scholarly journals Sequential Rift Valley Fever Outbreaks in Eastern Africa Caused by Multiple Lineages of the Virus

2010 ◽  
Vol 203 (5) ◽  
pp. 655-665 ◽  
Author(s):  
Leonard Nderitu ◽  
John S. Lee ◽  
Jared Omolo ◽  
Sylvia Omulo ◽  
Monica L. O'Guinn ◽  
...  
2010 ◽  
Vol 83 (2_Suppl) ◽  
pp. 38-42 ◽  
Author(s):  
Wun-Ju Shieh ◽  
Robert F. Breiman ◽  
Fausta Mosha ◽  
Peter Bloland ◽  
Carol Y. Rao ◽  
...  

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Jacqueline Kasiiti Lichoti ◽  
Absolomon Kihara ◽  
Abuu A. Oriko ◽  
Leonard Ateya Okutoyi ◽  
James Ogaa Wauna ◽  
...  

Rift Valley fever virus causes an important zoonotic disease of humans and small ruminants in Eastern Africa and is spread primarily by a mosquito vector. In this region, it occurs as epizootics that typically occur at 5–15-year intervals associated with unusual rainfall events. It has hitherto been known that the virus is maintained between outbreaks in dormant eggs of the mosquito vector and this has formed the basis of understanding of the epidemiology and control strategies of the disease. We show here that seroconversion and sporadic acute disease do occur during the interepidemic periods (IEPs) in the absence of reported cases in livestock or humans. The finding indicates that previously undetected low-level virus transmission during the IEPs does occur and that epizootics may also be due to periodic expansion of mosquito vectors in the presence of both circulating virus and naïve animals.


2016 ◽  
Vol 11 (1s) ◽  
Author(s):  
Joseph Leedale ◽  
Anne E. Jones ◽  
Cyril Caminade ◽  
Andrew P. Morse

Outbreaks of Rift Valley fever (RVF) in eastern Africa have previously occurred following specific rainfall dynamics and flooding events that appear to support the emergence of large numbers of mosquito vectors. As such, transmission of the virus is considered to be sensitive to environmental conditions and therefore changes in climate can impact the spatiotemporal dynamics of epizootic vulnerability. Epidemiological information describing the methods and parameters of RVF transmission and its dependence on climatic factors are used to develop a new spatio-temporal mathematical model that simulates these dynamics and can predict the impact of changes in climate. The Liverpool RVF (LRVF) model is a new dynamic, process-based model driven by climate data that provides a predictive output of geographical changes in RVF outbreak susceptibility as a result of the climate and local livestock immunity. This description of the multi-disciplinary process of model development is accessible to mathematicians, epidemiological modellers and climate scientists, uniting dynamic mathematical modelling, empirical parameterisation and state-of-the-art climate information.


Viruses ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1453
Author(s):  
Gian Mario Cosseddu ◽  
Kudakwashe Magwedere ◽  
Umberto Molini ◽  
Chiara Pinoni ◽  
Sigfried Khaiseb ◽  
...  

Outbreaks of Rift Valley fever (RVF) occurred in Namibia in 2010 and 2011. Complete genome characterization was obtained from virus isolates collected during disease outbreaks in southern Namibia in 2010 and from wildlife in Etosha National Park in 2011, close to the area where RVF outbreaks occurred in domestic livestock. The virus strains were sequenced using Sanger sequencing (Namibia_2010) or next generation sequencing (Namibia_2011). A sequence-independent, single-primer amplification (SISPA) protocol was used in combination with the Illumina Next 500 sequencer. Phylogenetic analysis of the sequences of the small (S), medium (M), and large (L) genome segments of RVF virus (RVFV) provided evidence that two distinct RVFV strains circulated in the country. The strain collected in Namibia in 2010 is genetically similar to RVFV strains circulating in South Africa in 2009 and 2010, confirming that the outbreaks reported in the southern part of Namibia in 2010 were caused by possible dissemination of the infection from South Africa. Isolates collected in 2011 were close to RVFV isolates from 2010 collected in humans in Sudan and which belong to the large lineage containing RVFV strains that caused an outbreak in 2006–2008 in eastern Africa. This investigation showed that the RVFV strains circulating in Namibia in 2010 and 2011 were from two different introductions and that RVFV has the ability to move across regions. This supports the need for risk-based surveillance and monitoring.


2016 ◽  
Vol 11 (1s) ◽  
Author(s):  
David Taylor ◽  
Michael Hagenlocher ◽  
Anne E. Jones ◽  
Stefan Kienberger ◽  
Joseph Leedale ◽  
...  

Outbreaks of Rift Valley fever (RVF), a relatively recently emerged zoonosis endemic to large parts of sub-Saharan Africa that has the potential to spread beyond the continent, have profound health and socio-economic impacts, particularly in communities where resilience is already low. Here output from a new, dynamic disease model [the Liverpool RVF (LRVF) model], driven by downscaled, bias-corrected climate change data from an ensemble of global circulation models from the Inter-Sectoral Impact Model Intercomparison Project run according to two radiative forcing scenarios [representative concentration pathway (RCP)4.5 and RCP8.5], is combined with results of a spatial assessment of social vulnerability to the disease in eastern Africa. The combined approach allowed for analyses of spatial and temporal variations in the risk of RVF to the end of the current century. Results for both scenarios highlight the high-risk of future RVF outbreaks, including in parts of eastern Africa to date unaffected by the disease. The results also highlight the risk of spread from/to countries adjacent to the study area, and possibly farther afield, and the value of considering the geography of future projections of disease risk. Based on the results, there is a clear need to remain vigilant and to invest not only in surveillance and early warning systems, but also in addressing the socio-economic factors that underpin social vulnerability in order to mitigate, effectively, future impacts.


2016 ◽  
Vol 10 (9) ◽  
pp. e0004999 ◽  
Author(s):  
Annelise Tran ◽  
Carlène Trevennec ◽  
Julius Lutwama ◽  
Joseph Sserugga ◽  
Marie Gély ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document