| adjuvant activity of a novel metabolizable lipid emulsion with inactivated viral vaccines. | studies were conducted in mice, hamsters, sheep, and two species of nonhuman primates which demonstrate the adjuvant activity of a new metabolizable lipid emulsion with marginally immunogenic doses of formalin-inactivated viral vaccines. the lipid base consists of highly refined peanut oil emulsified in aqueous vaccines with glycerol and lecithin. hamsters and mice inoculated with lipid emulsion plus western or venezuelan equine encephalitis vaccine were significantly more resistant than vaccina ... | 1980 | 6772571 |
| respiratory infectivity of a recently isolated egyptian strain of rift valley fever virus. | the respiratory infectivity of a strain of rift valley fever virus isolated in egypt (strain zh-501) was compared with that of one isolate from uganda (entebbe strain) and two isolates from south africa (strains sa-51 and sa-75). studies were performed with icr mice which were infected by exposure to infectious aerosols composed of particles with a mass median diameter of 0.96 micrometer. the respiratory median lethal doses for zh-501, entebbe, sa-51, and sa-75 were 2.2, 1.9, 2.6, and 1.9 log10 ... | 1981 | 7287187 |
| a serological survey for rift valley fever antibody in food animals in kaduna and sokoto states of nigeria. | a total of 1106 serum samples from cattle, sheep, goats and camels were collected from kaduna and sokoto states of nigeria. these were tested for the presence of antibody to rift valley fever virus by the agar gel immunodiffusion method. the antibody prevalence rates were 2.85% in cattle, 6.67% in sheep, 0.98% in goats and 3.13% in camels. | 1982 | 6820360 |
| a rift valley fever vaccine trial. i. side effects and serologic response over a six-month follow-up. | a formalin-inactivated rift valley fever vaccine, originally produced in primary monkey kidney cells, has been used to protect laboratory workers. a trial of a modified vaccine, newly formulated in well-characterized diploid fetal rhesus lung cells, was conducted with 114 men aged 19--24 years. of the 107 subjects who received up to three injections of 0.1 to 1 ml vaccine (an additional seven received a placebo) one had a local hypersensitivity-type reaction and another a generalized urticarial ... | 1982 | 6890766 |
| the hemorrhagic fevers of southern africa with special reference to studies in the south african institute for medical research. | in this review of studies on the hemorrhagic fevers of southern africa carried out in the south african institute for medical research, attention has been called to occurrence of meningococcal septicemia in recruits to the mining industry and south african army, to cases of staphylococcal and streptococcal septicemia with hemorrhagic manifestations, and to the occurrence of plague which, in its septicemic form, may cause a hemorrhagic state. "onyalai," a bleeding disease in tropical africa, ofte ... | 1982 | 6897472 |
| biochemical characterization of rift valley fever virus. | | 1980 | 7414952 |
| reduced pathogenicity associated with a small plaque variant of the egyptian strain of rift valley fever virus (zh501). | variants of rift valley fever virus producing plaques in cer cells of four different sizes are described. a plaque-forming unit (pfu) variant forming minute plaques was isolated and purified. virus derived from this variant was not pathogenic to adult swiss albino mice by the intraperitoneal (i.p.) route and was less pathogenic than the parent strain (zh501) to adult sprague dawley rats by i.p. route, but produced typical severe liver necrosis in adult syrian hamsters with intranuclear and intra ... | 1982 | 6926765 |
| rift valley fever: an emerging human and animal problem. | | 1982 | 7102093 |
| identification of a major non-structural protein in the nuclei of rift valley fever virus-infected cells. | a non-structural protein of mol. wt. 34 x 10(3) was demonstrated in the nuclei of rift valley fever virus-infected vero cells by sds-polyacrylamide gel electro-phoresis. the protein appears to correspond to the virus-induced antigen demonstrated by indirect immunofluorescence in intranuclear inclusions. | 1982 | 7108491 |
| inbred rat strains mimic the disparate human response to rift valley fever virus infection. | | 1982 | 7130966 |
| sequential development of the liver lesions in new-born lambs infected with rift valley fever virus. i. macroscopic and microscopic pathology. | ten new-born lambs were necropsied at various intervals after artificial infection with rift valley fever virus for the study of the sequential development of the hepatic lesions. during the late stage of the disease, the livers were slightly to moderately swollen and mottled yellow, orange-brown and red. greyish-white foci, approximately 0,25-0,5 mm in diameter, were also scattered throughout the parenchyma. microscopically, the liver lesions progressed from sparsely distributed acidophilic bod ... | 1982 | 7177580 |
| enhanced arboviral transmission by mosquitoes that concurrently ingested microfilariae. | infection, dissemination, and transmission of an arbovirus in mosquitoes are enhanced by concurrent ingestion of microfilariae. ingestion of rift valley fever virus alone infected only 64 percent of female aedes taeniorhynchus. of these, only 5 percent of refeeding mosquitoes actually transmitted virus. in contrast, ingestion of the same amount of virus from concurrently microfilaremic (brugia malayi) gerbils resulted in 88 percent infection and 31 percent transmission. enhanced transmission of ... | 1984 | 6474165 |
| active and passive immunization against rift valley fever virus infection in syrian hamsters. | the protection by active and passive immunization of golden syrian hamsters challenged with rift valley fever (rvf) virus intraperitoneally was studied. six groups of 10 hamsters were inoculated with different amounts of immune serum while five groups were actively immunized with different doses of a formalin-inactivated rvf vaccine. one day after passive and three weeks after active immunization all hamsters were challenged with 5000 plaque-forming units of rvf virus. plaque reduction neutraliz ... | 1984 | 6507105 |
| [rift valley fever and zinga virus: a pathogenic arbovirus in man and animal new for madagascar]. | virus zinga strains have been isolated from several pools of mosquitoes collected in perinet area, 130 km far from tananarive, at the institut pasteur of madagascar in 1980. although this virus is pathogenic for man, it seemed to give only a mild illness and did not appear to constitute a problem of public health. but today it is seen in quite a different way; since the who center for arbovirus reference and research of new haven has shown the serologic identity between virus zinga and an anothe ... | 1984 | 6534285 |
| rift valley fever and its epidemiology in egypt: a review. | | 1983 | 6577119 |
| the use of veterinary vaccines for prevention and control of rift valley fever: memorandum from a who/fao meeting. | this memorandum considers the use of veterinary vaccines for the prevention of rift valley fever (rvf) and for its control during outbreaks. veterinary vaccines are the first line of defence against rvf. existing live and inactivated vaccines have been used extensively in africa but further development of both is warranted. the live virus vaccine may cause abortion and its potential for reversion to virulence has not been adequately investigated. it should be used only in enzootic and epizootic ... | 1983 | 6602663 |
| antibodies to hemorrhagic fever viruses in domestic livestock in niger: rift valley fever and crimean-congo hemorrhagic fever. | a repository of domestic animal sera collected in niger between 1984 and 1988 was assayed for antibody against two zoonotic hemorrhagic fever viruses known to be present in the west african sahel. a total of 2,540 serum samples from 2,324 cattle, sheep, goats, and camels were tested by an igg-specific enzyme-linked immunosorbent assay (elisa) and the 80% plaque reduction neutralization test (prnt80) for rift valley fever (rvf) virus antibody. of the 2,540 sera tested for rvf-specific igg antibod ... | 1995 | 7573699 |
| rift valley fever virus vaccine trial: study of side-effects in humans. | | 1982 | 7201671 |
| the extended horizons of rift valley fever: current and projected immunogens. | | 1980 | 7208510 |
| rift valley fever virus infection in man in nigeria. | | 1980 | 7229623 |
| synthesis and antiviral activity of certain 9-beta-d-ribofuranosylpurine-6-carboxamides. | to examine the structural parameters necessary for antiviral efficacy of certain purine nucleosides, several 9-beta-d-ribofuranosylpurine-6-carboxamides have been synthesized. glycosylation of the me3si derivative of purine--6-carboxamide with protected ribofuranose in the presence of a lewis acid gave the blocked nucleoside which on deprotection furnished 9-beta-d-ribofuranosyl-6-iodopurine with cyanide ion. certain 2-amino- and 2-methyl-9-beta-d-ribofuranosylpurine-6-carboxamides have also bee ... | 1981 | 7328597 |
| abortion in vaccinated sheep and cattle after challenge with rift valley fever virus. | | 1981 | 7340068 |
| experimental infection of the african buffalo with the virus of rift valley fever. | | 1981 | 7344184 |
| recurrence of rift valley fever in egypt. | rift valley fever (rvf) has been recorded in man and in domestic animals in egypt after a 12-year absence. human infections were first noted in the aswan governorate in late may, 1993. only cases of ocular disease, an infrequent and late manifestation, were reported. of 41 cases, 35 were tested serologically and 27 (77%) had rvf virus-specific igm antibodies. an estimated 600-1500 infections occurred in the region. abortions in cattle and buffalo were seen concurrently and antibodies to rvfv wer ... | 1993 | 7901480 |
| glucan-induced enhancement of host resistance to selected infectious diseases. | we conducted studies with mice, rats, and monkeys which demonstrated the ability of glucan to induce either nonspecific or specific enhancement of host resistance to infectious diseases. intravenous pretreatment of mice with glucan significantly enhanced the survival of mice challenged with either venezuelan equine encephalomyelitis (vee) virus or rift valley fever virus. pretreatment was beneficial when initiated 3 days before challenge with vee virus and 7 days before challenge with rift valle ... | 1980 | 7439978 |
| experimental transmission and field isolation studies implicating culex pipiens as a vector of rift valley fever virus in egypt. | attempts were made to isolate virus from wild caught mosquitoes during the 1977 and 1978 rift valley fever (rvf) epizootics in egypt. over 95% of the 55,126 mosquitoes collected from epizootic areas in the nile delta and valley were culex pipiens. two strains of rvf virus were isolated from unengorged female c. pipiens taken in 1978. laboratory-reared c. pipiens originating from a population sample from the nile delta epizootic area transmitted rvf virus. the infection rate of mosquitoes that fe ... | 1980 | 7446827 |
| arthropod-borne viral infections associated with a fever outbreak in the northern province of sudan. | an outbreak of acute febrile illness occurred during august and september 1989 in the northern province of sudan coinciding with a high population density of phlebotomine sandflies. an investigation was conducted to determine whether arboviruses were associated with human illness during this outbreak. sera were obtained from 185 febrile individuals and tested for igg and igm antibody to selected arboviruses by enzyme immunoassay (eia). the prevalence of igg antibody was 59% for west nile (wn), 5 ... | 1994 | 8064945 |
| rift valley fever--egypt, 1993. | in june 1993, several persons in aswan governorate (1993 population: 952,000) in southern egypt sought medical care for acute loss of vision following an illness characterized by fever, headache, retro-orbital pain, and myalgias. ophthalmologists who examined these persons noted paramacular retinal hemorrhages and edema, and rift valley fever (rvf) was suspected; serologic studies of these patients confirmed the diagnosis of acute rvf (1,2). in august 1993, serologic surveys were conducted in tw ... | 1994 | 8084333 |
| [surveillance of the circulation of arbovirus of medical interest in the region of eastern senegal]. | a study about the circulation of arboviruses of medical interest in southeastern senegal was conducted from 1988 to 1991, during and around the periods of transmission. specific igm antibodies were detected by elisa test in human sera, as a sign of a recent infection within 2 to 5 months. the comparison of the serological igm results from human surveys in different villages, and the isolations of arboviruses from mosquitoes during the same period of time permitted a rapid and global evaluation o ... | 1993 | 8099299 |
| [an ominous zoonosis: rift valley fever]. | | 1980 | 7455276 |
| host-feeding patterns of culex pipiens and cx. antennatus (diptera: culicidae) from a village in sharqiya governorate, egypt. | host-selection patterns of mosquitoes were determined over a 1-yr period at abu heif, a village in sharqiya governorate, egypt, that has had a history of rift valley fever virus (rvfv) transmission. culex pipiens l. and cx. antennatus becker were the most common mosquito species collected, and 8,252 blood meals from both species were analyzed by a precipitin technique. host availability was estimated by a monthly census of human and animal populations. both mosquito species exhibited opportunist ... | 1995 | 7473609 |
| first isolations of arboviruses from phlebotomine sand flies in west africa. | for the first time in west africa, arboviruses were isolated from phlebotomine sand fly pools. one strain of chandipura virus (a vesiculovirus), four strains of saboya virus (a flavivirus), and one strain of a not yet identified virus were isolated. three hundred twenty-two pools were established from a population of 33,917 sand flies caught in co2 light traps in the ferlo sahelian region of senegal from november 1991 to december 1992. this is the first isolation of chandipura virus from any art ... | 1994 | 8203705 |
| first isolations of arboviruses from phlebotomine sand flies in west africa. | for the first time in west africa, arboviruses were isolated from phlebotomine sand fly pools. one strain of chandipura virus (a vesiculovirus), four strains of saboya virus (a flavivirus), and one strain of a not yet identified virus were isolated. three hundred twenty-two pools were established from a population of 33,917 sand flies caught in co2 light traps in the ferlo sahelian region of senegal from november 1991 to december 1992. this is the first isolation of chandipura virus from any art ... | 1994 | 8203705 |
| molecular approaches for the treatment of hemorrhagic fever virus infections. | viruses causing hemorrhagic fevers in man belong to the following virus groups: togavirus (chikungunya), flavivirus (dengue, yellow fever, kyasanur forest disease, omsk hemorrhagic fever), arenavirus (argentinian hemorrhagic fever, bolivian hemorrhagic fever, lassa fever), filovirus (ebola, marburg), phlebovirus (rift valley fever), nairovirus (crimian-congo hemorrhagic fever) and hantavirus (hemorrhagic fever with renal syndrome, nephropathic epidemia). hemorrhagic fever virus infections can be ... | 1993 | 8250543 |
| haemorrhagic fever virus activity in equatorial africa: distribution and prevalence of filovirus reactive antibody in the central african republic. | seroepidemiological surveys were conducted to determine the frequency and distribution of haemorrhagic fever virus (hfv) activity in the central african republic. human serum specimens (4295) were collected from 5 ecologically distinct zones. serological evidence of hfv activity was found in all the zones. the filovirus antibody prevalence (24.4%, 1051/4295) was greater than the combined prevalence for lassa virus, rift valley fever virus and crimean-congo hfv antibody (1.1%, 45/4295; p < 0.01). ... | 1993 | 8266402 |
| rift valley fever virus in the cardia of culex pipiens: an immunocytochemical and ultrastructural study. | in this paper, we consider the movement of rift valley fever (rvf) virus from infected mosquito midgut epithelial cells into the hemocoel as an important factor in the ultimate ability of the insect to transmit the virus. our results are therefore significant in the context of vector competence. the mosquito culex pipiens was identified as the primary vector of rvf in an epidemic that occurred in egypt in the 1970s. on this basis, we have carried out several studies of rvf virus in this mosquito ... | 1995 | 7485683 |
| prevalence of antibody to rift valley fever virus in the nile river delta of egypt, 13 years after a major outbreak. | | 1993 | 8337715 |
| characterization of clone 13, a naturally attenuated avirulent isolate of rift valley fever virus, which is altered in the small segment. | the 74hb59 strain of rift valley fever (rvf) virus, isolated from a human case in the central african republic, was shown to be composed of a heterogeneous population of viruses when plaque-purified clones were analyzed for their reactivity with monoclonal antibodies (mabs) directed against the nucleocapsid (n) protein or the nonstructural (nss) protein. one of these clones, c13, was of particular interest in that it proved to be avirulent in mice and hamsters, and highly immunogenic. although c ... | 1995 | 7485695 |
| efficacy of coxiella burnetii and its chloroform-methanol residue (cmr) fraction against rift valley fever virus infection in mice. | strains of coxiella burnetii phase i and ii whole cells (wc-i and wc-ii) or whole cell fractions were assessed for their potential to induce long-lasting protection in endotoxin-non-responder c3h/hej or cd-1 mice against rift valley fever (rvf) virus challenge. among the whole cell fractions, only the chloroform-methanol residue (cmr), administered as a single dose (100 micrograms per mouse) 24 h before viral challenge, effectively protected 100% of the mice from rvf virus; the cmr of the ohio s ... | 1995 | 7486951 |
| rift valley fever epizootic in small ruminants in southern mauritania (october 1993): risk of extensive outbreaks. | following the 1987 rift valley fever (rvf) epizootic/epidemic in southern mauritania, rvf antibody prevalence in small ruminants decreased significantly from 1988 to 1992. in october 1993, at the end of the rainy season, an active rvf virus transmission was detected in several locations of southern mauritania in small ruminants, in association with an increase of abortions. rvf igm and igg antibodies were recorded respectively in 65/390 (16.67%) and 73/390 (18.72%) animals. rvf igm antibody prev ... | 1995 | 7487201 |
| rift valley fever virus l segment: correction of the sequence and possible functional role of newly identified regions conserved in rna-dependent polymerases. | the sequence of rift valley fever virus l segment that we published in a previous paper was erroneous in the 3'-terminal region of the antigenomic rna molecule. here, we have shown that the l segment is in fact 6404 nucleotides long and encodes a polypeptide of 237.7k in the viral complementary sense. sequence comparisons performed between the rna-dependent rna polymerases of 22 negative-stranded rna viruses revealed the existence of two novel regions located at the amino termini of the proteins ... | 1994 | 7515937 |
| the susceptibility of culicoides variipennis coq. (diptera: ceratopogonidae) to laboratory infection with rift valley fever virus. | the vector potential of culicoides variipennis for rift valley fever virus (rvfv) was investigated. insects from a colony maintained at the animal virus research institute, pirbright, were fed through a membrane on a mixture of mouse blood and rvfv (virus concentration of blood meal 7 x 95 log10 mld50ml). engorged insects were maintained at 25 degrees c +/- 1 degrees c. samples of insects were tested at daily intervals to determine their virus content. four of the five females tested immediately ... | 1982 | 7179410 |
| [rift valley fever. a threat for middle europe?]. | | 1980 | 7191369 |
| vector competence of egyptian mosquitoes for rift valley fever virus. | reintroduction of rift valley fever (rvf) into egypt in 1993 raised concerns about the potential for egyptian mosquitoes to transmit the virus. we evaluated the ability of aedes caspius, culex pipiens, cx. antennatus, cx. perexiguus, cx. poicilipes, and anopheles pharoensis collected in the aswan area and cx. pipiens collected in the nile delta to transmit rvf virus. all mosquito species tested were susceptible to rvf virus infection, with an. pharoensis and ae. caspius being the most sensitive ... | 1996 | 8619436 |
| [retinal abnormalities caused by rift valley fever virus]. | | 1980 | 7192368 |
| prevalence of anti-rift-valley-fever igm antibody in abattoir workers in the nile delta during the 1993 outbreak in egypt. | in the early summer of 1993, an outbreak of rift valley fever (rvf) was reported among both humans and animals in aswan governorate, upper egypt. to determine whether rvf infection had spread to the nile delta region of the country, we carried out a cross-sectional survey of 1181 occupationally exposed abattoir workers (97% male; age 10-72 years) in 15 governorates of egypt in november 1993. the overall prevalence of anti-rvf virus igm antibody was 2% (range: 0% (7 governorates) to 10%). the hig ... | 1996 | 8706230 |
| rift valley fever in humans in south africa. | during an epizootic of rift valley fever in south africa in 1974/1975, mainly affecting sheep and cattle, a large number of human cases occurred. the majority of the patients, mostly farmers, farm labourers and veterinary surgeons, acquired the infection while handling the carcasses of animals which had died of rift valley fever. some gave no history of contact with infected animals and it is presumed that they were infected by mosquitoes. complications were common. retinitis clinically associat ... | 1980 | 7192434 |
| workshop on the geographic spread of aedes albopictus in europe and the concern among public health authorities. proceedings of a workshop held at the istituto superiore di sanità, rome, italy, 19-20 december 1994. | | 1995 | 8778669 |
| ocular disease resulting from infection with rift valley fever virus. | the demonstration of serological conversion to rift valley fever (rvf) virus in paired acute and convalescent sera established rvf as the cause of two cases of retinitis seen during the 1977 rvf epidemic in egypt. colour photography of the retina revealed macular, paramacular and extramacular exudate-like lesions with associated haemorrage and oedema. one patient has not recovered central vision during a six-month convalescence. an ongoing study of a larger group of rvf patients with ocular dise ... | 1980 | 7192443 |
| rift valley fever retinitis. | a 57-year-old dutch woman, who had lived and worked in tanzania for 26 years, developed serious, progressive bilateral retinitis after suffering from a fever of unknown origin. fundus abnormalities in both eyes suggested that the woman had been infected with rift valley fever virus. serologic studies confirmed this suspicion. white macular lesions accompanied to extensive vasculitis appear to be specific for rift valley fever retinitis. | 1981 | 7196157 |
| arbovirus infections among laboratory personnel in ibadan, nigeria. | laboratory-acquired infections encountered between 1963 and 1977 among personnel of the virus research laboratory, ibadan, nigeria, are reported. two cases of chikungunya infection occurred and one each with dugbe, wesselsbron, and dengue viruses. in each case, virus was isolated or development of antibody demonstrated. among virus and two each to chikungunya and rift valley fever viruses, without experiencing any clinically recognized disease. | 1981 | 7196163 |
| antibodies to rift valley fever virus in the human population of sudan. | | 1981 | 7196612 |
| experimental infection of three nigerian breeds of sheep with the zinga strain of the rift valley fever virus. | experimental infection of three indigenous breeds of sheep in nigeria, namely the west african dwarf (wad), yankasa and ouda resulted in fatal disease with the zinga rift valley fever virus. infected sheep of the three breeds responded by pyrexia within 24 h of infection, that lasted 6 to 7 days, but peaked between day 2 and 4 post-infection. viraemia coincided with pyrexia and peaked (10(9) pfu/ml) 3 days p.i. in yankasa and wad sheep, but with highest titre (10(7.5) pfu/ml) in ouda sheep. zing ... | 1996 | 8881413 |
| rift valley fever antibody prevalence in domestic ungulates in cameroon and several west african countries (1989-1992) following the 1987 mauritanian outbreak. | | 1995 | 7754240 |
| [arbovirus circulation in the republic of guinea]. | in 1978-1991 the ussr-guinea virological and microbiological laboratory functioned in kindia, the republic of guinea. arbovirus activity in this country was studied by a number of virologists and other specialists. their personal contribution and achievements in this collaboration are reflected in the present paper. about 74,000 mosquitoes, 100,000 ixodidae ticks, 1,500 wild birds, 2,700 bats, 106 monkeys, and 308 other mammals, 927 blood samples collected from febrile patients were examined in ... | 1996 | 8926934 |
| the l protein of rift valley fever virus can rescue viral ribonucleoproteins and transcribe synthetic genome-like rna molecules. | overlapping cdnas representing the complete l segment of rift valley fever virus were assembled, and the l protein was expressed via a recombinant vaccinia virus. the transcriptase activity of the l protein was assayed with two types of templates: natural ribonucleoproteins (rnps) and artificial genome-like rnas. rnps purified in a cscl gradient did not retain the rna polymerase function, but the activity was restored when the l cdna was expressed in mammalian cells via a recombinant vaccinia vi ... | 1995 | 7769655 |
| short report: rift valley fever in western africa: isolations from aedes mosquitoes during an interepizootic period. | thirteen strains of rift valley fever virus were isolated from aedes vexans and ae. ochraceus mosquitoes collected in october and november 1993 in northern senegal. entomologic and serologic data show that the risk of a new epizootic is increasing in this region. | 1995 | 7771605 |
| rift valley fever virus ecology and the epidemiology of disease emergence. | | 1994 | 7840448 |
| rift valley fever in nigeria: infections in humans. | between 1985 and 1989, a total of 3,121 human sera collected from different population groups in six ecological zones of nigeria were tested for the presence of antibodies to rift valley fever (rvf) virus by the haemagglutination-inhibition test. all reactive sera were further tested by the plaque reduction neutralisation test and specific rvf immunoglobulin m (igm) assay. a total of 461 sera (14.8%) demonstrated haemagglutination-inhibiting antibody and 390 of the 461 initially reactive sera (8 ... | 1996 | 9025142 |
| rift valley fever in nigeria: infections in domestic animals. | between 1986 and 1989, 2,255 sera collected from six domestic animal species in nigeria were tested for antibodies to rift valley fever (rvf) virus. in addition, a longitudinal study was carried out from july 1987 to december 1988, using ten sentinel flocks on four farms at ibadan and ile-ife, to determine the activity of rvf virus (rvfv). all samples were tested for haemagglutination-inhibiting antibodies and positive sera were further screened, using the plaque reduction neutralisation test. o ... | 1996 | 9025143 |
| antiviral and immunomodulating inhibitors of experimentally-induced punta toro virus infections. | a major component of a us army medical research and development command-supported program to discover and develop new drugs for the treatment of rift valley fever, sandfly fever, and crimean-congo hemorrhagic fever has been to study candidate test materials against hepatotropic infections of c57bl/6 mice induced by the related but less biohazardous punta toro virus (ptv). the effects of 75 compounds, some of which were considered immunomodulators in their primary mechanism of activity, were stud ... | 1994 | 7847873 |
| rift valley fever in rural northern senegal: human risk factors and potential vectors. | to investigate past infection in and transmission of rift valley fever (rvf) virus to humans within an endemic focus, we undertook a retrospective cohort study of the seminomadic peul people living in sub-saharan northcentral senegal. residents of the rural settlement of yonofere five years of age or older were studied during february-may 1989. anti-rvf virus igg was found in blood samples of 22.3% of 273 persons who responded to a standard questionnaire; none had igm antibodies. seropositivity ... | 1994 | 7912905 |
| [decrease of natural immunity against rift valley fever in domestic ruminants of the senegal river basin after the epizootic outbreak of 1987]. | a domestic ruminants serosurvey of rift valley fever (rvf) neutralizing antibodies has been carried out during three years after the 1987 epidemic in the senegal river basin. authors present results from the 1990 serosurvey that are matched with the preview surveys. out of 1,225 ongulate tested, 17.2% had rvf virus antibodies. there is a global decrease in the herds immunity since the epizootic manifestation associated with the 1987 epidemic. significant differences in seroprevalence are observe ... | 1994 | 8003907 |
| effect of the developmental stage at infection on the ability of adult anopheles stephensi to transmit rift valley fever virus. | the ability of adult anopheles stephensi to transmit rift valley fever virus was determined for mosquitoes inoculated at selected times during development. none of 109 female an. stephensi inoculated as adults transmitted virus to hamsters. in contrast, 83% (50 of 60) of those inoculated as larvae transmitted virus by bite to hamsters. transmission rates decreased as the stage of the mosquito at the time of inoculation changed from larva to pupa to adult. transmission rates for adult mosquitoes ... | 1994 | 8166351 |
| rift valley fever. | | 1994 | 8193010 |
| effect of environmental temperature on the vector competence of aedes taeniorhynchus for rift valley fever and venezuelan equine encephalitis viruses. | studies were conducted to determine the effect of environmental temperature on the susceptibility of aedes taeniorhynchus mosquitoes for venezuelan equine encephalitis (vee) and rift valley fever (rvf) viruses. mosquitoes reared at low temperature (19 degrees c) were significantly more susceptible to infection with rvf virus (infection rate = 70%, 158 of 226) than were those mosquitoes reared at 26 degrees c (infection rate = 48%, 135 of 280), regardless of the temperature at which mosquitoes we ... | 1993 | 8279634 |
| purification of viruses by electrophoresis in sucrose concentration gradients. 1972. | zone electrophoresis (ze) in concentration gradients of sucrose proved to be a powerful technique in the purification of viruses although it is seldomly used as a single step for the separation of the infective agent from extraneous matter but usually as a final procedure. no difficulties were experienced in the purification of plant viruses with ze possibly because of the resistance of the agents to the chloroform butanol treatment which the impure plant viruses received prior to the ze. likewi ... | 1993 | 8367394 |
| systemic viral infections and their retinal and choroidal manifestations. | viruses are one of the most common causes of infections involving the posterior segment of the eye. such infections can occur either on a congenital or an acquired basis, and may affect primarily the retina or the choroid. congenital cytomegalovirus (cmv) and rubella infections may result in retinitis. cmv retinitis is also the most common cause of acquired viral retinitis, primarily because of the acquired immunodeficiency syndrome (aids). other types of viral retinitis, such as those caused by ... | 1993 | 8387231 |
| rift valley fever virus: a seroepidemiologic study of small terrestrial vertebrates in south africa. | epizootics of rift valley fever (rvf) are often associated with periods of heavy rainfall, which are favorable for mosquito vectors. however, in seasons with normal or low rainfall, enzootic circulation occurs, suggesting the existence of a natural host that can act as a cryptic carrier during interepizootic periods. to confirm the role of heavy rainfall in epizootic circulation, and to identify a possible natural host of rvf virus, serum samples from small terrestrial mammals in the free state ... | 1997 | 9430529 |
| toscana virus genomic l segment: molecular cloning, coding strategy and amino acid sequence in comparison with other negative strand rna viruses. | the complete nucleotide sequence of toscana (tos) virus (bunyaviridae, phlebovirus) l segment was determined. the l segment is 6404 nucleotides long, containing a single open reading frame (orf) in the viral complementary sense coding for a protein of 2095 amino acids that, as in the case of negative strand rna viruses, could be part of the rna polymerase of tos virus. this orf is expressed by a messenger rna (mrna) as long as the genomic segment. like the mrnas expressed by the genomic segments ... | 1993 | 8460526 |
| effect of controlled burning on survival of floodwater aedes eggs in kenya. | the effect of controlled burning on the survival of aedes mosquito eggs was evaluated in 2 distinct dambo habitats. in a dambo dominated by grasses, egg survival was 3.3% after burning compared with 43.8% in a similar dambo that was not burned. in a dambo dominated by sedges, egg survival was 0.7% after burning compared with 28.5% in a similar dambo that was not burned. mortality of mosquito eggs appeared to be caused by high temperatures associated with the fire and not elapsed time since egg s ... | 1993 | 8468577 |
| characterization of the non-specific humoral and cellular antiviral immunity stimulated by the chloroform-methanol residue (cmr) fraction of coxiella burnetii. | modulation of the immune response by the chloroform-methanol residue (cmr) of phase i coxiella burnetii whole cell was studied in rift valley fever virus-infected, or in naive endotoxin-non-responder c3h/hej mice. a single dose of cmr completely protected the mice from viral infection. treating virus-infected mice with antibodies directed against interferons alpha/beta (ifn-alpha beta) and gamma (ifn-gamma) eliminated the cmr-induced protection. cmr stimulated the production of high levels of if ... | 1995 | 8540758 |
| new vectors of rift valley fever in west africa. | after an outbreak of rift valley fever in southern mauritania in 1987, entomologic studies were conducted in a bordering region in sénégal from 1991 to 1996 to identify the sylvatic vectors of rift valley fever virus. the virus was isolated from the floodwater mosquitoes aedes vexans and ae. ochraceus. in 1974 and 1983, the virus had been isolated from ae. dalzieli. although these vectors differ from the main vectors in east and south africa, they use the same type of breeding sites and also fee ... | 1998 | 9621201 |
| the prevalence of antibody to the viruses of bovine virus diarrhoea, bovine herpes virus 1, rift valley fever, ephemeral fever and bluetongue and to leptospira sp in free-ranging wildlife in zimbabwe. | the prevalence of antibody to the viruses of bovine virus diarrhoea (bvd), bovine herpes virus typel (bhv1), rift valley fever (rvf), bovine ephemeral fever (bef) and bluetongue (bt) and to leptospira sp. was determined in wildlife populations in zimbabwe. evidence of infection with bvd virus was found in 14 of the 16 species examined but was greatest in eland taurotragus oryx, nyala tragelaphus angasi and bushbuck tragelaphus scriptus. persistent infection with bvd virus was found in 1 of 303 a ... | 1998 | 9825798 |
| the effect of neutralizing monoclonal antibodies on early events in rift valley fever virus infectivity. | monoclonal antibodies (mab) were used to examine possible stages at which antibody-mediated neutralization of rift valley fever virus occurs, and to assess whether binding of antibody is dependent on viral protein structure in order that antibody recognition take place. analysis of the structural properties of the antigenic determinants revealed that the neutralizing sites are highly conformation-dependent. none of the mab prevented virus binding, suggesting that the epitopes they define are spa ... | 1994 | 7517569 |
| nematocera (ceratopogonidae, psychodidae, simuliidae and culicidae) and control methods. | the biology, veterinary importance and control of certain nematocera are described and discussed. culicoides spp. (family ceratopogonidae) transmit the arboviruses of bluetongue (bt), african horse sickness (ahs), bovine ephemeral fever (bef) and akabane. some other arboviruses have been isolated from these species, while fowl pox has been transmitted experimentally by culicoides. these insects are vectors of the parasitic protozoans leucocytozoon caulleryi and haemoproteus nettionis, and the pa ... | 1994 | 7711309 |
| inhibition of bunyaviruses, phleboviruses, and hantaviruses by human mxa protein. | viruses of the bunyaviridae family cause a variety of diseases ranging from uncomplicated fever to potentially lethal encephalitis and hemorrhagic fever. little is known about the factors determining pathogenicity in the vertebrate host. interferons have been reported to be inhibitory, but their mode of action against members of the bunyaviridae has not yet been elucidated. the interferon-induced mxa protein encoded on human chromosome 21 is a large gtpase with antiviral activity against distinc ... | 1996 | 8551631 |
| the use of sucrose-acetone-extracted rift valley fever virus antigen derived from cell culture in an indirect enzyme-linked immunosorbent assay and haemagglutination-inhibition test. | a sucrose-acetone-extracted, madin-darby-bovine-kidney (mdbk)-derived rift valley fever virus (rvfv) antigen was tested both in an indirect elisa and a haemagglutination-inhibition test for its ability to detect serum antibodies to rvfv. optimal conditions for antigen concentration, serum and conjugate dilutions for the elisa were established by checkerboard titration. the specificity and sensitivity of elisa were determined by the use of paired pre- and post-vaccination sheep-serum samples. com ... | 1995 | 8668320 |
| seroprevalence of five arboviruses in zebu cattle in the central african republic. | sequential blood samples taken from 237 adult and 147 young zebu cattle in the central african republic (car) were examined by enzyme-linked immunosorbent assay for the presence of antibodies to rift valley fever (rvf), dugbe (dug), crimean-congo haemorrhagic fever (cchf), chikungunya (chik) and wesselsbron (wsl) viruses. antibodies to dug and cchf viruses were detected in 70% and 61% respectively, of the sera from adult cattle, probably due to common antigens. this hypothesis is supported by th ... | 1996 | 8730305 |
| serum antibody to rift valley fever virus in african carnivores. | | 1996 | 8784515 |
| imported vector- and rodent-borne virus infections--an introduction. | travel is a potent force in the emergence of virus infections. migration of humans and animals has been the pathway for disseminating virus diseases throughout history. in recent years, dengue virus has been identified as the most important travel-related, vector-borne virus disease. other vector-borne virus infections, such as sandfly fever, rift valley fever, chikungunya fever and japanese encephalitis, have been diagnosed in travelers returning from endemic areas. crimean-congo haemorrhagic f ... | 1996 | 8800802 |
| rift valley fever surveillance in the lower senegal river basin: update 10 years after the epidemic. | after the rift valley fever (rvf) epidemic of 1987 in the senegal river basin, rvf surveillance based on serosurveys has been conducted for 10 years. serum samples were obtained from 1336 persons and from sheep and goats in selected areas, and these were tested for igg/igm rvf antibodies by elisa. after a period of regular decrease in rvf prevalence in domestic animals until 1993, an epizootic was observed in all herds in 1994-95 with increases in igm levels and abortions. during the same period ... | 1999 | 10499082 |
| antiviral activities of tragacanthin polysaccharides on punta toro virus infections in mice. | tragacanthin polysaccharides from astragalus brachycentrus (av208) and astragalus echidnaeformis (av212) plants, which are devoid of in vitro antiviral activity, were evaluated in a mouse model of punta toro virus (ptv) infection. the ptv (a phlebovirus member of the bunyaviridae family of viruses) is a model for studying the treatment of rift valley fever and hantavirus infections. single intraperitoneal treatments with 12.5-200 mg/kg/day doses of av212 given 24 h before or 4 and 24 h after vir ... | 1996 | 8804797 |
| viral diseases of livestock in zambia. | this review is to provide information on viral diseases of livestock in zambia. the distribution of the diseases as well as the control measures and limited research that has been done, are described. foot and mouth disease (fmd) causes serious economic losses in the cattle industry. so far five serotypes (sat1, sat2, sat3, o and at of fmd virus have been isolated in zambia. other notifiable viral diseases are rabies, rift valley fever, lumpy skin disease, african horse sickness, bluetongue, afr ... | 1996 | 8870389 |
| an epizootic of rift valley fever in egypt in 1997. | an epizootic of rift valley fever (rvf) occurred in egypt between april and august 1997. the signs among infected cattle and sheep were high fever, icterus, bloody diarrhoea and abortion. aborted sheep foetuses and sera from the affected herds were collected in the aswan and assiut provinces, upper egypt, for virological and serological examination. a cytopathic effect was detected in vero cell cultures 48 h after inoculation with the foetal liver and spleen suspensions. the same suspensions cau ... | 1999 | 10588018 |
| host feeding of mosquitoes (diptera: culicidae) associated with the recurrence of rift valley fever in egypt. | in 1993, rift valley fever (rvf) virus reappeared in egypt. we determined the prevalence and feeding patterns of mosquitoes in 5 villages where the virus was active. of 10 species recovered, aedes caspius (pallas), culex pipiens l., cx. antennatus (becker), and cx. perexiguus theobald constituted 99% of > 35,000 mosquitoes captured in dry ice-baited cdc light traps. ae. caspius was most prevalent, except at nag' el hagar where it was replaced by cx. perexiguus. cx. pipiens ranked 2nd, except at ... | 1999 | 10593070 |
| the s segment of rift valley fever phlebovirus (bunyaviridae) carries determinants for attenuation and virulence in mice. | unlike all the other rift valley fever virus strains (bunyaviridae, phlebovirus) studied so far, clone 13, a naturally attenuated virus, does not form the filaments composed of the nss nonstructural protein in the nuclei of infected cells (r. muller, j. f. saluzzo, n. lopez, t. drier, m. turell, j. smith, and m. bouloy, am. j. trop. med. hyg. 53:405-411, 1995). this defect is correlated with a large in-frame deletion in the nss coding region of the s segment of the tripartite genome. here, we sh ... | 2000 | 10627566 |
| the s segment of rift valley fever phlebovirus (bunyaviridae) carries determinants for attenuation and virulence in mice. | unlike all the other rift valley fever virus strains (bunyaviridae, phlebovirus) studied so far, clone 13, a naturally attenuated virus, does not form the filaments composed of the nss nonstructural protein in the nuclei of infected cells (r. muller, j. f. saluzzo, n. lopez, t. drier, m. turell, j. smith, and m. bouloy, am. j. trop. med. hyg. 53:405-411, 1995). this defect is correlated with a large in-frame deletion in the nss coding region of the s segment of the tripartite genome. here, we sh ... | 2000 | 10627566 |
| an outbreak of west nile fever among migrants in kisangani, democratic republic of congo. | in february 1998, an outbreak of acute febrile illness was reported from the kapalata military camp in kisangani, the democratic republic of congo. the illness was characterized by an acute onset of fever associated with severe headache, arthralgia, backache, neurologic signs, abdominal pain, and coughing. in 1 individual, hemorrhagic manifestations were observed. the neurologic signs included an altered level of consciousness, convulsions, and coma. malaria was initially suspected, but the pati ... | 1999 | 10674664 |
| persistent infection of mammalian cells by rift valley fever virus. | infection of mammalian cells with rift valley fever virus (rvfv) leads generally to the production of virus and cell death. in this paper we examined the fate of vero cells infected with three strains of rvfv and observed that, while a large proportion of cells exhibited a clear cytopathic effect (cpe), a small but significant fraction did not undergo a lytic infection but was able to proliferate and establish a persistent infection. several independent rvfv persistently infected cell lines have ... | 1996 | 9000097 |
| analysis of the 3' terminal sequence recognized by the rift valley fever virus transcription complex in its ambisense s segment. | a reconstituted transcription system composed of the rift valley fever phlebovirus (bunyaviridae family) proteins l and n expressed via recombinant vaccinia viruses and an s-like model rna containing the cat gene in the antisense orientation, has been described previously by lopez et al. (j. virol., 1995, 69, 3972-3979). we extended the use of this in vivo system to determine the sequence at the 3' end of the ambisense s segment recognized by the transcription complex. a mutational analysis of t ... | 1997 | 9007072 |
| serosurvey for selected infectious disease agents in free-ranging black and white rhinoceros in africa. | two hundred and eighty one serum samples collected from free-ranging black (diceros bicornis) and white (ceratotherium simum) rhinoceros, in the republic of south africa (rsa), namibia, and kenya from 1987-97, were examined for antibody to 16 different infectious agents. positive antibody titers were detected against akabane (59.8%), bluetongue (55%), african horse sickness (27.9%), epizootic haemorrhagic disease of deer (19.4%), parainfluenza type 3 (25.3%), bovine herpes virus 1 (3.1%), equine ... | 2000 | 10813614 |
| analysis of the 3' terminal sequence recognized by the rift valley fever virus transcription complex in its ambisense s segment. | a reconstituted transcription system composed of the rift valley fever phlebovirus (bunyaviridae family) proteins l and n expressed via recombinant vaccinia viruses and an s-like model rna containing the cat gene in the antisense orientation, has been described previously by lopez et al. (j. virol., 1995, 69, 3972-3979). we extended the use of this in vivo system to determine the sequence at the 3' end of the ambisense s segment recognized by the transcription complex. a mutational analysis of t ... | 1997 | 9007072 |
| detection of rift valley fever virus in mosquitoes by rt-pcr. | a reverse transcriptase-polymerase chain reaction (rt-pcr) assay to detect rift valley fever (rvf) virus rna in experimentally infected mosquitoes was developed. the specificity of the assay was evaluated with three other phleboviruses; sandfly fever sicilian (sabin), sandfly fever naples (sabin) and punta toro (msp 3) viruses. the relative sensitivity of the assay, determined by using rvf virus rna extracted from serial dilutions of virus culture, was approximately 50 plaque forming units. this ... | 1997 | 9076714 |
| communicable disease surveillance with limited resources: the scope to link human and veterinary programmes. | zoonoses are an important cause of human disease in much of africa, but limitations in current diagnosis and surveillance strategies restrict the effectiveness of control and prevention programmes. outbreaks of disease, ranging from ebola virus infection to rift valley fever, that have occurred recently in africa have demonstrated the need for improved disease surveillance and monitoring. strategies are suggested for co-ordinating human and animal disease surveillance programmes, at the district ... | 2000 | 10913758 |
| enzootic activity of rift valley fever virus in senegal. | in two areas of senegal where previous evidence of rift valley fever (rvf) virus circulation was detected, barkedji in the sahelian bioclimatic zone and kedougou in the sudano-guinean zone, a longitudinal study of the enzootic maintenance of rvf virus was undertaken from 1991 to 1993. mosquitoes, sand flies, and ticks were collected and domestic ungulates were monitored with serologic surveys. rift valley fever virus was not isolated in kedougou. in barkedji, rvf virus was isolated from aedes ve ... | 1997 | 9129528 |
| distribution of viral antigen in tissues of new-born lambs infected with rift valley fever virus. | the distribution of rift valley fever (rvf) viral antigen was studied by immunohistochemistry in the liver, spleen, prescapular lymph node, lungs and kidneys ot eight experimentally infected new-born lambs and in four new-born lambs that died of rvf during the 1974-75 rvf epidemic. the eight experimentally infected lambs were euthanazed at 6, 12, 18, 24, 30, 33, 48 and 51 h post-infection (p.i.), respectively. immunohistochemical staining utilized polyclonal hyperimmune mouse ascites fluid to rv ... | 1996 | 9173366 |
| cladistic analysis of tospovirus using molecular characters. | the genus tospovirus was thought to be composed only of the tomato spotted wilt virus (tswv), but now at least four tospovirus species have been proposed based on serological and molecular data. a classification of tospoviruses has been proposed taking into account global similarities of the n gene and n protein sequences of 7 isolates of tospovirus. because phylogenetic analyses based on global similarities can lead to classifications which do not mirror the genealogy of the group, we have empl ... | 1997 | 9242593 |
| safety and efficacy of a mutagen-attenuated rift valley fever virus vaccine in cattle. | to examine safety and efficacy of a mutagen attenuated rift valley fever virus (rvfv) vaccine (rvf mp-12) in cattle. | 1997 | 9328662 |
| safety of a mutagen-attenuated rift valley fever virus vaccine in fetal and neonatal bovids. | to examine effects of in utero inoculation with a mutagen-attenuated rift valley fever virus (rvfv) vaccine (rvf mp-12) on fetal bovids and to assess the safety and efficacy of calfhood vaccination with rvf mp-12. | 1997 | 9328663 |