Anomalous High Rainfall and Soil Saturation as Combined Risk Indicator of Rift Valley Fever Outbreaks, South Africa, 2008–2011

Abstract

A prediction model that includes these factors shows promising potential for forecasting major outbreaks.

Climate Change and Infectious Livestock Diseases: The Case of Rift Valley Fever and Tick-Borne Diseases

“…The disease has also been reported in other countries including the Comoros archipelago, Madagascar, Mauritania, Saudi Arabia, Senegal and Sudan (Madani et al 2003) and Yemen (Abdo-Salem et al 2006). In South Africa, recent RVF outbreaks observed in 2008-2011 were associated with relentless and widespread strong seasonal rainfall and high soil saturation (Williams et al 2016). Areas affected by these outbreaks are shown in Fig.…”

“…The increasing frequency of droughts and erratic rainfall in arid and semi-arid areas would necessitate the construction of dams and irrigation schemes to support water supply and food production. Previously, outbreaks of RVF have been reported following flood irrigation in the Orange River region and Western Cape province, South Africa (Williams et al 2016), and the construction of dams, i.e. Aswan High Dam in Egypt in 1977 (Bett et al 2017).…”

A comparative genome analysis of Rift Valley Fever virus isolates from foci of the disease outbreak in South Africa in 2008-2010

“…Complete genome sequence analysis of viruses isolated from the 2008 outbreak clusters them in Lineage C together with isolates from a 2007 outbreak in Kenya, known as Lineage Kenya-1, Fig 2A, Fig 2B and Fig 2C [12,20]. In contrast to the localized outbreak of 2008, 19 outbreaks which were reported in 2009 were widespread, with single cases in Mpumalanga and Gauteng, and the rest in KwaZulu-Natal, the Eastern Cape or along the Orange River in the Northern Cape [34,38]. Similar to the isolates from the 2008 outbreaks, the 2009 isolate from Gauteng clustered in Lineage C, within Lineage Kenya-1 (Fig 2A and 2B).…”

The Impact and Control of Emerging and Re-Emerging Viral Diseases in the Environment: An African Perspective

“…The rainfall events result in flooding of dambo-type grassland depressions at greater depths and for extended periods compared to interepizootic periods. Consequently, previously dormant infected Aedes eggs are induced to hatch, causing the emergence and survival of at least one large generation of virus-infected Aedes mosquitoes (Williams et al 2016). These mosquitoes then transmit the virus to ungulate livestock, especially sheep, cattle and goats which serve as amplifying vertebrate hosts that may begin the epizootic cycle.…”