scholarly journals Development and Assessment of Localized Seasonal Rainfall Prediction Models: Mapping and Characterizing Rift Valley Fever Hotspot Areas in the Southern and Southeastern Ethiopia

2018 ◽  
Vol 11 (5) ◽  
pp. 102
Author(s):  
Ephrem Weledekidane
Keyword(s):  
East Africa ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Large Scale ◽  
Prediction Models ◽  
Rainfall Anomaly ◽  
Seasonal Rainfall ◽  
Valley Fever ◽  
Average Rainfall ◽  
Early Indicators

Rift Valley Fever disease has been recognized as being among permanent threats for the sustainability of livestock production in Ethiopia, owing to shared boarders with RVF endemic countries in East Africa. Above-normal and widespread rainfall have outweighed as immediate risk factor that facilitated historical outbreaks of the disease in the East Africa. The objective of the present study, thus, was to develop prospective localized seasonal rainfall anomaly prediction models, and assess their skills as early indicators to map high risk localized rift valley fever disease outbreak areas (hotspots) over the southern and southeastern part of Ethiopia. 21 years of daily rainfall data; for five meteorological stations, was employed in diagnosing existences of any anomalous patterns of rainfall, along with a cumulative rainfall analysis to determine if there were ideal conditions for potential flooding. The results indicated that rainfall in the region is highly variable; with non-significant trends, and attributed to be the results of the effects of large-scale climatic-teleconnection. The moderate to strong positive correlations found between the regional average rainfall and large scale teleconnection variables (r ≥ 0.48), indicated some potentials for early prediction of seasonal patterns of rainfall. Accordingly, models developed, based on the regional average rainfall and emerging developments of El Niño/Southern Oscillation and other regional climate forcings, showed maximum skills (ROC scores ≥ 0.7) and moderate reliability. Deterministically, most of the positive rainfall anomaly patterns, corresponding to El Niño years, were portrayed with some skills. The study demonstrated that localized climate prediction models are invaluable as early indicators to skillfully map climatically potential RVF hotspot areas.

Rift Valley fever virus activity in East Africa in 1989

1992 ◽  
Vol 130 (12) ◽  
pp. 247-249 ◽  
Author(s):  
F. Davies ◽  
T. Logan ◽  
Y. Binepal ◽  
P. Jessen
Keyword(s):  
East Africa ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Fever Virus ◽  
Valley Fever ◽  
Virus Activity

scholarly journals Genetic Reassortment of Rift Valley Fever Virus in Nature

1999 ◽  
Vol 73 (10) ◽  
pp. 8196-8200 ◽  
Author(s):  
A. A. Sall ◽  
P. M. de A. Zanotto ◽  
O. K. Sene ◽  
H. G. Zeller ◽  
J. P. Digoutte ◽  
...  
Keyword(s):  
East Africa ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Statistical Tests ◽  
Direct Sequencing ◽  
Fever Virus ◽  
Human Populations ◽  
Sylvatic Cycle ◽  
Valley Fever

ABSTRACT Rift Valley fever virus (RVFV), a phlebovirus of theBunyaviridae family, is an arthropod-borne virus which emerges periodically throughout Africa, emphasizing that it poses a major threat for animal and human populations. To assess the genetic variability of RVFV, several isolates from diverse localities of Africa were investigated by means of reverse transcription-PCR followed by direct sequencing of a region of the small (S), medium (M), and large (L) genomic segments. Phylogenetic analysis showed the existence of three major lineages corresponding to geographic variants from West Africa, Egypt, and Central-East Africa. However, incongruences detected between the L, M, and S phylogenies suggested that genetic exchange via reassortment occurred between strains from different lineages. This hypothesis, depicted by parallel phylogenies, was further confirmed by statistical tests. Our findings, which strongly suggest exchanges between strains from areas of endemicity in West and East Africa, strengthen the potential existence of a sylvatic cycle in the tropical rain forest. This also emphasizes the risk of generating uncontrolled chimeric viruses by using live attenuated vaccines in areas of endemicity.

scholarly journals Large-Scale International Validation of an Indirect ELISA Based on Recombinant Nucleocapsid Protein of Rift Valley Fever Virus for the Detection of IgG Antibody in Domestic Ruminants

Viruses ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1651
Author(s):  
Janusz T. Pawęska ◽  
Petrus Jansen van Vuren ◽  
Veerle Msimang ◽  
Modu Moustapha Lô ◽  
Yaya Thiongane ◽  
...  
Keyword(s):  
Rift Valley ◽  
Nucleocapsid Protein ◽  
Rift Valley Fever ◽  
Large Scale ◽  
Rift Valley Fever Virus ◽  
Fever Virus ◽  
Enzyme Linked Immunosorbent Assay ◽  
Igg Antibody ◽  
Valley Fever ◽  
Recombinant Nucleocapsid Protein

Diagnostic performance of an indirect enzyme-linked immunosorbent assay (I-ELISA) based on a recombinant nucleocapsid protein (rNP) of the Rift Valley fever virus (RVFV) was validated for the detection of the IgG antibody in sheep (n = 3367), goat (n = 2632), and cattle (n = 3819) sera. Validation data sets were dichotomized according to the results of a virus neutralization test in sera obtained from RVF-endemic (Burkina Faso, Democratic Republic of Congo, Mozambique, Senegal, Uganda, and Yemen) and RVF-free countries (France, Poland, and the USA). Cut-off values were defined using the two-graph receiver operating characteristic analysis. Estimates of the diagnostic specificity of the RVFV rNP I-ELISA in animals from RVF-endemic countries ranged from 98.6% (cattle) to 99.5% (sheep) while in those originating from RVF-free countries, they ranged from 97.7% (sheep) to 98.1% (goats). Estimates of the diagnostic sensitivity in ruminants from RVF-endemic countries ranged from 90.7% (cattle) to 100% (goats). The results of this large-scale international validation study demonstrate the high diagnostic accuracy of the RVFV rNP I-ELISA. Standard incubation and inactivation procedures evaluated did not have an adverse effect on the detectable levels of the anti-RVFV IgG in ruminant sera and thus, together with recombinant antigen-based I-ELISA, provide a simple, safe, and robust diagnostic platform that can be automated and carried out outside expensive bio-containment facilities. These advantages are particularly important for less-resourced countries where there is a need to accelerate and improve RVF surveillance and research on epidemiology as well as to advance disease control measures.

scholarly journals Rift Valley fever - a threat for Europe?

2010 ◽  
Vol 15 (10) ◽  
Author(s):  
V Chevalier ◽  
M Pépin ◽  
L Plée ◽  
R Lancelot
Keyword(s):  
Rift Valley ◽  
Rift Valley Fever ◽  
Large Scale ◽  
Large Population ◽  
Diagnostic Methods ◽  
Monitoring And Control ◽  
Valley Fever ◽  
Control Programmes ◽  
Eastern And Southern Africa ◽  
And Control

Rift Valley fever (RVF) is a severe mosquito-borne disease affecting humans and domestic ruminants, caused by a Phlebovirus (Bunyaviridae). It is widespread in Africa and has recently spread to Yemen and Saudi Arabia. RVF epidemics are more and more frequent in Africa and the Middle East, probably in relation with climatic changes (episodes of heavy rainfall in eastern and southern Africa), as well as intensified livestock trade. The probability of introduction and large-scale spread of RVF in Europe is very low, but localised RVF outbreaks may occur in humid areas with a large population of ruminants. Should this happen, human cases would probably occur in exposed individuals: farmers, veterinarians, slaughterhouse employees etc. Surveillance and diagnostic methods are available, but control tools are limited: vector control is difficult to implement, and vaccines are only available for ruminants, with either a limited efficacy (inactivated vaccines) or a residual pathogenic effect. The best strategy to protect Europe and the rest of the world against RVF is to develop more efficient surveillance and control tools and to implement coordinated regional monitoring and control programmes.

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