Article

Rift Valley fever in Kenya: history of epizootics and identification of vulnerable districts.

Kenya Ministry of Livestock Development, Kabete, Kenya.
Epidemiology and Infection (Impact Factor: 2.49). 03/2011; 139(3):372-80. DOI: 10.1017/S0950268810001020
Source: PubMed

ABSTRACT Since Kenya first reported Rift Valley fever (RVF)-like disease in livestock in 1912, the country has reported the most frequent epizootics of RVF disease. To determine the pattern of disease spread across the country after its introduction in 1912, and to identify regions vulnerable to the periodic epizootics, annual livestock disease records at the Department of Veterinary Services from 1910 to 2007 were analysed in order to document the number and location of RVF-infected livestock herds. A total of 38/69 (55%) administrative districts in the country had reported RVF epizootics by the end of 2007. During the 1912-1950 period, the disease was confined to a district in Rift Valley province that is prone to flooding and where livestock were raised in proximity with wildlife. Between 1951 and 2007, 11 national RVF epizootics were recorded with an average inter-epizootic period of 3·6 years (range 1-7 years); in addition, all epizootics occurred in years when the average annual rainfall increased by more than 50% in the affected districts. Whereas the first two national epizootics in 1951 and 1955 were confined to eight districts in the Rift Valley province, there was a sustained epizootic between 1961 and 1964 that spread the virus to over 30% of the districts across six out of eight provinces. The Western and Nyanza provinces, located on the southwestern region of the country, had never reported RVF infections by 2007. The probability of a district being involved in a national epizootic was fivefold higher (62%) in districts that had previously reported disease compared to districts that had no prior disease activity (11%). These findings suggests that once introduced into certain permissive ecologies, the RVF virus becomes enzootic, making the region vulnerable to periodic epizootics that were probably precipitated by amplification of resident virus associated with heavy rainfall and flooding.

0 Followers
 · 
130 Views
  • Source
    • "About 90% of the population of Ijara is directly dependent on livestock for food and as a source of income. During the last outbreak, a ban on livestock trade and imposition of quarantine resulted in severe economic losses of more than $9.3 million (Murithi et al. 2010). In Ijara district, cattle are driven over long distances towards the Tana River Delta or into Boni forest, passing through various ecosystems. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Ijara district in Kenya was one of the hotspots of Rift Valley fever (RVF) during the 2006/2007 outbreak, which led to human and animal deaths causing major economic losses. The main constraint for the control and prevention of RVF is inadequate knowledge of the risk factors for its occurrence and maintenance. This study was aimed at understanding the perceived risk factors and risk pathways of RVF in cattle in Ijara to enable the development of improved community-based disease surveillance, prediction, control and prevention. A cross-sectional study was carried out from September 2012 to June 2013. Thirty-one key informant interviews were conducted with relevant stakeholders to determine the local pastoralists' understanding of risk factors and risk pathways of RVF in cattle in Ijara district. All the key informants perceived the presence of high numbers of mosquitoes and large numbers of cattle to be the most important risk factors contributing to the occurrence of RVF in cattle in Ijara. Key informants classified high rainfall as the most important (12/31) to an important (19/31) risk factor. The main risk pathways were infected mosquitoes that bite cattle whilst grazing and at watering points as well as close contact between domestic animals and wildlife. The likelihood of contamination of the environment as a result of poor handling of carcasses and aborted foetuses during RVF outbreaks was not considered an important pathway. There is therefore a need to conduct regular participatory community awareness sessions on handling of animal carcasses in terms of preparedness, prevention and control of any possible RVF epizootics. Additionally, monitoring of environmental conditions to detect enhanced rainfall and flooding should be prioritised for preparedness.
    The Onderstepoort journal of veterinary research 11/2014; 81(1). DOI:10.4102/ojvr.v81i1.780 · 0.62 Impact Factor
  • Source
    • ", effects 2.1, 2.2 and 2.3). Cumulatively, the impact on other service providers within the livestock supply chain and other parts of the larger economy can be greater than the impact of RVF at the farm level (Bonnet et al., 2001; Murithi et al., 2011; Rich and Perry, 2011 "
    [Show abstract] [Hide abstract]
    ABSTRACT: Rift Valley fever (RVF) is a severe mosquito-borne disease affecting humans and domestic ruminants. RVF virus has been reported in most African countries, as well as in the Arabic Peninsula. This paper reviews the different types of socio-economic impact induced by RVF disease and the attempts to evaluate them. Of the 52 papers selected for this review, 13 types of socio-economic impact were identified according to the sector impacted, the level and temporal scale of the impact. RVF has a dramatic impact on producers and livestock industries, affecting public and animal health, food security and the livelihood of the pastoralist communities. RVF also has an impact on international trade and other agro-industries. The risk of introducing RVF into disease-free countries via the importation of an infected animal or mosquito is real, and the consequent restriction of access to export markets may induce dramatic economic consequences for national and local economies. Despite the important threat of RVF, few studies have been conducted to assess the socio-economic impact of the disease. The 17 studies identified for quantitative analysis in this review relied only on partial cost analysis, with limited reference to mid- and long-term impact, public health or risk mitigation measures. However, the estimated impacts were high (ranging from $5 to $470 million USD losses). To reduce the impact of RVF, early detection and rapid response should be implemented. Comprehensive disease impact studies are required to provide decision-makers with science-based information on the best intervention measure to implement ensuring efficient resource allocation. Through the analysis of RVF socio-economic impact, this scoping study proposes insights into the mechanisms underpinning its often-underestimated importance. This study highlights the need for comparative socio-economic studies to help decision-makers with their choices related to RVF disease management.
    Zoonoses and Public Health 09/2014; 62(5). DOI:10.1111/zph.12153 · 2.07 Impact Factor
  • Source
    • "About 90% of the human population Ijara is directly dependent on livestock for daily nourishment and as a source of income resource. During the last outbreak, a ban on livestock trade and imposition of quarantine resulted in severe economic losses greater than US$ 9.3 million (Murithi et al., 2010). In Ijara district, nomadic pastoralism is practiced where livestock (cattle) are driven over long distances towards Tana River Delta or into Boni forest passing through various ecosystems in search of pasture and water. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Ijara district in Kenya was one of the hotspots of rift valley fever (RVF) during the 2006/2007 outbreak which led to human and animal deaths causing huge economic and public health losses. The main constraint in the control and prevention of RVF is inadequate knowledge on its occurrence during the interepidemic period. This study was aimed at understanding the occurrence of RVF in cattle in Ijara to enable the development of improved community-based disease surveillance, prediction, control and prevention.
    Preventive Veterinary Medicine 08/2014; 117(1). DOI:10.1016/j.prevetmed.2014.08.008 · 2.51 Impact Factor
Show more