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Freeman TL, McElroy AK. Laboratory Animal Models for Rift Valley Fever Virus Disease. Methods Mol Biol 2024; 2824:425-445. [PMID: 39039428 DOI: 10.1007/978-1-0716-3926-9_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Rift Valley fever virus (RVFV) is an arboviral pathogen of clinical and agricultural relevance. The ongoing development of targeted RVFV prophylactics and therapeutics is overwhelmingly dependent on animal models due to both natural, that is, sporadic outbreaks, and structural, for example, underresourcing of endemic regions, limitations in accessing human patient samples and cohorts. Elucidating mechanisms of viral pathogenesis and testing therapeutics is further complicated by the diverse manifestations of RVFV disease and the heterogeneity of the host response to infection. In this chapter, we describe major clinical manifestations of RVFV infection and discuss the laboratory animal models used to study each.
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Affiliation(s)
- Tracey L Freeman
- University of Pittsburgh School of Medicine, Department of Pediatrics, Division of Pediatric Infectious Disease, Pittsburgh, PA, USA
- University of Pittsburgh Center for Vaccine Research, Pittsburgh, PA, USA
| | - Anita K McElroy
- University of Pittsburgh School of Medicine, Department of Pediatrics, Division of Pediatric Infectious Disease, Pittsburgh, PA, USA.
- University of Pittsburgh Center for Vaccine Research, Pittsburgh, PA, USA.
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Nair N, Osterhaus ADME, Rimmelzwaan GF, Prajeeth CK. Rift Valley Fever Virus-Infection, Pathogenesis and Host Immune Responses. Pathogens 2023; 12:1174. [PMID: 37764982 PMCID: PMC10535968 DOI: 10.3390/pathogens12091174] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 09/09/2023] [Accepted: 09/14/2023] [Indexed: 09/29/2023] Open
Abstract
Rift Valley Fever Virus is a mosquito-borne phlebovirus causing febrile or haemorrhagic illness in ruminants and humans. The virus can prevent the induction of the antiviral interferon response through its NSs proteins. Mutations in the NSs gene may allow the induction of innate proinflammatory immune responses and lead to attenuation of the virus. Upon infection, virus-specific antibodies and T cells are induced that may afford protection against subsequent infections. Thus, all arms of the adaptive immune system contribute to prevention of disease progression. These findings will aid the design of vaccines using the currently available platforms. Vaccine candidates have shown promise in safety and efficacy trials in susceptible animal species and these may contribute to the control of RVFV infections and prevention of disease progression in humans and ruminants.
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Issae AR, Katakweba AAS, Kicheleri RP, Chengula AA, Kasanga CJ. Knowledge, attitudes and practices on rift valley fever among pastoral and agropastoral communities of Ngorongoro in the rift valley ecosystem, Tanzania, conducted in 2021/2022. PLoS Negl Trop Dis 2023; 17:e0011560. [PMID: 37611063 PMCID: PMC10479901 DOI: 10.1371/journal.pntd.0011560] [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: 11/02/2022] [Revised: 09/05/2023] [Accepted: 07/27/2023] [Indexed: 08/25/2023] Open
Abstract
Epidemics of Rift Valley fever (RVF), a mosquito-borne zoonotic disease caused by RVF virus, have been linked to exceptionally heavy rainfall and widespread flooding. The disease is endemic in most African countries and pose a major global health risk. Given that the disease was reported in various districts of Tanzania, we hypothesized a lack of knowledge about RVF epidemiology among agropastoral and pastoral communities. The research took place in a period of 7 months, from July, 2021 to January, 2022. The aim of this study was to assess the knowledge, attitudes, and practices (KAP) among the agropastoral and pastoral communities of Ngorongoro district towards RVF. The survey employed a mixed method system, which included 3 focus groups (each comprised 12 individuals), 20 key informant interviews and administration of questionnaire (N = 352) in agropastoral and pastoral community members of Ngorongoro district. The relationship between demographic characteristics and communities' knowledge, attitudes, and practices regarding RVF was observed using a multiple logistic regression model. A total of 352 participants were interviewed, with the majority (67.61%) being male and 32.39% being female, majority (39.5%) attending primary school, and majority (58.2%) being pastoralists. The findings showed that only 36.1%, 38.64% and 16.19% of participants had good knowledge, positive attitude and good practices regarding RVF respectively. Significant demographic factors related with knowledge included: gender (OR = 1.9, CI = 1.03-3.56, P = 0.041), education levels (primary: OR = 3.97, CI = 2-8.16, P = 0.000; secondary: OR = 15.27, CI = 5.5-46.23, P = 0.000 and college: OR = 34. 23, CI = 5.4-67.22, P = 0.000), and locality (Pinyinyi: OR = 0.14, CI = 0.05-0.38, P = 0.000 and Sale: OR = 0.14, CI = 0.04-0.44, P = 0.001). Male participants showed significant positive attitude towards RVF compared to female (OR = 2.37, CI = 1.35-4.17, P = 0.003). Individuals with formal education showed a significant positive attitude toward RVF compared to informal (OR>1, P<0.05). Agropastoral members showed a significant negative attitude toward RVF compared to pastoralists (OR = 0.51, CI = 0.26-0.99, P = 0.048). The calculated RVF prevention practices values were insignificantly (P = 0.853) correlated with knowledge values. The significant correlation between knowledge and attitude, as well as attitude and practice were found (P<0.05). In general, the study revealed poor knowledge, negative attitude and poor practices of communities towards RVF. The lack of regular education programs to make the communities aware of the disease was implicated for these findings. This recommends that provision of health education should be a long-term practice among agropastoral and pastoral communities in order to prevent further RVF outbreaks in Tanzania.
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Affiliation(s)
- Amina Ramadhani Issae
- African Centre of Excellence for Innovative Rodent Pest Management and Biosensor Technology Development, Sokoine University of Agriculture, Morogoro, Tanzania
- Department of Wildlife Management, Sokoine University of Agriculture, Morogoro, Tanzania
- Institute of Pest Management, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Abdul Ahmed Selemani Katakweba
- African Centre of Excellence for Innovative Rodent Pest Management and Biosensor Technology Development, Sokoine University of Agriculture, Morogoro, Tanzania
- Institute of Pest Management, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Rose Peter Kicheleri
- Department of Wildlife Management, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Augustino Alfred Chengula
- Department of Veterinary Microbiology, Parasitology and Biotechnology, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Christopher Jacob Kasanga
- Department of Veterinary Microbiology, Parasitology and Biotechnology, Sokoine University of Agriculture, Morogoro, Tanzania
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Rugarabamu S, Sindato C, Rumisha SF, Mwanyika GO, Misinzo G, Lim HY, Mboera LEG. Community knowledge, attitude and practices regarding zoonotic viral haemorrhagic fevers in five geo-ecological zones in Tanzania. BMC Health Serv Res 2023; 23:360. [PMID: 37046281 PMCID: PMC10091607 DOI: 10.1186/s12913-023-09317-7] [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: 11/10/2022] [Accepted: 03/21/2023] [Indexed: 04/14/2023] Open
Abstract
BACKGROUND Viral haemorrhagic fevers (VHF) cause significant economic and public health impact in Sub-Saharan Africa. Community knowledge, awareness and practices regarding such outbreaks play a pivotal role in their management and prevention. This study was carried out to assess community knowledge, attitude and practices regarding VHF in five geo-ecological zones in Tanzania. METHODS A cross-sectional study was conducted in Buhigwe, Kalambo, Kyela, Kinondoni, Kilindi, Mvomero, Kondoa and Ukerewe districts representing five geo-ecological zones in Tanzania. Study participants were selected by multistage cluster sampling design. A semi-structured questionnaire was used to collect socio-demographic and information related to knowledge, attitude and practices regarding VHFs. Descriptive statistics and logistic regression were used for the analysis. RESULTS A total of 2,965 individuals were involved in the study. Their mean age was 35 (SD ± 18.9) years. Females accounted for 58.2% while males 41.8%. Most of the respondents (70.6%; n = 2093) had never heard of VHF, and those who heard, over three quarters (79%) mentioned the radio as their primary source of information. Slightly over a quarter (29.4%) of the respondents were knowledgeable, 25% had a positive attitude, and 17.9% had unfavourable practice habits. The level of knowledge varied between occupation and education levels (P < 0.005). Most participants were likely to interact with a VHF survivor or take care of a person suffering from VHF (75%) or visit areas with known VHF (73%). There were increased odds of having poor practice among participants aged 36-45 years (AOR: 3.566, 95% CI: 1.593-7.821) and those living in Western, North-Eastern and Lake Victoria zones (AOR: 2.529, 95% CI: 1.071-6.657; AOR: 2.639, 95% CI: 1.130-7.580 AOR: 2.248, 95% CI: 1.073-3.844, respectively). CONCLUSION Overall, the knowledge on VHF among communities is low, while a large proportion of individuals in the community are involved in activities that expose them to the disease pathogens in Tanzania. These findings highlight the need for strengthening health educational and promotion efforts on VHF targeting specific populations.
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Affiliation(s)
- Sima Rugarabamu
- SACIDS Foundation for One Health, Sokoine University of Agriculture, Morogoro, Tanzania.
- Department of Veterinary Microbiology, Parasitology & Biotechnology, Sokoine University of Agriculture, Morogoro, Tanzania.
- Department of Microbiology & Immunology, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania.
| | - Calvin Sindato
- SACIDS Foundation for One Health, Sokoine University of Agriculture, Morogoro, Tanzania
- Tabora Research Centre, National Institute for Medical Research, Tabora, Tanzania
| | - Susan F Rumisha
- National Institute for Medical Research, Headquarters, Dar Es Salaam, Tanzania
- Malaria Atlas Project, Geospatial Health and Development, Telethon Kids Institute, Perth, WA, Australia
| | - Gaspary O Mwanyika
- SACIDS Foundation for One Health, Sokoine University of Agriculture, Morogoro, Tanzania
- Department of Veterinary Microbiology, Parasitology & Biotechnology, Sokoine University of Agriculture, Morogoro, Tanzania
- Mbeya University of Science and Technology, Mbeya, Tanzania
| | - Gerald Misinzo
- SACIDS Foundation for One Health, Sokoine University of Agriculture, Morogoro, Tanzania
- Department of Veterinary Microbiology, Parasitology & Biotechnology, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Hee Young Lim
- Korea Disease Control and Prevention Agency, National Institute of Health, Osong, Chungchungbukdo, Republic of Korea
| | - Leonard E G Mboera
- SACIDS Foundation for One Health, Sokoine University of Agriculture, Morogoro, Tanzania
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de Glanville WA, Allan KJ, Nyarobi JM, Thomas KM, Lankester F, Kibona TJ, Claxton JR, Brennan B, Carter RW, Crump JA, Halliday JEB, Ladbury G, Mmbaga BT, Mramba F, Nyasebwa OM, Rubach MP, Rostal MK, Sanka P, Swai ES, Szemiel AM, Willett BJ, Cleaveland S. An outbreak of Rift Valley fever among peri-urban dairy cattle in northern Tanzania. Trans R Soc Trop Med Hyg 2022; 116:1082-1090. [PMID: 36040309 PMCID: PMC9623736 DOI: 10.1093/trstmh/trac076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 07/12/2022] [Accepted: 08/01/2022] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Human and animal cases of Rift Valley fever (RVF) are typically only reported during large outbreaks. The occurrence of RVF cases that go undetected by national surveillance systems in the period between these outbreaks is considered likely. The last reported cases of RVF in Tanzania occurred during a large outbreak in 2007-2008. METHODS Samples collected between 2017 and 2019 from livestock suffering abortion across northern Tanzania were retrospectively tested for evidence of RVF virus infection using serology and reverse transcription quantitative polymerase chain reaction (RT-qPCR). RESULTS A total of 14 RVF-associated cattle abortions were identified among dairy cattle in a peri-urban area surrounding the town of Moshi. RVF cases occurred from May to August 2018 and were considered to represent an undetected, small-scale RVF outbreak. Milk samples from 3 of 14 cases (21%) were found to be RT-qPCR positive. Genotyping revealed circulation of RVF viruses from two distinct lineages. CONCLUSIONS RVF outbreaks can occur more often in endemic settings than would be expected on the basis of detection by national surveillance. The occurrence of RVF cases among peri-urban dairy cattle and evidence for viral shedding in milk, also highlights potentially emerging risks for RVF associated with increasing urban and peri-urban livestock populations.
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Affiliation(s)
- William A de Glanville
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
- University of Global Health Equity, Kigali 6955, Rwanda
| | - Kathryn J Allan
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
- School of Veterinary Medicine, University of Glasgow, Glasgow G61 1QH, UK
| | - James M Nyarobi
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
- Nelson Mandela African Institution of Science and Technology, Arusha 255, Tanzania
| | - Kate M Thomas
- Centre for International Health, University of Otago, Dunedin 9054, New Zealand
- Kilimanjaro Clinical Research Institute, Moshi 2236, Tanzania
| | - Felix Lankester
- Paul G. Allen School for Global Health, Washington State University, Pullman, WA 99164, USA
- Global Animal Health Tanzania, Arusha 1642, Tanzania
| | - Tito J Kibona
- Nelson Mandela African Institution of Science and Technology, Arusha 255, Tanzania
| | - John R Claxton
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Benjamin Brennan
- MRC-University of Glasgow Centre for Virus Research, University of Glasgow, Glasgow, G61 1QH, UK
| | - Ryan W Carter
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - John A Crump
- Centre for International Health, University of Otago, Dunedin 9054, New Zealand
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC 27710, USA
- Duke Global Health Institute, Duke University, Durham, NC 27710, USA
- Kilimanjaro Christian Medical University College, Tumaini University, Moshi 3010, Tanzania
| | - Jo E B Halliday
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Georgia Ladbury
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Blandina T Mmbaga
- Kilimanjaro Clinical Research Institute, Moshi 2236, Tanzania
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC 27710, USA
- Kilimanjaro Christian Medical University College, Tumaini University, Moshi 3010, Tanzania
| | - Furaha Mramba
- Tanzania Veterinary Laboratory Agency, Dar es Salaam 9254, Tanzania
| | | | - Matthew P Rubach
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC 27710, USA
- Duke Global Health Institute, Duke University, Durham, NC 27710, USA
- Programme in Emerging Infectious Diseases, Duke-National University of Singapore, Singapore 169857, Singapore
| | - Melinda K Rostal
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
- EcoHealth Alliance, New York, NY 10018, USA
| | - Paul Sanka
- Tanzania Veterinary Laboratory Agency, Dar es Salaam 9254, Tanzania
| | | | - Agnieszka M Szemiel
- MRC-University of Glasgow Centre for Virus Research, University of Glasgow, Glasgow, G61 1QH, UK
| | - Brian J Willett
- MRC-University of Glasgow Centre for Virus Research, University of Glasgow, Glasgow, G61 1QH, UK
| | - Sarah Cleaveland
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
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de Glanville WA, Nyarobi JM, Kibona T, Halliday JEB, Thomas KM, Allan KJ, Johnson PCD, Davis A, Lankester F, Claxton JR, Rostal MK, Carter RW, de Jong RMF, Rubach MP, Crump JA, Mmbaga BT, Nyasebwa OM, Swai ES, Willett B, Cleaveland S. Inter-epidemic Rift Valley fever virus infection incidence and risks for zoonotic spillover in northern Tanzania. PLoS Negl Trop Dis 2022; 16:e0010871. [PMID: 36306281 PMCID: PMC9665400 DOI: 10.1371/journal.pntd.0010871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 11/15/2022] [Accepted: 10/06/2022] [Indexed: 11/06/2022] Open
Abstract
Rift Valley fever virus (RVFV) is a mosquito-borne pathogen that has caused epidemics involving people and animals across Africa and the Arabian Peninsula. A number of studies have found evidence for the circulation of RVFV among livestock between these epidemics but the population-level incidence of infection during this inter-epidemic period (IEP) is rarely reported. General force of infection (FOI) models were applied to age-adjusted cross-sectional serological data to reconstruct the annual FOI and population-level incidence of RVFV infection among cattle, goats, and sheep in northern Tanzania from 2009 through 2015, a period without reported Rift Valley fever (RVF) cases in people or animals. To evaluate the potential for zoonotic RVFV spillover during this period, the relationship between village-level livestock RVFV FOI and human RVFV seropositivity was quantified using multi-level logistic regression. The predicted average annual incidence was 72 (95% Credible Interval [CrI] 63, 81) RVFV infections per 10,000 animals and 96 (95% CrI 81, 113), 79 (95% CrI 62, 98), and 39 (95% CrI 28, 52) per 10,000 cattle, sheep, and goats, respectively. There was variation in transmission intensity between study villages, with the highest estimated village-level FOI 2.49% (95% CrI 1.89, 3.23) and the lowest 0.12% (95% CrI 0.02, 0.43). The human RVFV seroprevalence was 8.2% (95% Confidence Interval 6.2, 10.9). Human seropositivity was strongly associated with the village-level FOI in livestock, with the odds of seropositivity in an individual person increasing by around 1.2 times (95% CrI 1.1, 1.3) for each additional annual RVFV seroconversion per 1,000 animals. A history of raw milk consumption was also positively associated with human seropositivity. RVFV has circulated at apparently low levels among livestock in northern Tanzania in the period since the last reported epidemic. Although our data do not allow us to confirm human RVFV infections during the IEP, a strong association between human seropositivity and the FOI in cattle, goats, and sheep supports the hypothesis that RVFV circulation among livestock during the IEP poses a risk for undetected zoonotic spillover in northern Tanzania. We provide further evidence for the likely role of raw milk consumption in RVFV transmission from animals to people.
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Affiliation(s)
- William A. de Glanville
- School of Biodiversity, One Health, and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- University of Global Health Equity, Kigali, Rwanda
- * E-mail: (WAdG); (SC)
| | - James M. Nyarobi
- School of Biodiversity, One Health, and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania
| | - Tito Kibona
- Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania
| | - Jo E. B. Halliday
- School of Biodiversity, One Health, and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Kate M. Thomas
- Centre for International Health, University of Otago, Dunedin, New Zealand
- Kilimanjaro Clinical Research Institute, Moshi, United Republic of Tanzania
| | - Kathryn J. Allan
- School of Biodiversity, One Health, and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Paul C. D. Johnson
- School of Biodiversity, One Health, and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Alicia Davis
- School of Social and Political Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Felix Lankester
- Paul G. Allen School for Global Health, Washington State University, Pullman, Washington, United States of America
- Global Animal Health Tanzania, Arusha, Tanzania
| | - John R. Claxton
- School of Biodiversity, One Health, and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Melinda K. Rostal
- School of Biodiversity, One Health, and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- EcoHealth Alliance, New York, New York, United States of America
| | - Ryan W. Carter
- School of Biodiversity, One Health, and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Rosanne M. F. de Jong
- School of Biodiversity, One Health, and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Matthew P. Rubach
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, North Carolina, United States of America
- Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America
- Programme in Emerging Infectious Diseases, Duke-National University of Singapore, Singapore
| | - John A. Crump
- Centre for International Health, University of Otago, Dunedin, New Zealand
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, North Carolina, United States of America
- Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America
- Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania
| | - Blandina T. Mmbaga
- Kilimanjaro Clinical Research Institute, Moshi, United Republic of Tanzania
- Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America
- Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania
| | - Obed M. Nyasebwa
- Ministry of Livestock and Fisheries, Dodoma, United Republic of Tanzania
| | - Emanuel S. Swai
- Ministry of Livestock and Fisheries, Dodoma, United Republic of Tanzania
| | - Brian Willett
- MRC University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Sarah Cleaveland
- School of Biodiversity, One Health, and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- * E-mail: (WAdG); (SC)
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Adaptation to a Multiplex Bead Assay and Seroprevalence to Rift Valley Fever N Protein: Nampula Province, Mozambique, 2013-2014. J Virol 2022; 96:e0067222. [PMID: 35894603 PMCID: PMC9400480 DOI: 10.1128/jvi.00672-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Rift Valley fever virus (RVFV) is endemic in sub-Saharan Africa (SSA), with outbreaks reported in the Arabian Peninsula and throughout SSA. The natural reservoir for RVFV are ruminants, with livestock populations exceeding 50% exposure rates in some areas of SSA. Transmission to humans can occur through exposure to infected livestock products or multiple species of mosquito vectors. In 2013 and 2014, cross-sectional surveys occurred in two districts of Nacala-a-Velha and Mecubúri in northern Mozambique, and participants provided blood samples for later serological assays. IgG against the N protein of RVFV was detected through multiplex bead assay (MBA). Of the 2,278 persons enrolled between the two surveys and study sites, 181 (7.9%, 95% confidence interval (CI): 6.9%-9.1%) were found to be IgG seropositive with increasing seroprevalence with older age and significantly higher seroprevalence in Nacala-a-Velha (10.5%, 8.8%-12.5%) versus Mecubúri (5.7%, 4.5%-7.1%). Seroprevalence estimates were not significantly different between the 2013 and 2014 surveys. Significant spatial clustering of IgG positive persons were consistent among surveys and within the two districts, pointing toward the consistency of serology data for making population-level assumptions regarding RVFV seroprevalence. A subset of persons (n = 539) provided samples for both the 2013 and 2014 surveys, and a low percentage (0.81%) of these were found to seroconvert between these two surveys. Including the RVFV N protein in an MBA antigen panel could assist elucidate RVFV exposure in SSA. IMPORTANCE Due to sporadic transmission, human contact with Rift Valley Fever Virus (RVFV) is difficult to ascertain at a population level. Detection of antibodies against RVFV antigens assist in estimating exposure as antibodies remain in the host long after the virus has been cleared. In this study, we show that antibodies against RVFV N protein can be detected from dried blood spot (DBS) samples being assayed by multiplex bead assay. DBS from two districts in northern Mozambique were tested for IgG against the N protein, and 7.9% of all enrolled persons were seropositive. Older persons, males, and persons residing closer to the coast had higher RVFV N protein seroprevalence. Spatial clustering of IgG positive persons was noted in both districts. These results show low exposure rates to RVFV in these two northern districts in Mozambique, and the ability to perform serology for the RVFV N protein from dried blood samples.
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Gerken KN, LaBeaud AD, Mandi H, L’Azou Jackson M, Breugelmans JG, King CH. Paving the way for human vaccination against Rift Valley fever virus: A systematic literature review of RVFV epidemiology from 1999 to 2021. PLoS Negl Trop Dis 2022; 16:e0009852. [PMID: 35073355 PMCID: PMC8812886 DOI: 10.1371/journal.pntd.0009852] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 02/03/2022] [Accepted: 12/22/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Rift Valley fever virus (RVFV) is a lethal threat to humans and livestock in many parts of Africa, the Arabian Peninsula, and the Indian Ocean. This systematic review's objective was to consolidate understanding of RVFV epidemiology during 1999-2021 and highlight knowledge gaps relevant to plans for human vaccine trials. METHODOLOGY/PRINCIPAL FINDINGS The review is registered with PROSPERO (CRD42020221622). Reports of RVFV infection or exposure among humans, animals, and/or vectors in Africa, the Arabian Peninsula, and the Indian Ocean during the period January 1999 to June 2021 were eligible for inclusion. Online databases were searched for publications, and supplemental materials were recovered from official reports and research colleagues. Exposures were classified into five groups: 1) acute human RVF cases, 2) acute animal cases, 3) human RVFV sero-surveys, 4) animal sero-surveys, and 5) arthropod infections. Human risk factors, circulating RVFV lineages, and surveillance methods were also tabulated. In meta-analysis of risks, summary odds ratios were computed using random-effects modeling. 1104 unique human or animal RVFV transmission events were reported in 39 countries during 1999-2021. Outbreaks among humans or animals occurred at rates of 5.8/year and 12.4/year, respectively, with Mauritania, Madagascar, Kenya, South Africa, and Sudan having the most human outbreak years. Men had greater odds of RVFV infection than women, and animal contact, butchering, milking, and handling aborted material were significantly associated with greater odds of exposure. Animal infection risk was linked to location, proximity to water, and exposure to other herds or wildlife. RVFV was detected in a variety of mosquito vectors during interepidemic periods, confirming ongoing transmission. CONCLUSIONS/SIGNIFICANCE With broad variability in surveillance, case finding, survey design, and RVFV case confirmation, combined with uncertainty about populations-at-risk, there were inconsistent results from location to location. However, it was evident that RVFV transmission is expanding its range and frequency. Gaps assessment indicated the need to harmonize human and animal surveillance and improve diagnostics and genotyping. Given the frequency of RVFV outbreaks, human vaccination has strong potential to mitigate the impact of this now widely endemic disease.
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Affiliation(s)
- Keli N. Gerken
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - A. Desirée LaBeaud
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Henshaw Mandi
- Coalition for Epidemic Preparedness Innovations (CEPI), Oslo, Norway
| | | | | | - Charles H. King
- Center for Global Health and Diseases, Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
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Ahmed A, Ali Y, Elduma A, Eldigail MH, Mhmoud RA, Mohamed NS, Ksiazek TG, Dietrich I, Weaver SC. Unique Outbreak of Rift Valley Fever in Sudan, 2019. Emerg Infect Dis 2021; 26:3030-3033. [PMID: 33219787 PMCID: PMC7706939 DOI: 10.3201/eid2612.201599] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We report a unique outbreak of Rift Valley fever in the Eldamar area, Sudan, May–July 2019, that resulted in 1,129 case-patients and 19 (1.7%) deaths. Patients exhibited clinical signs including fever (100%), headache (79%), and bleeding (4%). Most (98%) patients also reported death and abortions among their livestock.
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10
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Rift Valley fever virus detection in susceptible hosts with special emphasis in insects. Sci Rep 2021; 11:9822. [PMID: 33972596 PMCID: PMC8110843 DOI: 10.1038/s41598-021-89226-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 04/15/2021] [Indexed: 11/09/2022] Open
Abstract
Rift Valley fever phlebovirus (RVFV, Phenuiviridae) is an emerging arbovirus that can cause potentially fatal disease in many host species including ruminants and humans. Thus, tools to detect this pathogen within tissue samples from routine diagnostic investigations or for research purposes are of major interest. This study compares the immunohistological usefulness of several mono- and polyclonal antibodies against RVFV epitopes in tissue samples derived from natural hosts of epidemiologic importance (sheep), potentially virus transmitting insect species (Culex quinquefasciatus, Aedes aegypti) as well as scientific infection models (mouse, Drosophila melanogaster, C6/36 cell pellet). While the nucleoprotein was the epitope most prominently detected in mammal and mosquito tissue samples, fruit fly tissues showed expression of glycoproteins only. Antibodies against non-structural proteins exhibited single cell reactions in salivary glands of mosquitoes and the C6/36 cell pellet. However, as single antibodies exhibited a cross reactivity of varying degree in non-infected specimens, a careful interpretation of positive reactions and consideration of adequate controls remains of critical importance. The results suggest that primary antibodies directed against viral nucleoproteins and glycoproteins can facilitate RVFV detection in mammals and insects, respectively, and therefore will allow RVFV detection for diagnostic and research purposes.
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11
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Fakour S, Naserabadi S, Ahmadi E. A serological and hematological study on Rift valley fever and associated risk factors in aborted sheep at Kurdistan province in west of Iran. Comp Immunol Microbiol Infect Dis 2021; 75:101620. [PMID: 33609990 DOI: 10.1016/j.cimid.2021.101620] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/29/2021] [Accepted: 02/04/2021] [Indexed: 10/22/2022]
Abstract
Rift Valley fever (RVF) is a disease caused by RVF virus (RVFV) which can cause infections in a range of wild and domestic ruminants as well as in humans and characterized by an increased incidence of abortion in ruminants. This study aims to survey the seroprevalence and risk factors of this zoonose among aborted sheep in Kurdistan province, the west of Iran. 182 blood samples were collected from aborted sheep during the past one month under age groups <1, ≥1-3, >3-5 year in four seasons in two groups of border and non-border cities of Kurdistan province. The presence of RVFV-specific Antibodies was investigated by using competitive ELISA. Indirect immunofluorescence assay (IIFA) was used to confirm positive samples, after separation of serum, as well as blood samples were analyzed for description of hematological parameters. Of a total sheep sampled 1.65 % (n = 3) were positive for RVFV antibodies in both test. The results of IIFA were correlated with the ELISA results. All of the positive samples showed leucopenia and had significant relation with seroprevalence of RVF (P < 0.05). The seroprevalence of RVF in the border cities were significantly higher than other group (P < 0.05) Age of sheep and season had no significant effect on prevalence of RVF (P > 0.05). Results obtained in this study indicated the presence of low-level RVFV circulation among the sheep of Kurdistan Province in Iran, so it is necessary to carry out further studies in other areas of Iran. Doing an epidemiologically study aimed at isolating RVFV in the ruminants of Kurdistan province is recommended. The risk factor of bordering with Iran's western neighbor (Iraq) requires seriously control of the exchange of animals and the relevant products between the two countries.
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Affiliation(s)
- Shahin Fakour
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Sanandaj Branch Islamic Azad University, Sanandaj, Iran.
| | - Salahedin Naserabadi
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Sanandaj Branch Islamic Azad University, Sanandaj, Iran
| | - Elham Ahmadi
- Department of Microbiology, Faculty of Veterinary Medicine, Sanandaj Branch Islamic Azad University, Sanandaj, Iran
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12
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Akinyemi MO, Ayeni KI, Ogunremi OR, Adeleke RA, Oguntoyinbo FA, Warth B, Ezekiel CN. A review of microbes and chemical contaminants in dairy products in sub-Saharan Africa. Compr Rev Food Sci Food Saf 2021; 20:1188-1220. [PMID: 33506591 DOI: 10.1111/1541-4337.12712] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 12/17/2022]
Abstract
Animal milk types in sub-Saharan Africa (SSA) are processed into varieties of products using different traditional methods and are widely consumed by households to support nutritional intake and diet. Dairy products contain several microorganisms, their metabolites, and other chemical compounds, some with health benefits and many others considered as potential health hazards. Consumption of contaminated milk products could have serious health implications for consumers. To access the safety of milk products across SSA, studies in the region investigating the occurrences of pathogens as well as chemical compounds such as heat stable toxins and veterinary drug residues in animal milk and its products were reviewed. This is done with a holistic view in light of the emerging exposome paradigm for improving food safety and consumer health in the region. Herein, we showed that several published studies in SSA applied conventional and/or less sensitive methods in detecting microbial species and chemical contaminants. This has serious implications in food safety because the correct identity of a microbial species and accurate screening for chemical contaminants is crucial for predicting the potential human health effects that undermine the benefits from consumption of these foods. Furthermore, we highlighted gaps in determining the extent of viral and parasitic contamination of milk products across SSA as well as investigating multiple classes of chemical contaminants. Consequently, robust studies should be conducted in this regard. Also, efforts such as development cooperation projects should be initiated by all stakeholders including scientists, regulatory agencies, and policy makers to improve the dairy product chain in SSA in view of safeguarding consumer health.
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Affiliation(s)
- Muiz O Akinyemi
- Department of Microbiology, Babcock University, Ogun State, Ilishan Remo, Nigeria.,Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Kolawole I Ayeni
- Department of Microbiology, Babcock University, Ogun State, Ilishan Remo, Nigeria
| | - Omotade R Ogunremi
- Department of Biological Sciences, First Technical University, Ibadan, Oyo State, Nigeria
| | - Rasheed A Adeleke
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Folarin A Oguntoyinbo
- A.R. Smith Department of Chemistry and Fermentation Sciences, Appalachian State University, Boone, North Carolina, 28608, USA
| | - Benedikt Warth
- Faculty of Chemistry, Department of Food Chemistry and Toxicology, University of Vienna, Währinger Straße 38, Vienna, 1090, Austria
| | - Chibundu N Ezekiel
- Department of Microbiology, Babcock University, Ogun State, Ilishan Remo, Nigeria
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13
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Abstract
Rift Valley fever (RVF) is a zoonotic, vector-borne infectious disease of ruminants and camels transmitted mainly by the Aedes and Culex mosquito species. Contact with the blood or organs of infected animals may infect humans. Its etiological factor is the Rift Valley fever virus (RVFV) of the Phlebovirus genus and Bunyaviridae family. Sheep and goats are most susceptible to infection and newborns and young individuals endure the most severe disease course. High abortion rates and infant mortality are typical for RVF; its clinical signs are high fever, lymphadenitis, nasal and ocular secretions and vomiting. Conventional diagnosis is done by the detection of specific IgM or IgG antibodies and RVFV nucleic acids and by virus isolation. Inactivated and live-attenuated vaccines obtained from virulent RVFV isolates are available for livestock. RVF is endemic in sub-Saharan Africa and the Arabian Peninsula, but in the last two decades, it was also reported in other African regions. Seropositive animals were detected in Turkey, Tunisia and Libya. The wide distribution of competent vectors in non-endemic areas coupled with global climate change threaten to spread RVF transboundarily. The EFSA considers the movement of infected animals and vectors to be other plausible pathways of RVF introduction into Europe. A very low risk both of introduction of the virus through an infected animal or vector and of establishment of the virus, and a moderate risk of its transmission through these means was estimated for Poland. The risk of these specific modes of disease introduction into Europe is rated as very low, but surveillance and response capabilities and cooperation with the proximal endemic regions are recommended.
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14
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Kroeker AL, Babiuk S, Pickering BS, Richt JA, Wilson WC. Livestock Challenge Models of Rift Valley Fever for Agricultural Vaccine Testing. Front Vet Sci 2020; 7:238. [PMID: 32528981 PMCID: PMC7266933 DOI: 10.3389/fvets.2020.00238] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 04/07/2020] [Indexed: 11/13/2022] Open
Abstract
Since the discovery of Rift Valley Fever virus (RVFV) in Kenya in 1930, the virus has become widespread throughout most of Africa and is characterized by sporadic outbreaks. A mosquito-borne pathogen, RVFV is poised to move beyond the African continent and the Middle East and emerge in Europe and Asia. There is a risk that RVFV could also appear in the Americas, similar to the West Nile virus. In light of this potential threat, multiple studies have been undertaken to establish international surveillance programs and diagnostic tools, develop models of transmission dynamics and risk factors for infection, and to develop a variety of vaccines as countermeasures. Furthermore, considerable efforts to establish reliable challenge models of Rift Valley fever virus have been made and platforms for testing potential vaccines and therapeutics in target species have been established. This review emphasizes the progress and insights from a North American perspective to establish challenge models in target livestock such as cattle, sheep, and goats in comparisons to other researchers' reports. A brief summary of the potential role of wildlife, such as buffalo and white-tailed deer as reservoir species will also be discussed.
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Affiliation(s)
- Andrea Louise Kroeker
- Canadian Food Inspection Agency, National Centre for Foreign Animal Disease, 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
| | - Bradley S Pickering
- Canadian Food Inspection Agency, National Centre for Foreign Animal Disease, Winnipeg, MB, Canada.,Department of Medical Microbiology, University of Manitoba, Winnipeg, MB, Canada
| | - Juergen A Richt
- Center of Excellence for Emerging and Zoonotic Animal Diseases (CEEZAD), Manhattan, KS, United States
| | - William C Wilson
- USDA, Arthropod-Borne Animal Diseases Research Unit (ABADRU), Manhattan, KS, United States
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15
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Grossi-Soyster EN, LaBeaud AD. Rift Valley Fever: Important Considerations for Risk Mitigation and Future Outbreaks. Trop Med Infect Dis 2020; 5:tropicalmed5020089. [PMID: 32498264 PMCID: PMC7345646 DOI: 10.3390/tropicalmed5020089] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 05/22/2020] [Accepted: 05/28/2020] [Indexed: 12/02/2022] Open
Abstract
Rift Valley fever virus (RVFV) is a zoonotic phlebovirus of the Phenuiviridae family with great opportunity for emergence in previously unaffected regions, despite its current geographical limits. Outbreaks of RVFV often infect humans or domesticated animals, such as livestock, concurrently and occur sporadically, ranging from localized outbreaks in villages to multi-country events that spread rapidly. The true burden of Rift Valley fever (RVF) is not well defined due to underreporting, misdiagnosis caused by the broad spectrum of disease presentation, and minimal access for rapid and accurate laboratory confirmation. Severe symptoms may include hemorrhagic fever, loss of vision, psychological impairment or disturbances, and organ failure. Those living in endemic areas and travelers should be aware of the potential for exposure to ongoing outbreaks or interepidemic transmission, and engage in behaviors to minimize exposure risks, as vaccinations in humans are currently unavailable and animal vaccinations are not used routinely or ubiquitously. The lack of vaccines approved for use in humans is concerning, as RVFV has proven to be highly pathogenic in naïve populations, causing severe disease in a large percent of confirmed cases, which could have considerable impact on human health.
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16
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Kroeker AL, Smid V, Embury-Hyatt C, Collignon B, Pinette M, Babiuk S, Pickering B. Increased Susceptibility of Cattle to Intranasal RVFV Infection. Front Vet Sci 2020; 7:137. [PMID: 32411730 PMCID: PMC7200984 DOI: 10.3389/fvets.2020.00137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 02/24/2020] [Indexed: 11/13/2022] Open
Abstract
Rift Valley Fever virus (RVFV) is a zoonotic mosquito-borne virus that belongs to the Phenuiviridae family. Infections in animal herds cause abortion storms, high mortality rates in neonates, and mild to severe symptoms. Infected animals can also transmit the virus to people, particularly people who live or work in close contact with livestock. There is currently an ongoing effort to produce safe and efficacious veterinary vaccines against RVFV in livestock to protect against both primary infection in animals and zoonotic infections in people. To test the efficacy of these vaccines it is essential to have a reliable challenge model in relevant target species, including ruminants. In this study we evaluated three routes of inoculation (intranasal, intradermal and a combination of routes) in Holstein cattle using an infectious dose of 107 pfu/ml and a virus strain from the 2006-2007 outbreak in Kenya and Sudan. Our results demonstrated that all routes of inoculation were effective at producing viremia in all animals; however, the intranasal route induced the highest levels and longest duration of viremia, the most noticeable clinical signs, and the most widespread infection of tissues. We therefore recommend using the intranasal inoculation for future vaccine and challenge studies.
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Affiliation(s)
- Andrea L Kroeker
- Canadian Food Inspection Agency, National Centre for Foreign Animal Disease, Winnipeg, MB, Canada
| | - Valerie Smid
- Canadian Food Inspection Agency, National Centre for Foreign Animal Disease, Winnipeg, MB, Canada
| | - Carissa Embury-Hyatt
- Canadian Food Inspection Agency, National Centre for Foreign Animal Disease, Winnipeg, MB, Canada
| | - Brad Collignon
- Canadian Food Inspection Agency, National Centre for Foreign Animal Disease, Winnipeg, MB, Canada
| | - Mathieu Pinette
- Canadian Food Inspection Agency, National Centre for Foreign Animal Disease, 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
| | - Bradley Pickering
- Canadian Food Inspection Agency, National Centre for Foreign Animal Disease, Winnipeg, MB, Canada.,Department of Medical Microbiology, University of Manitoba, Winnipeg, MB, Canada.,College of Veterinary Medicine, Iowa State University, Ames, IA, United States
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17
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Nielsen SS, Alvarez J, Bicout DJ, Calistri P, Depner K, Drewe JA, Garin-Bastuji B, Rojas JLG, Schmidt CG, Michel V, Chueca MÁM, Roberts HC, Sihvonen LH, Stahl K, Calvo AV, Viltrop A, Winckler C, Bett B, Cetre-Sossah C, Chevalier V, Devos C, Gubbins S, Monaco F, Sotiria-Eleni A, Broglia A, Abrahantes JC, Dhollander S, Stede YVD, Zancanaro G. Rift Valley Fever - epidemiological update and risk of introduction into Europe. EFSA J 2020; 18:e06041. [PMID: 33020705 PMCID: PMC7527653 DOI: 10.2903/j.efsa.2020.6041] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Rift Valley fever (RVF) is a vector-borne disease transmitted by a broad spectrum of mosquito species, especially Aedes and Culex genus, to animals (domestic and wild ruminants and camels) and humans. Rift Valley fever is endemic in sub-Saharan Africa and in the Arabian Peninsula, with periodic epidemics characterised by 5-15 years of inter-epizootic periods. In the last two decades, RVF was notified in new African regions (e.g. Sahel), RVF epidemics occurred more frequently and low-level enzootic virus circulation has been demonstrated in livestock in various areas. Recent outbreaks in a French overseas department and some seropositive cases detected in Turkey, Tunisia and Libya raised the attention of the EU for a possible incursion into neighbouring countries. The movement of live animals is the most important pathway for RVF spread from the African endemic areas to North Africa and the Middle East. The movement of infected animals and infected vectors when shipped by flights, containers or road transport is considered as other plausible pathways of introduction into Europe. The overall risk of introduction of RVF into EU through the movement of infected animals is very low in all the EU regions and in all MSs (less than one epidemic every 500 years), given the strict EU animal import policy. The same level of risk of introduction in all the EU regions was estimated also considering the movement of infected vectors, with the highest level for Belgium, Greece, Malta, the Netherlands (one epidemic every 228-700 years), mainly linked to the number of connections by air and sea transports with African RVF infected countries. Although the EU territory does not seem to be directly exposed to an imminent risk of RVFV introduction, the risk of further spread into countries neighbouring the EU and the risks of possible introduction of infected vectors, suggest that EU authorities need to strengthen their surveillance and response capacities, as well as the collaboration with North African and Middle Eastern countries.
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