Eighteen years of implementation of a control programme against Rift Valley fever, 2000-2018, Saudi Arabia: a review study.

Rift Valley fever (RVF) is a serious life-threatening disease with severe clinical manifestations and health consequences for humans and a wide range of domestic animals. In September 2000, an RVF outbreak was reported in the Jazan region in the south-west part of Saudi Arabia with 886 human cases including 124 deaths. This review provides: a) an overview of the RVF control programme in Saudi Arabia, and b) an assessment of some of the control measures that have been launched since the early recognition of RVF. Currently, with the exception of Saudi Arabia, devastating outbreaks of RVF continue to occur and the number of countries reporting cases has increased rapidly. At least 19 large outbreaks including substantial numbers of human and animal deaths have been reported for the period between 2000 and 2018. In contrast to the aforementioned situation in endemic areas, the RVF control programme that was set up in Saudi Arabia has completely reversed the risk of re-occurrence of RVF over the past 18 years and provided long-term protection against Rift Valley fever virus (RVFV) exposure. The control programme involved: a) vector control campaigns (using conventional and microbial insecticides, drainage and filling of water swamps with soil, and mosquito surveillance) and b) host-driven controls such as sustained vaccination campaigns, regular examination of sentinel herds, including seasonal surveillance reinforcement (targeted sero-surveillance during rainy seasons), and serological examination of clandestine animal imports kept at Al-Twal quarantine station, at the border with Yemen. The effectiveness of the current control programme can be demonstrated not only by the decrease in antibody prevalence of RVF virus-specific immunoglobulin M, from 12.3% (95% confidence interval [CI]: 6.8-17.8) in 2000 to 0.10% (95% CI: 0.01-0.2) in 2017, but also by the absence of human and animal cases since the 2000 outbreak. The mosquito infection rates with RVFV have also declined, from 0.045 per 1,000 for the genus Culex in 2014 to zero from 2015 to 2018. Additionally, the integrated vector management methods targeting outdoor habitats in the Jazan region substantially contributed to vector control and should be considered one of the most important factors contributing to the significant reduction of malaria case incidence from 2000 to 2014. The Saudi current control initiative could be used as a guideline for control of RVF or as a suitable model for other endemic countries.