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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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Sankhe S, Talla C, Thiam MS, Faye M, Barry MA, Diarra M, Dia M, Ndiaye O, Sembene PM, Diop B, Fall G, Faye O, Faye O, Diagne MM, Loucoubar C. Seroprevalence of Crimean-Congo Hemorrhagic Fever Virus and Rift Valley Fever Virus in human population in Senegal from October to November 2020. IJID REGIONS 2023; 7:216-221. [PMID: 37153883 PMCID: PMC10160495 DOI: 10.1016/j.ijregi.2023.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 03/24/2023] [Accepted: 03/27/2023] [Indexed: 05/10/2023]
Abstract
Objectives Rift Valley Fever and Crimean-Congo Hemorrhagic Fever are two infections classified among the emerging diseases to be monitored with highest priority. Studies undertaken in human and animals have shown endemicity of these two arboviruses in several African countries. However, most of the investigations were carried out on domestic cattle and the studies conducted on human populations are either outdated or limited to a small number of well-known endemic areas. It is then critical to better evaluate the burden of these viruses in Senegal at a national scale. Methods This work relies on a previous seroprevalence survey undertaken in all regions of Senegal at the end of 2020. The existing biobank was used to determine the immunoglobulin G [IgG] Rift Valley Fever and Crimean-Congo Hemorrhagic Fever seroprevalences by indirect enzyme-linked immunosorbent assay. Results The crude seroprevalences of Rift Valley Fever and Crimean-Congo Hemorrhagic Fever were 3.94% and 0.7% respectively, with the northern and central part of the countries as the main exposed areas. However, acute infections reported in both high and low exposed regions suggest sporadic introductions. Conclusions This study gives updated information and could be of interest to support the stakeholders in the management of these zoonoses.
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Affiliation(s)
- Safietou Sankhe
- Arboviruses and Hemorrhagic Fever Viruses Unit, Virology Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
- Animal Biology Department, Faculty of Sciences and Techniques, Cheikh Anta Diop University of Dakar, Dakar, Senegal
| | - Cheikh Talla
- Epidemiology, Clinical Research and Data Science Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
| | - Mareme Seye Thiam
- Epidemiology, Clinical Research and Data Science Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
| | - Martin Faye
- Arboviruses and Hemorrhagic Fever Viruses Unit, Virology Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
| | - Mamadou Aliou Barry
- Epidemiology, Clinical Research and Data Science Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
| | - Maryam Diarra
- Epidemiology, Clinical Research and Data Science Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
| | - Moussa Dia
- Arboviruses and Hemorrhagic Fever Viruses Unit, Virology Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
| | - Oumar Ndiaye
- Arboviruses and Hemorrhagic Fever Viruses Unit, Virology Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
| | - Pape Mbacke Sembene
- Animal Biology Department, Faculty of Sciences and Techniques, Cheikh Anta Diop University of Dakar, Dakar, Senegal
| | - Boly Diop
- Epidemiological Surveillance Division, Prevention Department, Ministry of Health, Dakar, Senegal
| | - Gamou Fall
- Arboviruses and Hemorrhagic Fever Viruses Unit, Virology Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
| | - Oumar Faye
- Arboviruses and Hemorrhagic Fever Viruses Unit, Virology Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
| | - Ousmane Faye
- Arboviruses and Hemorrhagic Fever Viruses Unit, Virology Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
| | - Moussa Moise Diagne
- Arboviruses and Hemorrhagic Fever Viruses Unit, Virology Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
- Corresponding author
| | - Cheikh Loucoubar
- Epidemiology, Clinical Research and Data Science Department, Institut Pasteur de Dakar, BP220 Dakar, Senegal
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Human and Livestock Surveillance Revealed the Circulation of Rift Valley Fever Virus in Agnam, Northern Senegal, 2021. Trop Med Infect Dis 2023; 8:tropicalmed8020087. [PMID: 36828503 PMCID: PMC9962223 DOI: 10.3390/tropicalmed8020087] [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: 11/15/2022] [Revised: 01/08/2023] [Accepted: 01/20/2023] [Indexed: 02/03/2023] Open
Abstract
The mosquito-borne disease caused by the Rift Valley Fever Virus (RVFV) is a viral hemorrhagic fever that affects humans and animals. In 1987, RVFV emerged in Mauritania, which caused the first RVFV outbreak in West Africa. This outbreak was shortly followed by reported cases in humans and livestock in Senegal. Animal trade practices with neighboring Mauritania suggest northern regions of Senegal are at high risk for RVF. In this study, we aim to conduct a molecular and serological survey of RVFV in humans and livestock in Agnam (northeastern Senegal) by RT-PCR (reverse transcription real-time polymerase chain reaction) and ELISA (Enzyme-Linked Immunosorbent Assay), respectively. Of the two hundred fifty-five human sera, one (0.39%) tested RVFV IgM positive, while fifty-three (20.78%) tested positive for RVFV IgG. For animal monitoring, out of 30 sheep recorded and sampled over the study period, 20 (66.67%) showed seroconversion to RVFV IgG antibodies, notably during the rainy season. The presence of antibodies increased significantly with age in both groups (p < 0.05), as the force of RVF infection (FOI), increased by 16.05% per year for humans and by 80.4% per month for livestock sheep. This study supports the usefulness of setting up a One Health survey for RVF management.
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Rift Valley fever, Mauritania, 2020: Lessons from a one health approach. One Health 2022; 15:100413. [PMID: 36277109 PMCID: PMC9582547 DOI: 10.1016/j.onehlt.2022.100413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/23/2022] [Accepted: 06/23/2022] [Indexed: 11/26/2022] Open
Abstract
A new outbreak of Rift Valley fever (RVF) occurred in Mauritania from September to November 2020, involving 78 reported human cases and 186 reported animal cases. Eleven out of the 13 regions of the country were affected by the epidemic, with the highest number of both human and animal cases in Tagant, Assaba and Brakna regions. The most affected animal species in this outbreak was camels, followed by small ruminants. Among the 10 mosquito species caught, 7 species, Culex poicilipes, Cx. quinquefasciatus, Cx. antennatus, Cx. univitattus, Aedes vexans, Mansonia africana and Ma. uniformis, are known to be involved in the transmission of RVF virus. Phylogenetic analyses based on the partial NSs gene revealed close proximity between the human/animal Mauritania 2020 viral strains and the Mauritania 2015/Niger 2016 strains, suggesting re-emergence of the RVF virus in the country since the last reported outbreak in 2015. New outbreak of Rift Valley fever (RVF) in Mauritania in 2020, 78 human and 186 animal reported cases. Eleven regions of the country were affected by the epidemic, with the highest number of human and animal cases in Tagant, Assaba and Brakna regions. The most affected animal species were dromedaries followed by small ruminants. Close proximity of the human/animal Mauritania 2020 viral strains with the Mauritania 2015/Niger 2016 strains based on NSs phylogenetic analysis
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Kainga H, Phonera MC, Chatanga E, Kallu SA, Mpundu P, Samutela M, Chambaro HM, Kajihara M, Shempela DM, Sikalima J, Muleya W, Shawa M, Chulu J, Njunga G, Simuunza M, Takada A, Sawa H, Simulundu E, Saasa N. Seroprevalence and Associated Risk Factors of Rift Valley Fever in Livestock from Three Ecological Zones of Malawi. Pathogens 2022; 11:1349. [PMID: 36422600 PMCID: PMC9698272 DOI: 10.3390/pathogens11111349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 11/04/2022] [Accepted: 11/10/2022] [Indexed: 09/17/2023] Open
Abstract
The epidemiology of Rift Valley fever (RVF) is poorly understood in Malawi. Here, a cross-sectional study was conducted (March-June 2020) to investigate the seroprevalence and potential risk factors of RVF virus (RVFV) in cattle, goats, and sheep in three ecological zones of Malawi. A total of 1523 serum samples were tested for anti-RVFV IgG and IgM antibodies by ELISA. Additionally, a questionnaire survey was used to assess potential RVF risk factors. The overall seroprevalence was 17.14% (261/1523; 95% CI = 15.33-19.11) for individual livestock and 33.24% (120/361; 95% CI = 28.18-38.11) for the livestock herd. Seroprevalence was significantly high in sheep (25.68%, 95% CI = 19.31-33.26) compared with cattle (21.35%, 95% CI = 18.74-24.22) and goats (7.72%, 95% CI = 5.72-10.34), (p = 0.047). At the individual livestock level, the risk was elevated in female livestock (OR: 1.74, 95% CI = 1.08-12.82) (p = 0.016), while at the herd level, areas receiving approximately 1001-1500 mm of rainfall (OR: 2.47, 95% CI = 1.14-5.37) (p = 0.022), areas of rainfall amount greater than approximately 1600 mm (OR: 2.239, 95% CI = 1.07-8.82) (p = 0.023), and mixed species herds (OR: 10.410, 95% CI = 3.04-35.59) (p = 0.001), were significant risk factors. The detection of IgM antibodies confirmed active circulation of RVFV in Malawi. Therefore, monitoring of RVF in animals, humans, and vectors using a "One Health" approach, along with community sensitization among the high-risk populations, could help mitigate the threat posed by this zoonotic disease in Malawi.
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Affiliation(s)
- Henson Kainga
- Department of Veterinary Epidemiology and Public Health, Faculty of Veterinary Medicine, Lilongwe University of Agriculture and Natural Resources, Lilongwe 207203, Malawi
- Department of Disease Control, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia
| | - Marvin Collen Phonera
- Department of Animal Health and Livestock Development, Ministry of Agriculture, Lilongwe 207203, Malawi
| | - Elisha Chatanga
- Department of Veterinary Pathobiology, Faculty of Veterinary Medicine, Lilongwe University of Agriculture and Natural Resources, Lilongwe 207203, Malawi
| | - Simegnew Adugna Kallu
- Department of Disease Control, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia
- College of Veterinary Medicine, Haramaya University, Dire Dawa P.O. Box 138, Ethiopia
| | - Prudence Mpundu
- Department of Environmental and Occupational Health, Levy Mwanawasa Medical University, Lusaka 33991, Zambia
| | - Mulemba Samutela
- Department of Paraclinical Studies, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia
- Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka 10101, Zambia
| | - Herman Moses Chambaro
- Virology Unit, Central Veterinary Research Institute (CVRI), Ministry of Fisheries and Livestock, Lusaka 10101, Zambia
| | - Masahiro Kajihara
- Department of Disease Control, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia
- Division of Global Epidemiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan
| | | | - Jay Sikalima
- Churches Health Association of Zambia, Lusaka 10101, Zambia
| | - Walter Muleya
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia
| | - Misheck Shawa
- Division of Collaboration and Education, International Institute for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan
| | - Julius Chulu
- Department of Animal Health and Livestock Development, Ministry of Agriculture, Lilongwe 207203, Malawi
| | - Gilson Njunga
- Department of Animal Health and Livestock Development, Ministry of Agriculture, Lilongwe 207203, Malawi
| | - Martin Simuunza
- Department of Disease Control, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia
| | - Ayato Takada
- Department of Disease Control, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia
- Division of Collaboration and Education, International Institute for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan
| | - Hirofumi Sawa
- Department of Disease Control, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia
- Japan Division of International Research Promotion, International Institute for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan
- Japan Global Virus Network, Baltimore, ML 21201, USA
- One Health Research Center, Hokkaido University, Sapporo 001-0020, Japan
| | - Edgar Simulundu
- Department of Disease Control, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia
- Macha Research Trust, Choma 20100, Zambia
| | - Ngonda Saasa
- Department of Disease Control, School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia
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Mahmoud AS, Sawesi OK, El-Waer OR, Bennour EM. Rift valley fever in Africa with the emerging interest in Libya. INTERNATIONAL JOURNAL OF ONE HEALTH 2021. [DOI: 10.14202/ijoh.2021.237-245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Rift valley fever (RVF) is an acute vector-borne viral zoonotic disease of domestic and wild ruminants. The RVF virus (RVFV) belonging to the Phlebovirus genus of the Bunyaviridae family causes this disease. Studies have shown that mosquitoes are the vectors that transmit RVFV. Specifically, Aedes and Culex mosquito species are among the many vectors of this virus, which affects not only sheep, goats, buffalo, cattle, and camels but also human beings. Since the 30s of the last century, RVF struck Africa, and to a lesser extent, Asian continents, with subsequent episodes of epizootic, epidemic, and sporadic outbreaks. These outbreaks, therefore, resulted in the cumulative loss of thousands of human lives, thereby disrupting the livestock market or only those with seropositive cases. After that outbreak episode, RVF was not reported in Libya until January 13, 2020, where it was reported for the 1st time in a flock of sheep and goats in the southern region of the country. Although insufficient evidence to support RVF clinical cases among the confirmed seropositive animals exists, neither human cases nor death were reported in Libya. Yet, the overtime expansion of RVF kinetics in the Libyan neighborhoods, in addition to the instability and security vacuum experienced in the country, lack of outbreak preparedness, and the availability of suitable climatic and disease vector factors, makes this country a possible future scene candidate for RVF expansion. Urgently, strengthening veterinary services (VS) and laboratory diagnostic capacities, including improvement of monitoring and surveillance activity programs, should be implemented in areas at risk (where imported animals crossing borders from Libyan neighborhoods and competent vectors are found) at national, sub-national, and regional levels. The Libyan government should also implement a tripartite framework (one health approach) among the veterinary public health, public health authority, and environmental sanitation sectors to implement RVF surveillance protocols, along with an active partnership with competent international bodies (OIE, FAO, and WHO). Therefore, this review comprises the most updated data regarding the epidemiological situation of RVF infections and its socioeconomic impacts on African and Asian continents, and also emphasize the emerging interest of RVF in Libya.
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Affiliation(s)
- Abdusalam S. Mahmoud
- Department of Preventive Medicine, Faculty of Veterinary Medicine, University of Tripoli, Tripoli, Libya
| | - Osama K. Sawesi
- Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tripoli, Tripoli, Libya
| | - Osama R. El-Waer
- Department of Microbiology and Parasitology, Faculty of Veterinary Medicine, University of Tripoli, Tripoli, Libya
| | - Emad M. Bennour
- Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tripoli, Tripoli, Libya
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Rissmann M, Stoek F, Pickin MJ, Groschup MH. Mechanisms of inter-epidemic maintenance of Rift Valley fever phlebovirus. Antiviral Res 2019; 174:104692. [PMID: 31870761 DOI: 10.1016/j.antiviral.2019.104692] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 09/26/2019] [Accepted: 12/11/2019] [Indexed: 12/31/2022]
Abstract
Rift Valley fever phlebovirus (RVFV) is an arthropod-borne virus that has caused substantial epidemics throughout Africa and in the Arabian Peninsula. The virus can cause severe disease in livestock and humans and therefore the control and prevention of viral outbreaks is of utmost importance. The epidemiology of RVFV has some particular characteristics. Unexpected and significant epidemics have been observed in spatially and temporally divergent patterns across the African continent. Sudden epidemics in previously unaffected areas are followed by periods of long-term apparent absence of virus and sudden, unpredictable reoccurrence in disparate regions. Therefore, the elucidation of underlying mechanisms of viral maintenance is one of the largest gaps in the knowledge of RVFV ecology. It remains unknown whether the virus needs to be reintroduced before RVF outbreaks can occur, or if unperceived viral circulation in local vertebrates or mosquitoes is sufficient for maintenance of the virus. To gain insight into these knowledge gaps, we here review existing data that describe potential mechanisms of RVFV maintenance, as well as molecular and serological studies in endemic and non-endemic areas that provide evidence of an inter- or pre-epidemic virus presence. Basic and country-specific mechanisms of RVFV introduction into non-endemic countries are summarized and an overview of studies using mathematical modeling of RVFV persistence is given.
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Affiliation(s)
- Melanie Rissmann
- Friedrich-Loeffler-Institut, Institute of Novel and Emerging Infectious Diseases, Suedufer 10, 17489, Greifswald-Insel Riems, Germany
| | - Franziska Stoek
- Friedrich-Loeffler-Institut, Institute of Novel and Emerging Infectious Diseases, Suedufer 10, 17489, Greifswald-Insel Riems, Germany
| | - Matthew J Pickin
- Friedrich-Loeffler-Institut, Institute of Novel and Emerging Infectious Diseases, Suedufer 10, 17489, Greifswald-Insel Riems, Germany
| | - Martin H Groschup
- Friedrich-Loeffler-Institut, Institute of Novel and Emerging Infectious Diseases, Suedufer 10, 17489, Greifswald-Insel Riems, Germany.
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Teffera M, Babiuk S. Potential of Using Capripoxvirus Vectored Vaccines Against Arboviruses in Sheep, Goats, and Cattle. Front Vet Sci 2019; 6:450. [PMID: 31921911 PMCID: PMC6932975 DOI: 10.3389/fvets.2019.00450] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 11/27/2019] [Indexed: 11/26/2022] Open
Abstract
The genus capripoxvirus consists of sheeppox virus, goatpox virus, and lumpy skin disease virus, which affect sheep, goats, and cattle, respectively. Together capripoxviruses cause significant economic losses to the sheep, goat, and cattle industry where these diseases are present. These diseases have spread into previously free bordering regions most recently demonstrated with the spread of lumpy skin disease virus into the Middle East, some Eastern European countries, and Russia. This recent spread has highlighted the transboundary nature of these diseases. To control lumpy skin disease virus, live attenuated viral vaccines are used in endemic countries as well as in response to an outbreak. For sheeppox and goatpox, live attenuated viral vaccines are used in endemic countries; these diseases can also be contained through slaughter of infected animals to stamp out the disease. The thermostability, narrow host range, and ability of capripoxviruses to express a wide variety of antigens make capripoxviruses ideal vectors. The ability to immunize animals against multiple diseases simultaneously increases vaccination efficiency by decreasing the number of vaccinations required. Additionally, the use of capripoxvirus vectored vaccines allows the possibility of differentiating infected from vaccinated animals. Arboviruses such as bluetongue virus and Rift Valley fever viruses are also responsible for significant economic losses in endemic countries. In the case of Rift Valley fever virus, vaccination is not routinely practiced unless there is an outbreak making vaccination not as effective, therefore, incorporating Rift Valley fever vaccination into routine capripoxvirus vaccination would be highly beneficial. This review will discuss the potential of using capripoxvirus as a vector expressing protective arboviral antigens.
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Affiliation(s)
- Mahder Teffera
- Canadian Food Inspection Agency, National Centre for Foreign Animal Disease, Winnipeg, MB, Canada
- Department of Immunology, University of Manitoba, Winnipeg, MB, Canada
| | - Shawn Babiuk
- Canadian Food Inspection Agency, National Centre for Foreign Animal Disease, Winnipeg, MB, Canada
- Department of Immunology, University of Manitoba, Winnipeg, MB, Canada
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Spatial Modeling of Mosquito Vectors for Rift Valley Fever Virus in Northern Senegal: Integrating Satellite-Derived Meteorological Estimates in Population Dynamics Models. REMOTE SENSING 2019. [DOI: 10.3390/rs11091024] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mosquitoes are vectors of major pathogen agents worldwide. Population dynamics models are useful tools to understand and predict mosquito abundances in space and time. To be used as forecasting tools over large areas, such models could benefit from integrating remote sensing data that describe the meteorological and environmental conditions driving mosquito population dynamics. The main objective of this study is to assess a process-based modeling framework for mosquito population dynamics using satellite-derived meteorological estimates as input variables. A generic weather-driven model of mosquito population dynamics was applied to Rift Valley fever vector species in northern Senegal, with rainfall, temperature, and humidity as inputs. The model outputs using meteorological data from ground weather station vs satellite-based estimates are compared, using longitudinal mosquito trapping data for validation at local scale in three different ecosystems. Model predictions were consistent with field entomological data on adult abundance, with a better fit between predicted and observed abundances for the Sahelian Ferlo ecosystem, and for the models using in-situ weather data as input. Based on satellite-derived rainfall and temperature data, dynamic maps of three potential Rift Valley fever vector species were then produced at regional scale on a weekly basis. When direct weather measurements are sparse, these resulting maps should be used to support policy-makers in optimizing surveillance and control interventions of Rift Valley fever in Senegal.
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Biteye B, Fall AG, Ciss M, Seck MT, Apolloni A, Fall M, Tran A, Gimonneau G. Ecological distribution and population dynamics of Rift Valley fever virus mosquito vectors (Diptera, Culicidae) in Senegal. Parasit Vectors 2018; 11:27. [PMID: 29316967 PMCID: PMC5759860 DOI: 10.1186/s13071-017-2591-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 12/13/2017] [Indexed: 11/17/2022] Open
Abstract
Background Many zoonotic infectious diseases have emerged and re-emerged over the last two decades. There has been a significant increase in vector-borne diseases due to climate variations that lead to environmental changes favoring the development and adaptation of vectors. This study was carried out to improve knowledge of the ecology of mosquito vectors involved in the transmission of Rift Valley fever virus (RVFV) in Senegal. Methods An entomological survey was conducted in three Senegalese agro-systems, Senegal River Delta (SRD), Senegal River Valley (SRV) and Ferlo, during the rainy season (July to November) of 2014 and 2015. Mosquitoes were trapped using CDC light traps set at ten sites for two consecutive nights during each month of the rainy season, for a total of 200 night-traps. Ecological indices were calculated to characterize the different populations of RVFV mosquito vectors. Generalized linear models with mixed effects were used to assess the influence of climatic conditions on the abundance of RVFV mosquito vectors. Results A total of 355,408 mosquitoes belonging to 7 genera and 35 species were captured in 200 night-traps. RVFV vectors represented 89.02% of the total, broken down as follows: Ae. vexans arabiensis (31.29%), Cx. poicilipes (0.6%), Cx. tritaeniorhynchus (33.09%) and Ma. uniformis (24.04%). Comparison of meteorological indices (rainfall, temperature, relative humidity), abundances and species diversity indicated that there were no significant differences between SRD and SRV (P = 0.36) while Ferlo showed significant differences with both (P < 0.001). Mosquito collection increased significantly with temperature for Ae. vexans arabiensis (P < 0.001), Cx. tritaeniorhynchus (P = 0.04) and Ma. uniformis (P = 0.01), while Cx. poicilipes decreased (P = 0.003). Relative humidity was positively and significantly associated with the abundances of Ae. vexans arabiensis (P < 0.001), Cx. poicilipes (P = 0.01) and Cx. tritaeniorhynchus (P = 0.007). Rainfall had a positive and significant effect on the abundances of Ae. vexans arabiensis (P = 0.005). The type of biotope (temporary ponds, river or lake) around the trap points had a significant effect on the mosquito abundances (P < 0.001). Conclusions In terms of species diversity, the SRD and SRV ecosystems are similar to each other and different from that of Ferlo. Meteorological indices and the type of biotope (river, lake or temporary pond) have significant effects on the abundance of RVFV mosquito vectors. Electronic supplementary material The online version of this article (10.1186/s13071-017-2591-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Biram Biteye
- Institut Sénégalais de Recherches Agricoles/Laboratoire National de l'Elevage et de Recherches Vétérinaires, BP 2057, Dakar-Hann, Senegal. .,Université Cheikh Anta Diop, Faculté des Sciences et Techniques, Département de Biologie Animale, Laboratoire d'Ecologie Vectorielle et Parasitaire, Dakar, Senegal.
| | - Assane G Fall
- Institut Sénégalais de Recherches Agricoles/Laboratoire National de l'Elevage et de Recherches Vétérinaires, BP 2057, Dakar-Hann, Senegal
| | - Mamadou Ciss
- Institut Sénégalais de Recherches Agricoles/Laboratoire National de l'Elevage et de Recherches Vétérinaires, BP 2057, Dakar-Hann, Senegal
| | - Momar T Seck
- Institut Sénégalais de Recherches Agricoles/Laboratoire National de l'Elevage et de Recherches Vétérinaires, BP 2057, Dakar-Hann, Senegal
| | - Andrea Apolloni
- Institut Sénégalais de Recherches Agricoles/Laboratoire National de l'Elevage et de Recherches Vétérinaires, BP 2057, Dakar-Hann, Senegal.,CIRAD, UMR ASTRE, INRA, F-34398, Montpellier, France
| | - Moussa Fall
- Institut Sénégalais de Recherches Agricoles/Laboratoire National de l'Elevage et de Recherches Vétérinaires, BP 2057, Dakar-Hann, Senegal.,Université Cheikh Anta Diop, Faculté des Sciences et Techniques, Département de Biologie Animale, Laboratoire d'Ecologie Vectorielle et Parasitaire, Dakar, Senegal
| | - Annelise Tran
- CIRAD, UMR ASTRE, INRA, F-34398, Montpellier, France.,CIRAD, UMR TETIS, F-97940, Sainte-Clotilde, Reunion Island, France
| | - Geoffrey Gimonneau
- CIRAD, UMR INTERTRYP, F-34398, Montpellier, France.,Centre International de Recherche - Développement sur l'Elevage en zone subhumide, Bobo-Dioulasso 01, BP 454, Burkina Faso
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Danzetta ML, Bruno R, Sauro F, Savini L, Calistri P. Rift Valley fever trasmission dynamics described by compartmental models. Prev Vet Med 2016; 134:197-210. [PMID: 27707507 DOI: 10.1016/j.prevetmed.2016.09.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 08/11/2016] [Accepted: 09/10/2016] [Indexed: 11/18/2022]
Abstract
Rift Valley fever (RVF) is one of the most important zoonotic Transboundary Animal Diseases able to cross international borders and cause devastating effect on animal health and food security. Climate changes and the presence of competent vectors in the most of the current RVF-free temperate countries strongly support the inclusion of RVF virus (RVFV) among the most significant emerging viral threats for public and animal health. The transmission of RVFV is driven by complex eco-climatic factors making the epidemiology of RVF infection difficult to study and to understand. Mathematical, statistical and spatial models are often used to explain the mechanisms underlying these biological processes, providing new and effective tools to plan measures for public health protection. In this paper we performed a systematic literature review on RVF published papers with the aim of identifying and describing the most recent papers developing compartmental models for the study of RVFV transmission dynamics.
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Affiliation(s)
- Maria Luisa Danzetta
- Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Teramo, Italy
| | - Rossana Bruno
- Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Teramo, Italy
| | - Francesca Sauro
- Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Teramo, Italy
| | - Lara Savini
- Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Teramo, Italy
| | - Paolo Calistri
- Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Teramo, Italy.
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Sow A, Faye O, Ba Y, Diallo D, Fall G, Faye O, Bob NS, Loucoubar C, Richard V, Dia AT, Diallo M, Malvy D, Sall AA. Widespread Rift Valley Fever Emergence in Senegal in 2013-2014. Open Forum Infect Dis 2016; 3:ofw149. [PMID: 27704007 PMCID: PMC5047427 DOI: 10.1093/ofid/ofw149] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 07/11/2016] [Indexed: 11/16/2022] Open
Abstract
Rift Valley fever (RVF), which caused epizootics and epidemics among human and livestock populations, occurred in Senegal in 2013–2014. A multidisciplinary field investigation was carried out in 3 regions of Senegal. We found 11 confirmed human cases of Rift Valley fever, including severe cases with encephalitis and retinitis, 1 pool of mosquito (Aedes ochraceus), and 52 animals tested positive for the disease. Symptoms such as encephalitis and macular retinitis were the most severe cases reported so far in Senegal. The outbreak was widespread due to animals' movements, leading to the largest RVF outbreak in Senegal in terms of geographic spreading and reaching areas that never reported RVF activity previously.
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Affiliation(s)
- Abdourahmane Sow
- Arbovirus and Viral Hemorrhagic Fevers Unit, Institut Pasteur Dakar, Senegal; Institut de Santé Publique d'Epidémiologie et de Développement, Centre de Recherche Institut National de la Santé et de la Recherche Médicale Unité 897 Epidémiologie-Biostatistique, Bordeaux University, France; Institut Santé et Développement, Cheikh Anta Diop University, Dakar, Senegal; West African Health Organization, Bobo-Dioulasso, Burkina Faso
| | - Ousmane Faye
- Arbovirus and Viral Hemorrhagic Fevers Unit , Institut Pasteur Dakar , Senegal
| | | | | | - Gamou Fall
- Arbovirus and Viral Hemorrhagic Fevers Unit , Institut Pasteur Dakar , Senegal
| | - Oumar Faye
- Arbovirus and Viral Hemorrhagic Fevers Unit , Institut Pasteur Dakar , Senegal
| | - Ndeye Sakha Bob
- Arbovirus and Viral Hemorrhagic Fevers Unit , Institut Pasteur Dakar , Senegal
| | - Cheikh Loucoubar
- Arbovirus and Viral Hemorrhagic Fevers Unit , Institut Pasteur Dakar , Senegal
| | - Vincent Richard
- Infectious Diseases Epidemiology Unit , Institut Pasteur Dakar , Senegal
| | - Anta Tal Dia
- Institut Santé et Développement, Cheikh Anta Diop University , Dakar , Senegal
| | | | - Denis Malvy
- Institut de Santé Publique d'Epidémiologie et de Développement, Centre de Recherche Institut National de la Santé et de la Recherche Médicale Unité 897 Epidémiologie-Biostatistique , Bordeaux University , France
| | - Amadou Alpha Sall
- Arbovirus and Viral Hemorrhagic Fevers Unit , Institut Pasteur Dakar , Senegal
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13
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MAMAK N, BİLGİLİ İ. RİFT VADİSİ HUMMASI. MEHMET AKIF ERSOY ÜNIVERSITESI VETERINER FAKÜLTESI DERGISI 2016. [DOI: 10.24880/maeuvfd.260789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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14
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Talla C, Diallo D, Dia I, Ba Y, Ndione JA, Morse AP, Diop A, Diallo M. Modelling hotspots of the two dominant Rift Valley fever vectors (Aedes vexans and Culex poicilipes) in Barkédji, Sénégal. Parasit Vectors 2016; 9:111. [PMID: 26922792 PMCID: PMC4769837 DOI: 10.1186/s13071-016-1399-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 02/20/2016] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Climatic and environmental variables were used successfully by using models to predict Rift Valley fever (RVF) virus outbreaks in East Africa. However, these models are not replicable in the West African context due to a likely difference of the dynamic of the virus emergence. For these reasons specific models mainly oriented to the risk mapping have been developed. Hence, the areas of high vector pressure or virus activity are commonly predicted. However, the factors impacting their occurrence are poorly investigated and still unknown. In this study, we examine the impact of climate and environmental factors on the likelihood of occurrence of the two main vectors of RVF in West Africa (Aedes vexans and Culex poicilipes) hotspots. METHODS We used generalized linear mixed models taking into account spatial autocorrelation, in order to overcome the default threshold for areas with high mosquito abundance identified by these models. Getis' Gi*(d) index was used to define local adult mosquito abundance clusters (hotspot). RESULTS For Culex poicilipes, a decrease of the minimum temperature promotes the occurrence of hotspots, whereas, for Aedes vexans, the likelihood of hotspot occurrence is negatively correlated with relative humidity, maximum and minimum temperatures. However, for the two vectors, proximity to ponds would increase the risk of being in an hotspot area. CONCLUSIONS These results may be useful in the improvement of RVF monitoring and vector control management in the Barkedji area.
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Affiliation(s)
- Cheikh Talla
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, B.P. 220, Dakar, Sénégal. .,Laboratoire d'Etudes et de Recherches en Statistiques et Développement, Université Gaston Berger, Saint-Louis, Sénégal.
| | - Diawo Diallo
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, B.P. 220, Dakar, Sénégal.
| | - Ibrahima Dia
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, B.P. 220, Dakar, Sénégal.
| | - Yamar Ba
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, B.P. 220, Dakar, Sénégal.
| | | | - Andrew P Morse
- School of Environmental Sciences, University of Liverpool, Liverpool, UK. .,National Health Service, National Institute of Health Research, Health Protection Research Unit in Emerging and Zoonotic Infections, Liverpool, UK.
| | - Aliou Diop
- Laboratoire d'Etudes et de Recherches en Statistiques et Développement, Université Gaston Berger, Saint-Louis, Sénégal.
| | - Mawlouth Diallo
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, B.P. 220, Dakar, Sénégal.
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15
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Ndiaye EH, Fall G, Gaye A, Bob NS, Talla C, Diagne CT, Diallo D, B A Y, Dia I, Kohl A, Sall AA, Diallo M. Vector competence of Aedes vexans (Meigen), Culex poicilipes (Theobald) and Cx. quinquefasciatus Say from Senegal for West and East African lineages of Rift Valley fever virus. Parasit Vectors 2016; 9:94. [PMID: 26897521 PMCID: PMC4761212 DOI: 10.1186/s13071-016-1383-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 02/16/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Rift Valley fever virus (RVFV; Phlebovirus, Bunyaviridae) is a mosquito-borne, zoonotic pathogen. In Senegal, RVFV was first isolated in 1974 from Aedes dalzieli (Theobald) and thereafter from Ae. fowleri (de Charmoy), Ae. ochraceus Theobald, Ae. vexans (Meigen), Culex poicilipes (Theobald), Mansonia africana (Theobald) and Ma. uniformis (Theobald). However, the vector competence of these local species has never been demonstrated making hypothetical the transmission cycle proposed for West Africa based on serological data and mosquito isolates. METHODS Aedes vexans and Cx. poicilipes, two common mosquito species most frequently associated with RVFV in Senegal, and Cx. quinquefasciatus, the most common domestic species, were assessed after oral feeding with three RVFV strains of the West and East/central African lineages. Fully engorged mosquitoes (420 Ae. vexans, 563 Cx. quinquefasciatus and 380 Cx. poicilipes) were maintained at 27 ± 1 °C and 70-80% relative humidity. The saliva, legs/wings and bodies were tested individually for the RVFV genome using real-time RT-PCR at 5, 10, 15 and 20 days post exposure (dpe) to estimate the infection, dissemination, and transmission rates. Genotypic characterisation of the 3 strains used were performed to identify factors underlying the different patterns of transmission. RESULTS The infection rates varied between 30.0-85.0% for Ae. vexans, 3.3-27% for Cx. quinquefasciatus and 8.3-46.7% for Cx. poicilipes, and the dissemination rates varied between 10.5-37% for Ae. vexans, 9.5-28.6% for Cx. quinquefasciatus and 3.0-40.9% for Cx. poicilipes. However only the East African lineage was transmitted, with transmission rates varying between 13.3-33.3% in Ae. vexans, 50% in Cx. quinquefasciatus and 11.1% in Cx. poicilipes. Culex mosquitoes were less susceptible to infection than Ae. vexans. Compared to other strains, amino acid variation in the NSs M segment proteins of the East African RVFV lineage human-derived strain SH172805, might explain the differences in transmission potential. CONCLUSION Our findings revealed that all the species tested were competent for RVFV with a significant more important role of Ae. vexans compared to Culex species and a highest potential of the East African lineage to be transmitted.
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Affiliation(s)
- El Hadji Ndiaye
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal. .,Université Cheikh Anta Diop de Dakar, Département de Biologie Animale, Faculté des Sciences et Techniques, Dakar, Senegal.
| | - Gamou Fall
- Institut Pasteur de Dakar, Unité des Arbovirus et Virus de Fièvres hémorragiques, Dakar, Senegal.
| | - Alioune Gaye
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal. .,Université Cheikh Anta Diop de Dakar, Département de Biologie Animale, Faculté des Sciences et Techniques, Dakar, Senegal.
| | - Ndeye Sakha Bob
- Institut Pasteur de Dakar, Unité des Arbovirus et Virus de Fièvres hémorragiques, Dakar, Senegal.
| | - Cheikh Talla
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
| | - Cheikh Tidiane Diagne
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal. .,Université Cheikh Anta Diop de Dakar, Département de Biologie Animale, Faculté des Sciences et Techniques, Dakar, Senegal.
| | - Diawo Diallo
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
| | - Yamar B A
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
| | - Ibrahima Dia
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, G61 1QH, Scotland, UK.
| | - Amadou Alpha Sall
- Institut Pasteur de Dakar, Unité des Arbovirus et Virus de Fièvres hémorragiques, Dakar, Senegal.
| | - Mawlouth Diallo
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
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16
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Ndione JA, Diop M, Lacaux JP, Gaye AT. Variabilité intra-saisonnière de la pluviométrie et émergence de la fièvre de la vallée du Rift dans la vallée du fleuve Sénégal : nouvelles considérations. ACTA ACUST UNITED AC 2015. [DOI: 10.4267/climatologie.794] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
L’analyse de la variabilité intra-saisonnière de la pluviométrie à Barkédji, Ross-Béthio et Ranérou, localités ayant enregistré des événements de Fièvre de la Vallée du Rift (FVR) respectivement durant les saisons des pluies 1993, 1994, 1999 et 2002 permet de voir que toutes ces saisons des pluies se terminent par un pic pluviométrique précédé d’une pause assez longue, ayant entraîné par endroits l’assèchement des mares avant leur remise en eau. Ces fortes pluies survenues en fin de saison permettent le maintien à un niveau élevé des populations de Culex mais aussi, et surtout, l’éclosion des œufs des Aedes. Grâce à la transmission transovarienne, le virus se retrouve dans un environnement doublement favorable avec des possibilités de dispersion et d’amplification. La combinaison de tous ces facteurs laisse à penser que l’émergence de la FVR en fin de saison des pluies est à mettre en relation avec le rythme pluviométrique à ce moment de l’année.
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Sindato C, Pfeiffer DU, Karimuribo ED, Mboera LEG, Rweyemamu MM, Paweska JT. A Spatial Analysis of Rift Valley Fever Virus Seropositivity in Domestic Ruminants in Tanzania. PLoS One 2015; 10:e0131873. [PMID: 26162089 PMCID: PMC4498811 DOI: 10.1371/journal.pone.0131873] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 06/03/2015] [Indexed: 12/04/2022] Open
Abstract
Rift Valley fever (RVF) is an acute arthropod-borne viral zoonotic disease primarily occurring in Africa. Since RVF-like disease was reported in Tanzania in 1930, outbreaks of the disease have been reported mainly from the eastern ecosystem of the Great Rift Valley. This cross-sectional study was carried out to describe the variation in RVF virus (RVFV) seropositivity in domestic ruminants between selected villages in the eastern and western Rift Valley ecosystems in Tanzania, and identify potential risk factors. Three study villages were purposively selected from each of the two Rift Valley ecosystems. Serum samples from randomly selected domestic ruminants (n = 1,435) were tested for the presence of specific immunoglobulin G (IgG) and M (IgM), using RVF enzyme-linked immunosorbent assay methods. Mixed effects logistic regression modelling was used to investigate the association between potential risk factors and RVFV seropositivity. The overall RVFV seroprevalence (n = 1,435) in domestic ruminants was 25.8% and speciesspecific seroprevalence was 29.7%, 27.7% and 22.0% in sheep (n = 148), cattle (n = 756) and goats (n = 531), respectively. The odds of seropositivity were significantly higher in animals sampled from the villages in the eastern than those in the western Rift Valley ecosystem (OR = 1.88, CI: 1.41, 2.51; p<0.001), in animals sampled from villages with soils of good than those with soils of poor water holding capacity (OR = 1.97; 95% CI: 1.58, 3.02; p< 0.001), and in animals which had been introduced than in animals born within the herd (OR = 5.08, CI: 2.74, 9.44; p< 0.001). Compared with animals aged 1–2 years, those aged 3 and 4–5 years had 3.40 (CI: 2.49, 4.64; p< 0.001) and 3.31 (CI: 2.27, 4.82, p< 0.001) times the odds of seropositivity. The findings confirm exposure to RVFV in all the study villages, but with a higher prevalence in the study villages from the eastern Rift Valley ecosystem.
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Affiliation(s)
- Calvin Sindato
- National Institute for Medical Research, Tabora, Tanzania
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
- Southern African Centre for Infectious Disease Surveillance, Morogoro, Tanzania
- * E-mail:
| | - Dirk U. Pfeiffer
- Veterinary Epidemiology, Economics & Public Health Group, Royal Veterinary College, London, United Kingdom
| | - Esron D. Karimuribo
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
- Southern African Centre for Infectious Disease Surveillance, Morogoro, Tanzania
| | | | - Mark M. Rweyemamu
- Southern African Centre for Infectious Disease Surveillance, Morogoro, Tanzania
| | - Janusz T. Paweska
- Center for Emerging and Zoonotic Diseases, National Institute for Communicable Diseases, National Health Laboratory Service, Sandringham, South Africa
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Paul PNT, Bah A, Ndiaye PI, Ndione JA. An Agent-Based Model for Studying the Impact of Herd Mobility on the Spread of Vector-Borne Diseases: The Case of Rift Valley Fever (Ferlo Senegal). ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ojmsi.2014.23012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Drake JM, Hassan AN, Beier JC. A statistical model of Rift Valley fever activity in Egypt. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2013; 38:251-259. [PMID: 24581353 PMCID: PMC3947558 DOI: 10.1111/j.1948-7134.2013.12038.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 04/03/2013] [Indexed: 05/30/2023]
Abstract
Rift Valley fever (RVF) is a viral disease of animals and humans and a global public health concern due to its ecological plasticity, adaptivity, and potential for spread to countries with a temperate climate. In many places, outbreaks are episodic and linked to climatic, hydrologic, and socioeconomic factors. Although outbreaks of RVF have occurred in Egypt since 1977, attempts to identify risk factors have been limited. Using a statistical learning approach (lasso-regularized generalized linear model), we tested the hypotheses that outbreaks in Egypt are linked to (1) River Nile conditions that create a mosquito vector habitat, (2) entomologic conditions favorable to transmission, (3) socio-economic factors (Islamic festival of Greater Bairam), and (4) recent history of transmission activity. Evidence was found for effects of rainfall and river discharge and recent history of transmission activity. There was no evidence for an effect of Greater Bairam. The model predicted RVF activity correctly in 351 of 358 months (98.0%). This is the first study to statistically identify risk factors for RVF outbreaks in a region of unstable transmission.
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Affiliation(s)
- John M Drake
- Eugene P. Odum School of Ecology, University of Georgia, Athens, GA 30602, U.S.A.; Department of Zoology, Oxford University, Oxford, UK.
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Soti V, Chevalier V, Maura J, Bégué A, Lelong C, Lancelot R, Thiongane Y, Tran A. Identifying landscape features associated with Rift Valley fever virus transmission, Ferlo region, Senegal, using very high spatial resolution satellite imagery. Int J Health Geogr 2013; 12:10. [PMID: 23452759 PMCID: PMC3600004 DOI: 10.1186/1476-072x-12-10] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 02/14/2013] [Indexed: 11/14/2022] Open
Abstract
INTRODUCTION Dynamics of most of vector-borne diseases are strongly linked to global and local environmental changes. Landscape changes are indicators of human activities or natural processes that are likely to modify the ecology of the diseases. Here, a landscape approach developed at a local scale is proposed for extracting mosquito favourable biotopes, and for testing ecological parameters when identifying risk areas of Rift Valley fever (RVF) transmission. The study was carried out around Barkedji village, Ferlo region, Senegal. METHODS In order to test whether pond characteristics may influence the density and the dispersal behaviour of RVF vectors, and thus the spatial variation in RVFV transmission, we used a very high spatial resolution remote sensing image (2.4 m resolution) provided by the Quickbird sensor to produce a detailed land-cover map of the study area. Based on knowledge of vector and disease ecology, seven landscape attributes were defined at the pond level and computed from the land-cover map. Then, the relationships between landscape attributes and RVF serologic incidence rates in small ruminants were analyzed through a beta-binomial regression. Finally, the best statistical model according to the Akaike Information Criterion corrected for small samples (AICC), was used to map areas at risk for RVF. RESULTS Among the derived landscape variables, the vegetation density index (VDI) computed within a 500 m buffer around ponds was positively correlated with serologic incidence (p<0.001), suggesting that the risk of RVF transmission was higher in the vicinity of ponds surrounded by a dense vegetation cover. The final risk map of RVF transmission displays a heterogeneous spatial distribution, corroborating previous findings from the same area. CONCLUSIONS Our results highlight the potential of very high spatial resolution remote sensing data for identifying environmental risk factors and mapping RVF risk areas at a local scale.
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Affiliation(s)
- Valérie Soti
- Cirad, UPR AGIRs, Montpellier, F-34398, France
- Cirad, UPR SCA-Carabe, Montpellier, F-34398, France
- Cirad, UMR TETIS, Montpellier, F-34093, France
| | | | - Jonathan Maura
- Cirad, UPR AGIRs, Montpellier, F-34398, France
- Cirad, UMR TETIS, Montpellier, F-34093, France
| | - Agnès Bégué
- Cirad, UMR TETIS, Montpellier, F-34093, France
| | | | | | | | - Annelise Tran
- Cirad, UPR AGIRs, Montpellier, F-34398, France
- Cirad, UMR TETIS, Montpellier, F-34093, France
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Abstract
Rift Valley fever (RVF) is an emerging zoonotic disease distributed in sub-Saharan African countries and the Arabian Peninsula. The disease is caused by the Rift Valley fever virus (RVFV) of the family Bunyaviridae and the genus Phlebovirus. The virus is transmitted by mosquitoes, and virus replication in domestic ruminant results in high rates of mortality and abortion. RVFV infection in humans usually causes a self-limiting, acute and febrile illness; however, a small number of cases progress to neurological disorders, partial or complete blindness, hemorrhagic fever, or thrombosis. This review describes the pathology of RVF in human patients and several animal models, and summarizes the role of viral virulence factors and host factors that affect RVFV pathogenesis.
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Diallo D, Talla C, Ba Y, Dia I, Sall AA, Diallo M. Temporal distribution and spatial pattern of abundance of the Rift Valley fever and West Nile fever vectors in Barkedji, Senegal. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2011; 36:426-436. [PMID: 22129415 DOI: 10.1111/j.1948-7134.2011.00184.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The temporal distribution and spatial pattern of abundance of mosquito vectors of Rift Valley fever (RVf) and West Nile fever (WNf) were studied during the 2005 and 2006 rainy seasons at Barkedji, Senegal. Mosquitoes were collected every two weeks with CDC light traps with dry ice at 79 sites including temporary ponds, barren, shrubby savannah, wooded savannah, steppes, and villages at different distances (between 0 and 600 m) from the nearest pond. The temporal distributions of these vectors varied between 2005 and 2006 and were positively correlated with rainfall for Aedes (Aedimorphus) vexans Patton, with rainfall after a lag time of one month for Culex (Culex) poicilipes (Theobald) and Culex (Culex) neavei Theobald. All the vectors had their highest abundances and parity rates between September and November. The highest vector abundances were observed in the barren and temporary ponds. The distance of trap location to the nearest ponds was negatively correlated to the abundance of the vectors. Taking into account the linear regression equations, it was predicted that mosquitoes would not disperse and be collected by the light trap, up to 1,500 m to the nearest ponds. The implications of these findings in the epidemiology and control of RVF and WNF at Barkedji are discussed.
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Affiliation(s)
- Diawo Diallo
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36, Avenue Pasteur, BP 220, Dakar, Sénégal.
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Risk assessment of the introduction of Rift Valley fever from the Horn of Africa to Yemen via legal trade of small ruminants. Trop Anim Health Prod 2010; 43:471-80. [DOI: 10.1007/s11250-010-9719-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2010] [Indexed: 11/25/2022]
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Faye O, Diallo M, Diop D, Bezeid OE, Bâ H, Niang M, Dia I, Mohamed SAO, Ndiaye K, Diallo D, Ly PO, Diallo B, Nabeth P, Simon F, Lô B, Diop OM. Rift Valley fever outbreak with East-Central African virus lineage in Mauritania, 2003. Emerg Infect Dis 2008; 13:1016-23. [PMID: 18214173 PMCID: PMC2878230 DOI: 10.3201/eid1307.061487] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Phylogenetic studies demonstrated that outbreak strains belonged to the East-Central African lineage. In October 2003, 9 human cases of hemorrhagic fever were reported in 3 provinces of Mauritania, West Africa. Test results showed acute Rift Valley fever virus (RVFV) infection, and a field investigation found recent circulation of RVFV with a prevalence rate of 25.5% (25/98) and 4 deaths among the 25 laboratory-confirmed case-patients. Immunoglobulin M against RVFV was found in 46% (25/54) of domestic animals. RVFV was also isolated from the mosquito species Culex poicilipes. Genetic comparison of virion segments indicated little variation among the strains isolated. However, phylogenetic studies clearly demonstrated that these strains belonged to the East-Central African lineage for all segments. To our knowledge, this is the first time viruses of this lineage have been observed in an outbreak in West Africa. Whether these strains were introduced or are endemic in West Africa remains to be determined.
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Bionomics of malaria vectors and relationship with malaria transmission and epidemiology in three physiographic zones in the Senegal River Basin. Acta Trop 2008; 105:145-53. [PMID: 18068685 DOI: 10.1016/j.actatropica.2007.10.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 09/20/2007] [Accepted: 10/25/2007] [Indexed: 11/24/2022]
Abstract
Following the implementation of two dams in the Senegal River, entomological and parasitological studies were conducted in three different ecological zones in the Senegal River Basin (the low valley of Senegal River, the Guiers Lake area and the low valley of Ferlo) every 3 month in June 2004, September 2004, December 2004 and March 2005. The objective of this work was to study the influence of environmental heterogeneities on vector bionomics and malaria epidemiology. Mosquitoes were collected when landing on human volunteers and by pyrethrum spray catches. In the parasitological survey, blood samples were taken from a cohort of schoolchildren under 9 years during each entomology survey. Seven anopheline species were collected: Anopheles arabiensis, Anopheles gambiae M form, Anopheles funestus, Anopheles pharoensis, Anopheles coustani, Anopheles wellcomei and Anopheles rufipes. A. arabiensis, A. funestus and A. pharoensis were predominant in the low valley of the Senegal River, A. funestus in the Guiers Lake area and A. arabiensis in the low valley of Ferlo. Mosquito populations' dynamics varied temporally depending on the rainy season for each zone. The anthropophilic rates varied between 6 and 76% for A. gambiae s.l. and 23 and 80% for A. funestus. Only 4/396 A. pharoensis and 1/3076 A. funestus tested carried Plasmodium falciparum CS antigen. These results suggest the implication of A. pharoensis in malaria transmission. The related entomological inoculation rates were estimated to 10.44 in Mbilor and 3 infected bites in Gankette Balla and were due, respectively, to A. pharoensis and A. funestus. Overall, 1636 thick blood smears were tested from blood samples taken from schoolchildren with, respectively, a parasite and gametocyte average prevalence of 9 and 0.9%. The parasite prevalence was uniformly low in Mbilor and Gankette Balla whereas; it increased in September (16%) and then remained stable in December and March (22%) in Mboula where malaria transmission was not perceptible. However, significant differences were observed over time for parasite prevalence in Mbilor and Mboula villages whereas; it was only in Gankette Balla village where gametocyte prevalence was significantly different over time. Our study demonstrates the influence of ecological changes resulted from dams implementation in the Senegal River on the composition of vectorial system, malaria transmission and epidemiology. Such changes should be thoroughly surveyed in order to prevent any possible malaria outbreak in the Senegal River Basin.
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Weidmann M, Sanchez-Seco MP, Sall AA, Ly PO, Thiongane Y, Lô MM, Schley H, Hufert FT. Rapid detection of important human pathogenic Phleboviruses. J Clin Virol 2007; 41:138-42. [PMID: 18006376 DOI: 10.1016/j.jcv.2007.10.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Revised: 09/26/2007] [Accepted: 10/01/2007] [Indexed: 12/22/2022]
Abstract
BACKGROUND Rapid diagnostics are not available for several human pathogens in the genus Phlebovirus of the Bunyaviridae. OBJECTIVES To develop RT-PCR assays for Sandfly Fever Sicilian virus (SFSV), Sandfly Fever Naples virus (SFNV), Toscana virus (TOSV) and Rift Valley Fever virus (RVFV). STUDY DESIGN RNA standards were generated and used to test the performance of the assays. RESULTS A detection limit of 10-100 RNA molecules was determined for the SFSV, TOSV and RVFV assays. The sensitivity of the SFNV assay was not determined. The TOSV and the RVFV assays detected recent isolates from Spain and Africa, respectively. CONCLUSION The assays should help to improve surveillance of pathogenic Phleboviruses.
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Affiliation(s)
- Manfred Weidmann
- Institute of Virology, University of Göttingen, Kreuzbergring 57, 37075 Göttingen, Germany.
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Clements ACA, Pfeiffer DU, Martin V, Pittliglio C, Best N, Thiongane Y. Spatial risk assessment of Rift Valley fever in Senegal. Vector Borne Zoonotic Dis 2007; 7:203-16. [PMID: 17627440 DOI: 10.1089/vbz.2006.0600] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Rift Valley fever (RVF) is broadening its geographic range and is increasingly becoming a disease of global importance with potentially severe consequences for human and animal health. We conducted a spatial risk assessment of RVF in Senegal using serologic data from 16,738 animals in 211 locations. Bayesian spatial regression models were developed with interpolated seasonal rainfall, land surface temperature, distance to perennial water bodies, and time of year entered as fixed-effect variables. Average total monthly rainfall during December-February was the most important spatial predictor of risk of positive RVF serologic status. Maps derived from the models highlighted the lower Senegal River basin and the southern border regions of Senegal as high-risk areas. These risk maps are suitable for use in planning improved sentinel surveillance systems in Senegal, although further data collection is required in large areas of Senegal to better define the spatial distribution of RVF.
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Affiliation(s)
- Archie C A Clements
- Epidemiology Division, Department of Veterinary Clinical Sciences, Royal Veterinary College, Hatfield, Hertfordshire, United Kingdom.
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Clements ACA, Pfeiffer DU, Martin V, Otte MJ. A Rift Valley fever atlas for Africa. Prev Vet Med 2007; 82:72-82. [PMID: 17570545 DOI: 10.1016/j.prevetmed.2007.05.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 05/08/2007] [Accepted: 05/09/2007] [Indexed: 11/24/2022]
Abstract
Rift Valley fever (RVF) epidemics have serious consequences for human and animal health and the livestock trade. Recent epidemics have occurred in previously unaffected regions, increasing concerns that the geographical range of RVF will continue to expand. We conducted an extensive, systematic review of the literature to obtain serological data for RVF in Africa, collected between 1970 and 2000 from human, livestock and wild ungulate populations. Aims were to calculate sub-national estimates of RVF infection prevalence and to define areas where no information was available. We presented the data (aggregated at the first administrative level of countries) using a geographical information system. Data from 71 publications were used to build a spatially explicit Bayesian logistic-regression model, with spatial and non-spatial random effects, allowing us to identify clusters of high and low RVF seroprevalence, and fixed effects that described the disparate nature of the survey subjects and methods. Significant high-prevalence clusters encompassed areas that had experienced epidemics during the late 20th century and significant low-prevalence clusters were located in contiguous areas of Western and Central Africa.
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Affiliation(s)
- Archie C A Clements
- Epidemiology Division, Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, Hatfield, Hertfordshire, United Kingdom.
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Favier C, Chalvet-Monfray K, Sabatier P, Lancelot R, Fontenille D, Dubois MA. Rift Valley fever in West Africa: the role of space in endemicity. Trop Med Int Health 2007; 11:1878-88. [PMID: 17176353 DOI: 10.1111/j.1365-3156.2006.01746.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Rift Valley fever is an endemic vector-borne disease in West Africa, which mainly affects domestic ruminants and occasionally humans. The aetiological mechanisms of its endemicity remain under debate. We used a simple spatially explicit model to assess the possibility of endemicity without wild animals providing a permanent virus reservoir. Our model takes into account the vertical transmission in some mosquito species, the rainfall-driven emergence of their eggs and local and distant contacts because of herd migration. Endemicity without such a permanent virus reservoir would be impossible in a single site except when there is a strictly periodic rainfall pattern; but it would be possible when there are herd movements and sufficient inter-site variability in rainfall, which drives mosquito emergence.
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Opinion of the Scientific Panel on Animal Health and Welfare (AHAW) on a request from the Commission related to “The Risk of a Rift Valley Fever Incursion and its Persistence within the Community”. EFSA J 2005. [DOI: 10.2903/j.efsa.2005.238] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Yamar BA, Diallo D, Kebe CMF, Dia I, Diallo M. Aspects of bioecology of two Rift Valley Fever Virus vectors in Senegal (West Africa): Aedes vexans and Culex poicilipes (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2005; 42:739-50. [PMID: 16363157 DOI: 10.1603/0022-2585(2005)042[0739:aobotr]2.0.co;2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The dispersal, population dynamics, and age structure of two Rift Valley Fever Virus (Phlebovirus: Bunyaviridae) (RVFV) vectors, Aedes vexans Meigen and Culex poicilipes Theobald, were investigated in northern Senegal. The main objective was to investigate possible factors that mediate RVFV emergence and propagation at a site where humans and livestock live in proximity to temporary surface pools. In mark-release-recapture studies, recapture rates of 0.18% (156/85,500) and 3.46% (201/5,800) were obtained for Ae. vexans and Cx. poicilipes, respectively. The number of mosquitoes recaptured decreased with increasing distance from the release point and over time. The estimated daily survival rate for released females ranged from 91 to 96% for Ae. vexans and 70-79% for Cx. poicilipes. The maximum time after release when marked mosquitoes were collected was 23 and 12 d for Ae. vexans and Cx. poicilipes, respectively. The maximum distances from the release point that marked females were recaptured was 620 and 550 m for Ae vexans and Cx. poicilipes, respectively. Rainfall periodicity was a key factor controlling Ae. vexans population abundance. In contrast, rainfall had no discernible effect on the fluctuation of Cx. poicilipes numbers. The involvement of these two species in the transmission of RVFV is discussed with respect to their longevity and daily survival rate.
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Affiliation(s)
- B A Yamar
- Laboratoire d'Entomologie Médicale, Institut Pasteur de Dakar, BP 220, Dakar, Senegal
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Diallo M, Nabeth P, Ba K, Sall AA, Ba Y, Mondo M, Girault L, Abdalahi MO, Mathiot C. Mosquito vectors of the 1998-1999 outbreak of Rift Valley Fever and other arboviruses (Bagaza, Sanar, Wesselsbron and West Nile) in Mauritania and Senegal. MEDICAL AND VETERINARY ENTOMOLOGY 2005; 19:119-26. [PMID: 15958020 DOI: 10.1111/j.0269-283x.2005.00564.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Following an outbreak of Rift Valley fever (RVF) in south-eastern Mauritania during 1998, entomological investigations were conducted for 2 years in the affected parts of Senegal and Mauritania, spanning the Sénégal River basin. A total of 92 787 mosquitoes (Diptera: Culicidae), belonging to 10 genera and 41 species, were captured in light traps. In Senegal, Culex poicilipes (41%) and Mansonia uniformis (39%) were the most abundant species caught, whereas Aedes vexans (77%) and Cx. poicilipes (15%) predominated in Mauritania. RVF virus was isolated from 63 pools of Cx. poicilipes: 36 from Senegal in 1998 and 27 from Mauritania in 1999. These results are the first field evidence of Cx. poicilipes naturally infected with RVFV, and the first isolations of this virus from mosquitoes in Mauritania - the main West African epidemic and epizootic area. Additional arbovirus isolates comprised 25 strains of Bagaza (BAG) from Aedes fowleri, Culex neavei and Cx. poicilipes; 67 Sanar (ArD 66707) from Cx. poicilipes; 51 Wesselsbron (WSL) from Ae. vexans and 30 strains of West Nile (WN) from Ma. uniformis, showing differential specific virus-vector associations in the circulation activity of these five arboviruses.
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Affiliation(s)
- M Diallo
- Institut Pasteur de Dakar, Senegal.
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Abstract
The Bunyaviridae are a large group of viruses that infect a diversity of arthropod vectors and animal hosts. They have a worldwide distribution and can be the cause of human illness ranging from mild asymptomatic infection to hemorrhagic fever and fatal encephalitis. The growth of the human population, the expansion of agricultural and economic development, climatic changes, and the speed and frequency of global transportation all favor the emergence of bunyaviruses and other arthropod borne viruses. International monitoring of the Bunyaviridae and a greater understanding of their ecology and biology are needed to prepare for future outbreaks.
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Affiliation(s)
- Samantha S Soldan
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-4283, USA
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Abstract
Rift Valley fever (RVF) is an acute viral disease, affecting mainly livestock but also humans. The virus is transmitted to humans through mosquito bites or by exposure to blood and bodily fluids. Drinking raw, unpasteurized milk from infected animals can also transmit RVF. Routine vaccination of livestock in Africa has been prohibitively expensive, leading to endemicity of RVF in most African countries. Reports in September 2000 first documented RVF occurring outside of Africa in the Kingdom of Saudi Arabia and Yemen. Prior to this outbreak, the potential for RVF spread into the Arabian Peninsula had already been exemplified by a 1977 Egyptian epidemic. This appearance of RVF outside the African Continent might be related to importation of infected animals from Africa. In the most recent outbreak patients presented with a febrile haemorrhagic syndrome accompanied by liver and renal dysfunction. By the end of the outbreak, April 2001 statistics from the Saudi Ministry of Health documented a total of 882 confirmed cases with 124 deaths. Both the severity of disease and the relatively high 14% death rate might be a consequence of underreporting of less severe disease. Travellers to endemic areas may be at risk of acquiring the disease if exposed to animals or their body fluids directly or through mosquito bites. Special education regarding both modes of transmission and the geographical distribution of this disease needs to be given to travellers at risk.
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Affiliation(s)
- Hanan H Balkhy
- Department of Pediatrics, King Fahad National Guard Hospital, Riyadh, Saudi Arabia
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