvf virus geno ...200617361777
rift valley fever virus lacking nsm proteins retains high virulence in vivo and may provide a model of human delayed onset neurologic disease.rift valley fever virus is a significant human and veterinary pathogen responsible for explosive outbreaks throughout africa and the arabian peninsula. severe acute disease in humans includes rapid onset hepatic disease and hemorrhagic fever or delayed onset encephalitis. a highly efficient reverse genetics system was developed which allowed generation of recombinant rvf viruses to assess the role of nsm protein in virulence in a rat model in which wild-type rvf virus strain zh501 (wt-zh501) res ...200717412386
spectrum of rift valley fever virus transmission in kenya: insights from three distinct regions.rift valley fever virus (rvfv) is an emerging pathogen that maintains high biodefense priority based on its threat to livestock, its ability to cause human hemorrhagic fever, and its potential for aerosol spread. to define the range of human transmission during inter-epidemic and epidemic periods in kenya, we tested archived sera from defined populations (n = 1,263) for anti-rvfv igg by elisa and plaque reduction neutralization testing. rvfv seroprevalence was 10.8% overall and varied significan ...200717488893
short report: efficient oral infection of culex pipiens quinquefasciatus by rift valley fever virus using a cotton stick support.transmission experiments are essential to assess vector competence. in an attempt to study rift valley fever virus (rvfv) transmission in its arthropod vector, disseminated infection rates were measured in culex pipiens quinquefasciatus exposed to clone 13, an avirulent variant of rvfv. we compared the classic system of glass feeders covered with different membranes (0-1%) with an alternative system in which a cotton stick is used as a support of a blood meal. the latter system showed the highes ...200717488899
comparative analysis of the alphavirus-based vectors expressing rift valley fever virus glycoproteins.during the last decade, alphaviruses became widely used for expression of heterologous genetic information and development of recombinant vaccines against a variety of human and animal pathogens. in this study, we compared a number of vectors based on the genome of sindbis (sinv) and venezuelan equine encephalitis (veev) viruses for their ability to express the rift valley fever virus (rvfv) envelope glycoprotein gn and induce a protective immune response against rvfv infection. our results sugg ...200717507072
characterization of rift valley fever virus transcriptional terminations.rift valley fever virus (rvfv) (genus phlebovirus, family bunyaviridae) has a tripartite negative-strand genome and causes a mosquito-borne disease among humans and livestock in sub-saharan african and arabian peninsula countries. phlebovirus l, m, and n mrnas are synthesized from the virus-sense rna segments, while nss mrna is transcribed from the anti-virus-sense s segment. the present study determined the 3' termini of all rvfv mrnas. the 3' termini of n and nss mrnas were mapped within the s ...200717537856
antigenic and genetic relationships among rift valley fever virus and other selected members of the genus phlebovirus (bunyaviridae).preliminary serologic data indicated that two south american phleboviruses (belterra virus [beltv] and icoaraci virus [icov]) may be related to rift valley fever virus (rvfv), an african phlebovirus that causes severe hepatitis and hemorrhagic fever in humans. to further define this relationship and to investigate the underlying genetic basis, comparative serologic and genetic sequence analyses were performed with rvfv and five other new world phleboviruses (icov, beltv, salobo virus, joa virus, ...200717556635
in vitro and in vivo activities of t-705 against arenavirus and bunyavirus infections.there is a need for the development of effective antivirals for the treatment of severe viral diseases caused by members of the virus families bunyaviridae and arenaviridae. the pyrazine derivative t-705 (6-fluoro-3-hydroxy-2-pyrazinecarboxamide) has demonstrated remarkable antiviral activity against influenza virus and, to a lesser degree, against some other rna viruses (y. furuta, k. takahashi, y. fukuda, m. kuno, t. kamiyama, k. kozaki, n. nomura, h. egawa, s. minami, y. watanabe, h. narita, ...200717606691
spatial risk assessment of rift valley fever in senegal.rift valley fever (rvf) is broadening its geographic range and is increasingly becoming a disease of global importance with potentially severe consequences for human and animal health. we conducted a spatial risk assessment of rvf in senegal using serologic data from 16,738 animals in 211 locations. bayesian spatial regression models were developed with interpolated seasonal rainfall, land surface temperature, distance to perennial water bodies, and time of year entered as fixed-effect variables ...200717627440
improved method for the generation and selection of homogeneous lumpy skin disease virus (sa-neethling) recombinants.lumpy skin disease virus (lsdv) is being developed as a vector for recombinant vaccines against diseases of veterinary importance. a strategy for generating viral thymidine kinase (tk) gene-disrupted recombinants which are stable and homogeneous using the south african neethling vaccine strain of lsdv as vector has been developed. to assist with the selection process, the escherichia coli beta-galactosidase (lacz) visual marker gene was incorporated into the constructs. however, the use of lacz ...200717644196
validation of an indirect elisa based on a recombinant nucleocapsid protein of rift valley fever virus for the detection of igg antibody in humans.an indirect enzyme-linked immunoassay (i-elisa) based on the recombinant nucleocapsid protein (rnp) of rift valley fever virus was validated for the detection of specific igg antibody in human sera. validation data sets derived from testing sera collected in africa (n=2967) were categorized according to the results of a virus neutralisation test. the assay had high intra- and inter-plate repeatability in routine runs. no detectable cross-reactions between igg antibodies generated from mice exper ...200717645952
highly sensitive and broadly reactive quantitative reverse transcription-pcr assay for high-throughput detection of rift valley fever virus.rift valley fever (rvf) virus is a mosquito-borne virus associated with large-scale epizootics/epidemics throughout africa and the arabian peninsula. virus infection can result in economically disastrous "abortion storms" and high newborn mortality in livestock. human infections result in a flu-like illness, with 1 to 2% of patients developing severe complications, including encephalitis or hemorrhagic fever with high fatality rates. there is a critical need for a highly sensitive and specific m ...200717804663
optical fiber immunosensor for the detection of igg antibody to rift valley fever virus in humans.this paper describes the development and evaluation of an optical fiber immunosensor (ofis) for the detection of igg antibody to rift valley fever virus (rvfv) in humans. the ofis was based on a sandwich enzyme-linked immunosorbent assay (s-elisa) format, whereby gamma-irradiated rvfv and control antigens were immobilized on the optical fiber surface coated with a mouse anti-rvfv antibody. data sets derived from field-collected sera in africa (n=242) were dichotomized according to the results of ...200717869352
recombinant nucleocapsid-based elisa for detection of igg antibody to rift valley fever virus in african buffalo.wild ruminants are thought to serve as natural hosts for rift valley fever virus (rvfv) but the role of these animals as reservoirs for rvfv during inter-epidemic periods and as amplifiers during epidemics is not well understood. an indirect enzyme-linked immunoassay (i-elisa) based on the recombinant nucleocapsid protein (rnp) of rvfv was validated for the detection of specific igg antibodies in african buffalo. data sets derived from testing buffalo sera from kenya (n=405) and south africa (n= ...200817884306
nsm protein of rift valley fever virus suppresses virus-induced apoptosis.rift valley fever virus (rvfv) is a member of the genus phlebovirus within the family bunyaviridae. it can cause severe epidemics among ruminants and fever, myalgia, a hemorrhagic syndrome, and/or encephalitis in humans. the rvfv m segment encodes the nsm and 78-kda proteins and two major envelope proteins, gn and gc. the biological functions of the nsm and 78-kda proteins are unknown; both proteins are dispensable for viral replication in cell cultures. to determine the biological functions of ...200717913816
[study on dna immune of envelope protein gene of rift valley fever virus].dna vaccines have successfully induced effective antibody and cellular immune response to many viral pathogens. the antibody response of dna immunization induction in mouse model with envelope glycoproteins of rift valley fever virus (rvfv), g (n + c), gn and gc was investigated. for this purpose, three codon g (n + c), gn and gc gene were insert into mammalian expression vector pcaggs under chicken beta-actin promoter to construct pcagg-rvfv-gn, pcagg-rvfv-gc and pcagg-rvfv-g (n + c). the expre ...200717944371
the antiviral potential of interferon-induced cotton rat mx proteins against orthomyxovirus (influenza), rhabdovirus, and bunyavirus.influenza a virus (fluav) is an important human pathogen able to cause devastating pandemics. recently, cotton rats have been proposed as an animal model to study the innate immune response against fluav and other human pathogens. the interferon (ifn)-induced mx gtpases are part of the cell-autonomous innate immune response against viruses. we, therefore, tested the antiviral activity of the two cotton rat mx proteins that were recently identified. the nuclear cotton rat mx1 protein was found to ...200717970694
prevalence of antibodies against rift valley fever virus in kenyan wildlife.rift valley fever virus (rvfv) is an arbovirus associated with periodic outbreaks, mostly on the african continent, of febrile disease accompanied by abortion in livestock, and a severe, fatal haemorrhagic syndrome in humans. however, the maintenance of the virus during the inter-epidemic period (iep) when there is low or no disease activity detected in livestock or humans has not been determined. this study report prevalence of rvfv-neutralizing antibodies in sera (n=896) collected from 16 keny ...200817988425
rapid detection of important human pathogenic phleboviruses.rapid diagnostics are not available for several human pathogens in the genus phlebovirus of the bunyaviridae.200818006376
potential of antiviral therapy and prophylaxis for controlling rna viral infections of livestock.with intensification of trade, livestock are increasingly exposed to severe animal diseases caused by a range of rna viruses. recent prime examples include outbreaks of foot-and-mouth disease (fmd), peste des petits ruminants, rift valley fever and bluetongue. to minimise their impact, controlling the spread of virus is of utmost importance. good quality, reliable vaccines exist for some, although not all, of these diseases, but suffer from a set of drawbacks, not the least of which being the ti ...200818035428
novel 3-sulphonamido-quinazolin-4(3h)-one derivatives: microwave-assisted synthesis and evaluation of antiviral activities against respiratory and biodefense viruses.we designed and synthesized novel 2,3-disubstituted quinazolin-4(3h)-ones by microwave technique and characterized them by spectral analysis. synthesized compounds were screened for cytotoxicity and for antiviral activity against influenza a (h1n1, h3n2 and h5n1), severe acute respiratory syndrome corona, dengue, yellow fever, venezuelan equine encephalitis (vee), rift valley fever, and tacaribe viruses in cell culture. a neutral red uptake assay was used to determine 50% virus-inhibitory concen ...200718046963
rift valley fever virus lacking the nss and nsm genes is highly attenuated, confers protective immunity from virulent virus challenge, and allows for differential identification of infected and vaccinated animals.rift valley fever (rvf) virus is a mosquito-borne human and veterinary pathogen associated with large outbreaks of severe disease throughout africa and more recently the arabian peninsula. infection of livestock can result in sweeping "abortion storms" and high mortality among young animals. human infection results in self-limiting febrile disease that in approximately 1 to 2% of patients progresses to more serious complications including hepatitis, encephalitis, and retinitis or a hemorrhagic s ...200818199647
rift valley fever outbreak with east-central african virus lineage in mauritania, 2003.in october 2003, 9 human cases of hemorrhagic fever were reported in 3 provinces of mauritania, west africa. test results showed acute rift valley fever virus (rvfv) infection, and a field investigation found recent circulation of rvfv with a prevalence rate of 25.5% (25/98) and 4 deaths among the 25 laboratory-confirmed case-patients. immunoglobulin m against rvfv was found in 46% (25/54) of domestic animals. rvfv was also isolated from the mosquito species culex poicilipes. genetic comparison ...200718214173
prophylactic and therapeutic intervention of punta toro virus (phlebovirus, bunyaviridae) infection in hamsters with interferon alfacon-1.punta toro virus (ptv) is a member of the bunyaviridae family, genus phlebovirus, related to the highly pathogenic rift valley fever virus (rvfv). it produces a disease in hamsters that models severe rift valley fever (rvf) in humans. the recent outbreak of rvf in kenya stresses the need to identify prophylactic and therapeutic measures for preventing and treating severe forms of disease. to this end, interferon (ifn) alfacon-1 (consensus ifn-alpha) was evaluated in cell culture against rvfv and ...200818222548
a sap30 complex inhibits ifn-beta expression in rift valley fever virus infected cells.rift valley fever virus (rvfv) nonstructural protein nss acts as the major determinant of virulence by antagonizing interferon beta (ifn-beta) gene expression. we demonstrate here that nss interacts with the host protein sap30, which belongs to sin3a/ncor/hdacs repressor complexes and interacts with the transcription factor yy1 that regulates ifn-beta gene expression. using confocal microscopy and chromatin immunoprecipitation, we show that sap30, yy1, and sin3a-associated corepressor factors st ...200818225953
vector competence of kenyan culex zombaensis and culex quinquefasciatus mosquitoes for rift valley fever virus.rift valley fever (rvf) continues to be a significant problem in kenya as well as in egypt, yemen, and saudi arabia. in order to determine the ability of kenyan mosquitoes to transmit rvf virus (rvfv), we collected mosquitoes in the lake naivasha region of kenya and evaluated them for their potential to transmit rvfv under laboratory conditions. after feeding on a hamster (mesocricetus auratus) with a viremia of 10(9.7) plaque-forming units of virus/ml of blood, culex zombaensis were highly susc ...200718240513
evaluation of pathways for release of rift valley fever virus into domestic ruminant livestock, ruminant wildlife, and human populations in the continental united states.to evaluate the feasibility for rift valley fever virus (rvfv) to enter the continental united states by various routes as well as to identify states in which domestic and wild ruminant and human populations would be most vulnerable to exposure to rvfv.200818279085
vector competence of selected african mosquito (diptera: culicidae) species for rift valley fever virus.outbreaks of rift valley fever (rvf) in egypt, yemen, and saudi arabia have indicated the potential for this disease to spread from its enzootic areas in sub-saharan africa. because little is known about the potential for most african mosquito species to transmit rvf virus (family bunyaviridae, genus phlebovirus, rvfv), we conducted studies to determine the vector competence of selected african species of mosquitoes for this virus. all eight species tested [aedes palpalis (newstead), aedes mcint ...200818283949
blood-feeding patterns of culex quinquefasciatus and other culicines and implications for disease transmission in mwea rice scheme, kenya.studies were conducted in mwea rice scheme, kenya during the period april 2005 and january 2007 to determine the host-feeding pattern of culicine mosquitoes. mosquitoes were collected indoors and outdoors and tested for human, bovine, goat, and donkey blood meals by an enzyme-linked immunosorbent assay. a total of 1,714 blood-engorged samples comprising culex quinquefasciatus say (96.1%), culex annulioris theobald (1.8%), culex poicilipes theobald (0.9%), aedes cuminsi theobald (1.0%), aedes tay ...200818297310
[in vitro activity of russian ribavirin on the models of crimean-congo hemorrhagic fever virus, rift valley fever virus, and tahyna and dhori viruses].the high activity of ribavirin made by effective biotechnology in russia was established in in vitro experiments using the models crimean-congo hemorrhagic fever virus, rift valley fever virus, and tahyna and dhori viruses, which suggests that it is promising in using the drug in the treatment of infection with these viruses.200818318134
case report: rift valley fever with vertical transmission in a pregnant sudanese woman.rift valley fever (rvf) is a viral disease transmitted to humans by mosquito bite and contact with animals or their infected tissues. a 29-year old primigravidae presented in early labour with symptoms suggestive of rvf. she delivered baby of 3.2 kg with skin rash, palpable liver and spleen. the two samples from the mother and neonate were found to be positive for rvf-igm. this report demonstrate that, rvf can be vertically transmitted.200818360907
viral nucleic acid stabilization by rna extraction reagent.in the collection of field materials to test for the presence of arboviruses, samples must be appropriately maintained to detect arboviral nucleic acids. in austere field conditions this is often difficult to achieve because, during routine specimen processing, storage, and shipping viral rna degradation could result in detection failure. rna extraction reagents, while used commonly for their intended purpose of stabilizing rna during the extraction process, have not been assessed fully for thei ...200818387678
synthesis of 1-beta-d-ribofuranosyl-3-ethynyl-[1,2,4]triazole and its in vitro and in vivo efficacy against hantavirus.there are no fda approved drugs for the treatment of hemorrhagic fever with renal syndrome (hfrs), a serious human illnesses caused by hantaviruses. clinical studies using ribavirin (rbv) to treat hfrs patients suggest that it provides an improved prognosis when given early in the course of disease. given the unique antiviral activity of rbv and the lack of other lead scaffolds, we prepared a diverse series of 3-substituted 1,2,4-triazole-beta-ribosides and identified one with antiviral activity ...200818394724
processing of genome 5' termini as a strategy of negative-strand rna viruses to avoid rig-i-dependent interferon induction.innate immunity is critically dependent on the rapid production of interferon in response to intruding viruses. the intracellular pathogen recognition receptors rig-i and mda5 are essential for interferon induction by viral rnas containing 5' triphosphates or double-stranded structures, respectively. viruses with a negative-stranded rna genome are an important group of pathogens causing emerging and re-emerging diseases. we investigated the ability of genomic rnas from substantial representative ...200818446221
kinetics of rift valley fever virus in experimentally infected mice using quantitative real-time rt-pcr.rift valley fever (rvf) is an important viral zoonosis in africa affecting animals and humans. since no protective vaccines or effective treatments are available for human use, accurate and reliable diagnostic methods are essential for surveillance of the disease in order to implement adequate public health actions. to study the kinetics of the rvf virus (rvfv) infection, a sybr green-based quantitative real-time rt-pcr assay was developed. by using primers targeting the s-segment of rvfv, the d ...200818514921
rna polymerase i-mediated expression of viral rna for the rescue of infectious virulent and avirulent rift valley fever viruses.rift valley fever virus (rvfv, bunyaviridae, phlebovirus) is a mosquito-transmitted arbovirus that causes human and animal diseases in sub-saharan africa and was introduced into the arabian peninsula in 2000. here, we describe a method of reverse genetics to recover infectious rvfv from transfected plasmids based on the use of the cellular rna polymerase i promoter to synthesize viral transcripts. we compared its efficiency with a system using t7 rna polymerase and found that both are equally ef ...200818614193
potential vectors of rift valley fever virus in the mediterranean region.we evaluated the ability of three mosquito species (aedes caspius, aedes detritus, culex pipiens), collected in southern france and tunisia, and of different laboratory-established colonies (aedes aegypti, aedes albopictus, aedes vexans, anopheles gambiae, culex pipiens, culex quinquefasciatus) to disseminate two strains of rift valley fever virus (rvfv), the virulent zh548 and the avirulent clone 13. after feeding on an infectious blood meal at 10(8.5) plaque-forming units/ml, females were main ...200818620510
rift valley fever virus structural proteins: expression, characterization and assembly of recombinant proteins.studies on rift valley fever virus (rvfv) infection process and morphogenesis have been hampered due to the biosafety conditions required to handle this virus, making alternative systems such as recombinant virus-like particles, that may facilitate understanding of these processes are highly desirable. in this report we present the expression and characterization of rvfv structural proteins n, gn and gc and demonstrate the efficient generation of rvfv virus-like particles (vlps) using a baculovi ...200818638365
disease and destiny-mystery and mastery.when early people made their appearance, zoonotic infectious diseases were already waiting, but epidemic diseases did not appear in human history until people began to live in large numbers under conditions of close contact, mainly during the last 10,000 years. disease has decimated urban populations, conquered armies, and disrupted society. the focus here is on (1) the plague of athens and the black death; (2) smallpox, influenza, and rabies; (3) avian influenza prion diseases, and foot & mouth ...200818639356
[global threats from emerging viral diseases].emerging viral diseases are nothing new. smallpox probably reached europe from asia in the 5th century, and yellow fever emerged in the americas during the 16th century as a consequence of the african slave trade. dengue fever arose simultaneously in south-east asia, africa, and north america during the 18th century. in 1918-1919 the so-called spanish flu spread like wildfire through all five continents, killing between 25 and 40 million people. the second half of the 20th century saw the emerge ...200718666456
interepidemic rift valley fever virus seropositivity, northeastern kenya.most outbreaks of rift valley fever (rvf) occur in remote locations after floods. to determine environmental risk factors and long-term sequelae of human rvf, we examined rates of previous rift valley fever virus (rvfv) exposure by age and location during an interepidemic period in 2006. in a randomized household cluster survey in 2 areas of ijara district, kenya, we examined 248 residents of 2 sublocations, gumarey (village) and sogan-godud (town). overall, the rvfv seropositivity rate was 13% ...200818680647
priming with dna plasmids encoding the nucleocapsid protein and glycoprotein precursors from rift valley fever virus accelerates the immune responses induced by an attenuated vaccine in sheep.in this work we tested the ability of plasmid dna constructs encoding structural rift valley fever virus (rvfv) antigens to induce specific immune responses in sheep. the sole immunization of dna constructs encoding the glycoprotein precursor nsm/g2/g1 did not suffice to induce a detectable antibody response. in contrast, immunization of sheep with a plasmid vector encoding the viral nucleocapsid protein n elicited a potent and long lasting induction of antibodies but with low neutralizing titer ...200818682268
satellite vegetation index data as a tool to forecast population dynamics of medically important mosquitoes at military installations in the continental united states.the united states faces many existing and emerging mosquito-borne disease threats, such as west nile virus and rift valley fever. an important component of strategic prevention and control plans for these and other mosquito-borne diseases is forecasting the distribution, timing, and abundance of mosquito vector populations. populations of many medically important mosquito species are closely tied to climate, and historical climate-population associations may be used to predict future population ...200818700603
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