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Ebogo‐Belobo JT, Kenmoe S, Abanda NN, Bowo‐Ngandji A, Mbaga DS, Magoudjou‐Pekam JN, Kame‐Ngasse GI, Tchatchouang S, Menkem EZ, Okobalemba EA, Noura EA, Meta‐Djomsi D, Maïdadi‐Foudi M, Kenfack‐Zanguim J, Kenfack‐Momo R, Kengne‐Nde C, Esemu SN, Mbacham WF, Sadeuh‐Mba SA, Ndip L, Njouom R. Contemporary epidemiological data of Rift Valley fever virus in humans, mosquitoes and other animal species in Africa: A systematic review and meta-analysis. Vet Med Sci 2023; 9:2309-2328. [PMID: 37548116 PMCID: PMC10508527 DOI: 10.1002/vms3.1238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 03/29/2023] [Accepted: 07/21/2023] [Indexed: 08/08/2023] Open
Abstract
Rift Valley fever (RVF) is a severe zoonotic mosquito-borne disease that represents an important threat to human and animal health, with major public health and socioeconomic impacts. This disease is endemic throughout many African countries and the Arabian Peninsula. This systematic review with meta-analysis was conducted to determine the RVF prevalence in humans, mosquitoes and other animal species in Africa. The review also provides contemporary data on RVF case fatality rate (CFR) in humans. In this systematic review with meta-analysis, a comprehensive literature search was conducted on the PubMed, Embase, Web of Science and Global Index Medicus databases from January 2000 to June 2022 to identify relevant studies. Pooled CFR and prevalence estimates were calculated using the random-effects model. Subgroup analysis and sensitivity analysis were performed, and the I2 -statistic was used to investigate a potential source of heterogeneity. A total of 205 articles were included in the final analysis. The overall RVF CFR in humans was found to be 27.5% [95% CI = 8.0-52.5]. The overall pooled prevalence was 7.8% [95% CI = 6.2-9.6] in humans and 9.3% [95% CI = 8.1-10.6] in animals, respectively. The RVF prevalence in individual mosquitoes ranged from 0.0% to 25%. Subgroup analysis showed substantial heterogeneity with respect to geographical regions and human categories. The study shows that there is a correspondingly similar prevalence of RVF in human and animals; however, human CFR is much higher than the observed prevalence. The lack of a surveillance programme and the fact that this virus has subclinical circulation in animals and humans could explain these observations. The implementation of a One Health approach for RVF surveillance and control would be of great interest for human and animal health.
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Affiliation(s)
- Jean Thierry Ebogo‐Belobo
- Centre for Research on Health and Priority PathologiesInstitute of Medical Research and Medicinal Plants StudiesYaoundeCameroon
- Department of BiochemistryFaculty of SciencesThe University of Yaounde IYaoundéCameroon
| | - Sebastien Kenmoe
- Department of Microbiology and ParasitologyUniversity of BueaBueaCameroon
| | - Ngu Njei Abanda
- Virology DepartmentCentre Pasteur of CameroonYaoundéCameroon
| | - Arnol Bowo‐Ngandji
- Department of MicrobiologyFaculty of SciencesThe University of Yaounde IYaoundéCameroon
| | - Donatien Serge Mbaga
- Department of MicrobiologyFaculty of SciencesThe University of Yaounde IYaoundéCameroon
| | | | - Ginette Irma Kame‐Ngasse
- Centre for Research on Health and Priority PathologiesInstitute of Medical Research and Medicinal Plants StudiesYaoundeCameroon
| | | | | | | | - Efietngab Atembeh Noura
- Centre for Research on Health and Priority PathologiesInstitute of Medical Research and Medicinal Plants StudiesYaoundeCameroon
| | - Dowbiss Meta‐Djomsi
- Research Centre on Emerging and Re‐Emerging DiseasesInstitute of Medical Research and Medicinal Plants StudiesYaoundeCameroon
| | - Martin Maïdadi‐Foudi
- Research Centre on Emerging and Re‐Emerging DiseasesInstitute of Medical Research and Medicinal Plants StudiesYaoundeCameroon
| | | | - Raoul Kenfack‐Momo
- Department of BiochemistryFaculty of SciencesThe University of Yaounde IYaoundéCameroon
| | - Cyprien Kengne‐Nde
- Epidemiological Surveillance, Evaluation and Research UnitNational AIDS Control CommitteeYaoundéCameroon
| | | | - Wilfred Fon Mbacham
- Department of BiochemistryFaculty of SciencesThe University of Yaounde IYaoundéCameroon
| | - Serge Alain Sadeuh‐Mba
- Virology DepartmentCentre Pasteur of CameroonYaoundéCameroon
- Maryland Department of AgricultureSalisbury Animal Health LaboratorySalisburyMarylandUSA
| | - Lucy Ndip
- Department of Microbiology and ParasitologyUniversity of BueaBueaCameroon
| | - Richard Njouom
- Virology DepartmentCentre Pasteur of CameroonYaoundéCameroon
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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, Mutuku FM, Ndenga BA, Agola GA, Migliore E, Fabre EP, Malumbo S, Shaita KN, Rezende IM, LaBeaud AD. Urban risk factors for human Rift Valley fever virus exposure in Kenya. PLOS GLOBAL PUBLIC HEALTH 2022; 2:e0000505. [PMID: 36962424 PMCID: PMC10021321 DOI: 10.1371/journal.pgph.0000505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 06/01/2022] [Indexed: 11/18/2022]
Abstract
The Rift Valley fever virus (RVFV) is a zoonotic arbovirus that can also transmit directly to humans from livestock. Previous studies have shown consumption of sick animal products are risk factors for RVFV infection, but it is difficult to disentangle those risk factors from other livestock rearing activities. Urban areas have an increased demand for animal source foods, different vector distributions, and various arboviruses are understood to establish localized urban transmission cycles. Thus far, RVFV is an unevaluated public health risk in urban areas within endemic regions. We tested participants in our ongoing urban cohort study on dengue (DENV) and chikungunya (CHIKV) virus for RVFV exposure and found 1.6% (57/3,560) of individuals in two urban areas of Kenya had anti-RVFV IgG antibodies. 88% (50/57) of RVFV exposed participants also had antibodies to DENV, CHIKV, or both. Although livestock ownership was very low in urban study sites, RVFV exposure was overall significantly associated with seeing goats around the homestead (OR = 2.34 (CI 95%: 1.18-4.69, p = 0.02) and in Kisumu, RVFV exposure was associated with consumption of raw milk (OR = 6.28 (CI 95%: 0.94-25.21, p = 0.02). In addition, lack of piped water and use of small jugs (15-20 liters) for water was associated with a higher risk of RVFV exposure (OR = 5.36 (CI 95%: 1.23-16.44, p = 0.01) and this may contribute to interepidemic vector-borne maintenance of RVFV. We also investigated perception towards human vaccination for RVFV and identified high acceptance (91% (97/105) at our study sites. This study provides baseline evidence to guide future studies investigating the urban potential of RVFV and highlights the unexplored role of animal products in continued spread of RVFV.
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Affiliation(s)
- Keli Nicole Gerken
- Department of Pediatrics, Division of Infectious Diseases, Stanford University School of Medicine, Stanford, California, United States of America
| | - Francis Maluki Mutuku
- Department of Environment and Health Sciences, Technical University of Mombasa, Mombasa, Kenya
| | | | | | - Eleonora Migliore
- Department of Pediatrics, Division of Infectious Diseases, Stanford University School of Medicine, Stanford, California, United States of America
| | - Eduardo Palacios Fabre
- Department of Pediatrics, Division of Infectious Diseases, Stanford University School of Medicine, Stanford, California, United States of America
| | - Said Malumbo
- Vector Borne Disease Control Unit, Msambweni County Referral Hospital, Kwale, Kenya
| | | | - Izabela Mauricio Rezende
- Department of Pediatrics, Division of Infectious Diseases, Stanford University School of Medicine, Stanford, California, United States of America
| | - A Desiree LaBeaud
- Department of Pediatrics, Division of Infectious Diseases, Stanford University School of Medicine, Stanford, California, United States of America
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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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Rift Valley Fever Virus Propagates in Human Villous Trophoblast Cell Lines and Induces Cytokine mRNA Responses Known to Provoke Miscarriage. Viruses 2021; 13:v13112265. [PMID: 34835071 PMCID: PMC8625252 DOI: 10.3390/v13112265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/08/2021] [Accepted: 11/10/2021] [Indexed: 02/05/2023] Open
Abstract
The mosquito-borne Rift Valley fever (RVF) is a prioritised disease that has been listed by the World Health Organization for urgent research and development of counteraction. Rift Valley fever virus (RVFV) can cause a cytopathogenic effect in the infected cell and induce hyperimmune responses that contribute to pathogenesis. In livestock, the consequences of RVFV infection vary from mild symptoms to abortion. In humans, 1–3% of patients with RVFV infection develop severe disease, manifested as, for example, haemorrhagic fever, encephalitis or blindness. RVFV infection has also been associated with miscarriage in humans. During pregnancy, there should be a balance between pro-inflammatory and anti-inflammatory mediators to create a protective environment for the placenta and foetus. Many viruses are capable of penetrating that protective environment and infecting the foetal–maternal unit, possibly via the trophoblasts in the placenta, with potentially severe consequences. Whether it is the viral infection per se, the immune response, or both that contribute to the pathogenesis of miscarriage remains unknown. To investigate how RVFV could contribute to pathogenesis during pregnancy, we infected two human trophoblast cell lines, A3 and Jar, representing normal and transformed human villous trophoblasts, respectively. They were infected with two RVFV variants (wild-type RVFV and RVFV with a deleted NSs protein), and the infection kinetics and 15 different cytokines were analysed. The trophoblast cell lines were infected by both RVFV variants and infection caused upregulation of messenger RNA (mRNA) expression for interferon (IFN) types I–III and inflammatory cytokines, combined with cell line-specific mRNA expression of transforming growth factor (TGF)-β1 and interleukin (IL)-10. When comparing the two RVFV variants, we found that infection with RVFV lacking NSs function caused a hyper-IFN response and inflammatory response, while the wild-type RVFV suppressed the IFN I and inflammatory response. The induction of certain cytokines by RVFV infection could potentially lead to teratogenic effects that disrupt foetal and placental developmental pathways, leading to birth defects and other pregnancy complications, such as miscarriage.
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Risk based serological survey of Rift Valley fever in Tunisia (2017-2018). Heliyon 2021; 7:e07932. [PMID: 34522818 PMCID: PMC8427255 DOI: 10.1016/j.heliyon.2021.e07932] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/28/2021] [Accepted: 09/01/2021] [Indexed: 12/22/2022] Open
Abstract
Rift Valley fever (RVF) has been reported in the sub-Saharan region of Africa, Egypt and Arabian Peninsula - Yemen and Saudi Arabia, over the past 20 years and is a threat to both the animal and human populations in Tunisia. Tunisia is considered as a high-risk country for the introduction of RVF due to the informal movements of diseased animals already reported in the neighboring countries. The objective of this study was to assess the status of RVF in small ruminants and camels in Tunisia. A risk-based serological survey was conducted to evaluate the presence of RVF based on spatial qualitative risk analysis (SQRA). Samples were collected from small ruminants (sheep and goats) (n = 1,114), and camels (n = 173) samples, belonging to 18 breeders in 14 governorates between November 2017 and January 2018. Samples were tested using an RVF specific multispecies competitive ELISA. Out of the 1,287 samples tested for the presence of RVF IgG antibodies by ELISA, only one positive sample 0.07% (1/1 287) was detected but not confirmed with the virus neutralization test (VNT) used for confirmation. So far, no RVF outbreaks have been reported in Tunisia and our study confirmed the absence of RVF in livestock up to January 2018. Further investigations are needed to confirm the RVF-free status of Tunisia today.
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Youssouf H, Subiros M, Dennetiere G, Collet L, Dommergues L, Pauvert A, Rabarison P, Vauloup-Fellous C, Le Godais G, Jaffar-Bandjee MC, Jean M, Paty MC, Noel H, Oliver S, Filleul L, Larsen C. Rift Valley Fever Outbreak, Mayotte, France, 2018-2019. Emerg Infect Dis 2021; 26:769-772. [PMID: 32186500 PMCID: PMC7101114 DOI: 10.3201/eid2604.191147] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
From November 2018 through July 2019, an outbreak of Rift Valley fever in humans occurred in Mayotte, France; 142 cases were confirmed. Exposure to animals or their biological fluid was reported by 73% of patients. Health authorities have been implementing control measures, including veterinary surveys, vector control interventions, and prevention measures.
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Venkatesh A, Patel R, Goyal S, Rajaratnam T, Sharma A, Hossain P. Ocular manifestations of emerging viral diseases. Eye (Lond) 2021; 35:1117-1139. [PMID: 33514902 PMCID: PMC7844788 DOI: 10.1038/s41433-020-01376-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 12/02/2020] [Accepted: 12/14/2020] [Indexed: 02/07/2023] Open
Abstract
Emerging infectious diseases (EIDs) are an increasing threat to public health on a global scale. In recent times, the most prominent outbreaks have constituted RNA viruses, spreading via droplets (COVID-19 and Influenza A H1N1), directly between humans (Ebola and Marburg), via arthropod vectors (Dengue, Zika, West Nile, Chikungunya, Crimean Congo) and zoonotically (Lassa fever, Nipah, Rift Valley fever, Hantaviruses). However, specific approved antiviral therapies and vaccine availability are scarce, and public health measures remain critical. Patients can present with a spectrum of ocular manifestations. Emerging infectious diseases should therefore be considered in the differential diagnosis of ocular inflammatory conditions in patients inhabiting or returning from endemic territories, and more general vigilance is advisable in the context of a global pandemic. Eye specialists are in a position to facilitate swift diagnosis, improve clinical outcomes, and contribute to wider public health efforts during outbreaks. This article reviews those emerging viral diseases associated with reports of ocular manifestations and summarizes details pertinent to practicing eye specialists.
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Affiliation(s)
- Ashwin Venkatesh
- grid.5335.00000000121885934School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Ravi Patel
- grid.439257.e0000 0000 8726 5837Moorfields Eye Hospital, London, UK
| | - Simran Goyal
- grid.5335.00000000121885934School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Timothy Rajaratnam
- grid.5335.00000000121885934School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Anant Sharma
- grid.439257.e0000 0000 8726 5837Moorfields Eye Hospital, London, UK
| | - Parwez Hossain
- grid.430506.4Eye Unit, University Hospitals Southampton NHS Foundation Trust, Southampton, UK ,grid.5491.90000 0004 1936 9297Clinical Experimental Sciences, Faculty of Medicine, Univeristy of Southampton, Southampton, UK
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Kumalija MS, Chilongola JO, Budodo RM, Horumpende PG, Mkumbaye SI, Vianney JM, Mwakapuja RS, Mmbaga BT. Detection of Rift Valley Fever virus inter-epidemic activity in Kilimanjaro Region, North Eastern Tanzania. Glob Health Action 2021; 14:1957554. [PMID: 34415237 PMCID: PMC8381910 DOI: 10.1080/16549716.2021.1957554] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Background Rift Valley Fever virus (RVFV) is a zoonotic arbovirus of public health impact infecting livestock, wildlife, and humans mainly in Africa and other parts of the world. Despite its public health importance, mechanisms of RVFV maintenance during interepidemic periods (IEPS) remain unclear. Objective We aimed to examine comparatively exposure to RVFV between humans and goats and RVFV infection between humans, goats and mosquitoes. Methods A cross sectional study was performed in the Lower Moshi area of the Kilimanjaro region from March to June 2020. RVFV exposure was determined by detecting IgG/IgM to RVFV using a competitive enzyme linked immunosorbent assay whereas infection was determined by real time quantitative polymerase chain reaction (RT-qPCR) assay. Results Results show that the male gender was related to RVFV seropositivity (χ2 = 5.351; p=0.030). Being 50 years and above was related to seropositivity (χ2 =14.430; p=0.006) whereas bed net use, larger numbers of persons living in the same house (>7 persons) and RVFV seropositivity in goats were related to higher seropositivity to RVFV among humans χ2 =6.003; p=0.021, χ2 =23.213; p < 0.001 and χ2 =27.053; p < 0.001), respectively. By the use of RT-qPCR, goats exhibited the highest RVFV infection rate of 4.1%, followed by humans (2.6%), Ae. aegypti (2.3%), and Cx. pipiens complex(1.5%). Likewise, a higher proportion of goats (23.3%) were RVFV seropositive as compared with humans (13.2%). Conclusion Our findings suggest the Lower Moshi area as a potential hotspot for Rift Valley Fever (RVF), posing the danger of being a source of RVFV spread to other areas. Goats had the highest infection rate, suggesting goats as important hosts for virus maintenance during IEPs. We recommend the implementation of strategies that will warrant active RVF surveillance through the identification of RVF hotspots for targeted control of the disease.
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Affiliation(s)
- Medard S Kumalija
- Department of Global Health and Biomedical Sciences, Nelson Mandela Institution of Science and Technology, Arusha, Tanzania
| | - Jaffu O Chilongola
- Department of Medical Biochemistry and Molecular Biology, Kilimanjaro Christian Medical University College, Moshi Tanzania.,Department of Clinical Trials, Kilimanjaro Clinical Research Institute, Moshi, Tanzania
| | - Rule M Budodo
- Department of Clinical Trials, Kilimanjaro Clinical Research Institute, Moshi, Tanzania
| | - Pius G Horumpende
- Department of Public Health and Research, Lugalo Military College of Medical Sciences, Dar Es Salaam, Tanzania
| | - Sixbert I Mkumbaye
- Department of Clinical Trials, Kilimanjaro Clinical Research Institute, Moshi, Tanzania
| | - John-Mary Vianney
- Department of Global Health and Biomedical Sciences, Nelson Mandela Institution of Science and Technology, Arusha, Tanzania
| | - Richard S Mwakapuja
- Department of Bacterial Vaccines, Tanzania Veterinary Laboratory Agency (TVLA), Kibaha, Tanzania
| | - Blandina T Mmbaga
- Department of Clinical Trials, Kilimanjaro Clinical Research Institute, Moshi, Tanzania
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Abstract
Rift Valley fever virus (RVFV) is a pathogen of both humans and livestock in Africa and the Middle East. Severe human disease is associated with hepatitis and/or encephalitis. Current pathogenesis studies rely on rodents and nonhuman primates, which have advantages and disadvantages. We evaluated disease progression in Mustela putorius furo (the ferret) following intradermal (i.d.) or intranasal (i.n.) infection. Infected ferrets developed hyperpyrexia, weight loss, lymphopenia, and hypoalbuminemia. Three of four ferrets inoculated intranasally with RVFV developed central nervous system (CNS) disease that manifested as seizure, ataxia, and/or hind limb weakness at 8 to 11 days postinfection (dpi). Animals with clinical CNS disease had transient viral RNAemia, high viral RNA loads in the brain, and histopathological evidence of encephalitis. The ferret model will facilitate our understanding of how RVFV accesses the CNS and has utility for the evaluation of vaccines and/or therapeutics in preventing RVFV CNS disease.IMPORTANCE Animal models of viral disease are very important for understanding how viruses make people sick and for testing out drugs and vaccines to see if they can prevent disease. In this study, we identify the ferret as a model of encephalitis caused by Rift Valley fever virus (RVFV). This novel model will allow researchers to evaluate ways to prevent RVFV encephalitis.
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Cartwright HN, Barbeau DJ, McElroy AK. Rift Valley Fever Virus Is Lethal in Different Inbred Mouse Strains Independent of Sex. Front Microbiol 2020; 11:1962. [PMID: 32973712 PMCID: PMC7472459 DOI: 10.3389/fmicb.2020.01962] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 07/24/2020] [Indexed: 01/22/2023] Open
Abstract
Rift Valley fever virus (RVFV) is a zoonotic arbovirus affecting humans and livestock in Africa and the Arabian Peninsula. The majority of human cases are mild and self-limiting; however, severe cases can result in hepatitis, encephalitis, or hemorrhagic fever. There is a lack of immunocompetent mouse models that faithfully recapitulate the varied clinical outcomes of RVF in humans. However, there are easily accessible and commonly used inbred mouse strains that have never been challenged with wild-type RVFV. Here, RVFV susceptibility and pathogenesis were evaluated across five commonly used inbred laboratory mouse strains: C57BL/6J, 129S1/SvlmJ, NOD/ShiLtJ, A/J, and NZO/HILtJ. Comparisons between different mouse strains, challenge doses, and sexes revealed exquisite susceptibility to wild-type RVFV in an almost uniform manner. Never before challenged NOD/ShiLtJ, A/J, and NZO/HILtJ mice showed similar phenotypes of Rift Valley fever disease as previously tested inbred mouse strains. The majority of infected mice died or were euthanized by day 5 post-infection due to overwhelming hepatic disease as evidenced by gross liver pathology and high viral RNA loads in the liver. Mice surviving past day 6 across all strains succumbed to late-onset encephalitis. Remarkably, sex was not found to impact survival or viral load and showed only modest effect on time to death and weight loss for any of the challenged mouse strains following RVFV infection. Regardless of sex, these inbred mouse strains displayed extreme susceptibility to wild-type RVFV down to one virus particle.
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Affiliation(s)
- Haley N Cartwright
- Division of Pediatric Infectious Disease, Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA, United States.,Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Dominique J Barbeau
- Division of Pediatric Infectious Disease, Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA, United States.,Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Anita K McElroy
- Division of Pediatric Infectious Disease, Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA, United States.,Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States
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Alhaji NB, Aminu J, Lawan MK, Babalobi OO, Ghali-Mohammed I, Odetokun IA. Seropositivity and associated intrinsic and extrinsic factors for Rift Valley fever virus occurrence in pastoral herds of Nigeria: a cross sectional survey. BMC Vet Res 2020; 16:243. [PMID: 32664958 PMCID: PMC7359261 DOI: 10.1186/s12917-020-02455-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 07/03/2020] [Indexed: 11/10/2022] Open
Abstract
Background Rift Valley fever (RVF) is a vector-borne emerging zoonotic disease of animals and humans, characterized by socioeconomic losses to livestock farmers and global public health threat. The study determined RVFV seroprevalence in cattle, assessed pastoralists’ knowledge about RVF, and factors that influence its occurrence in pastoral cattle herds of Nigeria. A cross-sectional study was conducted in pastoral herds of North-central Nigeria from 2017 to 2018. Data were collected using serology and questionnaire tools. Descriptive statistics were used to analyze the obtained data. Categorical variables were presented as proportions and their associations determined by Chi-square tests. Associations of risk factors were analyzed by univariable and multivariable logistic regressions analyses at 95% confidence level. Results The overall IgM seropositivity of RVFV in pastoral cattle herds was 5.6%. This was higher in nomadic herds (7.4%) than in agro-pastoral herds (3.8%). All animal demographic characteristics of age, sex and breeds were not significantly (p > 0.05) associated with RVFV occurrence in pastoral herds. All the 403 pastoralists selected participated in the study, with the majorities of them being male, married and have no formal education. Majority of the pastoralists had low knowledge levels about zoonotic RVFV infection. All identified socio-ecological factors significantly (p < 0.05) influenced RVFV occurrence in herds. Mosquitoes availability in cattle environment (OR = 7.81; 95% CI: 4.85, 12.37), presence of rivers and streams at grazing fields (OR = 10.80; 95% CI: 6.77, 17.34), high rainfall (OR = 4.30; 95% CI: 2.74, 6.59), irrigated rice fields (OR = 5.14; 95% CI: 3.21, 7.79), bushy vegetation (OR = 6.11; 95% CI: 3.96, 9.43), animal movement (OR = 2.2; 95% CI: 1.45, 3.25), and seasons (OR = 2.34; 95% CI: 1.55, 3.51) were more likely to influenced RVFV occurrence in cattle herds. Conclusions Results of this study had illustrated recent circulation of RVFV in pastoral cattle herds in Nigeria and needs urgent interventions. The surveyed pastoralists had low knowledge level about RVF while the socio-ecological factors significantly influenced RVFV occurrence in herds. To address these gaps, pastoralists should be educated on clinical manifestations and modes of transmission of the disease in animals and humans, and mitigation measures. Adequate knowledge about RVF epidemiology will assure food security and public health.
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Affiliation(s)
- Nma Bida Alhaji
- Department of Public Health and Epidemiology, Niger State Ministry of Livestock and Fisheries, Minna, Nigeria.
| | - Jibrin Aminu
- Department of Public Health and Epidemiology, Niger State Ministry of Livestock and Fisheries, Minna, Nigeria
| | - Mohammed Kabiru Lawan
- Department of Veterinary Public Health and Preventive Medicine, Ahmadu Bello University, Zaria, Nigeria
| | - Olutayo Olajide Babalobi
- Department of Veterinary Public Health and Preventive Medicine, University of Ibadan, Ibadan, Nigeria
| | - Ibrahim Ghali-Mohammed
- Department of Veterinary Public Health and Preventive Medicine, University of Ilorin, Ilorin, Nigeria
| | - Ismail Ayoade Odetokun
- Department of Veterinary Public Health and Preventive Medicine, University of Ilorin, Ilorin, Nigeria
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Budodo RM, Horumpende PG, Mkumbaye SI, Mmbaga BT, Mwakapuja RS, Chilongola JO. Serological evidence of exposure to Rift Valley, Dengue and Chikungunya Viruses among agropastoral communities in Manyara and Morogoro regions in Tanzania: A community survey. PLoS Negl Trop Dis 2020; 14:e0008061. [PMID: 32687540 PMCID: PMC7402518 DOI: 10.1371/journal.pntd.0008061] [Citation(s) in RCA: 8] [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: 01/11/2020] [Revised: 08/04/2020] [Accepted: 06/11/2020] [Indexed: 11/19/2022] Open
Abstract
Tanzania has recently experienced outbreaks of dengue in two coastal regions of Dar es Salaam and Tanga. Chikungunya and Rift Valley Fever outbreaks have also been recorded in the past decade. Little is known on the burden of the arboviral disease causing viruses (Dengue, Rift Valley and Chikungunya) endemically in the inter-epidemic periods. We aimed at determining the prevalence of the dengue, rift valley and chikungunya among humans in two geo ecologically distinct sites. The community-based cross-sectional study was conducted in Magugu in Manyara region and Wami-Dakawa in Morogoro region in Tanzania. Venous blood was collected from participants of all age groups, serum prepared from samples and subjected to ELISA tests for RVFV IgG/IgM, DENV IgG/IgM, and CHIKV IgM/IgG. Samples that were positive for IgM ELISA tests were subjected to a quantitative RT PCR for each virus. A structured questionnaire was used to collect socio-demographic information. Data analysis was performed by using SPSSv22. A total of 191 individuals from both sites participated in the study. Only one individual was CHIKV seropositive in Magugu, but none was seropositive or positive for either RVFV or DENV. Of the 122 individuals from Wami-Dakawa site, 16.39% (n = 20) had recent exposure to RVFV while 9.83% (n = 12) were seropositive for CHIKV. All samples were negative by RVFV and CHIKV qPCR. Neither infection nor exposure to DENV was observed in participants from both sites. Being more than 5 in a household, having no formal education and having recently travelled to an urban area were risk factors associated with RVFV and CHIKV seropositivity. We report a considerable exposure to RVFV and CHIKV among Wami-Dakawa residents during the dry season and an absence of exposure of the viruses among humans in Magugu site. In both sites, neither DENV exposure nor infection was detected.
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Affiliation(s)
- Rule M. Budodo
- Kilimanjaro Clinical Research Institute, Moshi, Tanzania
| | - Pius G. Horumpende
- Kilimanjaro Clinical Research Institute, Moshi, Tanzania
- Department of Public Health and Research, Lugalo Military College of Medical Sciences (MCMS) and General Military Hospital (GMH), Dar es Salaam, Tanzania
| | - Sixbert I. Mkumbaye
- Kilimanjaro Clinical Research Institute, Moshi, Tanzania
- Department of Medical Biochemistry and Molecular Biology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Blandina T. Mmbaga
- Kilimanjaro Clinical Research Institute, Moshi, Tanzania
- Directorate of Research and Consultancies, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | | | - Jaffu O. Chilongola
- Kilimanjaro Clinical Research Institute, Moshi, Tanzania
- Department of Medical Biochemistry and Molecular Biology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
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Nielsen SS, Alvarez J, Bicout DJ, Calistri P, Depner K, Drewe JA, Garin‐Bastuji B, Gonzales Rojas JL, Gortázar Schmidt C, Michel V, Miranda Chueca MÁ, Roberts HC, Sihvonen LH, Stahl K, Velarde A, trop A, Winckler C, Cetre‐Sossah C, Chevalier V, de Vos C, Gubbins S, Antoniou S, Broglia A, Dhollander S, Van der Stede Y. Rift Valley Fever: risk of persistence, spread and impact in Mayotte (France). EFSA J 2020; 18:e06093. [PMID: 32874301 PMCID: PMC7448016 DOI: 10.2903/j.efsa.2020.6093] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Rift Valley fever (RVF) is a vector-borne disease transmitted by different mosquito species, especially Aedes and Culex genus, to animals and humans. In November 2018, RVF re-emerged in Mayotte (France) after 11 years. Up to the end of October 2019, 126 outbreaks in animals and 143 human cases were reported. RVF mortality was 0.01%, and the number of abortions reported in polymerase chain reaction (PCR)-positive ruminants was fivefold greater than the previous 7 years. Milk loss production in 2019 compared to 2015-2018 was estimated to be 18%, corresponding to an economic loss of around €191,000 in all of Mayotte. The tropical climate in Mayotte provides conditions for the presence of mosquitoes during the whole year, and illegal introductions of animals represent a continuous risk of (re)introduction of RVF. The probability of RVF virus (RVFV) persisting in Mayotte for 5 or more years was estimated to be < 10% but could be much lower if vertical transmission in vectors does not occur. Persistence of RVF by vertical transmission in Mayotte and Réunion appears to be of minor relevance compared to other pathways of re-introduction (i.e. animal movement). However, there is a high uncertainty since there is limited information about the vertical transmission of some of the major species of vectors of RVFV in Mayotte and Réunion. The only identified pathways for the risk of spread of RVF from Mayotte to other countries were by infected vectors transported in airplanes or by wind currents. For the former, the risk of introduction of RVF to continental France was estimated to 4 × 10-6 epidemic per year (median value; 95% CI: 2 × 10-8; 0.0007), and 0.001 epidemic per year to Réunion (95% CI: 4 × 10-6; 0.16). For the latter pathway, mosquitoes dispersing on the wind from Mayotte between January and April 2019 could have reached the Comoros Islands, Madagascar, Mozambique and, possibly, Tanzania. However, these countries are already endemic for RVF, and an incursion of RVFV-infected mosquitoes would have negligible impact.
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Shoemaker TR, Nyakarahuka L, Balinandi S, Ojwang J, Tumusiime A, Mulei S, Kyondo J, Lubwama B, Sekamatte M, Namutebi A, Tusiime P, Monje F, Mayanja M, Ssendagire S, Dahlke M, Kyazze S, Wetaka M, Makumbi I, Borchert J, Zufan S, Patel K, Whitmer S, Brown S, Davis WG, Klena JD, Nichol ST, Rollin PE, Lutwama J. First Laboratory-Confirmed Outbreak of Human and Animal Rift Valley Fever Virus in Uganda in 48 Years. Am J Trop Med Hyg 2020; 100:659-671. [PMID: 30675833 PMCID: PMC6402942 DOI: 10.4269/ajtmh.18-0732] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In March 2016, an outbreak of Rift Valley fever (RVF) was identified in Kabale district, southwestern Uganda. A comprehensive outbreak investigation was initiated, including human, livestock, and mosquito vector investigations. Overall, four cases of acute, nonfatal human disease were identified, three by RVF virus (RVFV) reverse transcriptase polymerase chain reaction (RT-PCR), and one by IgM and IgG serology. Investigations of cattle, sheep, and goat samples from homes and villages of confirmed and probable RVF cases and the Kabale central abattoir found that eight of 83 (10%) animals were positive for RVFV by IgG serology; one goat from the home of a confirmed case tested positive by RT-PCR. Whole genome sequencing from three clinical specimens was performed and phylogenetic analysis inferred the relatedness of 2016 RVFV with the 2006–2007 Kenya-2 clade, suggesting previous introduction of RVFV into southwestern Uganda. An entomological survey identified three of 298 pools (1%) of Aedes and Coquillettidia species that were RVFV positive by RT-PCR. This was the first identification of RVFV in Uganda in 48 years and the 10th independent viral hemorrhagic fever outbreak to be confirmed in Uganda since 2010.
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Affiliation(s)
- Trevor R Shoemaker
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, Georgia.,Viral Special Pathogens Branch, Centers for Disease Control and Prevention-Uganda, Entebbe, Uganda
| | - Luke Nyakarahuka
- Department of Biosecurity, Ecosystems and Veterinary Public Health, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala, Uganda.,Department of Arbovirology, Emerging and Reemerging Infectious Diseases, Uganda Virus Research Institute, Entebbe, Uganda
| | - Stephen Balinandi
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention-Uganda, Entebbe, Uganda
| | - Joseph Ojwang
- Global Health Security Unit, Centers for Disease Control and Prevention-Uganda, Kampala, Uganda
| | - Alex Tumusiime
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention-Uganda, Entebbe, Uganda
| | - Sophia Mulei
- Department of Arbovirology, Emerging and Reemerging Infectious Diseases, Uganda Virus Research Institute, Entebbe, Uganda
| | - Jackson Kyondo
- Department of Biosecurity, Ecosystems and Veterinary Public Health, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | | | | | | | | | - Fred Monje
- Ministry of Agriculture, Animal Industry and Fisheries, Kampala, Uganda
| | - Martin Mayanja
- Department of Arbovirology, Emerging and Reemerging Infectious Diseases, Uganda Virus Research Institute, Entebbe, Uganda
| | | | - Melissa Dahlke
- Public Health Emergency Operations Centre, Ministry of Health, Kampala, Uganda
| | - Simon Kyazze
- Public Health Emergency Operations Centre, Ministry of Health, Kampala, Uganda
| | - Milton Wetaka
- Public Health Emergency Operations Centre, Ministry of Health, Kampala, Uganda
| | - Issa Makumbi
- Public Health Emergency Operations Centre, Ministry of Health, Kampala, Uganda
| | - Jeff Borchert
- Global Health Security Unit, Centers for Disease Control and Prevention-Uganda, Kampala, Uganda
| | - Sara Zufan
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Ketan Patel
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Shannon Whitmer
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Shelley Brown
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - William G Davis
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - John D Klena
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Stuart T Nichol
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Pierre E Rollin
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Julius Lutwama
- Department of Arbovirology, Emerging and Reemerging Infectious Diseases, Uganda Virus Research Institute, Entebbe, Uganda
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Grossi-Soyster EN, Lee J, King CH, LaBeaud AD. The influence of raw milk exposures on Rift Valley fever virus transmission. PLoS Negl Trop Dis 2019; 13:e0007258. [PMID: 30893298 PMCID: PMC6443189 DOI: 10.1371/journal.pntd.0007258] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 04/01/2019] [Accepted: 02/23/2019] [Indexed: 02/07/2023] Open
Abstract
Rift Valley fever virus (RVFV) is a zoonotic phlebovirus that can be transmitted to humans or livestock by mosquitoes or through direct contact with contaminated bodily fluids and tissues. Exposure to bodily fluids and tissues varies by types of behaviors engaged for occupational tasks, homestead responsibilities, or use in dietary or therapeutic capacities. While previous studies have included milk exposures in their analyses, their primary focus on livestock exposures has been on animal handling, breeding, and slaughter. We analyzed data from multiple field surveys in Kenya with the aim of associating RVFV infection to raw milk exposures from common animal species. Of those with evidence of prior RVFV infection by serology (n = 267), 77.2% engaged in milking livestock compared to 32.0% for 3,956 co-local seronegative individuals (p < 0.001), and 86.5% of seropositive individuals consumed raw milk compared to 33.4% seronegative individuals (p < 0.001). Individuals who milked and also consumed raw milk had greater odds of RVFV exposure than individuals whose only contact to raw milk was through milking. Increased risks were associated with exposure to milk sourced from cows (p < 0.001), sheep (p < 0.001), and goats (p < 0.001), but not camels (p = 0.98 for consuming, p = 0.21 for milking). Our data suggest that exposure to raw milk may contribute to a significant number of cases of RVFV, especially during outbreaks and in endemic areas, and that some animal species may be associated with a higher risk for RVFV exposure. Livestock trade is regulated to limit RVFV spread from endemic areas, yet further interventions designed to fully understand the risk of RVFV exposure from raw milk are imperative.
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Affiliation(s)
- Elysse N. Grossi-Soyster
- Department of Pediatrics, Division of Infectious Diseases, Stanford University School of Medicine, Stanford, CA, United States of America
- * E-mail:
| | - Justin Lee
- Quantitative Sciences Unit, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Charles H. King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, United States of America
| | - A. Desiree LaBeaud
- Department of Pediatrics, Division of Infectious Diseases, Stanford University School of Medicine, Stanford, CA, United States of America
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Msimang V, Thompson PN, Jansen van Vuren P, Tempia S, Cordel C, Kgaladi J, Khosa J, Burt FJ, Liang J, Rostal MK, Karesh WB, Paweska JT. Rift Valley Fever Virus Exposure amongst Farmers, Farm Workers, and Veterinary Professionals in Central South Africa. Viruses 2019; 11:v11020140. [PMID: 30736488 PMCID: PMC6409972 DOI: 10.3390/v11020140] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 02/01/2019] [Accepted: 02/05/2019] [Indexed: 12/21/2022] Open
Abstract
Rift Valley fever (RVF) is a re-emerging arboviral disease of public health and veterinary importance in Africa and the Arabian Peninsula. Major RVF epidemics were documented in South Africa in 1950⁻1951, 1974⁻1975, and 2010⁻2011. The number of individuals infected during these outbreaks has, however, not been accurately estimated. A total of 823 people in close occupational contact with livestock were interviewed and sampled over a six-month period in 2015⁻2016 within a 40,000 km² study area encompassing parts of the Free State and Northern Cape provinces that were affected during the 2010⁻2011 outbreak. Seroprevalence of RVF virus (RVFV) was 9.1% (95% Confidence Interval (CI95%): 7.2⁻11.5%) in people working or residing on livestock or game farms and 8.0% in veterinary professionals. The highest seroprevalence (SP = 15.4%; CI95%: 11.4⁻20.3%) was detected in older age groups (≥40 years old) that had experienced more than one known large epidemic compared to the younger participants (SP = 4.3%; CI95%: 2.6⁻7.3%). The highest seroprevalence was in addition found in people who injected animals, collected blood samples (Odds ratio (OR) = 2.3; CI95%: 1.0⁻5.3), slaughtered animals (OR = 3.9; CI95%: 1.2⁻12.9) and consumed meat from an animal found dead (OR = 3.1; CI95%: 1.5⁻6.6), or worked on farms with dams for water storage (OR = 2.7; CI95%: 1.0⁻6.9). We estimated the number of historical RVFV infections of farm staff in the study area to be most likely 3849 and 95% credible interval between 2635 and 5374 based on seroprevalence of 9.1% and national census data. We conclude that human RVF cases were highly underdiagnosed and heterogeneously distributed. Improving precautions during injection, sample collection, slaughtering, and meat processing for consumption, and using personal protective equipment during outbreaks, could lower the risk of RVFV infection.
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Affiliation(s)
- Veerle Msimang
- Epidemiology Section, Department of Animal Production Studies; Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, National Health Laboratory Service, Sandringham 2192, South Africa.
| | - Peter N Thompson
- Epidemiology Section, Department of Animal Production Studies; Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.
| | - Petrus Jansen van Vuren
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, National Health Laboratory Service, Sandringham 2192, South Africa.
| | - Stefano Tempia
- MassGenics, Duluth, GA 30026, USA.
- Influenza Division, Centers for Disease Control and Prevention, Pretoria 0001, South Africa; Influenza Division and Centers for Disease Control and Prevention, Atlanta, GA 30301, USA.
| | | | - Joe Kgaladi
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, National Health Laboratory Service, Sandringham 2192, South Africa.
| | - Jimmy Khosa
- National Institute for Communicable Diseases, National Health Laboratory Service, Sandringham 2192, South Africa.
| | - Felicity J Burt
- Division of Virology, National Health Laboratory Service and Faculty of Health Sciences, University of the Free State, Bloemfontein 9300, South Africa.
| | | | | | | | - Janusz T Paweska
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, National Health Laboratory Service, Sandringham 2192, South Africa.
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Clark MHA, Warimwe GM, Di Nardo A, Lyons NA, Gubbins S. Systematic literature review of Rift Valley fever virus seroprevalence in livestock, wildlife and humans in Africa from 1968 to 2016. PLoS Negl Trop Dis 2018; 12:e0006627. [PMID: 30036382 PMCID: PMC6072204 DOI: 10.1371/journal.pntd.0006627] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 08/02/2018] [Accepted: 06/22/2018] [Indexed: 02/03/2023] Open
Abstract
Background Rift Valley fever virus (RVFV) is a zoonotic arbovirus that causes severe disease in livestock and humans. The virus has caused recurrent outbreaks in Africa and the Arabian Peninsula since its discovery in 1931. This review sought to evaluate RVFV seroprevalence across the African continent in livestock, wildlife and humans in order to understand the spatio-temporal distribution of RVFV seroprevalence and to identify knowledge gaps and areas requiring further research. Risk factors associated with seropositivity were identified and study designs evaluated to understand the validity of their results. Methodology The Preferred Reporting of Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to produce a protocol to systematically search for RVFV seroprevalence studies in PubMed and Web of Science databases. The Strengthening the Reporting of Observational studies in Epidemiology (STROBE) statement guided the evaluation of study design and analyses. Principal findings A total of 174 RVFV seroprevalence studies in 126 articles fulfilled the inclusion criteria. RVFV seroprevalence was recorded in 31 African countries from 1968 to 2016 and varied by time, species and country. RVFV seroprevalence articles including either livestock and humans or livestock and wildlife seroprevalence records were limited in number (8/126). No articles considered wildlife, livestock and human seroprevalence concurrently, nor wildlife and humans alone. Many studies did not account for study design bias or the sensitivity and specificity of diagnostic tests. Conclusions Future research should focus on conducting seroprevalence studies at the wildlife, livestock and human interface to better understand the nature of cross-species transmission of RVFV. Reporting should be more transparent and biases accounted for in future seroprevalence research to understand the true burden of disease on the African continent. Rift Valley fever virus (RVFV) is a vector-borne virus that infects wildlife and livestock, and can subsequently spread to humans. Due to the nature of the disease it has the potential to cause substantial economic and public health impacts. Rift Valley Fever (RVF) has been identified in Africa and the Arabian Peninsula, but has the potential to spread more widely. This systematic review assessed the distribution of RVF in livestock and humans in Africa by collating all the relevant studies we could find, extracting the data and critically evaluating them. Understanding when and where RVF has occurred in Africa and why some animals and humans get disease helps target control strategies and, in particular, those that reduce spread from livestock to humans. Furthermore, by evaluating past studies we can ensure that future ones are more robust and reproducible, so they can help us better understand the disease.
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Affiliation(s)
- Madeleine H. A. Clark
- Transmission Biology Group, The Pirbright Institute, Pirbright, Woking, United Kingdom
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- * E-mail:
| | - George M. Warimwe
- Biosciences Department, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Antonello Di Nardo
- Vesicular Disease Reference Laboratories, The Pirbright Institute, Pirbright, Woking, United Kingdom
| | - Nicholas A. Lyons
- Vesicular Disease Reference Laboratories, The Pirbright Institute, Pirbright, Woking, United Kingdom
| | - Simon Gubbins
- Transmission Biology Group, The Pirbright Institute, Pirbright, Woking, United Kingdom
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Ahmed A, Makame J, Robert F, Julius K, Mecky M. Sero-prevalence and spatial distribution of Rift Valley fever infection among agro-pastoral and pastoral communities during Interepidemic period in the Serengeti ecosystem, northern Tanzania. BMC Infect Dis 2018; 18:276. [PMID: 29898686 PMCID: PMC6001121 DOI: 10.1186/s12879-018-3183-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 06/03/2018] [Indexed: 11/30/2022] Open
Abstract
Background In the past two decades, Rift Valley Fever (RVF) outbreaks have been reported twice in Tanzania, with the most recent outbreak occurring in 2006/07. Given the ecology and climatic factors that support mosquito vectors in the Serengeti ecosystem, we hypothesized a continued transmission of RVF virus (RVFV) during interepidemic periods. This study was carried out to determine sero-prevalence, spatial distribution and factors associated with RVF in at-risk agro-pastoral and pastoral communities in the Serengeti Ecosystem in northern Tanzania. Methods A cross sectional study was carried out to establish the general exposure to RVFV by detecting anti–RVFV IgG and anti–RVFV IgM using ELISA techniques. The health facilities where human subjects were blood sampled concurrent with interviews included Bunda District Designated Hospital, Wasso DDH, Endulen hospital, Arash, Malambo, Olbabal, and Piyaya dispenaries (Ngorongoro district) and Nyerere DDH (Serengeti district) respectively. In addition, human subjects from Lamadi ward (Busega district) were recruited while receiving medical service at Bunda DDH. We conducted logistic regression to assess independent risk factor and mapped the hotspot areas for exposure to RVFV. Results A total of 751 subjects (males = 41.5%; females = 58.5%) with a median age of 35.5 years were enrolled at out-patient clinics. Of them, 34 (4.5, 95%CI 3.3–6.3%) tested positive for anti–RVFV IgG. Of the 34 that tested positive for anti–RVFV IgG, six (17.6%) tested positive for anti–RVFV IgM. Odds of exposure were higher among pastoral communities (aOR 2.9, 95% C.I: 1.21–6.89, p < 0.01), and agro-pastoral communities residing in Ngorongoro District (aOR 1.8, 95% C.I 1.14–3.39, p = 0.03). Hotspot areas for exposure to RVFV were Malambo, Olbalbal and Piyaya wards in Ngorongoro district, and Lamadi ward in Busega district. Conclusions The study found both previous and recent exposure of RVFV in humans residing in the Serengeti ecosystem as antibodies against both IgG and IgM were detected. Detection of anti-RVF IgM suggests an ongoing transmission of RVFV in humans during inter-epidemic periods. Residents of Ngorongoro district were most exposed to RVFV compared to Bunda and Serengeti districts. Therefore, the risk of exposure to RVFV was higher among pastoral communities compared to farming communities.
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Affiliation(s)
- Abade Ahmed
- Tanzania Field Epidemiology and Laboratory Training Program, Ministry of Health, Community Development, Gender, Elderly and Children, P.O Box 71286, Ocean Road, Dar es Salaam, Tanzania.
| | - Jabir Makame
- Tanzania Field Epidemiology and Laboratory Training Program, Ministry of Health, Community Development, Gender, Elderly and Children, P.O Box 71286, Ocean Road, Dar es Salaam, Tanzania.,Department of Microbiology and Immunology, Muhimbili University of Health and Allied Science, Dar es Salaam, Tanzania
| | | | - Keyyu Julius
- Tanzania Wildlife Research Institute, Arusha, Tanzania
| | - Matee Mecky
- Department of Microbiology and Immunology, Muhimbili University of Health and Allied Science, Dar es Salaam, Tanzania
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Nyakarahuka L, de St. Maurice A, Purpura L, Ervin E, Balinandi S, Tumusiime A, Kyondo J, Mulei S, Tusiime P, Lutwama J, Klena JD, Brown S, Knust B, Rollin PE, Nichol ST, Shoemaker TR. Prevalence and risk factors of Rift Valley fever in humans and animals from Kabale district in Southwestern Uganda, 2016. PLoS Negl Trop Dis 2018; 12:e0006412. [PMID: 29723189 PMCID: PMC5953497 DOI: 10.1371/journal.pntd.0006412] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 05/15/2018] [Accepted: 03/26/2018] [Indexed: 01/06/2023] Open
Abstract
Background Rift Valley fever (RVF) is a zoonotic disease caused by Rift Valley fever virus (RVFV) found in Africa and the Middle East. Outbreaks can cause extensive morbidity and mortality in humans and livestock. Following the diagnosis of two acute human RVF cases in Kabale district, Uganda, we conducted a serosurvey to estimate RVFV seroprevalence in humans and livestock and to identify associated risk factors. Methods Humans and animals at abattoirs and villages in Kabale district were sampled. Persons were interviewed about RVFV exposure risk factors. Human blood was tested for anti-RVFV IgM and IgG, and animal blood for anti-RVFV IgG. Principal findings 655 human and 1051 animal blood samples were collected. Anti-RVFV IgG was detected in 78 (12%) human samples; 3 human samples (0.5%) had detectable IgM only, and 7 (1%) had both IgM and IgG. Of the 10 IgM-positive persons, 2 samples were positive for RVFV by PCR, confirming recent infection. Odds of RVFV seropositivity were greater in participants who were butchers (odds ratio [OR] 5.1; 95% confidence interval [95% CI]: 1.7–15.1) and those who reported handling raw meat (OR 3.4; 95% CI 1.2–9.8). No persons under age 20 were RVFV seropositive. The overall animal seropositivity was 13%, with 27% of cattle, 7% of goats, and 4% of sheep seropositive. In a multivariate logistic regression, cattle species (OR 9.1; 95% CI 4.1–20.5), adult age (OR 3.0; 95% CI 1.6–5.6), and female sex (OR 2.1; 95%CI 1.0–4.3) were significantly associated with animal seropositivity. Individual human seropositivity was significantly associated with animal seropositivity by subcounty after adjusting for sex, age, and occupation (p < 0.05). Conclusions Although no RVF cases had been detected in Uganda from 1968 to March 2016, our study suggests that RVFV has been circulating undetected in both humans and animals living in and around Kabale district. RVFV seropositivity in humans was associated with occupation, suggesting that the primary mode of RVFV transmission to humans in Kabale district could be through contact with animal blood or body fluids. Viral hemorrhagic fevers are known to cause high morbidity and mortality and pose a serious threat to human and animal populations in endemic countries. An outbreak of Rift Valley fever was detected in Kabale district in March, 2016 and identified the first human cases in Uganda since 1968. There was a need to perform a rapid assessment of the burden of Rift valley fever in Kabale district, identify undetected acute cases, identify risk factors associated with human disease, identify areas at high-risk or future infections, and to determine if this was a newly emerging infection or an endemic disease. Our study found the seroprevalence to be as high as 28% in humans and 36% in animals within some subcounties of Kabale district. Human seropositivity correlated with animal seropositivity, suggesting that animal to human transmission may be the predominant mode of virus spread. Our findings also suggest that this virus may have been endemic for many years prior to these human cases being identified.
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Affiliation(s)
- Luke Nyakarahuka
- Uganda Virus Research Institute, Department of Arbovirology, Emerging and Re-emerging Infections, Entebbe, Uganda
| | - Annabelle de St. Maurice
- Centers for Disease Control and Prevention, Division of High Consequence Pathogens and Pathology, Viral Special Pathogens Branch, Atlanta, Georgia, United States of America
- University of California Los Angeles, Division of Pediatric Infectious Disease, Los Angeles, CA
| | - Lawrence Purpura
- Centers for Disease Control and Prevention, Division of High Consequence Pathogens and Pathology, Viral Special Pathogens Branch, Atlanta, Georgia, United States of America
| | - Elizabeth Ervin
- Centers for Disease Control and Prevention, Division of High Consequence Pathogens and Pathology, Viral Special Pathogens Branch, Atlanta, Georgia, United States of America
| | - Stephen Balinandi
- Centers for Disease Control and Prevention, Division of High Consequence Pathogens and Pathology, Viral Special Pathogens Branch, Entebbe, Uganda
| | - Alex Tumusiime
- Centers for Disease Control and Prevention, Division of High Consequence Pathogens and Pathology, Viral Special Pathogens Branch, Entebbe, Uganda
| | - Jackson Kyondo
- Uganda Virus Research Institute, Department of Arbovirology, Emerging and Re-emerging Infections, Entebbe, Uganda
| | - Sophia Mulei
- Uganda Virus Research Institute, Department of Arbovirology, Emerging and Re-emerging Infections, Entebbe, Uganda
| | | | - Julius Lutwama
- Uganda Virus Research Institute, Department of Arbovirology, Emerging and Re-emerging Infections, Entebbe, Uganda
| | - John D. Klena
- Centers for Disease Control and Prevention, Division of High Consequence Pathogens and Pathology, Viral Special Pathogens Branch, Atlanta, Georgia, United States of America
| | - Shelley Brown
- Centers for Disease Control and Prevention, Division of High Consequence Pathogens and Pathology, Viral Special Pathogens Branch, Atlanta, Georgia, United States of America
| | - Barbara Knust
- Centers for Disease Control and Prevention, Division of High Consequence Pathogens and Pathology, Viral Special Pathogens Branch, Atlanta, Georgia, United States of America
| | - Pierre E. Rollin
- Centers for Disease Control and Prevention, Division of High Consequence Pathogens and Pathology, Viral Special Pathogens Branch, Atlanta, Georgia, United States of America
| | - Stuart T. Nichol
- Centers for Disease Control and Prevention, Division of High Consequence Pathogens and Pathology, Viral Special Pathogens Branch, Atlanta, Georgia, United States of America
| | - Trevor R. Shoemaker
- Centers for Disease Control and Prevention, Division of High Consequence Pathogens and Pathology, Viral Special Pathogens Branch, Atlanta, Georgia, United States of America
- Centers for Disease Control and Prevention, Division of High Consequence Pathogens and Pathology, Viral Special Pathogens Branch, Entebbe, Uganda
- * E-mail:
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21
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Grossi-Soyster EN, Banda T, Teng CY, Muchiri EM, Mungai PL, Mutuku FM, Gildengorin G, Kitron U, King CH, Desiree Labeaud A. Rift Valley Fever Seroprevalence in Coastal Kenya. Am J Trop Med Hyg 2017; 97:115-120. [PMID: 28719329 DOI: 10.4269/ajtmh.17-0104] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Rift Valley fever virus (RVFV) causes severe disease in both animals and humans, resulting in significant economic and public health damages. The objective of this study was to measure RVFV seroprevalence in six coastal Kenyan villages between 2009 and 2011, and characterize individual-, household-, and community-level risk factors for prior RVFV exposure. Sera were tested for anti-RVFV IgG via enzyme-linked immunosorbent assay. Overall, 51 (1.8%; confidence interval [CI95] 1.3-2.3) of 2,871 samples were seropositive for RVFV. Seroprevalence differed significantly among villages, and was highest in Jego Village (18/300; 6.0%; CI95 3.6-9.3) and lowest in Magodzoni (0/248). Adults were more likely to be seropositive than children (P < 0.001). Seropositive subjects were less likely to own land or a motor vehicle (P < 0.01), suggesting exposure is associated with lower socioeconomic standing (P = 0.03). RVFV exposure appears to be low in coastal Kenya, although with some variability among villages.
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Affiliation(s)
| | - Tamara Banda
- Children's Hospital Oakland Research Institute, Oakland, California
| | - Crystal Y Teng
- Children's Hospital Oakland Research Institute, Oakland, California
| | - Eric M Muchiri
- Division of Vector Borne and Neglected Tropical Diseases, Ministry of Health, Msambweni, Kenya
| | - Peter L Mungai
- Division of Vector Borne and Neglected Tropical Diseases, Ministry of Health, Msambweni, Kenya
| | - Francis M Mutuku
- Department of Environmental studies, Emory University, Atlanta, Georgia.,Division of Vector Borne and Neglected Tropical Diseases, Ministry of Health, Msambweni, Kenya
| | | | - Uriel Kitron
- Department of Environmental studies, Emory University, Atlanta, Georgia
| | | | - A Desiree Labeaud
- Children's Hospital Oakland Research Institute, Oakland, California.,Stanford University School of Medicine, Stanford, California
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22
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Redding DW, Tiedt S, Lo Iacono G, Bett B, Jones KE. Spatial, seasonal and climatic predictive models of Rift Valley fever disease across Africa. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160165. [PMID: 28584173 PMCID: PMC5468690 DOI: 10.1098/rstb.2016.0165] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2017] [Indexed: 02/06/2023] Open
Abstract
Understanding the emergence and subsequent spread of human infectious diseases is a critical global challenge, especially for high-impact zoonotic and vector-borne diseases. Global climate and land-use change are likely to alter host and vector distributions, but understanding the impact of these changes on the burden of infectious diseases is difficult. Here, we use a Bayesian spatial model to investigate environmental drivers of one of the most important diseases in Africa, Rift Valley fever (RVF). The model uses a hierarchical approach to determine how environmental drivers vary both spatially and seasonally, and incorporates the effects of key climatic oscillations, to produce a continental risk map of RVF in livestock (as a proxy for human RVF risk). We find RVF risk has a distinct seasonal spatial pattern influenced by climatic variation, with the majority of cases occurring in South Africa and Kenya in the first half of an El Niño year. Irrigation, rainfall and human population density were the main drivers of RVF cases, independent of seasonal, climatic or spatial variation. By accounting more subtly for the patterns in RVF data, we better determine the importance of underlying environmental drivers, and also make space- and time-sensitive predictions to better direct future surveillance resources.This article is part of the themed issue 'One Health for a changing world: zoonoses, ecosystems and human well-being'.
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Affiliation(s)
- David W Redding
- Centre for Biodiversity and Environment Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Sonia Tiedt
- Centre for Biodiversity and Environment Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Gianni Lo Iacono
- Department of Veterinary Medicine, Disease Dynamics Unit, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
- Environmental Change, Public Health England, Didcot OX11 0RQ, UK
| | - Bernard Bett
- International Livestock Research Institute, PO Box 30709-00100, Nairobi, Kenya
| | - Kate E Jones
- Centre for Biodiversity and Environment Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK
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23
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Cook EAJ, Grossi-Soyster EN, de Glanville WA, Thomas LF, Kariuki S, Bronsvoort BMDC, Wamae CN, LaBeaud AD, Fèvre EM. The sero-epidemiology of Rift Valley fever in people in the Lake Victoria Basin of western Kenya. PLoS Negl Trop Dis 2017; 11:e0005731. [PMID: 28686589 PMCID: PMC5517073 DOI: 10.1371/journal.pntd.0005731] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 07/19/2017] [Accepted: 06/20/2017] [Indexed: 12/25/2022] Open
Abstract
Rift Valley fever virus (RVFV) is a zoonotic arbovirus affecting livestock and people. This study was conducted in western Kenya where RVFV outbreaks have not previously been reported. The aims were to document the seroprevalence and risk factors for RVFV antibodies in a community-based sample from western Kenya and compare this with slaughterhouse workers in the same region who are considered a high-risk group for RVFV exposure. The study was conducted in western Kenya between July 2010 and November 2012. Individuals were recruited from randomly selected homesteads and a census of slaughterhouses. Structured questionnaire tools were used to collect information on demographic data, health, and risk factors for zoonotic disease exposure. Indirect ELISA on serum samples determined seropositivity to RVFV. Risk factor analysis for RVFV seropositivity was conducted using multi-level logistic regression. A total of 1861 individuals were sampled in 384 homesteads. The seroprevalence of RVFV in the community was 0.8% (95% CI 0.5-1.3). The variables significantly associated with RVFV seropositivity in the community were increasing age (OR 1.2; 95% CI 1.1-1.4, p<0.001), and slaughtering cattle at the homestead (OR 3.3; 95% CI 1.0-10.5, p = 0.047). A total of 553 slaughterhouse workers were sampled in 84 ruminant slaughterhouses. The seroprevalence of RVFV in slaughterhouse workers was 2.5% (95% CI 1.5-4.2). Being the slaughterman, the person who cuts the animal's throat (OR 3.5; 95% CI 1.0-12.1, p = 0.047), was significantly associated with RVFV seropositivity. This study investigated and compared the epidemiology of RVFV between community members and slaughterhouse workers in western Kenya. The data demonstrate that slaughtering animals is a risk factor for RVFV seropositivity and that slaughterhouse workers are a high-risk group for RVFV seropositivity in this environment. These risk factors have been previously reported in other studies providing further evidence for RVFV circulation in western Kenya.
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Affiliation(s)
- Elizabeth Anne Jessie Cook
- Institute for Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom
- International Livestock Research Institute, Nairobi, Kenya
| | | | - William Anson de Glanville
- Institute for Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom
- International Livestock Research Institute, Nairobi, Kenya
| | - Lian Francesca Thomas
- Institute for Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom
- International Livestock Research Institute, Nairobi, Kenya
| | - Samuel Kariuki
- Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Barend Mark de Clare Bronsvoort
- The Roslin Institute, University of Edinburgh, Roslin, United Kingdom
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, United Kingdom
| | | | - Angelle Desiree LaBeaud
- Department of Pediatrics, Stanford University School of Medicine, Stanford, United States of America
| | - Eric Maurice Fèvre
- International Livestock Research Institute, Nairobi, Kenya
- Institute of Infection and Global Health, University of Liverpool, Neston, United Kingdom
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24
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RNA Interference Restricts Rift Valley Fever Virus in Multiple Insect Systems. mSphere 2017; 2:mSphere00090-17. [PMID: 28497117 PMCID: PMC5415632 DOI: 10.1128/msphere.00090-17] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 03/31/2017] [Indexed: 01/03/2023] Open
Abstract
The emerging bunyavirus Rift Valley fever virus (RVFV) is transmitted to humans and livestock by a large number of mosquito species. RNA interference (RNAi) has been characterized as an important innate immune defense mechanism used by mosquitoes to limit replication of positive-sense RNA flaviviruses and togaviruses; however, little is known about its role against negative-strand RNA viruses such as RVFV. We show that virus-specific small RNAs are produced in infected mosquito cells, in Drosophila melanogaster cells, and, most importantly, also in RVFV vector mosquitoes. By addressing the production of small RNAs in adult Aedes sp. and Culex quinquefasciatus mosquitoes, we showed the presence of virus-derived Piwi-interacting RNAs (piRNAs) not only in Aedes sp. but also in C. quinquefasciatus mosquitoes, indicating that antiviral RNA interference in C. quinquefasciatus mosquitoes is similar to the described activities of RNAi in Aedes sp. mosquitoes. We also show that these have antiviral activity, since silencing of RNAi pathway effectors enhances viral replication. Moreover, our data suggest that RVFV does not encode a suppressor of RNAi. These findings point toward a significant role of RNAi in the control of RVFV in mosquitoes. IMPORTANCE Rift Valley fever virus (RVFV; Phlebovirus, Bunyaviridae) is an emerging zoonotic mosquito-borne pathogen of high relevance for human and animal health. Successful strategies of intervention in RVFV transmission by its mosquito vectors and the prevention of human and veterinary disease rely on a better understanding of the mechanisms that govern RVFV-vector interactions. Despite its medical importance, little is known about the factors that govern RVFV replication, dissemination, and transmission in the invertebrate host. Here we studied the role of the antiviral RNA interference immune pathways in the defense against RVFV in natural vector mosquitoes and mosquito cells and draw comparisons to the model insect Drosophila melanogaster. We found that RVFV infection induces both the exogenous small interfering RNA (siRNA) and piRNA pathways, which contribute to the control of viral replication in insects. Furthermore, we demonstrate the production of virus-derived piRNAs in Culex quinquefasciatus mosquitoes. Understanding these pathways and the targets within them offers the potential of the development of novel RVFV control measures in vector-based strategies.
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25
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Affognon H, Mburu P, Hassan OA, Kingori S, Ahlm C, Sang R, Evander M. Ethnic groups' knowledge, attitude and practices and Rift Valley fever exposure in Isiolo County of Kenya. PLoS Negl Trop Dis 2017; 11:e0005405. [PMID: 28273071 PMCID: PMC5358895 DOI: 10.1371/journal.pntd.0005405] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 03/20/2017] [Accepted: 02/12/2017] [Indexed: 12/19/2022] Open
Abstract
Rift Valley fever (RVF) is an emerging mosquito-borne viral hemorrhagic fever in Africa and the Arabian Peninsula, affecting humans and livestock. For spread of infectious diseases, including RVF, knowledge, attitude and practices play an important role, and the understanding of the influence of behavior is crucial to improve prevention and control efforts. The objective of the study was to assess RVF exposure, in a multiethnic region in Kenya known to experience RVF outbreaks, from the behavior perspective. We investigated how communities in Isiolo County, Kenya were affected, in relation to their knowledge, attitude and practices, by the RVF outbreak of 2006/2007. A cross-sectional study was conducted involving 698 households selected randomly from three different ethnic communities. Data were collected using a structured questionnaire regarding knowledge, attitudes and practices that could affect the spread of RVF. In addition, information was collected from the communities regarding the number of humans and livestock affected during the RVF outbreak. This study found that better knowledge about a specific disease does not always translate to better practices to avoid exposure to the disease. However, the high knowledge, attitude and practice score measured as a single index of the Maasai community may explain why they were less affected, compared to other investigated communities (Borana and Turkana), by RVF during the 2006/2007 outbreak. We conclude that RVF exposure in Isiolo County, Kenya during the outbreak was likely determined by the behavioral differences of different resident community groups. We then recommend that strategies to combat RVF should take into consideration behavioral differences among communities.
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Affiliation(s)
- Hippolyte Affognon
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Bamako, Mali
- International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya
| | - Peter Mburu
- International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya
| | - Osama Ahmed Hassan
- Department of Clinical Microbiology, Virology, Umea University, Umea, Sweden
| | - Sarah Kingori
- International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya
| | - Clas Ahlm
- Department of Clinical Microbiology, Infectious Diseases, Umea University, Umea, Sweden
| | - Rosemary Sang
- International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya
| | - Magnus Evander
- Department of Clinical Microbiology, Virology, Umea University, Umea, Sweden
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26
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Kimani T, Schelling E, Bett B, Ngigi M, Randolph T, Fuhrimann S. Public Health Benefits from Livestock Rift Valley Fever Control: A Simulation of Two Epidemics in Kenya. ECOHEALTH 2016; 13:729-742. [PMID: 27830387 PMCID: PMC5161764 DOI: 10.1007/s10393-016-1192-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 08/30/2016] [Accepted: 09/05/2016] [Indexed: 06/06/2023]
Abstract
In controlling Rift Valley fever, public health sector optimises health benefits by considering cost-effective control options. We modelled cost-effectiveness of livestock RVF control from a public health perspective in Kenya. Analysis was limited to pastoral and agro-pastoral system high-risk areas, for a 10-year period incorporating two epidemics: 2006/2007 and a hypothetical one in 2014/2015. Four integrated strategies (baseline and alternatives), combined from three vaccination and two surveillance options, were compared. Baseline strategy included annual vaccination of 1.2-11% animals plus passive surveillance and monitoring of nine sentinel herds. Compared to the baseline, two alternatives assumed improved vaccination coverage. A herd dynamic RVF animal simulation model produced number of animals infected under each strategy. A second mathematical model implemented in R estimated number people who would be infected by the infected animals. The 2006/2007 RVF epidemic resulted in 3974 undiscounted, unweighted disability adjusted life years (DALYs). Improving vaccination coverage to 41-51% (2012) and 27-33% (2014) 3 years before the hypothetical 2014/2015 outbreak can avert close to 1200 DALYs. Improved vaccinations showed cost-effectiveness (CE) values of US$ 43-53 per DALY averted. The baseline practice is not cost-effective to the public health sector.
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Affiliation(s)
- Tabitha Kimani
- Department of Agricultural Economics & Agribusiness, Egerton University, Njoro, Kenya.
- International Livestock Research Institute, Nairobi, Kenya.
| | - Esther Schelling
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Bernard Bett
- International Livestock Research Institute, Nairobi, Kenya
| | - Margaret Ngigi
- Department of Agricultural Economics & Agribusiness, Egerton University, Njoro, Kenya
| | - Tom Randolph
- International Livestock Research Institute, Nairobi, Kenya
| | - Samuel Fuhrimann
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
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Bird BH, McElroy AK. Rift Valley fever virus: Unanswered questions. Antiviral Res 2016; 132:274-80. [PMID: 27400990 DOI: 10.1016/j.antiviral.2016.07.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 07/02/2016] [Accepted: 07/06/2016] [Indexed: 12/31/2022]
Abstract
This mosquito-borne pathogen of humans and animals respects no international or geographic boundaries. It is currently found in parts of Africa and the Arabian Peninsula where periodic outbreaks of severe and fatal disease occur, and threatens to spread into other geographic regions. In recent years, modern molecular techniques have led to many breakthroughs deepening our understanding of the mechanisms of RVFV virulence, phylogenetics, and the creation of several next-generation vaccine candidates. Despite tremendous progress in these areas, other challenges remain in RVF disease pathogenesis, the virus life-cycle, and outbreak response preparedness that deserve our attention. Here we discuss and highlight ten key knowledge gaps and challenges in RVFV research. Answers to these key questions may lead to the development of new effective therapeutics and enhanced control strategies for this serious human and veterinary health threat.
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Affiliation(s)
- Brian H Bird
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA; One Health Institute, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
| | - Anita K McElroy
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA; Pediatric Infectious Disease, Emory University Atlanta, GA 30322, USA
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28
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Tigoi C, Lwande O, Orindi B, Irura Z, Ongus J, Sang R. Seroepidemiology of selected arboviruses in febrile patients visiting selected health facilities in the lake/river basin areas of Lake Baringo, Lake Naivasha, and Tana River, Kenya. Vector Borne Zoonotic Dis 2016; 15:124-32. [PMID: 25700043 PMCID: PMC4340645 DOI: 10.1089/vbz.2014.1686] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Introduction: Arboviruses cause emerging and re-emerging infections affecting humans and animals. They are spread primarily by blood-sucking insects such as mosquitoes, ticks, midges, and sandflies. Changes in climate, ecology, demographic, land-use patterns, and increasing global travel have been linked to an upsurge in arboviral disease. Outbreaks occur periodically followed by persistent low-level circulation. Aim: This study was undertaken to determine the seroepidemiology of selected arboviruses among febrile patients in selected lake/river basins of Kenya. Methods: Using a hospital-based cross-sectional descriptive survey, febrile patients were recruited and their serum samples tested for exposure to immunoglobulin M (IgM) and IgG antibodies against Crimean–Congo hemorrhagic fever virus (CCHFV), Rift Valley fever virus (RVFV), West Nile virus (WNV), and chikungunya virus (CHIKV). Samples positive for CHIKV and WNV were further confirmed by the plaque reduction neutralization test (PRNT). Results: Of the 379 samples examined, 176 were IgG positive for at least one of these arboviruses (46.4%, 95% confidence interval [CI] 41.4–51.5%). Virus-specific prevalence for CCHF, RVF, WN, and CHIK was 25.6%, 19.5%, 12.4%, and 2.6%, respectively. These prevalences varied significantly with geographical site (p<0.001), with Tana recording the highest overall arboviral seropositivity. PRNT results for Alphaviruses confirmed that the actual viruses circulating in Baringo were Semliki Forest virus (SFV) and CHIKV, o'nyong nyong virus (ONNV) in Naivasha, and SFV and Sindbis virus (SINDV) in Tana delta. Among the flaviviruses tested, WNV was circulating in all the three sites. Conclusion: There is a high burden of febrile illness in humans due to CCHFV, RVFV, WNV, and CHIKV infection in the river/lake basin regions of Kenya.
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Affiliation(s)
- Caroline Tigoi
- 1 International Centre of Insect Physiology and Ecology , Nairobi, Kenya
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29
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Gray GC, Anderson BD, LaBeaud AD, Heraud JM, Fèvre EM, Andriamandimby SF, Cook EAJ, Dahir S, de Glanville WA, Heil GL, Khan SU, Muiruri S, Olive MM, Thomas LF, Merrill HR, Merrill MLM, Richt JA. Seroepidemiological Study of Interepidemic Rift Valley Fever Virus Infection Among Persons with Intense Ruminant Exposure in Madagascar and Kenya. Am J Trop Med Hyg 2015; 93:1364-1370. [PMID: 26458775 PMCID: PMC4674260 DOI: 10.4269/ajtmh.15-0383] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Accepted: 08/16/2015] [Indexed: 12/26/2022] Open
Abstract
In this cross-sectional seroepidemiological study we sought to examine the evidence for circulation of Rift Valley fever virus (RVFV) among herders in Madagascar and Kenya. From July 2010 to June 2012, we enrolled 459 herders and 98 controls (without ruminant exposures) and studied their sera (immunoglobulin G [IgG] and IgM through enzyme-linked immunosorbent assay [ELISA] and plaque reduction neutralization test [PRNT] assays) for evidence of previous RVFV infection. Overall, 59 (12.9%) of 459 herders and 7 (7.1%) of the 98 controls were positive by the IgG ELISA assay. Of the 59 ELISA-positive herders, 23 (38.9%) were confirmed by the PRNT assay (21 from eastern Kenya). Two of the 21 PRNT-positive study subjects also had elevated IgM antibodies against RVFV suggesting recent infection. Multivariate modeling in this study revealed that being seminomadic (odds ratio [OR] = 6.4, 95% confidence interval [CI] = 2.1-15.4) was most strongly associated with antibodies against RVFV. Although we cannot know when these infections occurred, it seems likely that some interepidemic RVFV infections are occurring among herders. As there are disincentives regarding reporting RVFV outbreaks in livestock or wildlife, it may be prudent to conduct periodic, limited, active seroepidemiological surveillance for RVFV infections in herders, especially in eastern Kenya.
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Affiliation(s)
- Gregory C. Gray
- Division of Infectious Diseases, Duke Global Health Institute, Duke University, Durham, North Carolina; Nicholas School of the Environment, Duke University, Durham, North Carolina; Emerging Pathogens Institute, University of Florida, Gainesville, Florida; Division of Pediatric Infectious Diseases, Stanford University, Palo Alto, California; Virology Unit, Institut Pasteur de Madagascar, Antananarivo, Madagascar; Institute of Infection and Global Health, University of Liverpool, United Kingdom; International Livestock Research Institute, Nairobi, Kenya; Centre for Microbiology Research, Kenya Medical Research Institute, Kenya; Division of Vector Borne and Neglected Tropical Diseases, Ministry of Health, Nairobi, Kenya; Department of Environmental Sciences, Technical University of Mombasa, Mombasa, Kenya; Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas
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Mansfield KL, Banyard AC, McElhinney L, Johnson N, Horton DL, Hernández-Triana LM, Fooks AR. Rift Valley fever virus: A review of diagnosis and vaccination, and implications for emergence in Europe. Vaccine 2015; 33:5520-5531. [PMID: 26296499 DOI: 10.1016/j.vaccine.2015.08.020] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 06/12/2015] [Accepted: 08/05/2015] [Indexed: 12/14/2022]
Abstract
Rift Valley fever virus (RVFV) is a mosquito-borne virus, and is the causative agent of Rift Valley fever (RVF), a zoonotic disease characterised by an increased incidence of abortion or foetal malformation in ruminants. Infection in humans can also lead to clinical manifestations that in severe cases cause encephalitis or haemorrhagic fever. The virus is endemic throughout much of the African continent. However, the emergence of RVFV in the Middle East, northern Egypt and the Comoros Archipelago has highlighted that the geographical range of RVFV may be increasing, and has led to the concern that an incursion into Europe may occur. At present, there is a limited range of veterinary vaccines available for use in endemic areas, and there is no licensed human vaccine. In this review, the methods available for diagnosis of RVFV infection, the current status of vaccine development and possible implications for RVFV emergence in Europe, are discussed.
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Affiliation(s)
- Karen L Mansfield
- Wildlife Zoonoses and Vector-borne Diseases Research Group, Animal and Plant Health Agency, Woodham Lane, New Haw KT15 3NB, UK.
| | - Ashley C Banyard
- Wildlife Zoonoses and Vector-borne Diseases Research Group, Animal and Plant Health Agency, Woodham Lane, New Haw KT15 3NB, UK
| | - Lorraine McElhinney
- Wildlife Zoonoses and Vector-borne Diseases Research Group, Animal and Plant Health Agency, Woodham Lane, New Haw KT15 3NB, UK; NIHR Health Protection Research Unit in Emerging and Zoonotic Infections, University of Liverpool, Liverpool L69 7BE, UK
| | - Nicholas Johnson
- Wildlife Zoonoses and Vector-borne Diseases Research Group, Animal and Plant Health Agency, Woodham Lane, New Haw KT15 3NB, UK
| | - Daniel L Horton
- School of Veterinary Medicine, University of Surrey, Guildford GU2 7XH, UK
| | - Luis M Hernández-Triana
- Wildlife Zoonoses and Vector-borne Diseases Research Group, Animal and Plant Health Agency, Woodham Lane, New Haw KT15 3NB, UK
| | - Anthony R Fooks
- Wildlife Zoonoses and Vector-borne Diseases Research Group, Animal and Plant Health Agency, Woodham Lane, New Haw KT15 3NB, UK; NIHR Health Protection Research Unit in Emerging and Zoonotic Infections, University of Liverpool, Liverpool L69 7BE, UK; Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool L69 7BE, UK
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LaBeaud AD, Pfeil S, Muiruri S, Dahir S, Sutherland LJ, Traylor Z, Gildengorin G, Muchiri EM, Morrill J, Peters CJ, Hise AG, Kazura JW, King CH. Factors associated with severe human Rift Valley fever in Sangailu, Garissa County, Kenya. PLoS Negl Trop Dis 2015; 9:e0003548. [PMID: 25764399 PMCID: PMC4357470 DOI: 10.1371/journal.pntd.0003548] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 01/20/2015] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Mosquito-borne Rift Valley fever virus (RVFV) causes acute, often severe, disease in livestock and humans. To determine the exposure factors and range of symptoms associated with human RVF, we performed a population-based cross-sectional survey in six villages across a 40 km transect in northeastern Kenya. METHODOLOGY/PRINCIPAL FINDINGS A systematic survey of the total populations of six Northeastern Kenyan villages was performed. Among 1082 residents tested via anti-RVFV IgG ELISA, seroprevalence was 15% (CI95%, 13-17%). Prevalence did not vary significantly among villages. Subject age was a significant factor, with 31% (154/498) of adults seropositive vs. only 2% of children ≤15 years (12/583). Seroprevalence was higher among men (18%) than women (13%). Factors associated with seropositivity included a history of animal exposure, non-focal fever symptoms, symptoms related to meningoencephalitis, and eye symptoms. Using cluster analysis in RVFV positive participants, a more severe symptom phenotype was empirically defined as having somatic symptoms of acute fever plus eye symptoms, and possibly one or more meningoencephalitic or hemorrhagic symptoms. Associated with this more severe disease phenotype were older age, village, recent illness, and loss of a family member during the last outbreak. In multivariate analysis, sheltering livestock (aOR = 3.5 CI95% 0.93-13.61, P = 0.065), disposing of livestock abortus (aOR = 4.11, CI95% 0.63-26.79, P = 0.14), and village location (P = 0.009) were independently associated with the severe disease phenotype. CONCLUSIONS/SIGNIFICANCE Our results demonstrate that a significant proportion of the population in northeastern Kenya has been infected with RVFV. Village and certain animal husbandry activities were associated with more severe disease. Older age, male gender, herder occupation, killing and butchering livestock, and poor visual acuity were useful markers for increased RVFV infection. Formal vision testing may therefore prove to be a helpful, low-technology tool for RVF screening during epidemics in high-risk rural settings.
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Affiliation(s)
- A. Desirée LaBeaud
- Stanford University, Department of Pediatrics, Palo Alto, California, United States of America
- UCSF Benioff Children’s Hospital Oakland, Oakland, California, United States of America
- * E-mail:
| | - Sarah Pfeil
- UCSF Benioff Children’s Hospital Oakland, Oakland, California, United States of America
| | - Samuel Muiruri
- Division of Vector Borne and Neglected Tropical Diseases, Ministry of Health, Nairobi, Kenya
| | - Saidi Dahir
- Division of Vector Borne and Neglected Tropical Diseases, Ministry of Health, Nairobi, Kenya
| | - Laura J. Sutherland
- Center For Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Zachary Traylor
- Center For Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Ginny Gildengorin
- UCSF Benioff Children’s Hospital Oakland, Oakland, California, United States of America
| | - Eric M. Muchiri
- Division of Vector Borne and Neglected Tropical Diseases, Ministry of Health, Nairobi, Kenya
| | - John Morrill
- Department of Microbiology and Immunology, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - C. J. Peters
- Department of Microbiology and Immunology, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Amy G. Hise
- Center For Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs, Cleveland, Ohio, United States of America
| | - James W Kazura
- Center For Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Charles H. King
- Center For Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
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Hise AG, Traylor Z, Hall NB, Sutherland LJ, Dahir S, Ermler ME, Muiruri S, Muchiri EM, Kazura JW, LaBeaud AD, King CH, Stein CM. Association of symptoms and severity of rift valley fever with genetic polymorphisms in human innate immune pathways. PLoS Negl Trop Dis 2015; 9:e0003584. [PMID: 25756647 PMCID: PMC4355584 DOI: 10.1371/journal.pntd.0003584] [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: 09/17/2014] [Accepted: 02/02/2015] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Multiple recent outbreaks of Rift Valley Fever (RVF) in Africa, Madagascar, and the Arabian Peninsula have resulted in significant morbidity, mortality, and financial loss due to related livestock epizootics. Presentation of human RVF varies from mild febrile illness to meningoencephalitis, hemorrhagic diathesis, and/or ophthalmitis with residual retinal scarring, but the determinants for severe disease are not understood. The aim of the present study was to identify human genes associated with RVF clinical disease in a high-risk population in Northeastern Province, Kenya. METHODOLOGY/PRINCIPAL FINDINGS We conducted a cross-sectional survey among residents (N = 1,080; 1-85 yrs) in 6 villages in the Sangailu Division of Ijara District. Participants completed questionnaires on past symptoms and exposures, physical exam, vision testing, and blood collection. Single nucleotide polymorphism (SNP) genotyping was performed on a subset of individuals who reported past clinical symptoms consistent with RVF and unrelated subjects. Four symptom clusters were defined: meningoencephalitis, hemorrhagic fever, eye disease, and RVF-not otherwise specified. SNPs in 46 viral sensing and response genes were investigated. Association was analyzed between SNP genotype, serology and RVF symptom clusters. The meningoencephalitis symptom phenotype cluster among seropositive patients was associated with polymorphisms in DDX58/RIG-I and TLR8. Having three or more RVF-related symptoms was significantly associated with polymorphisms in TICAM1/TRIF, MAVS, IFNAR1 and DDX58/RIG-I. SNPs significantly associated with eye disease included three different polymorphisms TLR8 and hemorrhagic fever symptoms associated with TLR3, TLR7, TLR8 and MyD88. CONCLUSIONS/SIGNIFICANCE Of the 46 SNPs tested, TLR3, TLR7, TLR8, MyD88, TRIF, MAVS, and RIG-I were repeatedly associated with severe symptomatology, suggesting that these genes may have a robust association with RVFV-associated clinical outcomes. Studies of these and related genetic polymorphisms are warranted to advance understanding of RVF pathogenesis.
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Affiliation(s)
- Amy G. Hise
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, United States of America
- * E-mail:
| | - Zachary Traylor
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Noémi B. Hall
- Division of Vector-Borne and Neglected Tropical Diseases, Ministry of Public Health and Sanitation, Nairobi, Kenya
| | - Laura J. Sutherland
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Saidi Dahir
- Division of Vector-Borne and Neglected Tropical Diseases, Ministry of Public Health and Sanitation, Nairobi, Kenya
| | - Megan E. Ermler
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Samuel Muiruri
- Division of Vector-Borne and Neglected Tropical Diseases, Ministry of Public Health and Sanitation, Nairobi, Kenya
| | - Eric M. Muchiri
- Division of Vector-Borne and Neglected Tropical Diseases, Ministry of Public Health and Sanitation, Nairobi, Kenya
| | - James W. Kazura
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - A. Desirée LaBeaud
- Division of Pediatric Infectious Diseases, UCSF Benioff Children's Hospital Oakland, Children's Hospital Oakland Research Institute, Oakland, California, United States of America
- Department of Pediatrics, Stanford University, Department of Pediatrics, Stanford, California, United States of America
| | - Charles H. King
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Catherine M. Stein
- Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, Ohio, United States of America
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Sumaye RD, Abatih EN, Thiry E, Amuri M, Berkvens D, Geubbels E. Inter-epidemic acquisition of Rift Valley fever virus in humans in Tanzania. PLoS Negl Trop Dis 2015; 9:e0003536. [PMID: 25723502 PMCID: PMC4344197 DOI: 10.1371/journal.pntd.0003536] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 01/13/2015] [Indexed: 11/26/2022] Open
Abstract
Background In East Africa, epidemics of Rift Valley fever (RVF) occur in cycles of 5–15 years following unusually high rainfall. RVF transmission during inter-epidemic periods (IEP) generally passes undetected in absence of surveillance in mammalian hosts and vectors. We studied IEP transmission of RVF and evaluated the demographic, behavioural, occupational and spatial determinants of past RVF infection. Methodology Between March and August 2012 we collected blood samples, and administered a risk factor questionnaire among 606 inhabitants of 6 villages in the seasonally inundated Kilombero Valley, Tanzania. ELISA tests were used to detect RVFV IgM and IgG antibodies in serum samples. Risk factors were examined by mixed effects logistic regression. Findings RVF virus IgM antibodies, indicating recent RVFV acquisition, were detected in 16 participants, representing 2.6% overall and in 22.5% of inhibition ELISA positives (n = 71). Four of 16 (25.0%) IgM positives and 11/71 (15.5%) of individuals with inhibition ELISA sero-positivity reported they had had no previous contact with host animals. Sero-positivity on inhibition ELISA was 11.7% (95% CI 9.2–14.5) and risk was elevated with age (odds ratio (OR) 1.03 per year; 95% CI 1.01–1.04), among milkers (OR 2.19; 95% CI 1.23–3.91), and individuals eating raw meat (OR 4.17; 95% CI 1.18–14.66). Households keeping livestock had a higher probability of having members with evidence of past infection (OR = 3.04, 95% CI = 1.42–6.48) than those that do not keep livestock. Conclusion There is inter-epidemic acquisition of RVFV in Kilombero Valley inhabitants. In the wake of declining malaria incidence, these findings underscore the need for clinicians to consider RVF in the differential diagnosis for febrile illnesses. Several types of direct contact with livestock are important risk factors for past infection with RVFV in this study’s population. However, at least part of RVFV transmission appears to have occurred through bites of infected mosquitoes. Rift Valley fever (RVF) is a disease of animals and people that is caused by the RVF virus. During epidemics, humans get RVF through direct contact with animals or through mosquito bites. In East Africa, epidemics occur every 5–15 years following unusually high rainfall. In between epidemics, the transmission of RVF might occur at low level. In an epidemic-free period, we measured whether people in the Kilombero Valley in Tanzania had evidence of past and recent RVF infection in their blood sample, and studied risk factors. Three per cent of people had been infected recently, and 12% had evidence of past infection, with increased risk with age, among milkers and among people eating raw meat. Some people with past or recent infection reported they had not had contact with animals. Households keeping livestock had more members with evidence of past infection. The findings show that people get infected with RVF in between epidemics, and that various types of contact with livestock are important risk factors. There is also evidence that some people get infected with RVFV by mosquitoes in the epidemic free period. Clinicians in the Kilombero Valley should consider RVF in the differential diagnosis of patients with fever.
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Affiliation(s)
- Robert David Sumaye
- Ifakara Health Institute, Ifakara, Tanzania
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
- Department of Infectious and Parasitic Diseases, Faculty of Veterinary Medicine, University of Liege, Liege, Belgium
- * E-mail:
| | - Emmanuel Nji Abatih
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Etienne Thiry
- Department of Infectious and Parasitic Diseases, Faculty of Veterinary Medicine, University of Liege, Liege, Belgium
| | | | - Dirk Berkvens
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
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Tokuda S, Do Valle TZ, Batista L, Simon-Chazottes D, Guillemot L, Bouloy M, Flamand M, Montagutelli X, Panthier JJ. The genetic basis for susceptibility to Rift Valley fever disease in MBT/Pas mice. Genes Immun 2015; 16:206-12. [PMID: 25569261 DOI: 10.1038/gene.2014.79] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 11/12/2014] [Accepted: 11/13/2014] [Indexed: 11/09/2022]
Abstract
The large variation in individual response to infection with Rift Valley fever virus (RVFV) suggests that host genetic determinants play a role in determining virus-induced disease outcomes. These genetic factors are still unknown. The systemic inoculation of mice with RVFV reproduces major pathological features of severe human disease, notably the hepatitis and encephalitis. A genome scan performed on 546 (BALB/c × MBT) F2 progeny identified three quantitative trait loci (QTLs), denoted Rvfs-1 to Rvfs-3, that were associated with disease susceptibility in MBT/Pas mice. Non-parametric interval-mapping revealed one significant and two suggestive linkages with survival time on chromosomes 2 (Rvfs-1), 5 (Rvfs-3) and 11 (Rvfs-2) with respective logarithm of odds (LOD) scores of 4.58, 2.95 and 2.99. The two-part model, combining survival time and survival/death, identified one significant linkage to Rvfs-2 and one suggestive linkage to Rvfs-1 with respective LOD scores of 5.12 and 4.55. Under a multiple model, with additive effects and sex as a covariate, the three QTLs explained 8.3% of the phenotypic variance. Sex had the strongest influence on susceptibility. The contribution of Rvfs-1, Rvfs-2 and Rvfs-3 to survival time of RVFV-infected mice was further confirmed in congenic mice.
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Affiliation(s)
- S Tokuda
- 1] Institut Pasteur, Developmental & Stem Cell Biology Department, Mouse functional Genetics, Paris, France [2] Centre National de la Recherche Scientifique, URA 2578, Paris, France
| | - T Z Do Valle
- 1] Institut Pasteur, Developmental & Stem Cell Biology Department, Mouse functional Genetics, Paris, France [2] Centre National de la Recherche Scientifique, URA 2578, Paris, France [3] Instituto Oswaldo Cruz, Laboratório de Imunomodulação e Protozoologia, Fiocruz, Rio de Janeiro, Brasil
| | - L Batista
- 1] Institut Pasteur, Developmental & Stem Cell Biology Department, Mouse functional Genetics, Paris, France [2] Centre National de la Recherche Scientifique, URA 2578, Paris, France [3] Sorbonne Universités, UPMC Univ Paris 06, IFD, Paris, France
| | - D Simon-Chazottes
- 1] Institut Pasteur, Developmental & Stem Cell Biology Department, Mouse functional Genetics, Paris, France [2] Centre National de la Recherche Scientifique, URA 2578, Paris, France
| | - L Guillemot
- 1] Institut Pasteur, Developmental & Stem Cell Biology Department, Mouse functional Genetics, Paris, France [2] Centre National de la Recherche Scientifique, URA 2578, Paris, France
| | - M Bouloy
- Institut Pasteur, Bunyaviruses Molecular Genetics, Paris, France
| | - M Flamand
- Institut Pasteur, Structural Virology, Paris, France
| | - X Montagutelli
- 1] Institut Pasteur, Developmental & Stem Cell Biology Department, Mouse functional Genetics, Paris, France [2] Centre National de la Recherche Scientifique, URA 2578, Paris, France
| | - J-J Panthier
- 1] Institut Pasteur, Developmental & Stem Cell Biology Department, Mouse functional Genetics, Paris, France [2] Centre National de la Recherche Scientifique, URA 2578, Paris, France
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Muiruri S, Kabiru EW, Muchiri EM, Hussein H, Kagondu F, LaBeaud AD, King CH. Cross-sectional survey of Rift Valley fever virus exposure in Bodhei village located in a transitional coastal forest habitat in Lamu county, Kenya. Am J Trop Med Hyg 2014; 92:394-400. [PMID: 25535309 DOI: 10.4269/ajtmh.14-0440] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Few studies have focused on Rift Valley fever virus (RVFV) transmission in less arid, transitional landscapes surrounding known high-risk regions. The objective of this study was to identify evidence of RVFV exposure in Bodhei Village in a forested area at the edge of the RVFV-epidemic Garissa region. In a household cluster-based survey conducted between epidemics in early 2006, 211 participants were enrolled. Overall seroprevalence for anti-RVFV was high (18%) and comparable with rates in the more arid, dense brush regions farther north. Seroprevalence of adults was 28%, whereas that of children was significantly lower (3%; P < 0.001); the youngest positive child was age 3 years. Males were more likely to be seropositive than females (25% versus 11%; P < 0.01), and animal husbandry activities (birthing, sheltering, and butchering) were strongly associated with seropositivity. The results confirm that significant RVFV transmission occurs outside of recognized high-risk areas and independent of known epidemic periods.
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Affiliation(s)
- Samuel Muiruri
- Department of Pathology, Kenyatta University, Nairobi, Kenya; Vector-Borne Diseases Control Unit, Ministry of Health, Nairobi, Kenya; Office of Director of Health, Garissa County, Kenya; Department of Ophthalmology, Thika Level 5 Hospital, Ministry of Health, Thika, Kenya; Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, California; Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - Ephantus W Kabiru
- Department of Pathology, Kenyatta University, Nairobi, Kenya; Vector-Borne Diseases Control Unit, Ministry of Health, Nairobi, Kenya; Office of Director of Health, Garissa County, Kenya; Department of Ophthalmology, Thika Level 5 Hospital, Ministry of Health, Thika, Kenya; Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, California; Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - Eric M Muchiri
- Department of Pathology, Kenyatta University, Nairobi, Kenya; Vector-Borne Diseases Control Unit, Ministry of Health, Nairobi, Kenya; Office of Director of Health, Garissa County, Kenya; Department of Ophthalmology, Thika Level 5 Hospital, Ministry of Health, Thika, Kenya; Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, California; Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - Hassan Hussein
- Department of Pathology, Kenyatta University, Nairobi, Kenya; Vector-Borne Diseases Control Unit, Ministry of Health, Nairobi, Kenya; Office of Director of Health, Garissa County, Kenya; Department of Ophthalmology, Thika Level 5 Hospital, Ministry of Health, Thika, Kenya; Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, California; Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - Frederick Kagondu
- Department of Pathology, Kenyatta University, Nairobi, Kenya; Vector-Borne Diseases Control Unit, Ministry of Health, Nairobi, Kenya; Office of Director of Health, Garissa County, Kenya; Department of Ophthalmology, Thika Level 5 Hospital, Ministry of Health, Thika, Kenya; Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, California; Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - A Desirée LaBeaud
- Department of Pathology, Kenyatta University, Nairobi, Kenya; Vector-Borne Diseases Control Unit, Ministry of Health, Nairobi, Kenya; Office of Director of Health, Garissa County, Kenya; Department of Ophthalmology, Thika Level 5 Hospital, Ministry of Health, Thika, Kenya; Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, California; Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - Charles H King
- Department of Pathology, Kenyatta University, Nairobi, Kenya; Vector-Borne Diseases Control Unit, Ministry of Health, Nairobi, Kenya; Office of Director of Health, Garissa County, Kenya; Department of Ophthalmology, Thika Level 5 Hospital, Ministry of Health, Thika, Kenya; Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, California; Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
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Nicholas DE, Jacobsen KH, Waters NM. Risk factors associated with human Rift Valley fever infection: systematic review and meta-analysis. Trop Med Int Health 2014; 19:1420-9. [DOI: 10.1111/tmi.12385] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Kortekaas J. One Health approach to Rift Valley fever vaccine development. Antiviral Res 2014; 106:24-32. [DOI: 10.1016/j.antiviral.2014.03.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 03/10/2014] [Accepted: 03/15/2014] [Indexed: 10/25/2022]
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Paweska JT. Rift Valley Fever. Emerg Infect Dis 2014. [DOI: 10.1016/b978-0-12-416975-3.00006-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Archer BN, Thomas J, Weyer J, Cengimbo A, Landoh DE, Jacobs C, Ntuli S, Modise M, Mathonsi M, Mashishi MS, Leman PA, le Roux C, Jansen van Vuren P, Kemp A, Paweska JT, Blumberg L. Epidemiologic Investigations into Outbreaks of Rift Valley Fever in Humans, South Africa, 2008-2011. Emerg Infect Dis 2013; 19. [PMID: 29360021 PMCID: PMC3840856 DOI: 10.3201/eid1912.121527] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Rift Valley fever continues to pose a notable public health threat to humans. Rift Valley fever (RVF) is an emerging zoonosis posing a public health threat to humans in Africa. During sporadic RVF outbreaks in 2008–2009 and widespread epidemics in 2010–2011, 302 laboratory-confirmed human infections, including 25 deaths (case-fatality rate, 8%) were identified. Incidence peaked in late summer to early autumn each year, which coincided with incidence rate patterns in livestock. Most case-patients were adults (median age 43 years), men (262; 87%), who worked in farming, animal health or meat-related industries (83%). Most case-patients reported direct contact with animal tissues, blood, or other body fluids before onset of illness (89%); mosquitoes likely played a limited role in transmission of disease to humans. Close partnership with animal health and agriculture sectors allowed early recognition of human cases and appropriate preventive health messaging.
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Newman-Gerhardt S, Muiruri S, Muchiri E, Peters CJ, Morrill J, Lucas AH, King CH, Kazura J, LaBeaud AD. Potential for autoimmune pathogenesis of Rift Valley Fever virus retinitis. Am J Trop Med Hyg 2013; 89:495-7. [PMID: 23918215 DOI: 10.4269/ajtmh.12-0562] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Rift Valley Fever (RVF) is a significant threat to human health because it can progress to retinitis, encephalitis, and hemorrhagic fever. The timing of onset of Rift Valley Fever virus (RVFV) retinitis suggests an autoimmune origin. To determine whether RVFV retinitis is associated with increased levels of IgG against retinal tissue, we measured and compared levels of IgG against healthy human eye tissue by immunohistochemical analysis. We found that serum samples from RVFV-exposed Kenyans with retinitis (n = 8) were slightly more likely to have antibodies against retinal tissue than control populations, but the correlation was not statistically significant. Further investigation into the possible immune pathogenesis of RVFV retinitis could lead to improved therapies to prevent or treat this severe complication.
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Affiliation(s)
- Shoshana Newman-Gerhardt
- National Institutes of Health, Building 29B, Room 2c17, 29 Lincoln Way, Bethesda, MD 20892, USA.
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Al Azraqi TA, El Mekki AA, Mahfouz AA. Rift Valley fever among children and adolescents in southwestern Saudi Arabia. J Infect Public Health 2013; 6:230-5. [DOI: 10.1016/j.jiph.2012.11.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 11/12/2012] [Accepted: 11/30/2012] [Indexed: 11/24/2022] Open
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Abstract
Rift Valley fever (RVF), a vector-borne zoonotic disease caused by a phlebovirus (family Bunyaviridae), is considered to be one of the most important viral zoonoses in Africa. It is also a potential bioterrorism agent. Transmitted by mosquitoes or by direct contact with viraemic products, RVF affects both livestock and humans, causing abortion storms in pregnant ruminants and sudden death in newborns. The disease provokes flu syndrome in most human cases, but also severe encephalitic or haemorrhagic forms and death. There is neither a treatment nor a vaccine for humans. The disease, historically confined to the African continent, recently spread to the Arabian Peninsula and Indian Ocean. Animal movements, legal or illegal, strongly contribute to viral spread, threatening the Mediterranean basin and Europe, where competent vectors are present. Given the unpredictability of virus introduction and uncertainties about RVF epidemiology, there is an urgent need to fill the scientific gaps by developing large regional research programmes, to build predictive models, and to implement early warning systems and surveillance designs adapted to northern African and European countries.
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Affiliation(s)
- V Chevalier
- UPR Animal et Gestion Intégrée des Risques (AGIRs), CIRAD, Montpellier, France.
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RNA helicase signaling is critical for type i interferon production and protection against Rift Valley fever virus during mucosal challenge. J Virol 2013; 87:4846-60. [PMID: 23408632 DOI: 10.1128/jvi.01997-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Rift Valley fever virus (RVFV) is an emerging RNA virus with devastating economic and social consequences. Clinically, RVFV induces a gamut of symptoms ranging from febrile illness to retinitis, hepatic necrosis, hemorrhagic fever, and death. It is known that type I interferon (IFN) responses can be protective against severe pathology; however, it is unknown which innate immune receptor pathways are crucial for mounting this response. Using both in vitro assays and in vivo mucosal mouse challenge, we demonstrate here that RNA helicases are critical for IFN production by immune cells and that signaling through the helicase adaptor molecule MAVS (mitochondrial antiviral signaling) is protective against mortality and more subtle pathology during RVFV infection. In addition, we demonstrate that Toll-like-receptor-mediated signaling is not involved in IFN production, further emphasizing the importance of the RNA cellular helicases in type I IFN responses to RVFV.
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Ahmed Kamal S. Observations on rift valley fever virus and vaccines in Egypt. Virol J 2011; 8:532. [PMID: 22152149 PMCID: PMC3264540 DOI: 10.1186/1743-422x-8-532] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 12/12/2011] [Indexed: 12/01/2022] Open
Abstract
Rift Valley Fever virus (RVFV, genus: Phlebovirus, family: Bunyaviridae), is an arbovirus which causes significant morbidity and mortality in animals and humans. RVFV was introduced for the first time in Egypt in 1977. In endemic areas, the insect vector control and vaccination is considering appropriate measures if applied properly and the used vaccine is completely safe and the vaccination programs cover all the susceptible animals. Egypt is importing livestock and camels from the African Horn & the Sudan for human consumption. The imported livestock and camels were usually not vaccinated against RVFV. But in rare occasions, the imported livestock were vaccinated but with unknown date of vaccination and the unvaccinated control contacts were unavailable for laboratory investigations. Also, large number of the imported livestock and camels are often escaped slaughtering for breeding which led to the spread of new strains of FMD and the introduction of RVFV from the enzootic African countries. This article provide general picture about the present situation of RVFV in Egypt to help in controlling this important disease.
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Affiliation(s)
- Samia Ahmed Kamal
- Virology department, Animal Health Research Institute, Dokki, Giza, Egypt.
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