Результаты поиска

A Spatial Analysis of Rift Valley Fever Virus Seropositivity in Domestic Ruminants in Tanzania.

Rift Valley fever (RVF) is an acute arthropod-borne viral zoonotic disease primarily occurring in Africa. Since RVF-like disease was reported in Tanzania in 1930, outbreaks of the disease have been reported mainly from the eastern ecosystem of the Great Rift Valley. This cross-sectional study was carried out to describe the variation in RVF virus (RVFV) seropositivity in domestic ruminants between selected villages in the eastern and western Rift Valley ecosystems in Tanzania, and identify potential risk factors. Three study villages were purposively selected from each of the two Rift Valley e…

Rift Valley fever virus: A review of diagnosis and vaccination, and implications for emergence in Europe.

Rift Valley fever virus (RVFV) is a mosquito-borne virus, and is the causative agent of Rift Valley fever (RVF), a zoonotic disease characterised by an increased incidence of abortion or foetal malformation in ruminants. Infection in humans can also lead to clinical manifestations that in severe cases cause encephalitis or haemorrhagic fever. The virus is endemic throughout much of the African continent. However, the emergence of RVFV in the Middle East, northern Egypt and the Comoros Archipelago has highlighted that the geographical range of RVFV may be increasing, and has led to the concern …

Spatial and temporal pattern of Rift Valley fever outbreaks in Tanzania; 1930 to 2007.

BACKGROUND: Rift Valley fever (RVF)-like disease was first reported in Tanzania more than eight decades ago and the last large outbreak of the disease occurred in 2006-07. This study investigates the spatial and temporal pattern of RVF outbreaks in Tanzania over the past 80 years in order to guide prevention and control strategies. MATERIALS AND METHODS: A retrospective study was carried out based on disease reporting data from Tanzania at district or village level. The data were sourced from the Ministries responsible for livestock and human health, Tanzania Meteorological Agency and researc…

Evidence for circulation of the rift valley fever virus among livestock in the union of Comoros.

Rift Valley fever virus (RVFV) is an arthropod-borne phlebovirus reported to be circulating in most parts of Africa. Since 2009, RVFV has been suspected of continuously circulating in the Union of Comoros. To estimate the incidence of RVFV antibody acquisition in the Comorian ruminant population, 191 young goats and cattle were selected in six distinct zones and sampled periodically from April 2010 to August 2011. We found an estimated incidence of RVFV antibody acquisition of 17.5% (95% confidence interval (CI): [8.9-26.1]) with a significant difference between islands (8.2% in Grande Comore,…

Rift Valley fever and a new paradigm of research and development for zoonotic disease control.

Although Rift Valley fever is a disease that, through its wider societal effects, disproportionately affects vulnerable communities with poor resilience to economic and environmental challenge, Rift Valley fever virus has since its discovery in 1931 been neglected by major global donors and disease control programs. We describe recent outbreaks affecting humans and animals and discuss the serious socioeconomic effects on the communities affected and the slow pace of development of new vaccines. We also discuss the mixed global response, which has largely been fueled by the classification of th…

Immunogenicity and safety of an inactivated Rift Valley fever vaccine in a 19-year study.

An investigational, formalin-inactivated Rift Valley fever (RVF) vaccine, known as The Salk Institute-Government Services Division (TSI-GSD) 200 vaccine, was administered to 1860 at-risk subjects (5954 doses) between 1986 and 2004 as a three-dose primary series (days 0, 7, and 28) followed by booster doses as needed for declining titers. An initial positive serological response (PRNT(80)≥1:40) to the primary series was observed in 90% of subjects. Estimate of the PRNT(80) response half-life in initial responders to the primary series by Kaplan-Meier plot was 315 days after the primary series d…

Prevalence of Rift Valley fever infection in ruminants in Madagascar after the 2008 outbreak.

A Rift Valley fever (RVF) outbreak occurred in Madagascar from January to May 2008. The objectives of this study were (1) to assess the current and past circulation of RVF virus (RVFV) in livestock in Madagascar and (2) to evaluate the extent and magnitude of the 2008 RVF outbreak in livestock. The results of a country-wide serosurvey conducted in August 2008 on small and large ruminants are reported here. The study included 3437 cattle and 989 small ruminants (227 sheep and 762 goats) sampled in 30 of the 111 Malagasy districts, selected to be representative of the different ecozones and live…

Для поддержания стабильности генома вируса лихорадки разлома долины необходима смена хоста.

Большинство вирусов, передаваемых через артроподы (арбовирусы), являются вирусами РНК, которые поддерживаются в природе посредством циклов воспроизведения, которые чередуются между артроподами и носителями позвоночных. Похоже, что у арбовирусов более низкие темпы эволюции, чем у вирусов РНК, которые воспроизводятся в одном носителе. Предполагается, что эта генетическая стабильность является результатом фитнес-композиции, навязанной чередованием хост-компьютеров, которая ограничивает эволюцию генома арбовируса. Для проверки этой гипотезы мы использовали вирус лихорадки Рифт-Вэлли (RVFV), арбови

Совпадение в аннотации оригинала
BACKGROUND: Most arthropod-borne viruses (arboviruses) are RNA viruses, which are maintained in nature by replication cycles that alternate … by host alternation, which constrains arbovirus genome evolution. To test this hypothesis, we used Rift Valley fever virus (RVFV), an arbovirus that can be transmitted either directly (between vertebrates during the manipulation of infected tissues, and between mosquitoes by vertical transmission) or indirectly (from one vertebrate to another by mosquito-borne tra …

Safety and efficacy of Rift Valley fever Smithburn and Clone 13 vaccines in calves.

Two modified live attenuated vaccines against the disease Rift Valley fever (RVF) have been tested for safety and efficacy in young calves. The RVF Smithburn vaccine produced in South Africa and used successfully to prevent and control the disease in endemic sub-Saharan countries was compared to the candidate vaccine RVF Clone 13. Five sero-negative calves per vaccine group were vaccinated with a single dose of each vaccine and tested for antibody response. All vaccinated calves were challenged with a highly virulent RVF virus together with five unvaccinated calves used as control of the chall…

The epidemiology and socio-economic impact of rift valley fever epidemics in Tanzania: a review.

Rift Valley Fever (RVF) is an acute, mosquito-borne viral disease that has a significant global threat to humans and livestock. This review was conducted to provide comprehensive update on Rift Valley Fever (RVF) in Tanzania, with particular attention devoted to trend of occurrence, epidemiological factors, socio-economic impact and measures which were applied to its control. Information presented in this paper was obtained through extensive literature review. RVF occurred for the first time in Tanzania in 1930. This was followed by periodic epidemics of 10-20 years, i.e., 1947, 1957, 1977, 19…

Evaluation of the efficacy and safety of the Rift Valley Fever Clone 13 vaccine in sheep.

The efficacy and safety of the naturally attenuated Rift Valley Fever (RVF) Clone 13 vaccine were evaluated in ovines in three different experiments involving 38 ewes at different stages of pregnancy, their offsprings and four rams. In Experiment 1, 4 rams and a total of 13 pregnant ewes were vaccinated and monitored during vaccination and after a challenge with a virulent RVF virus. The ewes were vaccinated at either 50 or 100 days of pregnancy and some were challenged after lambing. In Experiment 2, nine oestrus-synchronized ewes were vaccinated at 50 days of pregnancy and challenged at 100 …

Epidemiological assessment of the Rift Valley fever outbreak in Kenya and Tanzania in 2006 and 2007.

To capture lessons from the 2007 Rift Valley fever (RVF) outbreak, epidemiological studies were carried out in Kenya and Tanzania. Somali pastoralists proved to be adept at recognizing symptoms of RVF and risk factors such as heavy rainfall and mosquito swarms. Sandik, which means "bloody nose," was used by Somalis to denote disease consistent with RVF. Somalis reported that sandik was previously seen in 1997/98, the period of the last RVF epidemic. Pastoralists communicated valuable epidemiological information for surveillance and early warning systems that was observed before international w…

Pathogenicity and neurovirulence of a mutagen-attenuated Rift Valley fever vaccine in rhesus monkeys.

Rhesus macaques, intravenously inoculated with virulent Rift Valley fever virus, develop viremia and biochemical evidence of liver damage and serve as a model for human disease. Some of these monkeys suffer more serious disease with hemorrhagic phenomena and approximately 20% die with frank hemorrhage. Presently, the only Rift Valley fever vaccine approved for use in humans is a formalin-killed product that requires annual booster vaccinations. Efforts to produce an improved vaccine to replace the present vaccine have led to a mutagen-attenuated strain of Rift Valley fever virus that was found…

Immunogenicity of an inactivated Rift Valley fever vaccine in humans: a 12-year experience.

Rift Valley fever (RVF) virus causes serious and fatal disease in animals and man. To protect personnel who work with RVF virus in the laboratory, or troops who may be exposed to this virus, the US Army successfully developed an improved version of inactivated RVF vaccine, TSI-GSD-200. From early 1986 to late 1997, 598 at-risk workers at the US Army Medical Research Institute of Infectious Diseases (USAMRIID) were vaccinated as part of an occupational safety and health program. The subjects of this study received three subcutaneous doses (0, 7 and 28 days) of 0.5 ml of TSI-GSD-200. A total of …

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 species. In the research reported here, we used immunocytochemical and transmission electron micros…

The synergistic neutralization of Rift Valley fever virus by monoclonal antibodies to the envelope glycoproteins.

A panel of monoclonal antibodies (MAbs) mapping to different antigenic sites on the RVFV G1 and G2 proteins were used to examine the mechanisms involved in neutralization of the virus. Three types of synergistic neutralization of RVFV were observed on mixing various pairs of MAbs. Firstly, enhanced neutralization occurred for two MAb pairs that showed augmented binding for G2. These comprised a combination of a neutralizing MAb with a non-neutralizing antibody, as well as two antibodies which were non-neutralizing individually. In the second category, synergistic neutralization was observed be

An immunocytochemical study of the distribution of Rift Valley fever virus in the mosquito Culex pipiens.

The dissemination of Rift Valley fever (RVF) virus in females of the epidemic vector Culex pipiens was studied immunocytochemically. Among orally infected specimens, viral antigen was detected in all major midgut regions, although individuals varied with respect to which regions were infected. Among specimens with disseminated infections (infections beyond the midgut epithelium), antigen was detected in most tissues, including those of the nervous and endocrine systems. However, no antigen was found in the ovarian follicular epithelia, oocytes/nurse cells, or female accessory gland. A viral di…

Электронная микроскопическая идентификация вируса Зинга как штамма вируса лихорадки Рифт-Вэлли.

Электронный микроскопический анализ негативно запятнанной подвески вируса Зинга показал наличие частиц диаметром 90-100 нм, покрытых шипами длиной 12-20 нм и диаметром 5 нм. Дальнейшая идентификация вируса с помощью иммунной электронной микроскопии показала реактивность вируса лихорадки Рифт-Вэлли с положительной сывороткой с вирусом Зинга. Результаты этого исследования согласуются с предыдущими сообщениями о том, что вирус Цинга является штаммом вируса лихорадки Рифт-Вэлли.

Совпадение в аннотации оригинала
Electron microscopic examination of a negatively stained suspension of Zinga virus showed particles 90-100 nm in diameter, enveloped with spikes 12-20 nm in length and 5 nm in diameter. Further identification of the virus by immune electron microscopy showed the reactivity of human Rift Valley fever virus-positive serum with Zinga virus. Results of this stud…

Efficacy of a Rift Valley fever virus vaccine against an aerosol infection in rats.

The formalin-inactivated Rift Valley fever virus (RVFV) vaccine, TSI-GSD-200, was administered subcutaneously to highly susceptible adult Wistar-Furth rats (LD50-1 p.f.u., ZH501 strain). Vaccine was administered on days 0, 7 and 28, the same time course used for at-risk personnel. Six months postimmunization, when the serum plaque-reduction neutralization titre (PRNT)80 had declined to low or undetectable levels, rats were challenged with 4.4 log10 p.f.u. of the virulent ZH501 strain in a nose-only dynamic aerosol apparatus. Ninety-seven per cent (33/34) of the non-vaccinated control rats died…