Protectivity of Freeze Dried Inactivated Rift Valley Fever Vaccine

Background: Vaccinations for animals are crucial for food production, animal welfare, public health, and animal health. They are an affordable way to stop animal sickness, increase food production efficiency, and lessen or stop the spread of zoonotic diseases to humans. Animal vaccines that are both safe and efficacious are vital to modern culture. The vaccine should induce a strong, protective and prolonged immune response against the antigenic factor. In order to achieve these goals, novel vaccination techniques and an efficient adjuvant are required to render the vaccine immunogenically protective and trigger a strong immune response. Aim: Our study aims to promote and enhance the immunogenicity against RVF virus disease through lyophilized inactivated RVF vaccine through induction of early cellular, high and prolonged humeral immunity in vaccinated animals using cabopol as stabilizer and Saponin or normal saline as a diluent at time of vaccination. Moreover, manufacturing of these vaccines is easy to be done. Results: The gained results revealed that RVF freeze-dried vaccine with Carbopol that reconstituted using Saponin elicited better immune response than that reconstituted using normal saline (NaCl). The cell mediated immune response as represented by lymphocyte blastogenesis and phagocytic activity were markedly increased with high levels when we used Saponin as a diluent than that in group vaccinated with vaccine diluted with NaCl, on the other side the humeral immune response in group vaccinated using the Saponin as diluent is more detected and stayed within the protective level till the end of 11th month post vaccination (1.5 TCID50) while the immune response induced after using normal saline as a diluent stayed within the protective level till the end of 10th month post vaccination (1.8 TCID50). Conclusion: The use of Saponin as a diluent for reconstitution of the freeze dried RVF vaccine is preferable than the use of normal saline enhancing both sheep cellular and humeral immune response.

Modeling Rift Valley Fever with Treatment and Trapping Control Strategies

We consider a rift valley fever model with treatment in human and livestock populations and trapping in the vector (mosquito) population. The basic reproduction number R 0 is established and used to determine whether the disease dies out or is established in the three populations. When R 0 ≤ 1, the disease-free equilibrium is shown to be globally asymptotically stable and the disease does not spread and when R 0 > 1, a unique endemic equilibrium exists which is globally stable and the disease will spread. The mathematical model is analyzed analytically and numerically to obtain insight of the impact of intervention in reducing the burden of rift valley fever disease’s spread or epidemic and also to determine factors influencing the outcome of the epidemic. Sensitivity analysis for key parameters is also done.

Import of Rift Valley fever to China:a potential new threat?

Several recent studies in Virologica Sinica and other journals have highlighted the enormous international challenge of emerging arboviral diseases,such as Zika virus disease,dengue,and chikungunya(Islam et al.,2015;Maurice et al.,2015;Dai et al.,2016;Deng et al.,2016;Song et al.,2016;Wang et al.,2016;Xu et al.,2016;Zhang et al.,2016;Zhou

DYNAMICS OF A KIND OF RIFT VALLEY FEVER MODEL

A novel mathematical model of the epidemiology of Rift Valley fever (RVF) is studied, which is an ordinary differential equation model for a population of mosquito species and the hosts. A disease-free equilibrium is discussed as well as its local stability. The prevalence of disease is proved under some conditions. Finally the vertical transmission is considered in a model for such a mosquito population.

Support for research towards understanding the population health vulnerabilities to vector-borne diseases:increasing resilience under climate change conditions in Africa

Background:Diseases transmitted to humans by vectors account for 17%of all infectious diseases and remain significant public health problems.Through the years,great strides have been taken towards combatting vectorborne diseases(VBDs),most notably through large scale and coordinated control programmes,which have contributed to the decline of the global mortality attributed to VBDs.However,with environmental changes,including climate change,the impact on VBDs is anticipated to be significant,in terms of VBD-related hazards,vulnerabilities and exposure.While there is growing awareness on the vulnerability of the African continent to VBDs in the context of climate change,there is still a paucity of research being undertaken in this area,and impeding the formulation of evidence-based health policy change.Main body:One way in which the gap in knowledge and evidence can be filled is for donor institutions to support research in this area.The collaboration between the WHO Special Programme for Research and Training in Tropical Diseases(TDR)and the International Centre for Research and Development(IDRC)builds on more than 10 years of partnership in research capacity-building in the field of tropical diseases.From this partnership was born yet another research initiative on VBDs and the impact of climate change in the Sahel and sub-Saharan Africa.This paper lists the projects supported under this research initiative and provides a brief on some of the policy and good practice recommendations emerging from the ongoing implementation of the research projects.Conclusion:Data generated from the research initiative are expected to be uptaken by stakeholders(including communities,policy makers,public health practitioners and other relevant partners)to contribute to a better understanding of the impacts of social,environmental and climate change on VBDs(i.e.the nature of the hazard,vulnerabilities,exposure),and improve the ability of African countries to adapt to and reduce the effects of these changes in ways that benefit their most vulnerable populations.

Mapping the viruses belonging to the order Bunyavirales in China

Background:Viral pathogens belonging to the orderBunyavirales pose a continuous background threat to global health,but the fact remains that they are usually neglected and their distribution is still ambiguously known.We aim to map the geographical distribution ofBunyavirales viruses and assess the environmental suitability and transmission risk of majorBunyavirales viruses in China.Methods:We assembled data on allBunyavirales viruses detected in humans,animals and vectors from multiple sources,to update distribution maps of them across China.In addition,we predicted environmental suitability at the 10 km×10 km pixel level by applying boosted regression tree models for two importantBunyavirales viruses,including Crimean-Congo hemorrhagic fever virus(CCHFV)and Rift Valley fever virus(RVFV).Based on model-projected risks and air travel volume,the imported risk of RVFV was also estimated from its endemic areas to the cities in China.Results:Here we mapped all 89 species ofBunyavirales viruses in China from January 1951 to June 2021.Nineteen viruses were shown to infect humans,including ten species first reported as human infections.A total of 447,848 cases infected withBunyavirales viruses were reported,and hantaviruses,Dabie bandavirus and Crimean-Congo hemorrhagic fever virus(CCHFV)had the severest disease burden.Model-predicted maps showed that Xinjiang and southwestern Yunnan had the highest environmental suitability for CCHFV occurrence,mainly related toHyalomma asiaticum presence,while southern China had the highest environmental suitability for Rift Valley fever virus(RVFV)transmission all year round,mainly driven by livestock density,mean precipitation in the previous month.We further identified three cities including Guangzhou,Beijing and Shanghai,with the highest imported risk of RVFV potentially from Egypt,South Africa,Saudi Arabia and Kenya.Conclusions:A variety ofBunyavirales viruses are widely distributed in China,and the two major neglectedBunyavirales viruses including CCHFV and RVFV,both have the potential for outbreaks in local areas of China.Our study can help to promote the understanding of risk distribution and disease burden ofBunyavirales viruses in China,and the risk maps of CCHFV and RVFV occurrence are crucial to the targeted surveillance and control,especially in seasons and locations at high risk.