Effects of Irrigation and Rainfall on the Population Dynamics of Rift Valley Fever and Other Arbovirus Mosquito Vectors in the Epidemic-Prone Tana River County, Kenya

Sang, Rosemary; Lutomiah, Joel; Said, Mohammed Yahya; Makio, Albina; Koka, Hellen; Koskei, Edith; Nyunja, Albert; Owaka, Samuel; Matoke-Muhia, Damaris; Bukachi, Salome A.; Lindahl, Johanna F.; Grace, Delia; Bett, Bernard K.

doi:10.1093/jme/tjw206

Cited by 25 publications

(24 citation statements)

References 45 publications

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“…Studies using global records of each species found that temperature is the most influential predictor and that precipitation, vegetation indices and urban land cover also play a role [ 33 , 65 ]. Few studies have looked at these relationships in African populations, but temperature is still likely to be important [ 66 , 67 ] and rainfall is strongly linked to Aedes vector abundance in Kenyan populations [ 68 ]. Specific landscape factors are more likely to vary between different regions of the world and the influence of some of these have been studied in African locations.…”

Section: Range and Distribution Of Aedes Vectormentioning

confidence: 99%

Aedes Mosquitoes and Aedes-Borne Arboviruses in Africa: Current and Future Threats

Weetman

Kamgang

Badolo

et al. 2018

IJERPH

197

203

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The Zika crisis drew attention to the long-overlooked problem of arboviruses transmitted by Aedes mosquitoes in Africa. Yellow fever, dengue, chikungunya and Zika are poorly controlled in Africa and often go unrecognized. However, to combat these diseases, both in Africa and worldwide, it is crucial that this situation changes. Here, we review available data on the distribution of each disease in Africa, their Aedes vectors, transmission potential, and challenges and opportunities for Aedes control. Data on disease and vector ranges are sparse, and consequently maps of risk are uncertain. Issues such as genetic and ecological diversity, and opportunities for integration with malaria control, are primarily African; others such as ever-increasing urbanization, insecticide resistance and lack of evidence for most control-interventions reflect problems throughout the tropics. We identify key knowledge gaps and future research areas, and in particular, highlight the need to improve knowledge of the distributions of disease and major vectors, insecticide resistance, and to develop specific plans and capacity for arboviral disease surveillance, prevention and outbreak responses.

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Section: Range and Distribution Of Aedes Vectormentioning

confidence: 99%

Aedes Mosquitoes and Aedes-Borne Arboviruses in Africa: Current and Future Threats

Weetman

Kamgang

Badolo

et al. 2018

IJERPH

197

203

View full text Add to dashboard Cite

show abstract

“…Each of these vectors may have specific bioecology and population dynamics. While future research should aim at collecting such data, in their absence, we used rainfall as a proxy for the presence of RVF vectors, as it was found to be associated with the occurrence of RVF outbreaks (17,20). We assumed a 14-d lag between rainfall and its impact on vector abundance based on previous modeling studies on RVF vector population dynamics (21,22).…”

Section: Discussionmentioning

confidence: 99%

Estimation of Rift Valley fever virus spillover to humans during the Mayotte 2018–2019 epidemic

Métras

Edmunds

Youssouffi³

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Rift Valley fever (RVF) is an emerging, zoonotic, arboviral hemorrhagic fever threatening livestock and humans mainly in Africa. RVF is of global concern, having expanded its geographical range over the last decades. The impact of control measures on epidemic dynamics using empirical data has not been assessed. Here, we fitted a mathematical model to seroprevalence livestock and human RVF case data from the 2018–2019 epidemic in Mayotte to estimate viral transmission among livestock, and spillover from livestock to humans through both direct contact and vector-mediated routes. Model simulations were used to assess the impact of vaccination on reducing the epidemic size. The rate of spillover by direct contact was about twice as high as vector transmission. Assuming 30% of the population were farmers, each transmission route contributed to 45% and 55% of the number of human infections, respectively. Reactive vaccination immunizing 20% of the livestock population reduced the number of human cases by 30%. Vaccinating 1 mo later required using 50% more vaccine doses for a similar reduction. Vaccinating only farmers required 10 times as more vaccine doses for a similar reduction in human cases. Finally, with 52.0% (95% credible interval [CrI] [42.9–59.4]) of livestock immune at the end of the epidemic wave, viral reemergence in the next rainy season (2019–2020) is unlikely. Coordinated human and animal health surveillance, and timely livestock vaccination appear to be key to controlling RVF in this setting. We furthermore demonstrate the value of a One Health quantitative approach to surveillance and control of zoonotic infectious diseases.

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“…Rainfall is a known driver for RVF virus transmission (19) and was used as a proxy for vector abundance. We assumed a 14-days lag between rainfall and its impact on vector abundance based on previous modelling studies on RVF vectors population dynamics (20,21).…”

Section: Discussionmentioning

confidence: 99%

Estimation of Rift Valley fever virus spillover to humans during the Mayotte 2018-2019 epidemic

Métras

Edmunds²,

Youssouffi³

et al. 2020

Preprint

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Rift Valley fever (RVF) is an emerging, zoonotic, arboviral haemorrhagic fever threatening livestock and humans mainly in Africa. RVF is of global concern, having expanded its geographical range over the last decades. The impact of control measures on epidemic dynamics using empirical data has not been assessed. Here, we combined seroprevalence livestock and human RVF case data from the 2018-2019 epidemic in Mayotte, with a dynamic mathematical model. Using a Bayesian inference framework, we estimated viral transmission potential amongst livestock, and spillover from livestock to humans, through both direct contact and vector-mediated routes. Model simulations were used to assess the impact of vaccination on reducing the human epidemic size. Reactive vaccination immunising 20% of the livestock population reduced the number of human cases by 30%. To achieve a similar impact, delaying the vaccination by one month required using 50% more vaccine doses, and vaccinating only humans required 20 times as more as the number of doses for livestock. Finally, with 53. ) of livestock estimated to be immune at the end of the epidemic wave, viral re-emergence in the next rainy season (2019-2020) was unlikely. We present the first mathematical model for RVF fitted to real-world data to estimate virus transmission parameters, and able to inform potential control programmes. Human and animal health surveillance, and timely livestock vaccination appear to be key in reducing disease risk in humans. We furthermore demonstrate the value of a One Health quantitative approach to surveillance and control of zoonotic infectious diseases.

show abstract

Effects of Irrigation and Rainfall on the Population Dynamics of Rift Valley Fever and Other Arbovirus Mosquito Vectors in the Epidemic-Prone Tana River County, Kenya

Cited by 25 publications

References 45 publications

Aedes Mosquitoes and Aedes-Borne Arboviruses in Africa: Current and Future Threats

Aedes Mosquitoes and Aedes-Borne Arboviruses in Africa: Current and Future Threats

Estimation of Rift Valley fever virus spillover to humans during the Mayotte 2018–2019 epidemic

Estimation of Rift Valley fever virus spillover to humans during the Mayotte 2018-2019 epidemic

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