Search

Bovine leukemia virus (BLV) infection is endemic in Japanese dairy farms. To promote the participation of farmers in BLV infection control in Japan, it is important to provide estimates of the economic losses caused by this infection. We hypothesized that decreased immune function due to BLV infection would increase visceral abnormalities, in turn reducing carcass weight. We employed mediation analysis to estimate the annual economic loss due to carcass weight reduction caused by BLV infection. Culled Holstein cows from 12 commercial dairy farms in the Nemuro and Kushiro regions of Hokkaido, Japan, were traced. Information on age and the last delivery day were collected. A non-infected culled cow was defined as a cow from which BLV provirus was not detected. A high-proviral-load (H-PVL) cow was defined as a cow whose PVL titer was above 2465 copies/50 ng DNA or 56,765 copies/10 5 cells. A BLV-infected cow with PVL titer lower than the thresholds was categorized as low-proviral load (L-PVL). Post-mortem examination results for culled cows were collected from a meat inspection center. The hypothesis was tested by three models, using data from 222 culled dairy cows. Model 1, a generalized linear mixed-effects model, selected carcass weight as an outcome variable, BLV status and the potential confounders (lactation stage and age) as explanatory variables, and herd as a random effect. Model 2 additionally included the number of abnormal findings in the post-mortem examination (AFPE) as an explanatory variable. Model 3 applied a Bayesian generalized linear mixed model, which employed a mediator separately modeled for AFPE, to estimate the amount of direct, indirect, and total carcass weight loss with adjustment for known confounding factors. Compared to the mean carcass weight for the non-infected culled cows, the carcass weight for H-PVL culled cows was significantly decreased by 30.4 kg on average. For each increase of one in the number of AFPE, the mean carcass weight was decreased by 8.6 kg. Only the indirect effect of BLV H-PVL status on carcass weight loss through AFPE was significant, accounting for 21.6 % of the total effect on carcass weight reduction. In 2017, 73,650 culled dairy cows were slaughtered in Hokkaido, and the economic loss due to carcass weight loss caused by BLV infection that year was estimated to be US $1,391,649. In summary, unlike L-PVL cows, H-PVL status was associated with carcass weight reduction, which was partially mediated by an increase in the number of visceral abnormalities., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Brucellosis is endemic in Tanzania. A cross-sectional study was conducted at 17 cattle farms in agro-pastoral areas in Tanzania to identify risk factors associated with the within-farm prevalence of bovine brucellosis and to quantitatively assess the infection dynamics through disease modelling. Cattle blood sampling and interviews with farmers using a structured questionnaire were conducted. A total of 673 serum samples were screened using the Rose-Bengal plate test (RBPT), and sero-positivity of RBPT-positive samples was confirmed using a competitive enzyme-linked immunosorbent assay. Zero-inflated binomial regression was performed for univariable and multivariable risk factor analyses of within-farm prevalence. Several susceptible-infectious (SI) models were compared based on deviance information criteria, and age-dependent force of infection (FOI) was measured using age-specific prevalence data for the 10 infection-positive farms. Using the diagnoses of cows on the 17 farms, the basic reproduction number, R 0 , was also calculated. The farm-level prevalence and animal-level adjusted prevalence were 58.8 % (10/17, 95 % confidence interval: 33.5-80.6 %) and 7.0 % (28/673, 95 % credible interval: 5.7-8.4 %), respectively. The risk factor for high within-farm prevalence was introduction of cattle from other herds. A mathematical model with constant FOI showed the annual probability of infection as 1.4 % (95 % credible interval: 1.0 %-2.0 %). The R 0 was 1.07. The constant FOI could have been due to the predominant mode of infection being transmission of Brucella from contaminated aborted materials during grazing. Direct purchase of infected cattle could facilitate efficient transmission between susceptible animals through abortion., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)

The objective of this case-control study was to determine the herd- and cow-level risk factors associated with an outbreak of Mycoplasma bovine mastitis in the winter of 2014-2015 in Nemuro, Hokkaido, Japan. Two questionnaire surveys were sent to all 40 Mycoplasma-infected farms in the area and 73 non-infected farms for the farm-level analysis. Infected cows were matched to twice the number of non-infected cows in the same herds by parity and days after calving. Movement records, dairy herd test records, and clinical records of infected cows and matched non-infected cows were collected for the cow-level analysis. Risk factors for Mycoplasma infection were explored by multivariable analyses at both levels. In the herd-level analysis, tie stall housing for milking cows (odds ratio [OR] = 0.20, 95 % confidence interval [CI]: 0.07-0.60, p =  0.004), consciously wiping of teat openings before milking (OR = 0.15, 95 % CI: 0.02-0.76, p =  0.030), and use of paper towels to wipe teats (OR = 0.31, 95 % CI: 0.09-0.92, p =  0.045) were identified as preventive factors, whereas introduction of cattle (OR = 3.43, 95 % CI: 1.14-10.86, p =  0.030) was identified as a risk factor. In the cow-level analysis, a history of presence in livestock markets (OR = 10.80, 95 % CI: 1.12-104.38, p =  0.040), higher milk yield 2 months prior to Mycoplasma infection (OR = 1.09, 95 % CI: 1.02-1.18, p =  0.014), and previous diagnosis of acute mastitis without isolation of the causal pathogen (OR = 3.14, 95 % CI: 0.86-11.41, p =  0.082) were identified as risk factors. These results highlight the importance of proper milking hygiene control and quarantine of introduced cattle to prevent Mycoplasma infection., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The aim of this study was to use exponential random graph models (ERGMs) to explain networks of movement of backyard chickens in provinces which had been hotspots for avian influenza outbreaks in Thailand during 2004-2005. We used structured questionnaires to collect data for the period January to December 2009 from participants who were involved in the backyard chicken farming network in three avian influenza hotspots (Ratchaburi, Suphan Buri, and Nakhon Pathom provinces) in Thailand. From 557 questionnaires, we identified nodes, points of entry and exit from nodes, and activities relating to backyard chicken farming and movement of chickens, and generated ERGMs based on non-festive periods (Model 1) and the Chinese New Year period (Model 2). In Model 1, k-star (the central node is connected to k other nodes) connections were predominant (P <  0.001). In Model 2, the frequency of movement increased by 10.62 times, k-star connections were still predominant (P <  0.001), and the model was scale-free. Hubs were formed from owners/observers in the arenas/training fields, farmers who raised chickens for consumption only, and traders. In conclusion, our models indicated that, if avian influenza was introduced during non-festive periods, the authorities would need to regularly restrict the movement of chickens. However, during high-frequency periods of movement of backyard chickens, authorities would also need to focus on the network hubs. Our research can be used by the relevant authorities to improve control measures and reduce the risk or lessen the magnitude of disease spread during an avian influenza epidemic., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Rabies is a fatal zoonosis, and in Vietnam, it remains problematic despite the availability of dog rabies vaccination. The purpose of this study was to clarify the socio-economic factors associated with voluntary rabies control measures among the general population using a "Knowledge, Attitudes, and Practice" framework to provide health and veterinary authorities in Vietnam with baseline information for better planning of policy supports. A questionnaire survey with interviews was conducted in 495 households (64 mountainous and 431 plain-area households) in Thai Nguyen Province in September 2016. After the survey, uni- and multivariable analyses were performed to detect factors associated with the practices of dog rabies vaccination and tethering dogs. Structural equation modelling (SEM) was performed to understand the structures associated with practice decisions. Contingent valuation was performed to calculate willingness-to-pay for vaccination. Vaccination coverage was 77.4% (724/935 dogs), and was significantly lower in mountainous areas dominated by ethnic minorities (63.8%, 67/105) than in plains (79.2%, 657/830, x 2  = 11.7, df = 1, p <  0.001). Mean estimation of willingness-to-pay for a vaccination was 2.30 USD (51,959 Vietnamese dong), which was more than double the current price. The willingness-to-pay in mountainous areas was 2.16 USD, while that in plain areas was 2.32 USD. The proportion that never confined dogs was significantly higher in mountainous areas (65.6%, 42/64 households) than in plain areas (26.5%, 114/430, x 2  = 37.7, df = 1, p < 0.001). Despite the low proportion of households tethering dogs, the majority answered that they would confine (479/489, 98.0%) or leash while walking (482/491, 98.2%) if such orders were enforced. SEM result showed that higher social status promoted better knowledge (β, the coefficient, = 0.75, se = 0.05, p <  0.001), better knowledge positive attitudes (β = 1.0, se = 0.0, p value not calculated), and positive attitudes better practices of confinement (β = 0.4, se = 0.05, p <  0.001), vaccination (β = 0.52, se = 0.06, p <  0.001), and sterilization (β = 0.11, se = 0.04, p <  0.001). Our study suggested that rabies education targeted to mountainous areas using local languages for ethnic minority groups as well as the national language, and higher subsidies on dog rabies vaccination for poor households may improve vaccination coverage. Dog management may be improved by promotion campaigns., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The objective of this study was to investigate factors that caused rapid spread during the early phase of the porcine epidemic diarrhea (PED) epidemic in Japan in 2013 and 2014. Anonymized datasets from all pig farms were provided by Kagoshima (709 farms) and Miyazaki Prefectures (506 farms). Semi-parametric survival analysis was conducted using the first 180 days from the first case on December 3, 2013 in Kagoshima Prefecture. To compare the hazard between different farm management types, univariable survival analysis was conducted. As farm sizes varied among different farm types, bivariable survival analysis was conducted for farm size categories and farm density per km 2 for each management type. A case-control study using a postal questionnaire survey was conducted in September 2014, and risk factor analysis was performed using generalized linear models with binomial errors. The hazard was significantly higher in farrow-to-finish farms than fattening farms [hazard ratio (HR) = 1.6, p < 0.01], but was not significantly different between reproduction and fattening farms (HR = 1.3, p = 0.16). In separate bivariable survival analyses for each farm type, large- and middle-scale farms had higher hazard than small-scale farms in fattening (HR = 5.8 and 2.6, respectively, both p < 0.01) and reproduction farms (HR = 4.0 and 3.6, respectively, both p < 0.01). In farrow-to-finish farms, large-scale farms had higher hazard than small-scale farms (HR = 2.8, p < 0.01), and higher farm density per km 2 was also a risk factor (HR = 7.6, p < 0.01). In the case-control study, questionnaires were returned from 78 PED virus-infected and 91 non-infected farms. The overall response rate was 34%. Risk factors of the final model were occurrence of porcine reproductive and respiratory syndrome in the past 5 years [odds ratio (OR) = 1.97, 95% confidence interval (CI): 0.97-4.00, p = 0.054], use of a common compost station (OR = 2.51, 95%CI: 1.08-5.83, p = 0.03), and use of a pig excrement disposal service (OR = 2.64, 95%CI: 1.05-6.63, p = 0.04). High hazard in farrow-to-finish farms suggested transmission from slaughterhouses to susceptible suckling piglets. Hazard associated with large-scale farms and high density might be due to frequent vehicle entrance and transmission by roads. Improvement of farm hygiene management and avoidance of risky practices associated with contact with pig excrement were keys in preventing invasion of PED virus to a farm., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A cross-sectional study was designed to generate information on the herd level prevalence and the risk factors for Leptospira serovar Hardjo (L. Hardjo) in Yamagata, the southern Tohoku, Japan. Bulk tank milk samples from 109 dairy herds were used to test the herd level sero-prevalence of L. Hardjo using a commercial ELISA kit, which detects both L. interrogans serovar Hardjo and L. borgpetersenii serovar Hardjo. A questionnaire survey was conducted at the sampled farms, and univariable and multivariable analyses were performed. Spatial clustering of L. Hardjo at the herd level was examined using spatial scan statistics. Seventy-one herds were found to be positive for L. Hardjo, and the apparent herd prevalence was 65.1% (95% CI: 56.2-74.1%). The risk factors for sero-positivity were larger herd size (p=0.004) and cows with a history of staying in Hokkaido (p <0.001). The spatial scan statistic detected a most likely cluster (relative risk=1.87, log likelihood ratio=9.93, radius=13.70km, p<0.01) in the southern part of the study area where there are large herd sizes and farm density is high. This study revealed that L. Hardjo is prevalent throughout Yamagata, and large scale herd owners introducing cows from Hokkaido in particular should be aware of the risk of infection., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Echinococcus multilocularis is a parasite that causes highly pathogenic zoonoses and is maintained in foxes and rodents on Hokkaido Island, Japan. Detection of E. multilocularis infections in swine is epidemiologically important. In Hokkaido, administrative information is provided to swine producers based on the results of meat inspections. However, as the current criteria for providing administrative information often results in delays in providing information to producers, novel criteria are needed. Time series models were developed to monitor autocorrelations between data and lags using data collected from 84 producers at the Higashi-Mokoto Meat Inspection Center between April 2003 and November 2015. The two criteria were quantitatively compared using the sign test for the ability to rapidly detect farm-level outbreaks. Overall, the time series models based on an autoexponentially regressed zero-inflated negative binomial distribution with 60th percentile cumulative distribution function of the model detected outbreaks earlier more frequently than the current criteria (90.5%, 276/305, p<0.001). Our results show that a two-part model with autoexponential regression can adequately deal with data involving an excessive number of zeros and that the novel criteria overcome disadvantages of the current criteria to provide an earlier indication of increases in the rate of echinococcosis., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The aim of the study was to investigate the farmers' socio-economic factors and their association with Brucella prevalence in the dry zone of Sri Lanka. A cross-sectional survey was planned and a total of 1,153 blood samples were collected from milking and dry animals of 155 farms from three selected veterinary ranges of Kalmunai, Navithanveli, and Mahaoya in the Ampara district, which is a multi-ethnic area. The 　Rose Bengal Test (RBT) and competitive enzyme-linked immunosorbent assay (c-ELISA) were used for the Brucella screening and confirmation, respectively. Socio-economic attributes such as family income, poverty, education, main job, ethnicity, parent farmer, farming experience, and training in animal husbandry were determined as potential farmer-level risk factors. Meanwhile, herd size, grazing practice, breeding method, animal brought-in to the farm, and abortions were considered as herd factors. The results revealed that the overall animal level sero-prevalence of brucellosis was 2.7% (35/1153; 95% confidence interval [CI]: 1.7, 3.7%) and the herd prevalence was 9.6% (15/155; 95% CI: 5.7, 15.7%) in the area of study. Brucellosis prevalence varies significantly (p<0.001) among the selected veterinary ranges with the highest herd prevalence in Kalmunai (20.0%) followed by Navithanveli (11.9%) and Mahaoya (2.7%). Disease prevalence showed variability (p<0.001) among ethnicities with the highest in Muslims (27.3%) followed by Tamils (8.1%) and Sinhalese (2.7%). Poverty was highly associated (OR=3.75; 95% CI: 1.43-10.00) with the disease. Free movement grazing practices (p<0.01) with OR=7.2 and animal brought-in from outside (p<0.06) with OR=3.06 were positively related to brucellosis. It was revealed that farmers' socio-economics, such as ethnicity and poverty, and animal movement patterns, such as grazing practices are significantly associated with epidemiology of brucellosis in the dry zone of Sri Lanka. Therefore, the "farmer factor" should be carefully considered in veterinary epidemiological studies and animal disease control plans in the future.　., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Porcine epidemic diarrhea (PED) was detected for the first time in seven years in Japan in October 2013 in Okinawa Prefecture. By December 2013, PED had spread into Miyazaki and Kagoshima Prefectures in the southern part of Kyushu, one of the regions with the highest farm density in the country. The objective of the study here was to assess the spatial dynamics of PED spread during the 8 months of the epidemic in the southern part of Kyushu between December 2013, the month observed first case in the studied region, and July 2014. Information on location and capacity of all farms in the prefectures (n=1269) was obtained from a government database containing demographic information for livestock producers. Additionally, data on PED detection (positive or negative) was obtained from the regional Livestock Hygiene Service Center. The Cuzick-Edwards (CE) test, the Knox test, the directional test, and the permutation model of the scan statistic were used to assess the spatio-temporal distribution of the epidemic. PED cumulative farm level incidence was 19.5% (248/1269) through the study period. The highest density of positive farms was observed in the most farm-populated areas of the prefecture. The CE test revealed an extensive degree of spatial clustering, with clustering of positive sites being significant (P<0.01) up to the 35th level of neighborhood (approximately 5km in the studied data). The observed-to-expected ratio of cases was maximized at short spatio-temporal distances, with values of the observed-to-expected ratio of cases maximized when the thresholds were set at 2km and 10days, respectively. A significant (P<0.01) direction of spread was detected towards the northeastern direction. The permutation model detected five significant (P<0.01) clusters occurring at different stages of the epidemic wave. The strong spatio-temporal clustering of PED-infected farms during the first 6 months of the epidemic in the southern part of Kyushu is consistent with results obtained elsewhere and demonstrates the rapid spread of the virus in naïve populations., (Copyright © 2017 Elsevier B.V. All rights reserved.)