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Quellec J, Piro-Megy C, Cannac M, Nisole S, Marty FH, Gosselet F, Shimizu F, Kanda T, Cêtre-Sossah C, Salinas S. Rift Valley fever virus is able to cross the human blood-brain barrier in vitro by direct infection with no deleterious effects. J Virol 2024:e0126724. [PMID: 39345143 DOI: 10.1128/jvi.01267-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2024] [Accepted: 09/11/2024] [Indexed: 10/01/2024] Open
Abstract
Rift Valley fever (RVF) is a zoonotic arboviral disease that causes recurrent epidemics in Africa that may trigger fatal neurological disorders. However, the mechanisms of neuroinvasion by which the RVF virus (RVFV) reaches the human central nervous system (CNS) remain poorly characterized. In particular, it is not clear how RVFV is able to cross the human blood-brain barrier (hBBB), which is a neurovascular endothelium that protects the brain by regulating brain and blood exchanges. To explore these mechanisms, we used an in vitro hBBB model to mimic in vivo hBBB selectiveness and apicobasal polarity. Our results highlight the ability of RVFV to cross the hBBB by direct infection in a non-structural protein S (NSs)-independent but strain-dependent manner, leading to astrocyte and pericyte infections. Interestingly, RVFV infection did not induce hBBB disruption and was associated with progressive elimination of infected cells with no impairment of the tight junction protein scaffold and barrier function. Our work also shows that NSs, a well described RVFV virulence factor, limited the establishment of the hBBB-induced innate immune response and subsequent lymphocyte recruitment. These results provide in vitro confirmation of the ability of RVFV to reach human CNS by direct infection of the hBBB without altering its barrier function, and provide new directions to explore human RVFV neurovirulence and neuroinvasion mechanisms.IMPORTANCEThe RVF virus (RVFV) is capable of infecting humans and inducing severe and fatal neurological disorders. Neuropathogenesis and human central nervous system (CNS) invasion mechanisms of RVFV are still unknown, with only historical studies of autopsy data from fatal human cases in the 1980s and exploration studies in rodent models. One of the gaps in understanding RVFV human pathogenesis is how RVFV is able to cross the blood-brain barrier (BBB) in order to reach the human CNS. For the first time, we show that RVFV is able to directly infect cells of the human BBB in vitro to release viral particles into the human CNS, a well-characterized neuroinvasion mechanism of pathogens. Furthermore, we demonstrate strain-dependent variability of this neuroinvasion mechanism, identifying possible viral properties that could be explored to prevent neurological disorders during RVFV outbreaks.
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Affiliation(s)
- Jordan Quellec
- ASTRE, CIRAD, INRAE, University of Montpellier, Montpellier, France
- PCCEI, University of Montpellier, INSERM, Etablissement Français du Sang, Montpellier, France
| | | | - Marion Cannac
- IRIM, CNRS UMR9004, University of Montpellier, Montpellier, France
| | - Sébastien Nisole
- IRIM, CNRS UMR9004, University of Montpellier, Montpellier, France
| | - Florent H Marty
- PCCEI, University of Montpellier, INSERM, Etablissement Français du Sang, Montpellier, France
| | - Fabien Gosselet
- Blood Brain Barrier Laboratory, Faculty of Science Jean Perrin, Artois University, Lens, France
| | - Fumitaka Shimizu
- Department of Neurology and Clinical Neuroscience, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Takashi Kanda
- Department of Neurology and Clinical Neuroscience, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | | | - Sara Salinas
- PCCEI, University of Montpellier, INSERM, Etablissement Français du Sang, Montpellier, France
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O’Neill L, Gubbins S, Reynolds C, Limon G, Giorgakoudi K. The socioeconomic impacts of Rift Valley fever: A rapid review. PLoS Negl Trop Dis 2024; 18:e0012347. [PMID: 39207938 PMCID: PMC11361445 DOI: 10.1371/journal.pntd.0012347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024] Open
Abstract
Rift Valley fever (RVF) is a neglected vector-borne disease which is endemic in many countries across Africa and has seen recent geographical expansions into the Arabian Peninsula. RVF can cause severe infections in both animals and humans. RVF infections in livestock can lead to mass fatalities. In humans, the symptoms are nonspecific and can often lead to misdiagnosis. However, a small proportion progresses to haemorrhagic infection with a significantly higher mortality rate. The culmination of this can cause severe socioeconomic impacts. This review aims to identify the main socioeconomic impacts caused by RVF outbreaks as well as existing knowledge gaps. Ninety-three academic and grey papers were selected, covering 19 countries and 10 methodological approaches. A variety of socioeconomic impacts were found across all levels of society: Livestock trade disruptions consequently impacted local food security, local and national economies. Most livestock farmers in endemic countries are subsistence farmers and so rely on their livestock for sustenance and income. RVF outbreaks resulted in a variety of socioeconomic impacts, e.g., the inability to pay for school fees. Main barriers to vaccine uptake in communities were lack of access, funds, interest along with other social aspects. The occupational risks for women (and pregnant women) are largely unknown. To our knowledge, this is the first review on RVF to highlight the clear knowledge gap surrounding the potential gender differences on risks of RVF exposure, as well as differences on occupational health risk in pastoral communities. Further work is required to fill the gaps identified in this review and inform control policies.
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Affiliation(s)
- Luke O’Neill
- HSRM Department, School of Health and Psychological Sciences, City, University of London, London, United Kingdom
- The Pirbright Institute, Pirbright, United Kingdom
| | | | - Christian Reynolds
- HSRM Department, School of Health and Psychological Sciences, City, University of London, London, United Kingdom
| | | | - Kyriaki Giorgakoudi
- HSRM Department, School of Health and Psychological Sciences, City, University of London, London, United Kingdom
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Becquart P, Bohou Kombila L, Mebaley TN, Paupy C, Garcia D, Nesi N, Olive MM, Vanhomwegen J, Boundenga L, Mombo IM, Piro-Mégy C, Fritz M, Lenguiya LH, Ar Gouilh M, Leroy EM, N’Dilimabaka N, Cêtre-Sossah C, Maganga GD. Evidence for circulation of Rift Valley fever virus in wildlife and domestic animals in a forest environment in Gabon, Central Africa. PLoS Negl Trop Dis 2024; 18:e0011756. [PMID: 38427694 PMCID: PMC10936825 DOI: 10.1371/journal.pntd.0011756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 03/13/2024] [Accepted: 02/10/2024] [Indexed: 03/03/2024] Open
Abstract
Rift Valley fever (RVF) is a mosquito-borne viral zoonosis caused by the Rift Valley fever virus (RVFV) that can infect domestic and wild animals. Although the RVFV transmission cycle has been well documented across Africa in savanna ecosystems, little is known about its transmission in tropical rainforest settings, particularly in Central Africa. We therefore conducted a survey in northeastern Gabon to assess RVFV circulation among wild and domestic animals. Among 163 wildlife samples tested using RVFV-specific RT-qPCR, four ruminants belonging to subfamily Cephalophinae were detected positive. The phylogenetic analysis revealed that the four RVFV sequences clustered together with a virus isolated in Namibia within the well-structured Egyptian clade. A cross-sectional survey conducted on sheep, goats and dogs living in villages within the same area determined the IgG RVFV-specific antibody prevalence using cELISA. Out of the 306 small ruminants tested (214 goats, 92 sheep), an overall antibody prevalence of 15.4% (95% CI [11.5-19.9]) was observed with a higher rate in goats than in sheep (20.1% versus 3.3%). RVFV-specific antibodies were detected in a single dog out of the 26 tested. Neither age, sex of domestic animals nor season was found to be significant risk factors of RVFV occurrence. Our findings highlight sylvatic circulation of RVFV for the first time in Gabon. These results stress the need to develop adequate surveillance plan measures to better control the public health threat of RVFV.
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Affiliation(s)
- Pierre Becquart
- Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Institut de Recherche pour le Développement (IRD), Montpellier University, CNRS, Montpellier, France
| | - Linda Bohou Kombila
- Unité Emergence des Maladies Virales, Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon
| | - Telstar Ndong Mebaley
- Unité Emergence des Maladies Virales, Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon
| | - Christophe Paupy
- Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Institut de Recherche pour le Développement (IRD), Montpellier University, CNRS, Montpellier, France
| | - Déborah Garcia
- Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Institut de Recherche pour le Développement (IRD), Montpellier University, CNRS, Montpellier, France
| | - Nicolas Nesi
- INSERM Dynamicure UMR 1311, CHU Caen, department of virology, University of Caen Normandie, Caen, France
| | - Marie-Marie Olive
- ASTRE (Animaux, Santé, Territoires, Risques et Ecosystèmes), University of Montpellier, CIRAD (Centre de Coopération Internationale en Recherche Agronomique pour le Développement), INRAE (Institut national de recherche pour l’agriculture, l’alimentation et l’environnement), Montpellier, France
| | - Jessica Vanhomwegen
- Cellule d’Intervention Biologique d’Urgence (CIBU), Institut Pasteur, Paris, France
| | - Larson Boundenga
- Unité Emergence des Maladies Virales, Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon
- Department of Anthropology, University of Durham, Durham, United Kingdom
| | - Illich Manfred Mombo
- Unité Emergence des Maladies Virales, Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon
| | - Camille Piro-Mégy
- ASTRE (Animaux, Santé, Territoires, Risques et Ecosystèmes), University of Montpellier, CIRAD (Centre de Coopération Internationale en Recherche Agronomique pour le Développement), INRAE (Institut national de recherche pour l’agriculture, l’alimentation et l’environnement), Montpellier, France
| | - Matthieu Fritz
- Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Institut de Recherche pour le Développement (IRD), Montpellier University, CNRS, Montpellier, France
| | | | - Meriadeg Ar Gouilh
- INSERM Dynamicure UMR 1311, CHU Caen, department of virology, University of Caen Normandie, Caen, France
| | - Eric M. Leroy
- Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Institut de Recherche pour le Développement (IRD), Montpellier University, CNRS, Montpellier, France
| | - Nadine N’Dilimabaka
- Unité Emergence des Maladies Virales, Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon
- Département de Biologie, Faculté des Sciences, Université des Sciences et Techniques de Masuku (USTM), Franceville, Gabon
| | - Catherine Cêtre-Sossah
- ASTRE (Animaux, Santé, Territoires, Risques et Ecosystèmes), University of Montpellier, CIRAD (Centre de Coopération Internationale en Recherche Agronomique pour le Développement), INRAE (Institut national de recherche pour l’agriculture, l’alimentation et l’environnement), Montpellier, France
| | - Gael Darren Maganga
- Unité Emergence des Maladies Virales, Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon
- Institut National Supérieur d’Agronomie et de Biotechnologies (INSAB), Université des Sciences et Techniques de Masuku (USTM), Franceville, Gabon
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Hassan AM, Zehairy AA, Awatif Abid AJ, Sohrab SS, Esam IA. Cloning and phylogenetic analysis of N protein gene from Rift Valley Fever Virus (RVFV). Bioinformation 2024; 20:91-102. [PMID: 38497067 PMCID: PMC10941780 DOI: 10.6026/973206300200091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 02/29/2024] [Accepted: 02/29/2024] [Indexed: 03/19/2024] Open
Abstract
Rift Valley Fever (RVF) is a mosquito-borne viral zoonosis caused by RVFV in humans and livestock. Currently, there are no approved vaccines or antiviral therapies available. Additionally, in Saudi Arabia, there is a lack of a routine screening system to monitor RVFV in humans and animals which hinders to design and develop the preventive measures as well as the prediction of future outbreaks and the potential re-emergence of RVFV. Hence, we have performed the cloning, sequencing, and phylogenetic analysis, of nucleocapsid (N) protein gene. The sequence analysis showed high similarities with RVFV isolates reported from humans and animals. The highest similarity (99.5%) was observed with an isolate from Saudi Arabia (KU978775-Human) followed by 99.1% with four RVFV isolates (Human and Bovine) from other locations. A total of 51 nucleotides and 31 amino acid variations were observed throughout the N protein gene sequences. The phylogenetic relationship formed closed clusters with other isolates collected from Saudi Arabia. Thus, we report of the cloning, sequencing, and phylogenetic analysis of the RVFV-N protein gene from Saudi Arabia.
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Affiliation(s)
- Ahmed Mohamed Hassan
- Special Infectious Agents Unit, King Fahd Medical Research Centre, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Arwa Ahmed Zehairy
- Special Infectious Agents Unit, King Fahd Medical Research Centre, King Abdulaziz University, Jeddah, Saudi Arabia
- Department of Biological Sciences, College of Science, University of Jeddah, Jeddah, Saudi Arabia
| | - Al-Judaibi Awatif Abid
- Department of Biological Sciences, College of Science, University of Jeddah, Jeddah, Saudi Arabia
| | - Sayed Sartaj Sohrab
- Special Infectious Agents Unit, King Fahd Medical Research Centre, King Abdulaziz University, Jeddah, Saudi Arabia
- Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ibraheem Azhar Esam
- Special Infectious Agents Unit, King Fahd Medical Research Centre, King Abdulaziz University, Jeddah, Saudi Arabia
- Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
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Tinto B, Quellec J, Cêtre-Sossah C, Dicko A, Salinas S, Simonin Y. Rift Valley fever in West Africa: A zoonotic disease with multiple socio-economic consequences. One Health 2023; 17:100583. [PMID: 37664171 PMCID: PMC10474305 DOI: 10.1016/j.onehlt.2023.100583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 06/12/2023] [Accepted: 06/12/2023] [Indexed: 09/05/2023] Open
Abstract
Rift Valley fever virus (RVFV) is an arbovirus that causes Rift Valley fever (RVF), a zoonotic disease that mainly affects domestic and wildlife ruminants and humans. The first epidemic in North-Western and West Africa occurred in Senegal and Mauritania in 1987, two countries where RVF is now endemic. Slaughterhouse workers, farmers, herders and veterinarians are at high risk of exposure to RVF. Beyond the health threat, RVF is considered to cause major socio-economic problems, specifically in developing countries where livestock farming and trade are important economic activities. Indeed, the mortality rate linked to RVF infection can reach 95-100% in newborns and young animals. In West Africa, livestock production is a key factor for food production and for national economics. Epizootics caused by RVF can therefore have serious socio-economic consequences by impacting multisectoral economics, the psycho-social health of pastoral communities, and food security. Improving prevention strategies against RVF, including vaccination, enhancing knowledge of RVF and correcting any inappropriate behaviors by populations of endemics areas, as well as better monitoring of RVF ecological factors are effective ways to better foresee and control outbreaks of RVF and its socio-economical side-effects in countries at high risk of occurrence of the disease.
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Affiliation(s)
- Bachirou Tinto
- Pathogenesis and Control of Chronic and Emerging Infections, University of Montpellier, INSERM, Etablissement Français du Sang, Montpellier, France
- Laboratoire National de Référence des Fièvres Hémorragiques Virale, Centre MURAZ, Institut National de Santé Publique (INSP), Bobo-Dioulasso, Burkina Faso
| | - Jordan Quellec
- Pathogenesis and Control of Chronic and Emerging Infections, University of Montpellier, INSERM, Etablissement Français du Sang, Montpellier, France
- ASTRE, University of Montpellier, CIRAD, INRAe, Montpellier, France
| | | | - Amadou Dicko
- Laboratoire central de référence, Institut National de Santé Publique (INSP), Ouagadougou, Burkina Faso
- Ministère de l'Agriculture, des ressources animales et halieutiques du Burkina Faso, Ouagadougou, Burkina Faso
| | - Sara Salinas
- Pathogenesis and Control of Chronic and Emerging Infections, University of Montpellier, INSERM, Etablissement Français du Sang, Montpellier, France
| | - Yannick Simonin
- Pathogenesis and Control of Chronic and Emerging Infections, University of Montpellier, INSERM, Etablissement Français du Sang, Montpellier, France
- ASTRE, University of Montpellier, CIRAD, INRAe, Montpellier, France
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Aceng FL, Kayiwa J, Elyanu P, Ojwang J, Nyakarahuka L, Balinandi S, Byakika-Tusiime J, Wejuli A, Harris JR, Opolot J. Rift valley fever outbreak in Sembabule District, Uganda, December 2020. ONE HEALTH OUTLOOK 2023; 5:16. [PMID: 38012800 PMCID: PMC10680244 DOI: 10.1186/s42522-023-00092-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 11/08/2023] [Indexed: 11/29/2023]
Abstract
BACKGROUND Rift Valley Fever (RVF) is a viral zoonosis that can cause severe haemorrhagic fevers in humans and high mortality rates and abortions in livestock. On 10 December 2020, the Uganda Ministry of Health was notified of the death of a 25-year-old male who tested RVF-positive by reverse-transcription polymerase chain reaction (RT-PCR) at the Uganda Virus Research Institute. We investigated to determine the scope of the outbreak, identify exposure factors, and institute control measures. METHODS A suspected case was acute-onset fever (or axillary temperature > 37.5 °C) and ≥ 2 of: headache, muscle or joint pain, unexpected bleeding, and any gastroenteritis symptom in a resident of Sembabule District from 1 November to 31 December 2020. A confirmed case was the detection of RVF virus nucleic acid by RT-PCR or serum IgM antibodies detected by enzyme-linked immunosorbent assay (ELISA). A suspected animal case was livestock (cattle, sheep, goats) with any history of abortion. A confirmed animal case was the detection of anti-RVF IgM antibodies by ELISA. We took blood samples from herdsmen who worked with the index case for RVF testing and conducted interviews to understand more about exposures and clinical characteristics. We reviewed medical records and conducted an active community search to identify additional suspects. Blood samples from animals on the index case's farm and two neighbouring farms were taken for RVF testing. RESULTS The index case regularly drank raw cow milk. None of the seven herdsmen who worked with him nor his brother's wife had symptoms; however, a blood sample from one herdsman was positive for anti-RVF-specific IgM and IgG. Neither the index case nor the additional confirmed case-patient slaughtered or butchered any sick/dead animals nor handled abortus; however, some of the other herdsmen did report high-risk exposures to animal body fluids and drinking raw milk. Among 55 animal samples collected (2 males and 53 females), 29 (53%) were positive for anti-RVF-IgG. CONCLUSIONS Two human RVF cases occurred in Sembabule District during December 2020, likely caused by close interaction between infected cattle and humans. A district-wide animal serosurvey, animal vaccination, and community education on infection prevention practices campaign could inform RVF exposures and reduce disease burden.
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Affiliation(s)
- Freda Loy Aceng
- Department of Integrated Epidemiology, Surveillance and Public Health Emergencies, Ministry of Health, Kampala, Uganda.
| | - Joshua Kayiwa
- Department of Integrated Epidemiology, Surveillance and Public Health Emergencies, Ministry of Health, Kampala, Uganda
- Uganda Public Health Emergency Operations Centre, Ministry of Health, Kampala, Uganda
| | - Peter Elyanu
- Baylor College of Medicine - Children's Foundation, Kampala, Uganda
| | - Joseph Ojwang
- Division of Global Health Protection, Centers for Disease Control and Prevention, Kampala, Uganda
| | | | | | | | - Alfred Wejuli
- Department of Integrated Epidemiology, Surveillance and Public Health Emergencies, Ministry of Health, Kampala, Uganda
| | - Julie Rebecca Harris
- Division of Global Health Protection, Centers for Disease Control and Prevention, Kampala, Uganda
| | - John Opolot
- Department of Integrated Epidemiology, Surveillance and Public Health Emergencies, Ministry of Health, Kampala, Uganda
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Schwarz MM, Ganaie SS, Feng A, Brown G, Yangdon T, White JM, Hoehl RM, McMillen CM, Rush RE, Connors KA, Cui X, Leung DW, Egawa T, Amarasinghe GK, Hartman AL. Lrp1 is essential for lethal Rift Valley fever hepatic disease in mice. SCIENCE ADVANCES 2023; 9:eadh2264. [PMID: 37450601 PMCID: PMC10348670 DOI: 10.1126/sciadv.adh2264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Accepted: 06/12/2023] [Indexed: 07/18/2023]
Abstract
Rift Valley fever virus (RVFV) is an emerging arbovirus found in Africa. While RVFV is pantropic and infects many cells and tissues, viral replication and necrosis within the liver play a critical role in mediating severe disease. The low-density lipoprotein receptor-related protein 1 (Lrp1) is a recently identified host factor for cellular entry and infection by RVFV. The biological significance of Lrp1, including its role in hepatic disease in vivo, however, remains to be determined. Because Lrp1 has a high expression level in hepatocytes, we developed a mouse model in which Lrp1 is specifically deleted in hepatocytes to test how the absence of liver Lrp1 expression affects RVF pathogenesis. Mice lacking Lrp1 expression in hepatocytes showed minimal RVFV replication in the liver, longer time to death, and altered clinical signs toward neurological disease. In contrast, RVFV infection levels in other tissues showed no difference between the two genotypes. Therefore, Lrp1 is essential for RVF hepatic disease in mice.
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Affiliation(s)
- Madeline M. Schwarz
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Infectious Diseases and Microbiology, School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Safder S. Ganaie
- Department of Pathology & Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Annie Feng
- Department of Pathology & Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Griffin Brown
- Department of Pathology & Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Tenzin Yangdon
- Department of Pathology & Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - J. Michael White
- Transgenic, Knockout and Micro-Injection Core, Department of Pathology & Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Ryan M. Hoehl
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, USA
| | - Cynthia M. McMillen
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Infectious Diseases and Microbiology, School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Rachael E. Rush
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Infectious Diseases and Microbiology, School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kaleigh A. Connors
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Infectious Diseases and Microbiology, School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Xiaoxia Cui
- Genome Engineering & Stem Cell Center, Department of Genetics, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Daisy W. Leung
- Department of Pathology & Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
- Department of Medicine, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Takeshi Egawa
- Department of Pathology & Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Gaya K. Amarasinghe
- Department of Pathology & Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Amy L. Hartman
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Infectious Diseases and Microbiology, School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
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Said TAE, Ibrahim SMMM, Hammad MY, Youssef NE. Identity of tissue culture adapted Rift Valley Fever Virus (ZH501).. [DOI: 10.21203/rs.3.rs-2456880/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Abstract
Rift Valley Fever (RVF) is still a threatening zoonotic disease with periodic reemergence in several countries. Egypt is endemic with RVF and uses an inactivated vaccine for control of the disease. Routine testing of the tissue culture adapted seed virus (ZH501-TC), to assess the effect of nucleotide mutations, is essential for the purpose of vaccine production. At the present work we have analyzed partial nucleotide and deduced amino acid sequence of amplified 745 bp product of M segment Gn ectodomain and checked virulence in mice. Allocation of ZH501-TC strain at the A designated lineage with the virulent parental RVFV isolated in 1977, ZH501 Egy Sh 77 indicates its genomic stability after passaging in tissue culture cells for vaccine preparation. Here we denoted a new missense nucleotide mutation A1312G corresponding to the amino acid mutation N371S, in current study the ZH501-TC strain (MZ218760) compared to the parental virulent RVFV isolate ZH501 Egy Sh 77 ( previous sequence ). That mutation enhanced ß sheet formation in ZH501-TC 367AQYASAYCS375 motif which might increase virus antigenicity. In addition, we have confirmed the presence of two sites of nucleotides substitutions; C1033T and A1206C, corresponding to two amino acids changes; T287I and S336R. Our study declared the false notion of the presence of one missense nucleotide mutation; A1252G corresponding to the amino acid mutation K351R, and two other silent nucleotide substitutions; T1257A and G1258C at the strain ZH501-VSVRI. Although we found these mutations, the virulence of the ZH501-TC strain was still present as approved by mice pathogenicity test.
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Bastard J, Durand GA, Parenton F, Hassani Y, Dommergues L, Paireau J, Hozé N, Ruello M, Grard G, Métras R, Noël H. Reconstructing Mayotte 2018-19 Rift Valley Fever outbreak in humans by combining serological and surveillance data. COMMUNICATIONS MEDICINE 2022; 2:163. [PMID: 36543938 PMCID: PMC9772320 DOI: 10.1038/s43856-022-00230-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Rift Valley Fever (RVF) is a zoonosis that affects large parts of Africa and the Arabian Peninsula. RVF virus (RVFV) is transmitted to humans through contacts with infected animals, animal products, mosquito bites or aerosols. Its pathogenesis in humans ranges from asymptomatic forms to potentially deadly haemorrhagic fevers, and the true burden of human infections during outbreaks is generally unknown. METHODS We build a model fitted to both passive surveillance data and serological data collected throughout a RVF epidemic that occurred in Mayotte Island in 2018-2019. RESULTS We estimate that RVFV infected 10,797 (95% CrI 4,728-16,127) people aged ≥15 years old in Mayotte during the entire outbreak, among which only 1.2% (0.67%-2.2%) were reported to the syndromic surveillance system. RVFV IgG seroprevalence in people ≥15 years old was estimated to increase from 5.5% (3.6%-7.7%) before the outbreak to 12.9% (10.4%-16.3%) thereafter. CONCLUSIONS Our results suggest that a large part of RVFV infected people present subclinical forms of the disease and/or do not reach medical care that could lead to their detection by the surveillance system. This may threaten the implementation of exhaustive RVF surveillance and adequate control programs in affected countries.
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Affiliation(s)
- Jonathan Bastard
- grid.493975.50000 0004 5948 8741Santé publique France, French national public health agency, F-94415 Saint-Maurice, France
| | - Guillaume André Durand
- grid.476258.aFrench Armed Forces Biomedical Research Institute, National Reference Laboratory for Arboviruses, Marseille, France ,grid.5399.60000 0001 2176 4817Unité des Virus Émergents (UVE: Aix-Marseille Univ-IRD 190-Inserm 1207), Marseille, France
| | - Fanny Parenton
- grid.493975.50000 0004 5948 8741Santé publique France, French national public health agency, F-94415 Saint-Maurice, France
| | - Youssouf Hassani
- grid.493975.50000 0004 5948 8741Santé publique France, French national public health agency, F-94415 Saint-Maurice, France
| | | | - Juliette Paireau
- grid.493975.50000 0004 5948 8741Santé publique France, French national public health agency, F-94415 Saint-Maurice, France ,Mathematical Modelling of Infectious Diseases Unit, Institut Pasteur, Université Paris Cité, UMR2000, CNRS, Paris, France
| | - Nathanaël Hozé
- Mathematical Modelling of Infectious Diseases Unit, Institut Pasteur, Université Paris Cité, UMR2000, CNRS, Paris, France
| | - Marc Ruello
- grid.493975.50000 0004 5948 8741Santé publique France, French national public health agency, F-94415 Saint-Maurice, France
| | - Gilda Grard
- grid.476258.aFrench Armed Forces Biomedical Research Institute, National Reference Laboratory for Arboviruses, Marseille, France ,grid.5399.60000 0001 2176 4817Unité des Virus Émergents (UVE: Aix-Marseille Univ-IRD 190-Inserm 1207), Marseille, France
| | - Raphaëlle Métras
- Sorbonne Université, INSERM, Institut Pierre Louis d’Épidémiologie et de Santé Publique (IPLESP, UMRS 1136), Paris, France
| | - Harold Noël
- grid.493975.50000 0004 5948 8741Santé publique France, French national public health agency, F-94415 Saint-Maurice, France
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10
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Mechanistic models of Rift Valley fever virus transmission: A systematic review. PLoS Negl Trop Dis 2022; 16:e0010339. [PMID: 36399500 PMCID: PMC9718419 DOI: 10.1371/journal.pntd.0010339] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 12/02/2022] [Accepted: 10/31/2022] [Indexed: 11/19/2022] Open
Abstract
Rift Valley fever (RVF) is a zoonotic arbovirosis which has been reported across Africa including the northernmost edge, South West Indian Ocean islands, and the Arabian Peninsula. The virus is responsible for high abortion rates and mortality in young ruminants, with economic impacts in affected countries. To date, RVF epidemiological mechanisms are not fully understood, due to the multiplicity of implicated vertebrate hosts, vectors, and ecosystems. In this context, mathematical models are useful tools to develop our understanding of complex systems, and mechanistic models are particularly suited to data-scarce settings. Here, we performed a systematic review of mechanistic models studying RVF, to explore their diversity and their contribution to the understanding of this disease epidemiology. Researching Pubmed and Scopus databases (October 2021), we eventually selected 48 papers, presenting overall 49 different models with numerical application to RVF. We categorized models as theoretical, applied, or grey, depending on whether they represented a specific geographical context or not, and whether they relied on an extensive use of data. We discussed their contributions to the understanding of RVF epidemiology, and highlighted that theoretical and applied models are used differently yet meet common objectives. Through the examination of model features, we identified research questions left unexplored across scales, such as the role of animal mobility, as well as the relative contributions of host and vector species to transmission. Importantly, we noted a substantial lack of justification when choosing a functional form for the force of infection. Overall, we showed a great diversity in RVF models, leading to important progress in our comprehension of epidemiological mechanisms. To go further, data gaps must be filled, and modelers need to improve their code accessibility.
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11
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Shaw CL, Kennedy DA. Developing an empirical model for spillover and emergence: Orsay virus host range in Caenorhabditis. Proc Biol Sci 2022; 289:20221165. [PMID: 36126684 PMCID: PMC9489279 DOI: 10.1098/rspb.2022.1165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 08/24/2022] [Indexed: 11/20/2022] Open
Abstract
A lack of tractable experimental systems in which to test hypotheses about the ecological and evolutionary drivers of disease spillover and emergence has limited our understanding of these processes. Here we introduce a promising system: Caenorhabditis hosts and Orsay virus, a positive-sense single-stranded RNA virus that naturally infects C. elegans. We assayed species across the Caenorhabditis tree and found Orsay virus susceptibility in 21 of 84 wild strains belonging to 14 of 44 species. Confirming patterns documented in other systems, we detected effects of host phylogeny on susceptibility. We then tested whether susceptible strains were capable of transmitting Orsay virus by transplanting exposed hosts and determining whether they transmitted infection to conspecifics during serial passage. We found no evidence of transmission in 10 strains (virus undetectable after passaging in all replicates), evidence of low-level transmission in 5 strains (virus lost between passage 1 and 5 in at least one replicate) and evidence of sustained transmission in 6 strains (including all three experimental C. elegans strains) in at least one replicate. Transmission was strongly associated with viral amplification in exposed populations. Variation in Orsay virus susceptibility and transmission among Caenorhabditis strains suggests that the system could be powerful for studying spillover and emergence.
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Affiliation(s)
- Clara L. Shaw
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - David A. Kennedy
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
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12
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Tennant WSD, Cardinale E, Cêtre-Sossah C, Moutroifi Y, Le Godais G, Colombi D, Spencer SEF, Tildesley MJ, Keeling MJ, Charafouddine O, Colizza V, Edmunds WJ, Métras R. Modelling the persistence and control of Rift Valley fever virus in a spatially heterogeneous landscape. Nat Commun 2021; 12:5593. [PMID: 34552082 PMCID: PMC8458460 DOI: 10.1038/s41467-021-25833-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 09/02/2021] [Indexed: 02/08/2023] Open
Abstract
The persistence mechanisms of Rift Valley fever (RVF), a zoonotic arboviral haemorrhagic fever, at both local and broader geographical scales have yet to be fully understood and rigorously quantified. We developed a mathematical metapopulation model describing RVF virus transmission in livestock across the four islands of the Comoros archipelago, accounting for island-specific environments and inter-island animal movements. By fitting our model in a Bayesian framework to 2004-2015 surveillance data, we estimated the importance of environmental drivers and animal movements on disease persistence, and tested the impact of different control scenarios on reducing disease burden throughout the archipelago. Here we report that (i) the archipelago network was able to sustain viral transmission in the absence of explicit disease introduction events after early 2007, (ii) repeated outbreaks during 2004-2020 may have gone under-detected by local surveillance, and (iii) co-ordinated within-island control measures are more effective than between-island animal movement restrictions.
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Affiliation(s)
- Warren S D Tennant
- The Zeeman Institute: SBIDER, University of Warwick, Coventry, CV4 7AL, UK.
- Mathematics Institute, University of Warwick, Coventry, CV4 7AL, UK.
| | - Eric Cardinale
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement, UMR Animal, Santé, Territoires, Risques, et Écosystèmes, F-97490, Sainte Clotilde, La Réunion, France
- Animal, Santé, Territoires, Risques, et Écosystèmes, Université de Montpellier, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, INRAE, Montpellier, France
| | - Catherine Cêtre-Sossah
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement, UMR Animal, Santé, Territoires, Risques, et Écosystèmes, F-97490, Sainte Clotilde, La Réunion, France
- Animal, Santé, Territoires, Risques, et Écosystèmes, Université de Montpellier, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, INRAE, Montpellier, France
| | - Youssouf Moutroifi
- Vice-Présidence en charge de l'Agriculture, l'Elevage, la Pêche, l'Industrie, l'Energie et l'Artisanat, B.P. 41 Mdé, Moroni, Union of the Comoros
| | - Gilles Le Godais
- Direction de l'Alimentation, de l'Agriculture et de la Forêt de Mayotte, Service de l'Alimentation, 97600, Mamoudzou, France
| | - Davide Colombi
- Aizoon Technology Consulting, Str. del Lionetto 6, Torino, Italy
| | - Simon E F Spencer
- The Zeeman Institute: SBIDER, University of Warwick, Coventry, CV4 7AL, UK
- Department of Statistics, University of Warwick, Coventry, CV4, 7AL, UK
| | - Mike J Tildesley
- The Zeeman Institute: SBIDER, University of Warwick, Coventry, CV4 7AL, UK
- Mathematics Institute, University of Warwick, Coventry, CV4 7AL, UK
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Matt J Keeling
- The Zeeman Institute: SBIDER, University of Warwick, Coventry, CV4 7AL, UK
- Mathematics Institute, University of Warwick, Coventry, CV4 7AL, UK
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Onzade Charafouddine
- Vice-Présidence en charge de l'Agriculture, l'Elevage, la Pêche, l'Industrie, l'Energie et l'Artisanat, B.P. 41 Mdé, Moroni, Union of the Comoros
| | - Vittoria Colizza
- INSERM, Sorbonne Université, Institut Pierre Louis d'Épidémiologie et de Santé Publique (Unité Mixte de Recherche en Santé 1136), 75012, Paris, France
| | - W John Edmunds
- Centre for the Mathematical Modelling of Infectious Diseases, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Raphaëlle Métras
- INSERM, Sorbonne Université, Institut Pierre Louis d'Épidémiologie et de Santé Publique (Unité Mixte de Recherche en Santé 1136), 75012, Paris, France
- Centre for the Mathematical Modelling of Infectious Diseases, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
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13
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Risk based serological survey of Rift Valley fever in Tunisia (2017-2018). Heliyon 2021; 7:e07932. [PMID: 34522818 PMCID: PMC8427255 DOI: 10.1016/j.heliyon.2021.e07932] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/28/2021] [Accepted: 09/01/2021] [Indexed: 12/22/2022] Open
Abstract
Rift Valley fever (RVF) has been reported in the sub-Saharan region of Africa, Egypt and Arabian Peninsula - Yemen and Saudi Arabia, over the past 20 years and is a threat to both the animal and human populations in Tunisia. Tunisia is considered as a high-risk country for the introduction of RVF due to the informal movements of diseased animals already reported in the neighboring countries. The objective of this study was to assess the status of RVF in small ruminants and camels in Tunisia. A risk-based serological survey was conducted to evaluate the presence of RVF based on spatial qualitative risk analysis (SQRA). Samples were collected from small ruminants (sheep and goats) (n = 1,114), and camels (n = 173) samples, belonging to 18 breeders in 14 governorates between November 2017 and January 2018. Samples were tested using an RVF specific multispecies competitive ELISA. Out of the 1,287 samples tested for the presence of RVF IgG antibodies by ELISA, only one positive sample 0.07% (1/1 287) was detected but not confirmed with the virus neutralization test (VNT) used for confirmation. So far, no RVF outbreaks have been reported in Tunisia and our study confirmed the absence of RVF in livestock up to January 2018. Further investigations are needed to confirm the RVF-free status of Tunisia today.
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14
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Kim Y, Métras R, Dommergues L, Youssouffi C, Combo S, Le Godais G, Pfeiffer DU, Cêtre-Sossah C, Cardinale E, Filleul L, Youssouf H, Subiros M, Fournié G. The role of livestock movements in the spread of Rift Valley fever virus in animals and humans in Mayotte, 2018-19. PLoS Negl Trop Dis 2021; 15:e0009202. [PMID: 33684126 PMCID: PMC7939299 DOI: 10.1371/journal.pntd.0009202] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 02/03/2021] [Indexed: 11/18/2022] Open
Abstract
Rift Valley fever (RVF) is a vector-borne viral disease of major animal and public health importance. In 2018–19, it caused an epidemic in both livestock and human populations of the island of Mayotte. Using Bayesian modelling approaches, we assessed the spatio-temporal pattern of RVF virus (RVFV) infection in livestock and human populations across the island, and factors shaping it. First, we assessed if (i) livestock movements, (ii) spatial proximity from communes with infected animals, and (iii) livestock density were associated with the temporal sequence of RVFV introduction into Mayotte communes’ livestock populations. Second, we assessed whether the rate of human infection was associated with (a) spatial proximity from and (b) livestock density of communes with infected animals. Our analyses showed that the temporal sequence of RVFV introduction into communes’ livestock populations was associated with livestock movements and spatial proximity from communes with infected animals, with livestock movements being associated with the best model fit. Moreover, the pattern of human cases was associated with their spatial proximity from communes with infected animals, with the risk of human infection sharply increasing if livestock in the same or close communes were infected. This study highlights the importance of understanding livestock movement networks in informing the design of risk-based RVF surveillance programs. Rift Valley fever (RVF) is a vector-borne zoonotic disease, endemic in many sub-Saharan Africa regions with substantial outbreaks. RVF virus (RVFV) is transmitted to animals primarily by the bite of infected mosquitos, whereas direct or indirect contact with infected animals forms the primary route of RVFV transmission to humans. In 2018–19, Mayotte, an archipelago in the Indian Ocean between Madagascar and the coast of Eastern Africa, experienced an RVF epidemic in both livestock and humans. In this study, we investigated factors shaping the spatio-temporal pattern of RVFV infection in livestock and human populations across Mayotte. The diffusion of RVFV through Mayotte’s livestock population was associated with livestock movements and, potentially to a lesser extent, spatial proximity from communes with infected animals. Moreover, the pressure of infection on humans was the highest if nearby livestock were infected. This study highlights the value of accounting for the structure of livestock movement networks in the surveillance of zoonotic diseases at the human-animal interface, and the need for One Health approaches.
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Affiliation(s)
- Younjung Kim
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China
- * E-mail:
| | - Raphaëlle Métras
- INSERM, Sorbonne Université, Institut Pierre Louis d’Épidémiologie et de Santé Publique (UMRS-1136), Paris, France
| | | | | | - Soihibou Combo
- Direction de l’Alimentation, de l’Agriculture et de la Forêt de Mayotte, Mamoudzou, France
| | - Gilles Le Godais
- Direction de l’Alimentation, de l’Agriculture et de la Forêt de Mayotte, Mamoudzou, France
| | - Dirk U. Pfeiffer
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China
- Veterinary Epidemiology, Economics and Public Health group, Department of Pathobiology and Population Sciences, The Royal Veterinary College, Hatfield, United Kingdom
| | - Catherine Cêtre-Sossah
- CIRAD, UMR ASTRE, Sainte Clotilde, La Réunion, France
- ASTRE, CIRAD, Univ Montpellier, INRAE, Montpellier, France
| | - Eric Cardinale
- CIRAD, UMR ASTRE, Sainte Clotilde, La Réunion, France
- ASTRE, CIRAD, Univ Montpellier, INRAE, Montpellier, France
| | | | | | | | - Guillaume Fournié
- Veterinary Epidemiology, Economics and Public Health group, Department of Pathobiology and Population Sciences, The Royal Veterinary College, Hatfield, United Kingdom
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15
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Nielsen SS, Alvarez J, Bicout DJ, Calistri P, Depner K, Drewe JA, Garin‐Bastuji B, Gonzales Rojas JL, Gortázar Schmidt C, Herskin M, Michel V, Miranda Chueca MÁ, Pasquali P, Roberts HC, Sihvonen LH, Stahl K, Calvo AV, Viltrop A, Winckler C, Gubbins S, Antoniou S, Broglia A, Abrahantes JC, Dhollander S, Van der Stede Y. Rift Valley Fever - assessment of effectiveness of surveillance and control measures in the EU. EFSA J 2020; 18:e06292. [PMID: 33193869 PMCID: PMC7642843 DOI: 10.2903/j.efsa.2020.6292] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Effectiveness of surveillance and control measures against Rift Valley Fever (RVF) in Mayotte (overseas France) and in continental EU were assessed using mathematical models. Surveillance for early detection of RVF virus circulation implies very low design prevalence values and thus sampling a high number of animals, so feasibility issues may rise. Passive surveillance based on notified abortions in ruminants is key for early warning and at present the only feasible surveillance option. The assessment of vaccination and culling against RVF in Mayotte suggests that vaccination is more effective when quickly implemented throughout the population, e.g. at a rate of 200 or 2,000 animals vaccinated per day. Test and cull is not an option for RVF control in Mayotte given the high number of animals that would need to be tested. If the risk of RVFV introduction into the continental EU increases, ruminant establishments close to possible points of disease incursion should be included in the surveillance. An enhanced surveillance on reproductive disorders should be applied during summer in risk areas. Serosurveillance targets of 0.3% animals should be at least considered. RVF control measures possibly applied in the continental EU have been assessed in the Netherlands, as an example. Culling animals on farms within a 20 km radius of detected farms appears as the most effective measure to control RVF spread, although too many animals should be culled. Alternative measures are vaccination in a 50 km radius around detection, ring vaccination between 20 and 50 km and culling of detected farms. The assessment of zoning showed that, following RVFV introduction and considering an R0 = 2, a mean vector dispersal of 10 km and 10 farms initially detected, RVFV would spread beyond a radius of up to 100 km or 50 km from the infected area with 10% or 55% probability, respectively.
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