Spatial and seasonal patterns of FMD primary outbreaks in cattle in Zimbabwe between 1931 and 2016

Foot and mouth disease (FMD) is an important livestock disease impacting mainly intensive production systems. In southern Africa, the FMD virus is maintained in wildlife and its control is therefore complicated. However, FMD control is an important task to allow countries access to lucrative foreign meat market and veterinary services implement drastic control measures on livestock populations living in the periphery of protected areas, negatively impacting local small-scale livestock producers. This study investigated FMD primary outbreak data in Zimbabwe from 1931 to 2016 to describe the spatio-temporal distribution of FMD outbreaks and their potential drivers. The results suggest that: (i) FMD outbreaks were not randomly distributed in space across Zimbabwe but are clustered in the Southeast Lowveld (SEL); (ii) the proximity of protected areas with African buffalos was potentially responsible for primary FMD outbreaks in cattle; (iii) rainfall per se was not associated with FMD outbreaks, but seasons impacted the temporal occurrence of FMD outbreaks across regions; (iv) the frequency of FMD outbreaks increased during periods of major socio-economic and political crisis. The differences between the spatial clusters and other areas in Zimbabwe presenting similar buffalo/cattle interfaces but with fewer FMD outbreaks can be interpreted in light of the recent better understanding of wildlife/livestock interactions in these areas. The types of wildlife/livestock interfaces are hypothesized to be the key drivers of contacts between wildlife and livestock, triggering a risk of FMD inter-species spillover. The management of wildlife/livestock interfaces is therefore crucial for the control of FMD in southern Africa

Multi-criteria decision analysis (MCDA) for control of transboundary livestock diseases using the example of the 2010/11 foot-and-mouth disease (FMD) outbreak in the Republic of Korea : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatū

Decisions regarding transboundary livestock disease control strategies differ from personal decisions, such as buying groceries, in important ways: the stakes are high and the outcome of a decision will affect people in different fields. Decision making for transboundary livestock disease control strategies requires consideration of a number of factors including the epidemiology of the disease, economic cost of control, and environmental and social impact. For example, when applying pre-emptive slaughtering as a control measure for FMD, decision makers need to consider the epidemiologic effectiveness of the control measure, financial loss to farmers, the operational cost of slaughtering, negative impacts on the environment due to burning or burial of culled animals, and the public’s concerns for the welfare of slaughtered animals. Therefore, it can be challenging for decision makers to choose the best control strategy among alternative strategies. The study presented in the thesis describes the application of multi-criteria decision analysis (MCDA) process as a decision support tool for decision making about transboundary livestock disease control strategies using an example of a simulated FMD outbreak. The first research chapter (Chapter 3) investigates the preferences of chief veterinary officers (CVOs) for the criteria of FMD-control strategies in the Asia-Oceania region, which comprises countries free from or having experienced FMD. Criteria were grouped into epidemiologic, economic, and social-environmental. The CVOs in the Asia-Oceania region considered the epidemiologic criterion more important than the economic or the social-environmental criterion. The importance of the economic criterion differed with FMD status of a country: specifically, those countries considered free of FMD ranked the economic criterion as more important than those without. Among the criteria comprising the epidemiologic criterion, the most important was the size of the FMD-infected area, defined as the geographical size of FMD outbreak area. Within the economic criterion, the operational cost of the FMD-control strategy was considered the most important, and within the social-environmental criterion, the mental health of FMD-affected farmers was the most important criterion. Chapter 4 describes the construction of an epidemiologic model of the spread of the 2010/11 FMD outbreak in the city of Andong, Republic of Korea, to measure the epidemiologic effectiveness of FMD-control strategies. According to the simulation results, the model accurately represented the FMD outbreak in two ways: 1) the median number of simulated FMD-detected farms was the same as the number of detected farms during the actual FMD epidemic, and 2) the simulated epidemic curve was similar to the actual epidemic curve for the 2010/11 FMD epidemic. Thus, the constructed model could be used as a reference for evaluating the effectiveness of alternative FMD-control strategies. The control strategy applied during the 2010/11 FMD epidemic consisted of a pre-emptive slaughter area with a radius of three kilometres, 100 day movement restriction, and vaccination of all FMD-susceptible animals in the country. This was used as a baseline strategy in the study. Alternative levels of these control measures for the FMD-control strategy were simulated to evaluate the effect of alternative strategies. Changes in control measures were: 1) pre-emptive slaughtering within a radius of 0.5, one, and five kilometres of FMD-infected farms; 2) movement restriction of 30 days and 60 days; 3) ring vaccination in a band three to five kilometres from FMD-infected farms. According to the simulation results, the five kilometres slaughtering strategy resulted in the fewest FMD-infected farms. Cost-effectiveness (CE) analysis was applied to evaluate the economic effectiveness of FMD-control strategies using the results of epidemiologic simulation model (Chapter 5). This showed that ring vaccination in a band three to five kilometres from FMD-infected farms was the most cost efficient among alternative FMD-control strategies. The other FMD-control strategies, in decreasing order of economic efficiency, were five kilometre slaughtering, 30 day stop movement, and 60 day stop movement. The 0.5 kilometre and one kilometre slaughtering strategy were excluded in the analysis because these strategies did not control FMD spread during the simulations. Chapter 6 describes the MCDA process for choosing the optimal FMD-control strategy based on the results from Chapters 3, 4 and 5. The measurements of the criteria were merged with the weight of criteria to calculate the overall score of each FMD-control strategy. In the Asia-Oceania region, CVOs preferred ring vaccination over alternative FMD-control strategies, with 30 day stop movement being the least preferred of the FMD-control strategies. The findings presented in each of these chapters have broadened our knowledge of the decision making process regarding FMD-control strategies. The processes were reliable, transparent, and reproducible and can be applied not only to FMD but also to other transboundary livestock diseases such as classical swine fever or highly pathogenic avian influenza

Foot-and-Mouth Disease Impact on Smallholders - What Do We Know, What Don't We Know and How Can We Find Out More?

Foot-and-mouth disease (FMD) endemic regions contain three-quarters of the world's FMD susceptible livestock and most of the world's poor livestock keepers. Yet FMD impact on smallholders in these regions is poorly understood. Diseases of low mortality can exert a large impact if incidence is high. Modelling and field studies commonly find high FMD incidence in endemic countries. Sero-surveys typically find a third of young cattle are sero-positive, however, the proportion of sero-positive animals that developed disease, and resulting impact, are unknown. The few smallholder FMD impact studies that have been performed assessed different aspects of impact, using different approaches. They find that FMD impact can be high (>10% of annual household income). However, impact is highly variable, being a function of FMD incidence and dependency on activities affected by FMD. FMD restricts investment in productive but less FMD-resilient farming methods, however, other barriers to efficient production may exist, reducing the benefits of FMD control. Applying control measures is costly and can have wide-reaching negative impacts; veterinary-cordon-fences may damage wildlife populations, and livestock movement restrictions and trade bans damage farmer profits and the wider economy. When control measures are ineffective, farmers, society and wildlife may experience the burden of control without reducing disease burden. Foot-and-mouth disease control has benefitted smallholders in South America and elsewhere. Success takes decades of regional cooperation with effective veterinary services and widespread farmer participation. However, both the likelihood of success and the full cost of control measures must be considered. Controlling FMD in smallholder systems is challenging, particularly when movement restrictions are hard to enforce. In parts of Africa this is compounded by endemically infected wildlife and limited vaccine performance. This paper reviews FMD impact on smallholders in endemic countries. Significant evidence gaps exist and guidance on the design of FMD impact studies is provided

Foot-and-mouth disease in Tanzania from 2001 to 2006.

Foot-and-mouth disease (FMD) is endemic in Tanzania, with outbreaks occurring almost each year in different parts of the country. There is now a strong political desire to control animal diseases as part of national poverty alleviation strategies. However, FMD control requires improving the current knowledge on the disease dynamics and factors related to FMD occurrence so control measures can be implemented more efficiently. The objectives of this study were to describe the FMD dynamics in Tanzania from 2001 to 2006 and investigate the spatiotemporal patterns of transmission. Extraction maps, the space-time K-function and space-time permutation models based on scan statistics were calculated for each year to evaluate the spatial distribution, the spatiotemporal interaction and the spatiotemporal clustering of FMD-affected villages. From 2001 to 2006, 878 FMD outbreaks were reported in 605 different villages of 5815 populated places included in the database. The spatial distribution of FMD outbreaks was concentrated along the Tanzania-Kenya, Tanzania-Zambia borders, and the Kagera basin bordering Uganda, Rwanda and Tanzania. The spatiotemporal interaction among FMD-affected villages was statistically significant (P≤0.01) and 12 local spatiotemporal clusters were detected; however, the extent and intensity varied across the study period. Dividing the country in zones according to their epidemiological status will allow improving the control of FMD and delimiting potential FMD-free areas

Retrospective evaluation of foot-and-mouth disease vaccineeffectiveness in Turkey

AbstractFoot-and-mouth disease (FMD) is present in much of Turkey and its control is largely based on vaccination. The arrival of the FMD Asia-1 serotype in Turkey in 2011 caused particular concern, spreading rapidly westwards across the country towards the FMD free European Union. With no prior natural immunity, control of spread would rely heavily on vaccination.Unlike human vaccines, field protection is rarely evaluated directly for FMD vaccines. Between September 2011 and July 2012 we performed four retrospective outbreak investigations to assess the vaccine effectiveness (VE) of FMD Asia-1 vaccines in Turkey. Vaccine effectiveness is defined as the reduction in risk in vaccinated compared to unvaccinated individuals with similar virus exposure in the field.The four investigations included 12 villages and 1230 cattle >4 months of age. One investigation assessed the FMD Asia-1 Shamir vaccine, the other three evaluated the recently introduced FMD Asia-1 TUR 11 vaccine made using a field isolate of the FMD Asia-1 Sindh-08 lineage that had recently entered Turkey.After adjustment for confounding, the TUR 11 vaccine provided moderate protection against both clinical disease VE=69% [95% CI: 50%–81%] and infection VE=63% [95% CI: 29%–81%]. However, protection was variable with some herds with high vaccine coverage still experiencing high disease incidence. Some of this variability will be the result of the variation in virus challenge and immunity that occurs under field conditions.In the outbreak investigated there was no evidence that the Asia-1 Shamir vaccine provided adequate protection against clinical FMD with an incidence of 89% in single vaccinated cattle and 69% in those vaccinated two to five times.Based on these effectiveness estimates, vaccination alone is unlikely to produce the high levels of herd immunity needed to control FMD without additional control measures

A New Decision Support Framework for Managing Foot-and-mouth Disease Epidemics

Animal disease epidemics such as the foot-and-mouth disease (FMD) pose recurrent threat to countries with intensive livestock production. Efficient FMD control is crucial in limiting the damage of FMD epidemics and securing food production. Decision making in FMD control involves a hierarchy of decisions made at strategic, tactical, and operational levels. These decisions are interdependent and have to be made under uncertainty about future development of the epidemic. Addressing this decision problem, this paper presents a new decision-support framework based on multi-level hierarchic Markov processes (MLHMP). The MLHMP model simultaneously optimizes decisions at strategic, tactical, and operational levels, using Bayesian forecasting methods to model uncertainty and learning about the epidemic. As illustrated by the example, the framework is especially useful in contingency planning for future FMD epidemic

Impact of foot-and-mouth disease on mastitis and culling on a large-scale dairy farm in Kenya

Foot and mouth disease (FMD) is a highly transmissible viral infection of cloven hooved animals associated with severe economic losses when introduced into FMD-free countries. Information on the impact of the disease in FMDV-endemic countries is poorly characterised yet essential for the prioritisation of scarce resources for disease control programmes. A FMD (virus serotype SAT2) outbreak on a large-scale dairy farm in Nakuru County, Kenya provided an opportunity to evaluate the impact of FMD on clinical mastitis and culling rate. A cohort approach followed animals over a 12-month period after the commencement of the outbreak. For culling, all animals were included; for mastitis, those over 18 months of age. FMD was recorded in 400/644 cattle over a 29-day period. During the follow-up period 76 animals were culled or died whilst in the over 18 month old cohort 63 developed clinical mastitis. Hazard ratios (HR) were generated using Cox regression accounting for non-proportional hazards by inclusion of time-varying effects. Univariable analysis showed FMD cases were culled sooner but there was no effect on clinical mastitis. After adjusting for possible confounders and inclusion of time-varying effects there was weak evidence to support an effect of FMD on culling (HR = 1.7, 95% confidence intervals [CI] 0.88-3.1, P = 0.12). For mastitis, there was stronger evidence of an increased rate in the first month after the onset of the outbreak (HR = 2.9, 95%CI 0.97-8.9, P = 0.057)

Fitness vs Fatness and Cardiovascular Health in Adolescents

Background: Adolescent obesity has been on the rise with studies showing obesity tracks into adulthood. Obesity is an independent risk factor for cardiovascular disease (CVD); CVD is the leading cause of adult death in the U.S. Previous research shows a strong positive relationship between physical activity (PA) and cardiovascular (CV) health even in an obese adult population. Thus, the relationship between adolescent physical fitness and lifetime risk for CVD and all-cause mortality should be investigated. Purpose: The purpose of this study is to determine associations between PA and adiposity with cardiovascular health in obese and non-obese weight adolescents, with the hypothesis that physical activity will be positively associated with cardiovascular health independent of adiposity. Methodology: A convenience sample of 30 adolescents (ages 12-18) from the community completed assessments of height, weight, a dual x-ray absorptiometry (DXA) scan, resting blood pressure, and a flow-mediated dilation ultrasound (FMD) as a measure of endothelial function and cardiac health. Participants wore an accelerometer for one week to track PA. Participants were assigned to non-obese and obese categories from DXA, the gold standard, measure of body fat. Activity level was also grouped by minutes of moderate-to-vigorous PA (MVPA) per day based on a median split of 15 minutes per day. FMD value was calculated as (maximum diameter – baseline diameter)/ baseline diameter x 100. Comparisons in FMD (dependent variable) between body fat and MVPA groups (independent variables) were made using t-tests and associations between body fat and MVPA were tested using linear regression adjusted for sex. Results: FMD data was only available for 10 participants: average age=14.6 (SD 1.8), 50% female, BMI=20.9 (2.6), FMD%=11.9 (8.5). There were no differences (p=.943) in FMD between the obese (mean FMD% = 12.2, SE 4.1) and non-obese (11.8, SE 3.4) groups. Similarly, when percent body fat was examined as a continuous variable, percent body fat was not associated with FMD (coefficient =0.16 (SE 0.31), p=.612). Those with greater than 15 minutes of MVPA per day had a higher FMD (15.0, SE 3.3) compared to those with less than 15 minutes of MVPA per day (8.9, SE 3.3, p=.024). When MVPA was examined as a continuous variable, MVPA was positively associated with MVPA (coefficient =.32 (SE 15), p=.067, however, not statistically significant. Discussion: Despite the small sample size, there does appear to be a positive association between FMD and MVPA in adolescents but not an association between FMD and percent body fat. These results suggest an important correlation between PA and cardiac health and may also support the notion that PA may be more important in overall CV health when compared to body composition. Clinicians should emphasize promoting physical activity among adolescents, and not just focus solely on body fat

Quantitative Assessment of the Risk of Release of Foot-and-Mouth Disease Virus via Export of Bull Semen from Israel

Various foot-and-mouth disease (FMD) virus strains circulate in the Middle East, causing frequent episodes of FMD outbreaks among Israeli livestock. Since the virus is highly resistant in semen, artificial insemination with contaminated bull semen may lead to the infection of the receiver cow. As a non-FMD-free country with vaccination, Israel is currently engaged in trading bull semen only with countries of the same status. The purpose of this study was to assess the risk of release of FMD virus through export of bull semen in order to estimate the risk for FMD-free countries considering purchasing Israeli bull semen. A stochastic risk assessment model was used to estimate this risk, defined as the annual likelihood of exporting at least one ejaculate of bull semen contaminated with viable FMD virus. A total of 45 scenarios were assessed to account for uncertainty and variability around specific parameter estimates and to evaluate the effect of various mitigation measures, such as performing a preexport test on semen ejaculates. Under the most plausible scenario, the annual likelihood of exporting bull semen contaminated with FMD virus had a median of 1.3 * 10(-7) for an export of 100 ejaculates per year. This corresponds to one infected ejaculate exported every 7 million years. Under the worst-case scenario, the median of the risk rose to 7.9 * 10(-5), which is equivalent to the export of one infected ejaculate every 12,000 years. Sensitivity analysis indicated that the most influential parameter is the probability of viral excretion in infected bulls