Farmers' preference and willingness to pay for a multivalent lumpy skin disease and Rift Valley fever novel vaccine: A discrete choice experiment in the Free State province, South Africa.

Rift Valley fever and lumpy skin disease are infectious ruminant diseases that are endemic in most African countries. The most cost-effective method of prevention and control is through annual vaccination. However, unlike lumpy skin disease, annual vaccination against Rift Valley fever is not practiced by many farmers due to its sporadic occurrences and shortcoming of the existing vaccines. This necessitates development of novel vaccines that would provide dual protection against a Rift Valley fever and a more prevalent disease. In this study, a discrete choice experiment was undertaken to guide vaccine development by examining the value smallholder livestock farmers place on different vaccine attributes and related attribute levels. The attributes considered are target-species, thermotolerance, nature of the vaccine, efficacy and price. The study was carried out with 164 smallholder livestock farmers in the Free State province. Results indicate that thermostaility is not a major deciding attribute to smallholder farmer's choice of vaccine. Farmers prefer multivalent vaccines, which are highly efficacious with about 90-100 % efficacy levels. Farmers were found to be heterogeneous in preference. The heterogeneity is explained by socio-economic factors such as type of livestock owned, income level, gender and perceived disease risk. Farmers were also willing to pay for preferred attribute levels. However, for less favourable levels such as multispecies, female farmers were willing to accept a lower compensation than males. These findings present a favourable potential for development of a novel multivalent vaccine and also provide vaccine research and development scientists with evidence based knowledge for development of vaccines that cater for the needs of smallholder farmers.

Willingness to pay for a Rift valley fever (RVF) vaccine among Kenyan cattle producers.

A double bounded contingent valuation (CV) model was used to assess the Willingness to Pay (WTP) for vaccination of cattle against RVF in a sample of 276 livestock producers in Murang'a, Laikipia and Kwale Counties. While the level of awareness about the disease was rather low, nearly all respondents expressed willingness to have their animals vaccinated against the disease. Average WTP was highest in Murang'a (mean = US$1.44) where farmers practice dairy farming using exotic breeds of cattle compared to Laikipia (mean = US$1.24), where both exotic dairy and local breeds of cattle together with their crosses are kept, and Kwale (mean = US$1.01) where local breeds are predominantly kept. These average levels of WTP were 17%-67% higher than the estimated cost incurred by government (US$0.86 per head of cattle) in the most recent vaccination campaign conducted during RVF outbreak. Surprisingly, WTP tended to be lower among producers with many heads of cattle probably because the large herds would translate to bigger total costs. The study recommended support for sensitization campaigns about RVF and its control measures. While the high average levels of WTP implies potential for commercialization of vaccination against RVF, there may be need for price differentiation by region to ensure that sufficiently high numbers of producers vaccinate their animals to prevent outbreaks.

Sociocultural and economic dimensions of Rift Valley fever.

Health researchers have advocated for a cross-disciplinary approach to the study and prevention of infectious zoonotic diseases, such as Rift Valley Fever. It is believed that this approach can help bring out the social determinants and effects of the zoonotic diseases for the design of appropriate interventions and public health policy. A comprehensive literature review using a systematic search strategy was undertaken to explore the sociocultural and economic factors that influence the transmission and spread of Rift Valley Fever. Although the findings reveal a paucity of social research on Rift Valley Fever, they suggest that livestock sacrificial rituals, food preparation and consumption practices, gender roles, and inadequate resource base for public institutions are the key factors that influence the transmission. It is concluded that there is need for cross-disciplinary studies to increase the understanding of Rift Valley Fever and facilitate appropriate and timely response and mitigation measures.

Modelling the effects of seasonality and socioeconomic impact on the transmission of rift valley Fever virus.

Rift Valley fever (RVF) is an important mosquito-borne viral zoonosis in Africa and the Middle East that causes human deaths and significant economic losses due to huge incidences of death and abortion among infected livestock. Outbreaks of RVF are sporadic and associated with both seasonal and socioeconomic effects. Here we propose an almost periodic three-patch model to investigate the transmission dynamics of RVF virus (RVFV) among ruminants with spatial movements. Our findings indicate that, in Northeastern Africa, human activities, including those associated with the Eid al Adha feast, along with a combination of climatic factors such as rainfall level and hydrological variations, contribute to the transmission and dispersal of the disease pathogen. Moreover, sporadic outbreaks may occur when the two events occur together: 1) abundant livestock are recruited into areas at risk from RVF due to the demand for the religious festival and 2) abundant numbers of mosquitoes emerge. These two factors have been shown to have impacts on the severity of RVF outbreaks. Our numerical results present the transmission dynamics of the disease pathogen over both short and long periods of time, particularly during the festival time. Further, we investigate the impact on patterns of disease outbreaks in each patch brought by festival- and seasonal-driven factors, such as the number of livestock imported daily, the animal transportation speed from patch to patch, and the death rate induced by ceremonial sacrifices. In addition, our simulations show that when the time for festival preparation starts earlier than usual, the risk of massive disease outbreaks rises, particularly in patch 3 (the place where the religious ceremony will be held).

A Systematic Scoping Study of the Socio-Economic Impact of Rift Valley Fever: Research Gaps and Needs.

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.

Potential effects of Rift Valley fever in the United States.

Rift Valley fever virus (RVFV) has been the cause of disease outbreaks throughout Africa and the Arabian Peninsula, and the infection often results in heavy economic costs through loss of livestock. If RVFV, which is common to select agent lists of the US Department of Health and Human Services and the US Department of Agriculture, entered the United States, either by accidental or purposeful means, the effects could be substantial. A group of subject matter experts met in December 2009 to discuss potential implications of an introduction of RVF to the United States and review current modeling capabilities. This workshop followed a similar meeting held in April 2007. This report summarizes the 2 workshop proceedings. Discussions primarily highlighted gaps in current economic and epidemiologic RVF models as well as gaps in the overall epidemiology of the virus.

Can environmental and socioeconomic factors explain the recent emergence of Rift Valley fever in Yemen, 2000-2001?

Rift Valley fever (RVF) is a major vector-borne zoonosis first identified on the African continent in the early 1900s. In 2000, RVF was reported for the first time in Yemen. In this study, we provide a descriptive analysis of the period 1999-2007 in Yemen, taking into account the environmental and socioeconomic factors likely to have been involved in the emergence of RVF in the country. We characterize each year in the study period by the environmental conditions (linked to vegetation indexes), the festival calendar, and economic data. We then use a principal component analysis to synthesize the different variables, assess whether the year 2000 was atypical compared with other years in the study period, and, if that was the case, in what respect. Our results show that 2000 presented above-normal vegetation index values, which reflect important precipitation, for both the two rainy seasons (the first between March and May; the second between July and October). These environmental conditions, ones favorable to mosquito vector populations, coincided that year with a late (March) starting date of the Eid al-Kabeer festival, which corresponds to a period with high host (cattle, sheep, goats) densities. According to these criteria, 2000 was an atypical year. These conclusions suggest that it is important to consider social variables in addition to environmental ones when assessing the risk of RVF emergence.

An assessment of the regional and national socio-economic impacts of the 2007 Rift Valley fever outbreak in Kenya.

Although Rift Valley fever (RVF) has significant impacts on human health and livestock production, it can also induce significant (and often overlooked) economic losses among various stakeholders in the marketing chain. This work assesses and quantifies the multi-dimensional socio-economic impacts of the 2007 RVF outbreak in Kenya based on a rapid assessment of livestock value chains in the northeast part of the country and a national macroeconomic analysis. Although study results show negative impacts among producers in terms of food insecurity and reductions in income, we also found significant losses among other downstream actors in the value chain, including livestock traders, slaughterhouses, casual laborers, and butchers, as well as other, non-agricultural sectors. The study highlights the need for greater sensitivity and analyses that address the multitude of economic losses resulting from an animal disease to better inform policy and decision making during animal health emergencies.