Abstract

Background: Vaccination is considered to be the best approach to control Rift Valley fever (RVF) in animals and consequently in humans. This study assessed the efficacy and safety of the RVF virus (RVFV) Clone 13 vaccine under field conditions.Methodology: A vaccine trial was conducted in sheep (230), goats (230), and cattle (140) in Ngorongoro district, Tanzania. Half of each of the animal species were vaccinated and the other half received the placebo. Animals were clinically monitored and bled before vaccination and at days 15, 30, 60, 180 and 360 (+/– 10) post-vaccination to measure Immunoglobulin M (IgM) and IgG antibody responses to RVFV. Survival analysis was conducted using cox-proportional hazard regression model to measure the time until an event of interest had occurred and to compare the cumulative proportion of events over time.Results: Of 600 animals included in the study, 120 animals were lost during the study, leaving a total of 480 (243 in the vaccinated group and 237 in the control group) for complete follow-up sampling. There was no adverse reaction reported at the injection site of the vaccine/placebo in all animals. Abortions, deaths, or body temperature variations were not associated with vaccination (p > 0.05). By day 15 post-inoculation, the IgG seroconversion in vaccinated goats, cattle and sheep was 27.0% (n = 115), 20.0% (n = 70) and 10.4% (n = 115), respectively. By day 30 post-inoculation, it was 75.0% (n = 113), 74.1% (n = 112) and 57.1% (n = 70) in vaccinated sheep, goats and cattle, respectively. By day 60 post-inoculation, IgG seroconversion in sheep, goats and cattle was 88.1% (n = 109), 84.3% (n = 108) and 64.60% (n = 65), respectively. By day 180, the IgG seroconversion in sheep, goats and cattle was 88.0% (n = 108), 83.8% (n = 105) and 66.1% (n = 62), respectively. By day 360, the IgG seroconversion in sheep, goats and cattle was 87.2% (n = 94), 85.6% (n = 90) and 66.1% (n = 59), respectively. Only five animals from the vaccinated group were RVFV IgM positive, which included four sheep and a goat.Conclusion: RVFV Clone 13 vaccine was well tolerated by sheep, goats, and cattle. The vaccine induced detectable, but variable levels of IgG responses, and of different duration. The vaccine is considered safe, with high immunogenicity in sheep and goats and moderate in cattle.

Highlights

  • Rift Valley fever (RVF) is a climate-sensitive, economically important, an acute mosquito-borne zoonotic viral disease that is caused by RVF virus (RVFV) [1]

  • Our study was designed to demonstrate safety, immunogenicity and antibody responses following vaccination with RVFV Clone 13 vaccine in domestic ruminants kept by nomadic pastoralists in the natural environment and under the traditional management system

  • During the follow-up period, there were no adverse effects associated with inoculations suggesting that the RVFV Clone 13 vaccine and placebo were well-tolerated by domestic ruminants

Read more

Summary

Introduction

Rift Valley fever (RVF) is a climate-sensitive, economically important, an acute mosquito-borne zoonotic viral disease that is caused by RVF virus (RVFV) [1]. The virus causes severe disease in livestock including cattle, sheep, goats, and camels as well as in humans mainly in Africa and the Arabian Peninsula [2]. The eastern Rift Valley ecosystem of the country has been identified to be at higher risk of RVF occurrence than the western Rift Valley ecosystem [7]. The past RVF outbreaks in Tanzania resulted in devastating health and socio-economic consequences. The disease caused high mortality rates in domestic ruminants and humans [8]. Vaccination is considered to be the best approach to control Rift Valley fever (RVF) in animals and in humans. This study assessed the efficacy and safety of the RVF virus (RVFV) Clone 13 vaccine under field conditions

Methods
Results
Discussion
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call