Reconstruction of Rift Valley fever transmission dynamics in Madagascar: estimation of force of infection from seroprevalence surveys using Bayesian modelling

Olive, Marie-Marie; Grosbois, Vladimir; Tran, Annelise; Nomenjanahary, Lalaina Arivony; Rakotoarinoro, Mihaja; Andriamandimby, Soa Fy; Rogier, Christophe; Héraud, Jean Michel; Chevalier, Véronique

doi:10.1038/srep39870

Cited by 16 publications

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References 42 publications

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“…Since its first recognition in 1931 in Kenya, RVF outbreaks have been regularly reported in sub-Saharan Africa [10][11][12][13][14][15][16], the Indian Ocean [17,18] and the Arabian Peninsula [19]. The most recent outbreaks occurred in Mauritania (2015), Niger (2016), Uganda (2016) and Mayotte (2018-2019) [10,[20][21][22].…”

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confidence: 99%

Rift Valley fever in northern Senegal: A modelling approach to analyse the processes underlying virus circulation recurrence

et al. 2020

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Rift Valley fever (RVF) is endemic in northern Senegal, a Sahelian area characterized by a temporary pond network that drive both RVF mosquito population dynamics and nomadic herd movements. To investigate the mechanisms that explain RVF recurrent circulation, we modelled a realistic epidemiological system at the pond level integrating vector population dynamics, resident and nomadic ruminant herd population dynamics, and nomadic herd movements recorded in Younoufere area. To calibrate the model, serological surveys were performed in 2015-2016 on both resident and nomadic domestic herds in the same area. Mosquito population dynamics were obtained from a published model trained in the same region. Model comparison techniques were used to compare five different scenarios of virus introduction by nomadic herds associated or not with vertical transmission in Aedes vexans. Our serological results confirmed a long lasting RVF endemicity in resident herds (IgG seroprevalence rate of 15.3%, n = 222), and provided the first estimation of RVF IgG seroprevalence in nomadic herds in West Africa (12.4%, n = 660). Multivariate analysis of serological data suggested an amplification of the transmission cycle during the rainy season with a peak of circulation at the end of that season. The best scenario of virus introduction combined yearly introductions of RVFV from 2008 to 2015 (the study period) by nomadic herds, with a proportion of viraemic individuals predicted to be larger in animals arriving during the 2 nd half of the rainy season (3.4%). This result is coherent with the IgM prevalence rate (4%) found in nomadic herds sampled during the 2 nd half of the rainy season. Although the existence of a vertical transmission mechanism in Aedes cannot be ruled out, our model demonstrates that nomadic movements are sufficient to account for this endemic circulation in northern Senegal.

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Section: Introductionmentioning

confidence: 99%

Rift Valley fever in northern Senegal: A modelling approach to analyse the processes underlying virus circulation recurrence

et al. 2020

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“…This has been motivated by the recent epidemiological situation in the area. Even though the malaria morbidity and mortality has declined on some islands [ 10 , 11 ], the region has faced major outbreaks of chikungunya [ 12 – 15 ] and endemic circulation of dengue virus [ 16 , 17 ], West Nile virus [ 18 , 19 ], Rift valley fever virus [ 20 – 26 ], bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) [ 27 – 30 ] among others.…”

Section: Introductionmentioning

confidence: 99%

Culicoides Latreille in the sun: faunistic inventory of Culicoides species (Diptera: Ceratopogonidae) in Mayotte (Comoros Archipelago, Indian Ocean)

Garros

Labuschagne

Dommergues³

et al. 2019

Parasites Vectors

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BackgroundThe south-west insular territories of the Indian Ocean have recently received attention concerning the diversity of arthropods of medical or veterinary interest. While a recent study highlighted the circulation of Culicoides-borne viruses, namely bluetongue and epizootic hemorrhagic disease, with clinical cases in Mayotte (comprising two islands, Petite-Terre and Grand-Terre), Comoros Archipelago, no data have been published concerning the species diversity of Culicoides present on the two islands.ResultsA total of 194,734 biting midges were collected in 18 sites, covering two collection sessions (April and June) in Mayotte. Our study reports for the first time livestock-associated Culicoides species and recorded at least 17 described Afrotropical species and one undescribed species. The most abundant species during the April collection session were C. trifasciellus (84.1%), C. bolitinos (5.4%), C. enderleini (3.9%), C. leucostictus (3.3%) and C. rhizophorensis (2.1%). All other species including C. imicola represented less than 1% of the total collection. Abundance ranged between 126–78,842 females with a mean and median abundance of 14,338 and 5111 individuals/night/site, respectively. During the June collection, the abundance per night was low, ranging between 6–475 individuals. Despite low abundance, C. trifasciellus and C. bolitinos were still the most abundant species. Culicoides sp. #50 is recorded for the first time outside South Africa.ConclusionsOur study reports for the first time the Culicoides species list for Mayotte, Comoros Archipelago, Indian Ocean. The low abundance and rare occurrence of C. imicola, which is usually considered the most abundant species in the Afrotropical region, is unexpected. The most abundant and frequent species is C. trifasciellus, which is not considered as a vector species so far, but its role needs further investigation. Further work is needed to describe Culicoides sp. #50 and to carry on faunistic investigations on the other islands of the archipelago as well as in neighboring countries.Electronic supplementary materialThe online version of this article (10.1186/s13071-019-3379-x) contains supplementary material, which is available to authorized users.

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“…Since its first recognition in 1931 in Kenya, RVF outbreaks have been regularly reported in sub-Saharan Africa [12–18], Indian Ocean [19, 20] and Arabic Peninsula [21]. The most recent outbreaks occurred in Mauritania (2015), Niger (2016), Uganda (2016) and Mayotte (2018-2019) [12, 22–24].…”

Section: Introductionmentioning

confidence: 99%

Rift Valley fever in northern Senegal : a modelling approach to analyse the processes underlying virus circulation recurrence

Durand

Modou

Tran

et al. 2019

Preprint

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23 24 2 25 Abstract: 26 Rift Valley fever (RVF) is endemic in northern Senegal, a Sahelian area characterized by a temporary 27 pond network that drive both RVF mosquito population dynamics and nomadic herd movements. To 28 investigate the mechanisms that explain RVF recurrent circulation, we modelled a realistic 29 epidemiological system at the pond level integrating vector population dynamics, resident and nomadic 30 ruminant herd population dynamics, and nomadic herd movements recorded in Younoufere area [1]. To 31 calibrate the model, serological surveys were performed in 2015-2016 on both resident and nomadic 32 herds in the same area. Mosquito population dynamics were obtained from a published model trained in 33 the same region [2]. Model comparison techniques were used to compare five different scenarios of 34 virus introduction by nomadic herds associated or not with vertical transmission in Aedes vexans. Our 35 serological results confirmed a long lasting RVF endemicity in resident herds (IgG seroprevalence rate 36 of 15.3%, n=222), and provided the first estimation of RVF IgG seroprevalence in nomadic herds in 37 West Africa (12.4%, n=660). Multivariate analysis of serological data suggested an amplification of the 38 transmission cycle during the rainy season with a peak of circulation at the end of that season. The best 39 scenario of virus introduction combined yearly introductions of RVFV from 2008 to 2015 (the study 40 period) by nomadic herds, with a proportion of viraemic individuals predicted to be larger in animals 41 arriving during the 2 nd half of the rainy season (3.4%). This result is coherent with the IgM prevalence 42 rate (4%) found in nomadic herds sampled during the 2 nd half of the rainy season. Although the existence 43 of a vertical transmission mechanism in Aedes cannot be ruled out, our model demonstrates that nomadic 44 movements are sufficient to account for this endemic circulation in northern Senegal. 45 46 3 47 Author summary: 48 Rift Valley fever (RVF) is one of the most important vector borne disease in Africa, seriously affecting 49 the health of domestic ruminants and humans and leading to severe economic consequences. This 50 disease is endemic in northern Senegal, a Sahelian area characterized by a temporary pond network that 51 drive both RVF mosquito population dynamics and nomadic herd movements. Two non-exclusive 52 mechanisms may support this endemicity: recurrent introductions of the virus by nomadic animals, and 53 vertical transmission of the virus (i.e. from infected female mosquito to eggs) in local Aedes populations. 54 The authors followed up during 1 year resident and nomadic herds. They used the data thus obtained to 55 model a realistic epidemiological system at the pond level integrating vector population dynamics, 56 resident and nomadic ruminant herd population dynamics. They found that the best scenario explaining 57 RVF remanence combined yearly introductions of RVFV by nomadic herds, with a proportion of 58 viraemic predicted to be larger in anima...

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Reconstruction of Rift Valley fever transmission dynamics in Madagascar: estimation of force of infection from seroprevalence surveys using Bayesian modelling

Cited by 16 publications

References 42 publications

Rift Valley fever in northern Senegal: A modelling approach to analyse the processes underlying virus circulation recurrence

Rift Valley fever in northern Senegal: A modelling approach to analyse the processes underlying virus circulation recurrence

Culicoides Latreille in the sun: faunistic inventory of Culicoides species (Diptera: Ceratopogonidae) in Mayotte (Comoros Archipelago, Indian Ocean)

Rift Valley fever in northern Senegal : a modelling approach to analyse the processes underlying virus circulation recurrence

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