Abstract
Rift Valley fever (RVF) is a vector-borne viral disease of ruminants mainly, and man, characterized by abortions and neonatal deaths in animals and flu-like to more severe symptoms that can result in death in humans. The disease is endemic in Africa, Saudi Arabia and Yemen, and outbreaks occur following proliferation of RVF virus (RVFV) infected mosquito vectors. Vertebrate animal maintenance hosts of RVFV, which serve as a source of virus during inter-epidemic periods remain unknown, with wild and domestic suids being largely overlooked. To address this, we evaluated the virus neutralization test (VNT) for RVF antibody detection in suid sera, as a first step in assessing the role of suids in the epidemiology of RVF in Africa. Testing of experimental and field sera from domestic pigs and warthogs with a commercial RVF competitive antibody ELISA, served as a reference standard against which the VNT results were compared. Results indicate that VNT can detect anti-RVFV antibodies within three days post-infection, has an analytical specificity of 100% and diagnostic sensitivity and specificity of 80% and 97%, respectively. Although labour-intensive and time-consuming, the VNT proved suitable for screening suid sera and plasma for presence of RVFV antibodies in viraemic and recovered animals.
Highlights
Rift Valley fever (RVF) is a vector-borne disease of ruminants, camels and man, characterized by widespread abortions, teratogenicity, and neonatal deaths in animals, and flu-like symptoms which can progress to severe disease and even death in humans [1,2]
It was believed that transovarial transmission of RVF virus (RVFV) by infected Aedes mosquitos allowed them to act as inter-epidemic period (IEP) reservoir hosts but current research indicates that whilst vertical transmission in mosquitoes is likely, there is insufficient evidence to support the hypothesis [8,9]
We report here on the evaluation of a virus neutralization test (VNT) capable of detecting RVFV antibodies in domestic and wild pig sera and plasma, implemented as part of a broader study investigating the potential role of suids in RVF epidemiology in Africa
Summary
Rift Valley fever (RVF) is a vector-borne disease of ruminants, camels and man, characterized by widespread abortions, teratogenicity, and neonatal deaths in animals, and flu-like symptoms which can progress to severe disease and even death in humans [1,2]. Outbreaks occur after periods of high rainfall or in environments supporting the proliferation of RVFV-infected mosquito vectors [7]. It was believed that transovarial transmission of RVFV by infected Aedes mosquitos allowed them to act as inter-epidemic period (IEP) reservoir hosts but current research indicates that whilst vertical transmission in mosquitoes is likely, there is insufficient evidence to support the hypothesis [8,9]. Serological evidence of low-level circulation of RVFV among wild and domestic animals during the IEP exists, but definitive mammalian reservoir hosts remain unidentified [10]. We report here on the evaluation of a VNT capable of detecting RVFV antibodies in domestic and wild pig sera and plasma, implemented as part of a broader study investigating the potential role of suids in RVF epidemiology in Africa
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