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Stratified Analysis Pages Show next xx. The seroprevalence of FMD was higher in cattle The age stratified seroprevalence in the districts showed that The farmers mostly employ traditional means to control FMD. In conclusion, the findings of the study indicated that FMD is a prevalent disease in the Amhara region with more importance in the intensive production systems and the lowlands of the region.
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High correlation in seroprevalence between small and large ruminants indicated a possible cross transmission between these species. Therefore, small ruminants should not be overlooked in FMD control. Farmers in the region have a good level of knowledge about the disease; however, currently they heavily rely on traditional practices primarily focused on treating wounds of infected animals. This calls for extension work on available effective preventive measures of the disease, such as vaccination and movement restriction.
Ethiopia possesses the largest domestic ruminants population in Africa, with an estimated population of about 60 million cattle, 30 million sheep, and 30 million goats 1. Despite this large resource base, the benefit derived from the livestock sector in Ethiopia is relatively low. Livestock diseases are among the many constraints which hinder the proper harnessing of the resource for food security and national development.
Foot and mouth disease FMD is one of the most important and highest priority livestock diseases globally 2. Foot and mouth disease is a highly contagious disease in cloven-hoofed animals caused by the FMD virus FMDV , a member of the Aphthovirus genus of genus the Picornaviridae genus. FMD is also among the most important livestock diseases that affects production and trade of animal and animal products in Ethiopia 5.
Outbreak incidence studies have also indicated that FMD occurs throughout the country with significant variation in geography and production systems A sound knowledge of the epidemiology of the disease is required to apply effective control measures locally or nationally.
Despite some seroprevalence studies mainly focusing on cattle in some parts of Ethiopia, a comprehensive epidemiological study of FMD in Amhara National Regional State in short Amhara region is not available. This study was aimed at investigating the seroepidemiology of FMD and assessing farmers' knowledge and practices about the disease in the Amhara region. The specific objectives were to determine the seroprevalence and to estimate the annual outbreak incidence of FMD in domestic ruminants, to identify factors associated with its occurrence, and to assess the knowledge and practice of farmers about the disease.
The region is administratively divided into eleven zones and districts Figure 1. The region has a ruminant population of The livestock production systems in the region is dominantly a subsistence crop-livestock mixed system. The study was a cross-sectional study, which targeted the domestic ruminant population of the Amhara region. Individual cattle, sheep and goats were sampled for the study. A multistage cluster sampling was employed to select sampling units. The ruminant population of the study area can be structured as individual animals clustered into household herds, household herds into kebeles, kebeles into districts and then finally, district populations together constitute the regions ruminant population.
First, the 12 districts that represent the three agro-ecological and two geographic zones of the region western Amhara and eastern Amhara were selected purposively. Among the districts within the same agro-ecology and geographical zone, the study districts were selected conveniently by their accessibility.
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Three kebeles that were considered typical of the district's agro-ecology in each selected district, were again selected purposively, based on the convenience of accessibility. Finally, as the animals from households within kebeles mix in common grazing areas and watering points, study animals from the selected kebeles were selected haphazardly to mimic random sampling.
Strict random sampling was not possible due to difficulty in establishing a sampling frame in that traditional extensive production system. The sample size was determined by the formula for the estimation of prevalence using random sampling as provided in Thrusfield The sample sizes determined for the simple random sampling method above were adjusted for the cluster sampling method employed in the study, by multiplying it with the design effect of five giving sample sizes of 1, cattle, and goats and sheep. A large design effect of five was used because of the high clustering effect of FMD, due its high transmissibility 13 , The sample size was equally distributed across the 36 selected kebeles resulting in 30 cattle, 10 sheep, and 10 goats per kebele.
For the questionnaire survey of farmers that was conducted parallel to the serosurvey, five households were haphazardly selected from each of the 36 kebeles selected for the serosurvey, resulting in a total of farmers.
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Blood samples were collected from the jugular vein of individual animals, using sterile plain vacutainer tubes. About six milliliters of blood was withdrawn from each animal. The samples were coded, stored overnight at room temperature for serum separation and transferred into sterile cryovials after separation.
For each sampled animal biodata such as breed, age, sex, and husbandry data, such as production system, history of vaccination, history of clinical FMD infection and life history of the animal were collected to assess their association with FMD seropositivity.
The breed of animal was categorized as exotic, cross and local.
Animals under 1 year of age were also noted separately for the sake of examining recent infection. The production system under which the sampled animals were kept was categorized as extensive livestock production systems when animals are kept free-range for part or all of their production cycle , intensive livestock production systems when animals are housed and hand fed and semi intensive livestock production systems when animals share the characteristics of both intensive and extensive production systems. Later in the analysis, breed was collapsed into two categories as the number of animals found in the exotic category were very few and were lumped to the cross breed category, and the production system was similarly collapsed into two categories, as the number of animals found in the intensive category were very few and were lumped to semi intensive category.
The diagnostic test has a sensitivity of This test detects only antibodies produced against non-structural proteins and can hence differentiate vaccinated animals from unvaccinated animals. The tests were done according to the manufacturers recommendation and the procedure provided by the OIE manual of diagnostic tests and vaccines for terrestrial animals A semi structured questionnaire was prepared Annex 1 mainly to assess the farmers' knowledge about FMD and their control practices, which was administered through interview.
Their perception of impact was assessed on how serious the disease is in causing mortality.
For the control practices, they were asked about all types of measures they take to tackle FMD before it occurs and during an outbreak. The questionnaire was first pilot tested in 10 farmers that were not included in the study and was revised for clarity to ensure the intended data would be collected. Oral informed consent was obtained from each farmer participating in the interview after reading a written consent form.
The use of oral consent was approved by the IRB, considering the fact that most study participants could not read and write to provide their consent in writing. The consent form mainly explains the purpose of the study, the risks and benefits of participation in the study, conditions of confidentiality, and the right to refusal or withdrawal from the study at any time.
The interviewers confirmed the participants' oral consent by signing on the respective consent form for each interviewee as per the Board's guidelines. Data generated from laboratory investigations were recorded and coded using a Microsoft Excel spreadsheet and analyzed using STATA version Descriptive analyses were used to assess the seroprevalence, and knowledge and control practices of farmers. Standard errors for the seroprevalence confidence intervals were calculated using the cluster sandwich variance estimator which accounts for the cluster correlated nature of the data Age stratified seroprevalence were used to estimate the annual occurrence of FMD outbreak.
Seroprevalence difference between cattle and small ruminants was compared using the chi-squared test. Mixed effect logistic regressions were employed to identify factors associated with the FMD seropositivity.
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In the mixed logistic regression, seropositivity status was the dependent variable and the putative FMD risk factors were the predictor variables. Districts and kebele were included as random effect predictor variables, to account for clustering that could arise from cluster sampling used in the data collection, and the putative risk factors were treated as fixed effect predictor variables.
Separate analyses were performed for cattle and small ruminants. The predictor variables that were included in the models were FMD putative risk factors, such as species only for the small ruminants model , age, sex, breed, FMD vaccination history, life history, agroecology and production system. First collinearity among the predictor variables was checked by correlation matrix and none of them were found collinear. The models were run again in the same manner until only statistically significant predictors and confounders were left, resulting in the final models. Intraclass correlations ICC's were provided for random effect variables district and kebele using the estat icc post-estimation command of stata.
These ICC's were calculated as the proportion of variances at a given cluster level random effect variable to the total variance sum of cluster variances and residual variance conditional on the effect of the fixed effect predictors The association between seropositivity and the clinical FMD infection history of animals in the preceding 3 years, was tested to evaluate the strength of recall of farmers with regard to FMD infection events in their herd.
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