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It's risky to wander in September: Modelling the epidemic potential of Rift Valley fever in a Sahelian setting.

Estimating the epidemic potential of vector-borne diseases, along with the relative contribution of underlying mechanisms, is crucial for animal and human health worldwide. In West African Sahel, several outbreaks of Rift Valley fever (RVF) have occurred over the last decades, but uncertainty remains about the conditions necessary to trigger these outbreaks. We use the basic reproduction number (R0) as a measure of RVF epidemic potential in northern Senegal, and map its value in two distinct ecosystems, namely the Ferlo and the Senegal River delta and valley. We consider three consecutive rain…

Diversity and Abundance of Potential Vectors of Rift Valley Fever Virus in the North Region of Cameroon.

Rift Valley fever (RVF) is a major viral zoonosis transmitted by mosquitoes. The virus is endemic in most parts of sub-Saharan Africa and can affect humans, livestock, and wild ungulates. Knowledge of the biology of vectors of Rift Valley fever virus (RVFV) is essential for the establishment of effective control measures of the disease. The objective of this study was to determine the species diversity and relative abundance of potential RVFV vectors in the North Region of Cameroon. Adult mosquitoes were trapped during the wet and dry seasons from December 2017 to January 2019 with "EVS Light"…

Evaluation of a Virus Neutralisation Test for Detection of Rift Valley Fever Antibodies in Suid Sera.

Rift Valley fever (RVF) is a vector-borne viral disease of ruminants mainly, and man, characterized by abortions and neonatal deaths in animals and flu-like to more severe symptoms that can result in death in humans. The disease is endemic in Africa, Saudi Arabia and Yemen, and outbreaks occur following proliferation of RVF virus (RVFV) infected mosquito vectors. Vertebrate animal maintenance hosts of RVFV, which serve as a source of virus during inter-epidemic periods remain unknown, with wild and domestic suids being largely overlooked. To address this, we evaluated the virus neutralization …

Peripheral Blood Biomarkers of Disease Outcome in a Monkey Model of Rift Valley Fever Encephalitis.

Rift Valley Fever (RVF) is an emerging arboviral disease of livestock and humans. Although the disease is caused by a mosquito-borne virus, humans are infected through contact with, or inhalation of, virus-laden particles from contaminated animal carcasses. Some individuals infected with RVF virus (RVFV) develop meningoencephalitis, resulting in morbidity and mortality. Little is known about the pathogenic mechanisms that lead to neurologic sequelae, and thus, animal models that represent human disease are needed. African green monkeys (AGM) exposed to aerosols containing RVFV develop a reprod…

A Protective Monoclonal Antibody Targets a Site of Vulnerability on the Surface of Rift Valley Fever Virus.

The Gn subcomponent of the Gn-Gc assembly that envelopes the human and animal pathogen, Rift Valley fever virus (RVFV), is a primary target of the neutralizing antibody response. To better understand the molecular basis for immune recognition, we raised a class of neutralizing monoclonal antibodies (nAbs) against RVFV Gn, which exhibited protective efficacy in a mouse infection model. Structural characterization revealed that these nAbs were directed to the membrane-distal domain of RVFV Gn and likely prevented virus entry into a host cell by blocking fusogenic rearrangements of the Gn-Gc latt…

Quantifying the potential pathways and locations of Rift Valley fever virus entry into the United States.

The global invasion of West Nile virus, chikungunya virus and Zika virus in the past two decades suggests an increasing rate of mosquito-borne virus (arbovirus) dispersal. Rift Valley fever virus (RVFV) is an arbovirus identified as a high-consequence threat to the United States (USA) because of the severe economic and health consequences associated with disease. Numerous studies demonstrate that the USA is receptive to RVFV transmission based on the widespread presence of competent mosquito species and vertebrate species. In this study, the potential pathways and locations of RVFV entry into …

Lay perceptions of risk factors for Rift Valley fever in a pastoral community in northeastern Kenya.

BACKGROUND: Human behavioral factors have been found to be central in the transmission of Rift Valley fever. Consumption of contaminated meat and milk in particular have been identified as one of the key risk factors for the transmission of Rift Valley fever in humans. In pastoral communities, livestock is the main source of livelihood from which many benefits such as food as well as economic and cultural services are derived. Zoonotic diseases therefore have a great impact on pastoral communities livelihoods. However, lay perceptions regarding the transmission of these diseases including Rift…

Association of ecological factors with Rift Valley fever occurrence and mapping of risk zones in Kenya.

OBJECTIVE: Rift Valley fever (RVF) is a mosquito-borne infection with great impact on animal and human health. The objectives of this study were to identify ecological factors that explain the risk of RVF outbreaks in eastern and central Kenya and to produce a spatially explicit risk map. METHODS: The sensitivity of seven selected ecological variables to RVF occurrence was assessed by generalized linear modelling (GLM). Vegetation seasonality variables (from normalized difference vegetation index (NDVI) data) and 'evapotranspiration' (ET) (metrics) were obtained from 0.25-1km MODIS satellite …

The Epidemiology of Rift Valley Fever in Mayotte: Insights and Perspectives from 11 Years of Data.

Rift Valley fever (RVF) is a zoonotic arboviral disease that is a threat to human health, animal health and production, mainly in Sub-Saharan Africa. RVF virus dynamics have been poorly studied due to data scarcity. On the island of Mayotte in the Indian Ocean, off the Southeastern African coast, RVF has been present since at least 2004. Several retrospective and prospective serological surveys in livestock have been conducted over eleven years (2004-15). These data are collated and presented here. Temporal patterns of seroprevalence were plotted against time, as well as age-stratified seropre…

Serum levels of inflammatory cytokines in Rift Valley fever patients are indicative of severe disease.

BACKGROUND: Rift Valley fever (RVF) is a mosquito-borne viral zoonosis affecting domestic and wild ruminants, camels and humans. Outbreaks of RVF are characterized by a sudden onset of abortions and high mortality amongst domestic ruminants. Humans develop disease ranging from a mild flu-like illness to more severe complications including hemorrhagic syndrome, ocular and neurological lesions and death. During the RVF outbreak in South Africa in 2010/11, a total of 278 human cases were laboratory confirmed, including 25 deaths. The role of the host inflammatory response to RVF pathogenesis is n…

Inhibition of Rift Valley fever virus replication and perturbation of nucleocapsid-RNA interactions by suramin.

Rift Valley fever virus (RVFV) is an emerging infectious pathogen that causes severe disease in humans and livestock and has the potential for global spread. There are currently no proven safe and effective treatment options for RVFV infection. Inhibition of RNA binding to RVFV nucleocapsid protein (N) represents an attractive antiviral therapeutic strategy because several essential steps in the RVFV replication cycle involve N binding to viral RNA. In this study, we demonstrate the therapeutic potential of the drug suramin by showing that it functions well as an inhibitor of RVFV replication …

Potential for populations of Aedes j. japonicus to transmit Rift Valley fever virus in the USA.

Aedes japonicus japonicus was introduced into the northeastern USA in 1998 and has since spread to more than 25 states. Because this species has been shown to be a competent laboratory vector of several viruses, readily feeds on large mammals, and has become a pest in several areas, there is concern that it might serve as a vector of Rift Valley fever virus (RVFV) should that virus be introduced into North America. Infection with RVFV causes mortality in > 90% of young domestic ungulates (e.g., calves, kids, and lambs), as well as causing a febrile illness and occasional deaths in humans. Ther…

The risk of Rift Valley fever virus introduction and establishment in the United States and European Union.

Rift Valley fever virus (RVFV) is an arthropod-borne disease resulting in severe morbidity and mortality in both human and ruminant populations. First identified in Kenya in 1930, the geographical range of RVFV has been largely constrained to the African continent, yet has recently spread to new regions, and is identified as a priority disease with potential for geographic emergence. We present a systematic literature review assessing the potential for RVFV introduction and establishment in the United States (US) and European Union (EU). Viable pathways for the introduction of RVFV include: tr…

[Assessment of the risk of introduction to Tunisia of the Rift Valley fever virus by the mosquito Culex pipiens].

The mosquito Culex pipiens has been involved as vector of the West Nile virus in Tunisia. Its bio-ecological characteristics in combination with some environmental factors have favoured the emergence of this virus in a West-Nile free zone. This leads to question about the potential risk of introducing another arbovirus, the Rift Valley fever (RVF) virus, in Tunisia from neighbouring countries where RVF circulates. In this study, we have evaluated the vector competence of different populations of Cx. pipiens towards two strains of RVF virus, the virulent ZH548 and the avirulent Clone 13 by expe…

Sequential Rift Valley fever outbreaks in eastern Africa caused by multiple lineages of the virus.

BACKGROUND: During the Rift Valley fever (RVF) epidemic of 2006-2007 in eastern Africa, spatial mapping of the outbreaks across Kenya, Somalia, and Tanzania was performed and the RVF viruses were isolated and genetically characterized. METHODS: Following confirmation of the RVF epidemic in Kenya on 19 December 2006 and in Tanzania on 2 February 2007, teams were sent to the field for case finding. Human, livestock, and mosquito specimens were collected and viruses isolated. The World Health Organization response team in Kenya worked with the WHO's polio surveillance team inside Somalia to coll…

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 a virus neutralization test. Compared to standard colorimetric S-ELISA, the OFIS technique was more…

Development of a diagnostic one-tube RT-PCR for the detection of Rift Valley fever virus.

Diagnosis of Rift Valley fever (RVF) is based on serology and virus isolation. The disadvantages of the former include poor sensitivity, high cost, risks associated with using infectious virus as antigen, the lengthy duration of ELISA as well as cross-reactivity with other Phleboviruses. We developed, optimised and evaluated a one-tube reverse-transcription-polymerase chain reaction (RT-PCR) for the detection of Rift Valley fever virus (RVFV) in ruminants. The PCR primers for this assay were designed to anneal to a region within the M segment of the virus genome, encoding glycoproteins G1 and …

Safety of a mutagen-attenuated Rift Valley fever virus vaccine in fetal and neonatal bovids.

OBJECTIVE: 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. ANIMALS: 18 pregnant Hereford and Hereford-type cows in the third or fifth month of gestation, their progeny, and 25 calves from cows immunized with RVF MP-12 during pregnancy. PROCEDURE: Bovine fetuses were inoculated, via laparotomy, with 1 ml of RVF MP-12 containing 5 log10 plaque-forming units (PFU) of virus. Blood was obtained from newborn calves prior to their inge…

Сопоставление патогенности для беременных овец вируса лихорадки Рифт-Вэлли и живой вакцины с ослабленным состоянием.

Живой мутант вируса лихорадки Рифт-Вэлли (MV P12) ранее был продемонстрирован как непатогенный у молодых ягнят, но способный обеспечить защитный иммунитет. Представленные здесь исследования показывают, что аборт на овцах, вызванный инфекцией вирусом вирулентности, является результатом некроза материнского вилли и котильдона, вызванного острым воспалением материнских кранов. Беременные овцы, инфицированные смягченным вирусом мутантов MV P12, не показали ни одного из этих повреждений в плаценте и родили здоровых ягнят. Колострум от овечек, инфицированных вирусом MV P12, смог вызвать защитный имм

Совпадение в аннотации оригинала
A live attenuated mutant of Rift Valley fever virus, MV P12, was previously shown to be non-pathogenic in young lambs, but capable of producing protective immunity. The studies reported here show that the abortion in sheep caused by an infection with virulent virus is the result of necrosis of the maternal villi and cotyledons arising from an acute inflammat…

[Evaluation of indicators of health in the area of Trarza during the epidemic of Rift Valley fever in 1987].

Randomized epidemiological studies conducted inside the Rift Valley fever epidemic area permitted an estimate of the different epidemiological rates. For the town of Rosso, the total number of infected persons was estimated at 9,320, the total number of symptomatic diseases at 1,013 and the number of deaths at 47. The minimal number of deaths for the area which had access to the hospital was 232. The immunity rate in the town was 34.89% after the epidemic. The ELISA test was used to test human and animal IgG and IgM antibodies. Human samples were collected using the "confetti" technique. After…