RESUMO
Wild animals, sharing pathogens with domestic animals, play a crucial role in the epidemiology of infectious diseases. Sampling from wild animals poses significant challenges, yet it is vital for inclusion in disease surveillance and monitoring programmes. Often, mass surveillance involves serological screenings using enzyme-linked immunosorbent assay (ELISA) tests, typically validated only for domestic animals. This study assessed the diagnostic specificity of commercially available ELISA tests on 342 wild ruminant serum samples and 100 from wild boars. We evaluated three tests for foot-and-mouth disease: two for Peste des petits ruminants, two for Rift Valley fever and one for Capripox virus. Diagnostic specificity was calculated using the formula True Negative/(False Positive + True Negative). Cohen's kappa coefficient measured agreement between tests. Results showed high specificity and agreement across all tests. Specificity for foot-and-mouth disease (FMD) ranged from 93.89% for Prionics to 100% for IDEXX, with IDvet showing 99.6%. The highest agreement was between FMD IDvet and IDEXX at 97.1%. Rift Valley fever (RVF) tests, Ingezim and IDvet, achieved specificities of 100% and 98.83%, respectively. The optimal specificity was attained by retesting single reactors and inactivating the complement.Contribution: Commercially available ELISA kits are specific for foot-and-mouth disease and similar transboundary animal diseases and can be used for highly specific wild animal testing.
Assuntos
Animais Selvagens , Ensaio de Imunoadsorção Enzimática , Sensibilidade e Especificidade , Animais , Ensaio de Imunoadsorção Enzimática/veterinária , Febre Aftosa/diagnóstico , Febre do Vale de Rift/diagnóstico , Febre do Vale de Rift/sangue , Sus scrofa , Ruminantes , Anticorpos Antivirais/sangueRESUMO
Rift Valley fever phlebovirus (RVFV) is a mosquito-transmitted phlebovirus (Family: Phenuiviridae, Order: Bunyavirales) causing severe neonatal mortality and abortion primarily in domestic ruminants. The susceptibility of young domestic swine to RVFV and this species' role in geographic expansion and establishment of viral endemicity is unclear. Six commercially bred Landrace-cross piglets were inoculated subcutaneously with 105 plaque-forming units of RVFV ZH501 strain and two piglets received a sham inoculum. All animals were monitored for clinical signs, viremia, viral shedding, and antibody response for 14 days. Piglets did not develop evidence of clinical disease, become febrile, or experience decreased weight gain during the study period. A brief lymphopenia followed by progressive lymphocytosis was observed following inoculation in all piglets. Four piglets developed a brief viremia for 2 days post-inoculation and three of these had detectable virus in oronasal secretions three days post-inoculation. Primary inoculated piglets seroconverted and those that developed detectable viremias had the highest titers assessed by serum neutralization (1:64-1:256). Two viremic piglets had a lymphoplasmacytic encephalitis with glial nodules; RVFV was not detected by immunohistochemistry in these sections. While young piglets do not appear to readily develop clinical disease following RVFV infection, results suggest swine could be subclinically infected with RVFV.
Assuntos
Febre do Vale de Rift/imunologia , Vírus da Febre do Vale do Rift/imunologia , Doenças dos Suínos/virologia , Animais , Encéfalo/patologia , Encéfalo/virologia , Suscetibilidade a Doenças , Feminino , Imuno-Histoquímica , Fígado/patologia , Fígado/virologia , Linfonodos/patologia , Linfonodos/virologia , Masculino , RNA Viral/sangue , RNA Viral/genética , RNA Viral/isolamento & purificação , Febre do Vale de Rift/sangue , Febre do Vale de Rift/transmissão , Febre do Vale de Rift/virologia , Vírus da Febre do Vale do Rift/isolamento & purificação , Vírus da Febre do Vale do Rift/patogenicidade , Baço/patologia , Baço/virologia , Sus scrofa , Suínos , Doenças dos Suínos/sangue , Doenças dos Suínos/imunologia , Doenças dos Suínos/transmissão , Viremia/sangue , Viremia/imunologia , Viremia/virologiaRESUMO
Diagnostic performance of an indirect enzyme-linked immunosorbent assay (I-ELISA) based on a recombinant nucleocapsid protein (rNP) of the Rift Valley fever virus (RVFV) was validated for the detection of the IgG antibody in sheep (n = 3367), goat (n = 2632), and cattle (n = 3819) sera. Validation data sets were dichotomized according to the results of a virus neutralization test in sera obtained from RVF-endemic (Burkina Faso, Democratic Republic of Congo, Mozambique, Senegal, Uganda, and Yemen) and RVF-free countries (France, Poland, and the USA). Cut-off values were defined using the two-graph receiver operating characteristic analysis. Estimates of the diagnostic specificity of the RVFV rNP I-ELISA in animals from RVF-endemic countries ranged from 98.6% (cattle) to 99.5% (sheep) while in those originating from RVF-free countries, they ranged from 97.7% (sheep) to 98.1% (goats). Estimates of the diagnostic sensitivity in ruminants from RVF-endemic countries ranged from 90.7% (cattle) to 100% (goats). The results of this large-scale international validation study demonstrate the high diagnostic accuracy of the RVFV rNP I-ELISA. Standard incubation and inactivation procedures evaluated did not have an adverse effect on the detectable levels of the anti-RVFV IgG in ruminant sera and thus, together with recombinant antigen-based I-ELISA, provide a simple, safe, and robust diagnostic platform that can be automated and carried out outside expensive bio-containment facilities. These advantages are particularly important for less-resourced countries where there is a need to accelerate and improve RVF surveillance and research on epidemiology as well as to advance disease control measures.
Assuntos
Anticorpos Antivirais/sangue , Ensaio de Imunoadsorção Enzimática/métodos , Imunoglobulina G/sangue , Febre do Vale de Rift/sangue , Vírus da Febre do Vale do Rift/imunologia , Animais , Bovinos/sangue , Cabras/sangue , Proteínas do Nucleocapsídeo/genética , Proteínas do Nucleocapsídeo/imunologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Febre do Vale de Rift/diagnóstico , Febre do Vale de Rift/imunologia , Febre do Vale de Rift/virologia , Vírus da Febre do Vale do Rift/genética , Vírus da Febre do Vale do Rift/isolamento & purificação , Ovinos/sangueRESUMO
Rift Valley fever phlebovirus (RVFV) is an arthropod-borne zoonotic pathogen, which is endemic in Africa, causing large epidemics, characterized by severe diseases in ruminants but also in humans. As in vitro and field investigations proposed amphibians and reptiles to potentially play a role in the enzootic amplification of the virus, we experimentally infected African common toads and common agamas with two RVFV strains. Lymph or sera, as well as oral, cutaneous and anal swabs were collected from the challenged animals to investigate seroconversion, viremia and virus shedding. Furthermore, groups of animals were euthanized 3, 10 and 21 days post-infection (dpi) to examine viral loads in different tissues during the infection. Our data show for the first time that toads are refractory to RVFV infection, showing neither seroconversion, viremia, shedding nor tissue manifestation. In contrast, all agamas challenged with the RVFV strain ZH501 carried virus genomes in the spleens at 3 dpi, but the animals displayed neither viremia nor virus shedding. In conclusion, the results of this study indicate that amphibians are not susceptible and reptiles are only susceptible to a low extent to RVFV, indicating that both species play, if at all, rather a subordinate role in the RVF virus ecology.
Assuntos
Anfíbios/virologia , Anticorpos Antivirais/sangue , Reservatórios de Doenças/veterinária , Répteis/virologia , Febre do Vale de Rift/sangue , Vírus da Febre do Vale do Rift/genética , Animais , Chlorocebus aethiops , Reservatórios de Doenças/virologia , Vírus da Febre do Vale do Rift/isolamento & purificação , Células Vero , Carga Viral , ViremiaRESUMO
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.
Assuntos
Anticorpos Antivirais/sangue , Febre de Chikungunya/sangue , Vírus Chikungunya/imunologia , Vírus da Dengue/imunologia , Dengue/sangue , Febre do Vale de Rift/sangue , Vírus da Febre do Vale do Rift/imunologia , Adulto , Animais , Febre de Chikungunya/epidemiologia , Febre de Chikungunya/virologia , Vírus Chikungunya/fisiologia , Estudos Transversais , Dengue/epidemiologia , Dengue/virologia , Vírus da Dengue/fisiologia , Feminino , Humanos , Imunoglobulina M/sangue , Masculino , Pessoa de Meia-Idade , Febre do Vale de Rift/epidemiologia , Febre do Vale de Rift/virologia , Vírus da Febre do Vale do Rift/fisiologia , Estudos Soroepidemiológicos , Tanzânia/epidemiologia , Adulto JovemRESUMO
INTRODUCTION: Multiple outbreaks of Rift Valley Fever (RVF) with devastating effects have occurred in East Africa. These outbreaks cause disease in both livestock and humans and affect poor households most severely. Communities living in areas practicing nomadic livestock movement may be at higher risk of infection. This study sought to i) determine the human exposure to Rift Valley fever virus (RVFV) in populations living within nomadic animal movement routes in Kenya; and ii) identify risk factors for RVFV infection in these communities. METHODS: A cross-sectional descriptive study design was used. Samples were collected from the year 2014 to 2015 in a community-based sampling exercise involving healthy individuals aged ≥18 years from Isiolo, Tana River, and Garissa counties. In total, 1210 samples were screened by ELISA for the presence of immunoglobulin IgM and IgG antibodies against RVFV. Positive results were confirmed by plaque reduction neutralization test. RESULTS: Overall, IgM and IgG prevalence for all sites combined was 1.4% (95% CI 0.8-2.3%) and 36.4% (95% CI 33.8-39.2%), respectively. Isiolo County recorded a non-significant higher IgG prevalence of 38.8% than Garissa 35.9% and Tana River 32.2% (Chi square = 2.5, df = 2, p = 0.287). Males were significantly at higher risk of infection by RVFV than females (OR = 1.67, 95% CI 1.17-2.39, p<0.005). Age was significantly associated with RVFV infection (Wald Chi = 94.2, df = 5, p<0.0001). Individuals who had regular contact with cattle (OR = 1.38, 95%CI 1.01-1.89) and donkeys (OR = 1.38, 95%CI 1.14-1.67), or contact with animals through birthing (OR = 1.69, 95%CI 1.14-2.51) were significantly at a greater risk of RVFV infection than those who did not. CONCLUSION: This study demonstrated that although the Isiolo County has been classified as being at medium risk for RVF, virus infection appeared to be as prevalent in humans as in Tana River and Garissa, which have been classified as being at high risk. Populations in these counties live within nomadic livestock movement routes and therefore at risk of being exposed to the RVFV. Interventions to control RVFV infections therefore, should target communities living along livestock movement pathways.
Assuntos
Febre do Vale de Rift/epidemiologia , Febre do Vale de Rift/transmissão , Vírus da Febre do Vale do Rift/fisiologia , Zoonoses/transmissão , Adolescente , Adulto , Idoso , Animais , Anticorpos Antivirais/sangue , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/virologia , Estudos Transversais , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imunoglobulina M/sangue , Quênia , Masculino , Pessoa de Meia-Idade , Febre do Vale de Rift/sangue , Febre do Vale de Rift/virologia , Vírus da Febre do Vale do Rift/genética , Vírus da Febre do Vale do Rift/imunologia , Vírus da Febre do Vale do Rift/isolamento & purificação , Adulto Jovem , Zoonoses/sangue , Zoonoses/epidemiologia , Zoonoses/virologiaRESUMO
Rift Valley fever (RVF) is a zoonotic viral disease of domestic ruminants in Africa and the Arabian Peninsula caused by a mosquito-borne Phlebovirus. Outbreaks in livestock and humans occur after heavy rains favour breeding of vectors, and the virus is thought to survive dry seasons in the eggs of floodwater-breeding aedine mosquitoes. We recently found high seroconversion rates to RVF virus (RVFV) in cattle and goats, in the absence of outbreaks, in far northern KwaZulu-Natal (KZN), South Africa. Here, we report the prevalence of, and factors associated with, neutralizing antibodies to RVFV in 326 sera collected opportunistically from nyala (Tragelaphus angasii) and impala (Aepyceros melampus) culled during 2016-2018 in two nature reserves in the same area. The overall seroprevalence of RVFV, determined using the serum neutralization test, was 35.0% (114/326; 95%CI: 29.8%-40.4%) and tended to be higher in Ndumo Game Reserve (11/20; 55.0%; 95%CI: 31.5%-76.9%) than in Tembe Elephant Park (103/306; 33.6%; 95%CI: 28.4%-39.3%) (p = .087). The presence of antibodies in juveniles (6/21; 28.6%; 95%CI: 11.3%-52.2%) and sub-adults (13/65; 20.0%; 95%CI: 11.1%-37.8%) confirmed that infections had occurred at least until 2016, well after the 2008-2011 RVF outbreaks in South Africa. Odds of seropositivity was higher in adults than in sub-adults (OR = 3.98; 95%CI: 1.83-8.67; p = .001), in males than in females (OR = 2.66; 95%CI: 1.51-4.68; p = .001) and in animals collected ≤2 km from a swamp or floodplain compared with those collected further away (OR = 3.30; 95%CI: 1.70-6.38; p < .001). Under similar ecological conditions, domestic and wild ruminants may play a similar role in maintenance of RVFV circulation and either or both may serve as the mammalian host in a vector-host reservoir system. The study confirms the recent circulation of RVFV in the tropical coastal plain of northern KZN, providing the basis for investigation of factors affecting virus circulation and the role of wildlife in RVF epidemiology.
Assuntos
Antílopes/sangue , Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/sangue , Febre do Vale de Rift/sangue , Vírus da Febre do Vale do Rift/imunologia , Animais , Animais Selvagens/imunologia , Surtos de Doenças/veterinária , Feminino , Humanos , Masculino , Febre do Vale de Rift/epidemiologia , Febre do Vale de Rift/imunologia , Estudos Soroepidemiológicos , África do Sul/epidemiologia , Zoonoses/epidemiologiaRESUMO
BACKGROUND: Rift Valley fever (RVF) is one of the main vector borne zoonotic diseases that affects a wide range of ruminants and human beings in Africa and the Arabian Peninsula. A rapid and specific test for RVF diagnosis at the site of a suspected outbreak is crucial for the implementation of control measures. METHODOLOGY/PRINCIPAL FINDINGS: A first-line lateral flow immunochromatographic strip test (LFT) was developed for the detection of the nucleoprotein (N) of the RVF virus (RVFV). Its diagnostic performance characteristics were evaluated using reference stocks isolates recovered from different hosts and in geographic regions mimicking clinical specimens and from known RVF negative serum samples. A high level of diagnostic accuracy (DSe (35/35), DSp (167/169)) was observed, including the absence of cross-reactivity with viruses belonging to different genera. CONCLUSION/SIGNIFICANCE: The fact no specialized reagents and laboratory equipment are needed, make this assay a valuable, first-line diagnostic tool in resource-poor diagnostic territories for on-site RVFV detection, however the staff require training.
Assuntos
Imunoensaio/métodos , Febre do Vale de Rift/diagnóstico , Vírus da Febre do Vale do Rift/isolamento & purificação , Animais , Artiodáctilos/virologia , Culicidae/virologia , Nucleoproteínas/análise , Febre do Vale de Rift/sangue , Febre do Vale de Rift/virologia , Sensibilidade e EspecificidadeRESUMO
BACKGROUND: Rift Valley fever (RVF) is a mosquito-borne zoonotic disease characterized in South Africa by large epidemics amongst ruminant livestock at very long, irregular intervals, mainly in the central interior. However, the presence and patterns of occurrence of the virus in the eastern parts of the country are poorly known. This study aimed to detect the presence of RVF virus (RVFV) in cattle and goats in far northern KwaZulu-Natal province and to estimate the prevalence of antibodies to the virus and the incidence rate of seroconversion. METHODOLOGY: Cross-sectional studies were performed in communally farmed cattle (n = 423) and goats (n = 104), followed by longitudinal follow-up of seronegative livestock (n = 253) 14 times over 24 months, representing 160.3 animal-years at risk. Exposure to RVFV was assessed using an IgG sandwich ELISA and a serum neutralization test (SNT) and seroconversion was assessed using SNT. Incidence density was estimated and compared using multivariable Poisson models and hazard of seroconversion was estimated over time. PRINCIPAL FINDINGS: Initial overall seroprevalence was 34.0% (95%CI: 29.5-38.8%) in cattle and 31.7% (95%CI: 22.9-41.6%) in goats, varying by locality from 18-54%. Seroconversions to RVFV based on SNT were detected throughout the year, with the incidence rate peaking during the high rainfall months of January to March, and differed considerably between years. Overall seroconversion rate in cattle was 0.59 per animal-year (95% CI: 0.46-0.75) and in goats it was 0.41 per animal-year (95% CI: 0.25-0.64), varying significantly over short distances. CONCLUSIONS/SIGNIFICANCE: The high seroprevalence in all age groups and evidence of year-round viral circulation provide evidence for a hyperendemic situation in the study area. This is the first study to directly estimate infection rate of RVFV in livestock in an endemic area in the absence of reported outbreaks and provides the basis for further investigation of factors affecting viral circulation and mechanisms for virus survival during interepidemic periods.
Assuntos
Anticorpos Antivirais/sangue , Doenças dos Bovinos/virologia , Doenças das Cabras/virologia , Febre do Vale de Rift/virologia , Vírus da Febre do Vale do Rift/isolamento & purificação , Animais , Bovinos , Doenças dos Bovinos/sangue , Doenças dos Bovinos/epidemiologia , Estudos Transversais , Surtos de Doenças , Feminino , Doenças das Cabras/sangue , Doenças das Cabras/epidemiologia , Cabras , Humanos , Imunoglobulina G/sangue , Masculino , Febre do Vale de Rift/sangue , Febre do Vale de Rift/epidemiologia , Vírus da Febre do Vale do Rift/genética , Vírus da Febre do Vale do Rift/imunologia , Soroconversão , Estudos Soroepidemiológicos , África do Sul/epidemiologiaRESUMO
The risk of exposure of slaughterhouse workers to Rift Valley fever (RVF) virus-infected animals in Nigeria was assessed by determining the prevalence of anti-RVF IgM in cattle, goats and sheep slaughtered in a major abattoir in Ibadan, Nigeria. Blood samples were collected from 290 animals in Bodija Municipal abattoir, Ibadan, Nigeria in January and February 2017 and analyzed for the presence of RVF virus using IgM Enzyme-Linked Immunosorbent Assay (ELISA) and Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) for detection of the virus RNA. Descriptive statistics was used to analyze data. Overall, an IgM prevalence of 0.7% (2/290) was found among the blood samples of the animals, suggesting recent exposure to the virus. Antibody was detected in the sera from a cow and one goat. RVF virus RNA was not detected in the 2 IgM positive blood samples. There was no statistically significant relationship between RVF IgM infection and some variables of the animals, including age, sex and breed (p ≥ 0.05). Results of this study indicate active RVF virus transmission in domestic livestock in Nigeria. The study emphasizes the need to embark on monitoring of human and animal populations to prevent outbreak of the virus in the country.
Assuntos
Febre do Vale de Rift/sangue , Animais , Bovinos , Ensaio de Imunoadsorção Enzimática , Feminino , Cabras , Imunoglobulina M/sangue , Imunoglobulina M/imunologia , Masculino , Nigéria , Febre do Vale de Rift/imunologia , Vírus da Febre do Vale do Rift/imunologia , OvinosRESUMO
Rift Valley fever virus (RVFV) is an important mosquito-borne pathogen with devastating impacts on agriculture and public health. With outbreaks being reported beyond the continent of Africa to the Middle East, there is great concern that RVFV will continue to spread to non-endemic areas such as the Americas and Europe. There is a need for safe and high throughput serological assays for rapid detection of RVFV during outbreaks and for surveillance. We evaluated a multiplexing fluorescence microsphere immunoassay (FMIA) for the detection of IgG and IgM antibodies in ruminant sera against the RVFV nucleocapsid Np, glycoprotein Gn, and non-structural protein NSs. Sheep and cattle sera from a region in Kenya with previous outbreaks were tested by FMIA and two commercially available competitive ELISAs (BDSL and IDvet). Our results revealed strong detection of RVFV antibodies against the Np, Gn and NSs antigen targets. Additionally, testing of samples with FMIA Np and Gn had 100% agreement with the IDvet ELISA. The targets developed in the FMIA assay provided a basis for a larger ruminant disease panel that can simultaneously screen several abortive and zoonotic pathogens.
Assuntos
Anticorpos Antivirais/sangue , Imunofluorescência/veterinária , Ensaios de Triagem em Larga Escala/veterinária , Imunoensaio/veterinária , Febre do Vale de Rift/diagnóstico , Febre do Vale de Rift/imunologia , Animais , Bovinos , Doenças dos Bovinos/diagnóstico , Doenças dos Bovinos/imunologia , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Quênia , Microesferas , Febre do Vale de Rift/sangue , Ruminantes/imunologia , Ovinos , Doenças dos Ovinos/diagnóstico , Doenças dos Ovinos/imunologia , Proteínas Virais/imunologiaAssuntos
Febre do Vale de Rift/urina , Vírus da Febre do Vale do Rift/isolamento & purificação , Febre Amarela/urina , Vírus da Febre Amarela/isolamento & purificação , Anticorpos Antivirais/sangue , Genoma Viral , Humanos , Febre do Vale de Rift/sangue , Vírus da Febre do Vale do Rift/genética , Sequenciamento Completo do Genoma , Febre Amarela/sangue , Vírus da Febre Amarela/genéticaRESUMO
On 16 September 2016, the World Health Organization confirmed a Rift Valley fever (RVF) outbreak in Niger. Epidemiological surveillance was reinforced among the French Armed Forces deployed in Niger and bordering countries: Chad, Mali and Burkina Faso. On 26 October, a probable case of RVF was reported in a service member sampled in Mali 3 weeks earlier. At the time the result was reported, the patient was on vacation on Martinique. An epidemiological investigation was conducted to confirm this case and identify other cases. Finally, the case was not confirmed, but three suspected cases of RVF were confirmed using serological and molecular testing. RVF viral RNA was detectable in whole blood for 57 and 67 days after onset of symptoms for two cases, although it was absent from plasma and serum. At the time of diagnosis, these cases had already returned from Mali to Europe. The infectivity of other arboviruses in whole blood has already been highlighted. That RVF virus has been detected in whole blood that long after the onset of symptoms (67 days) raises the question of its potential prolonged infectivity. Because of exposure to tropical infectious diseases during deployment, military populations could import emerging pathogens to Europe.
Assuntos
Febre/etiologia , Febre do Vale de Rift/diagnóstico , Vírus da Febre do Vale do Rift/isolamento & purificação , Adulto , Animais , Anticorpos Antivirais/sangue , Estudos Transversais , Culex/virologia , Surtos de Doenças , Europa (Continente)/epidemiologia , Humanos , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Masculino , Mali/epidemiologia , Militares , RNA Viral/sangue , RNA Viral/genética , RNA Viral/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Febre do Vale de Rift/sangue , Febre do Vale de Rift/epidemiologia , Febre do Vale de Rift/transmissão , Vírus da Febre do Vale do Rift/genética , Vigilância de Evento Sentinela , Estudos Soroepidemiológicos , ZoonosesRESUMO
This study aimed at assessing the serological and virological status of Rift Valley fever virus (RVFV) in cattle from four climatically diverse zones of the Democratic Republic of the Congo (DRC). A total of 1675 sera samples collected between 2014 and 2015 from cattle without clinical manifestation of RVF infection were tested using competitive and capture enzyme ELISA to detect both IgG and IgM. RT-PCR was used for the detection of nucleic acid of RVFV. Out of the 1675 cattle sera tested, 203 were found to be IgG-positive, giving an overall true seroprevalence of 12.37% (95% CI 10.86-14.05). This seroprevalence varied between the four zones with a seroprevalence of 16.16% (95% CI 12.86-20.12), 14.70% (95% CI 11.72-18.29), 10.82% (95% CI 7.19-14.19), and 7.34% (95% CI 5.13-10.41) recorded in cattle sampled in the mountainous, humid savannah, dry savannah, and forest zones, respectively (p < 0.05, χ2 = 17.26). A higher true seroprevalence of 14.58% (95% CI 9.3-22.13) was found in animals aged 1 year compared to 10.43% (95% CI 8.12-13.30) and 13.16% (95% CI 11.19-15.42) in groups aged between 2-3 and > 3 years, respectively, although the difference was not statistically significant (p > 0.05, χ2 = 2.95). Similarly, no statistically significant difference (p > 0.05, χ2 = 0.04) was found between the sexes of the animals. Among the IgG-positive samples screened for anti-RVFV IgM, only 1.47% (3/203) was IgM-positive. One of the IgM-positive samples was positive by RT-PCR. These findings reveal country-wide distribution of RVF in the DRC for the first time.
Assuntos
Doenças dos Bovinos/virologia , Febre do Vale de Rift/epidemiologia , Vírus da Febre do Vale do Rift , Animais , Anticorpos Antivirais/sangue , Bovinos , Doenças dos Bovinos/sangue , Doenças dos Bovinos/epidemiologia , República Democrática do Congo/epidemiologia , Ensaio de Imunoadsorção Enzimática , Febre do Vale de Rift/sangue , Estudos SoroepidemiológicosRESUMO
Rift Valley fever (RVF) is a mosquito-borne viral zoonosis causing abortions and high mortality among animals, whereas in humans, the disease is usually mild or asymptomatic. In September 2016, the Republic of Niger declared the first RVF outbreak in the northern region of Tahoua near the Malian border. This study describes the outbreak and reports the results of serological and molecular investigations of the human and animal samples collected. Serum samples from both human and animal suspected cases have been confirmed at the Centre de Recherche Médicale et Sanitaire (CERMES) and the Laboratoire Centrale d'Elevage (LABOCEL) public health and animal reference laboratories, respectively. Techniques for biological confirmation were real time reverse transcription polymerase chain reaction (RT-PCR) and enzyme linked immunosorbent assay (ELISA). Phylogenetic trees were established after genetic sequencing of the small and medium segments of the RVF virus (RVFV) genome. Out of the 399 human samples collected, 17 (4.3%) were confirmed positive for RVFV. Overall, 33 (8.3%) deaths occurred out of which five (29%) were among the 17 confirmed cases. Regarding animals, 45 samples were tested, three of which were RT-PCR positive and 24 were IgG positive. The phylogenetic analyses showed that the Niger strains clustered with Senegal 2013 and Mauritania 2015 RVFV strains. This first outbreak of RVF was very challenging for public and animal health laboratories in Niger. Besides resulting in human deaths, important loss of cattle has been reported. Therefore, vigilance has to be strengthened emphasising vector control strategies and active surveillance among animals.
Assuntos
Surtos de Doenças/veterinária , Febre do Vale de Rift/epidemiologia , Vírus da Febre do Vale do Rift/isolamento & purificação , Adolescente , Animais , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Níger/epidemiologia , Febre do Vale de Rift/sangue , Estudos Soroepidemiológicos , Fatores de Tempo , ZoonosesRESUMO
BACKGROUND & OBJECTIVES: Rift Valley fever virus (RVFV) is a vector-borne pathogen that causes serious outbreaks among livestock, and severe symptoms and mortality in humans. The virus is known to be widespread throughout African countries and Arabian peninsula. The aim of the present study was to investigate the seroprevalence of RVFV infection among human populations of Mersin province, Turkey. METHODS: A region-wide serological survey was conducted on humans residing in rural and urban areas of Mersin province located in the subtropical mediterranean region of Turkey from July 2011- January 2014. Plasma samples were tested for the presence of anti-RVFV antibodies using commercially available indirect immunofluorescence assay. RESULTS: The overall past infections were detected in 48 (4.9%) of the 977 human blood samples. The RVF virus- specific IgG positivity was detected in 33 (4.9%) of the 677 blood samples obtained from the urban area and in 15 (5%) of the 300 samples obtained from the rural area. There was no statistically significant difference in the distribution of RVFV IgG positivity rates between urban and rural areas (p = 0.933); though difference was significant between the rural areas (p = 0.029). INTERPRETATION & CONCLUSION: The study confirmed for the first time, the presence of the RVFV antibody in the urban and rural areas of mediterranean province of Mersin in Turkey, suggesting wide circulation of RVFV in the human population.
Assuntos
Anticorpos Antivirais/sangue , Febre do Vale de Rift/sangue , Vírus da Febre do Vale do Rift/imunologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Surtos de Doenças , Feminino , Humanos , Imunoglobulina G/sangue , Masculino , Pessoa de Meia-Idade , Febre do Vale de Rift/epidemiologia , Febre do Vale de Rift/virologia , Vírus da Febre do Vale do Rift/isolamento & purificação , População Rural , Estudos Soroepidemiológicos , Turquia/epidemiologia , População Urbana , Adulto JovemRESUMO
Rift Valley fever virus (RVFV) is a zoonotic arbovirus of the Phenuiviridae family. Infection causes abortions in pregnant animals, high mortality in neonate animals, and mild to severe symptoms in both people and animals. There is currently an ongoing effort to produce safe and efficacious veterinary vaccines against RVFV in livestock to protect against both primary infection in animals and zoonotic infections in people. To test the efficacy of these vaccines, it is essential to have a reliable challenge model in relevant target species, including ruminants. We evaluated two goat breeds (Nubian and LaMancha), three routes of inoculation (intranasal, mosquito-primed subcutaneous, and subcutaneous) using an infectious dose of 107 pfu/mL, a virus strain from the 2006â»2007 Kenyan/Sudan outbreak and compared the effect of using virus stocks produced in either mammalian or mosquito cells. Our results demonstrated that the highest and longest viremia titers were achieved in Nubian goats. The Nubian breed was also efficient at producing clinical signs, consistent viremia (peak viremia: 1.2 × 10³â»1.0 × 105 pfu/mL serum), nasal and oral shedding of viral RNA (1.5 × 10¹â»8 × 106 genome copies/swab), a systemic infection of tissues, and robust antibody responses regardless of the inoculation route. The Nubian goat breed and a needle-free intranasal inoculation technique could both be utilized in future vaccine and challenge studies. These studies are important for preventing the spread and outbreak of zoonotic viruses like RVFV and are supported by the Canadian-led BSL4ZNet network.
Assuntos
Cabras/virologia , Injeções Subcutâneas/veterinária , Febre do Vale de Rift/sangue , Zoonoses/virologia , Animais , Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/sangue , Cruzamento , Modelos Animais de Doenças , Absorção Nasal , Filogenia , RNA Viral , Febre do Vale de Rift/patologia , Vírus da Febre do Vale do Rift , Viremia , Eliminação de Partículas ViraisRESUMO
BACKGROUND: Rift Valley fever virus (RVFV), the causative agent of Rift Valley fever, is an enveloped single-stranded negative-sense RNA virus in the genus Phlebovirus, family Bunyaviridae. The virus is spread by infected mosquitoes and affects ruminants and humans, causing abortion storms in pregnant ruminants, high neonatal mortality in animals, and morbidity and occasional fatalities in humans. The disease is endemic in parts of Africa and the Arabian Peninsula, but is described as emerging due to the wide range of mosquitoes that could spread the disease into non-endemic regions. There are different tests for determining whether animals are infected with or have been exposed to RVFV. The most common serological test is antibody ELISA, which detects host immunoglobulins M or G produced specifically in response to infection with RVFV. The presence of antibodies to RVFV nucleocapsid protein (N-protein) is among the best indicators of RVFV exposure in animals. This work describes an investigation of the feasibility of producing a recombinant N-protein in Nicotiana benthamiana and using it in an ELISA. RESULTS: The human-codon optimised RVFV N-protein was successfully expressed in N. benthamiana via Agrobacterium-mediated infiltration of leaves. The recombinant protein was detected as monomers and dimers with maximum protein yields calculated to be 500-558 mg/kg of fresh plant leaves. The identity of the protein was confirmed by liquid chromatography-mass spectrometry (LC-MS) resulting in 87.35% coverage, with 264 unique peptides. Transmission electron microscopy revealed that the protein forms ring structures of ~ 10 nm in diameter. Preliminary data revealed that the protein could successfully differentiate between sera of RVFV-infected sheep and from sera of those not infected with the virus. CONCLUSIONS: To the best of our knowledge this is the first study demonstrating the successful production of RVFV N-protein as a diagnostic reagent by Agrobacterium-mediated transient heterologous expression in N. benthamiana. Preliminary testing of the antigen showed its ability to distinguish RVFV-positive animal sera from RVFV negative animal sera when used in an enzyme linked immunosorbent assay (ELISA). The cost-effective, scalable and simple production method has great potential for use in developing countries where rapid diagnosis of RVFV is necessary.
Assuntos
Antígenos Virais/genética , Nicotiana/genética , Proteínas do Nucleocapsídeo/genética , Febre do Vale de Rift/diagnóstico , Vírus da Febre do Vale do Rift/genética , Vírus da Febre do Vale do Rift/metabolismo , Doenças dos Ovinos/diagnóstico , Animais , Antígenos Virais/sangue , Antígenos Virais/metabolismo , Ensaio de Imunoadsorção Enzimática/métodos , Expressão Gênica , Proteínas do Nucleocapsídeo/sangue , Proteínas do Nucleocapsídeo/metabolismo , Febre do Vale de Rift/sangue , Febre do Vale de Rift/virologia , Ovinos , Doenças dos Ovinos/sangue , Doenças dos Ovinos/virologia , Nicotiana/metabolismoRESUMO
Rift Valley fever phlebovirus (RVFV), the causative agent of an emerging zoonotic disease in Africa and Arabia, can infect a variety of species, predominantly ruminants, camelids, and humans. While clinical symptoms are mostly absent in adult ruminants and camelids, RVFV infection may lead to a serious, sometimes fatal disease in humans. Virus transmissions between individuals and between species mainly occur through mosquito bites, but direct or even indirect contact with infectious materials may also result in infection. Although the main reservoir of the virus is not yet identified, small mammals such as rodents and bats may act as amplifying hosts. We therefore inoculated Rousettusaegyptiacus fruit bats that are abundant in northern Africa with the vaccine strain MP-12, in order to elucidate the general competence of this species for virus propagation and transmission. We were able to detect the RVFV genome in the spleen of each of these animals, and re-isolated the virus from the spleen and liver of some animals. Moreover, we were able to identify the Gc RVFV surface antigen in mild subacute multifocal necrotizing hepatic lesions of one bat which was sacrificed 7 days post exposure. These findings demonstrate that Rousettusaegyptiacus fruit bats can propagate RVFV.
Assuntos
Quirópteros/imunologia , Quirópteros/virologia , Febre do Vale de Rift/prevenção & controle , Vírus da Febre do Vale do Rift/imunologia , Vacinas Virais/imunologia , Animais , Linhagem Celular , Feminino , Fígado/imunologia , Fígado/patologia , Fígado/virologia , Masculino , Febre do Vale de Rift/sangue , Febre do Vale de Rift/imunologia , Febre do Vale de Rift/patologia , Vírus da Febre do Vale do Rift/classificação , Vírus da Febre do Vale do Rift/genética , Vírus da Febre do Vale do Rift/isolamento & purificação , Testes SorológicosRESUMO
Livestock handlers are occupationally exposed to Rift Valley fever virus (RVFV) because of frequent and longer contact with mosquito vectors, animal blood and other tissues. We determined the seroprevalence of RVF virus infection among livestock handlers in Ibadan, Nigeria. Blood samples were collected from 265 workers in two major livestock markets and a livestock farm. Questionnaires were administered to obtain information on risk factors that may be associated with RVF virus transmission. The blood samples were tested using enzyme-linked immunosorbent assays (ELISA) to detect multispecies anti-RVF virus IgG/IgM and human anti-RVF virus IgM. In total, 14 (5.3%) of the 265 participants tested positive for anti-RVFV IgG. Seropositive individuals were more among livestock keepers (5.6%) than butchers (3.6%). Workers that frequently visited the livestock rearing areas of the northern part of Nigeria had a statistically significant (P = 0.004) higher rate of infection compared to those that did not. Very few (0.8%) of these workers knew about RVF virus while none had been vaccinated against the virus infection. This study indicates that RVF virus continues to circulate sub-clinically in Nigeria, thus the need to educate and vaccinate individuals who are occupationally at risk of infection.