Prevalence of bovine abortion, calf mortality, and bovine viral diarrhea virus (BVDV) persistently infected calves among pastoral, peri-urban, and mixed-crop livestock farms in central and Northwest Ethiopia.

BACKGROUND: Bovine Viral Diarrhea virus (BVDV) is one of important diseases of cattle worldwide causing economic losses to the cattle industry primarily due to increased premature culling and decreased reproductive performance. The virus can cross the placenta during early pregnancy and result in the birth of persistently infected (PI) calves that are efficient transmitters of BVDV and serving as the primary reservoirs for BVDV. Relatively few studies have focused on understanding BVDV seroprevalence, virus detection, genotyping and its distribution in Africa. Most BVDV research in Ethiopia has involved serologic surveys in adult cattle, rather than the identification of PI calves, despite their role in viral shedding and recurring infections. A cross-sectional study was undertaken in three different livestock production systems of Ethiopia with the objective to estimate the prevalence of bovine abortion, calf mortality, and BVDV persistently infected calves. RESULTS: Ear notch samples (882) collected from calves in 349 households were tested for BVDV antigen using antigen capture enzyme-linked immunosorbent assay (ACE). All samples tested were negative for BVDV antigen. The overall animal level crude abortion and calf mortality prevalence were 4.0% (95% CI: 2.9-5.2) and 9.2% (95% CI: 7.7-11.0) respectively. The lower BVDV PI prevalence may be due to a lower effective contact rate between cattle reared in small-scale extensive production systems in Ethiopia. CONCLUSIONS: This is the first report of BVDV Ag test in Ethiopia and no PI was detected in calves in the study areas. Since BVDV is a disease of great economic importance, this study finding must be interpreted with care since absence of evidence is not evidence of absence and even a single BVDV infected animal can serve as source of infection and contribute to the persistent spread of the virus. Greater attention needs to be given to screening for PI animals through testing large number of animals and culling positive animals. Hence, future research should focus on regions and production systems with high BVDV seroprevalence followed by antigen ELISA or BVDV real-time PCR to detect persistently infected and acutely viremic animals.

Mortality rate of Boer, Central Highland goat and their crosses in Ethiopia: Nonparametric survival analysis and piecewise exponential model.

BACKGROUND: Analysis of survival data by linear or logistic model ignores censoring and skewness inherent in the mortality data. The objective of this study is to estimate the morbidity and mortality rates of kids and adult goats, identify important risk factors for mortality using survival analysis and summarise important causes of goat death. METHODS: Nonparametric survival analysis and a piecewise exponential model (PEM) were used. RESULTS: The mortality rates of kids and adult goats were 0.629 and 0.302 per animal year, respectively. The 25th, 50th and 75th percentiles of survival time of kids were 5, 162 and 1300 days, respectively, and those of adults and goats were 280, 828 and 1,735 days, respectively. Gastrointestinal-related diseases, pneumonia, weak kid, agalactia, mismothering and heartwater (cowdriosis) were the most important causes of mortality. Constant piecewise exponential regression analysis of risk factors indicated that breed, kid birth weight, doe post-partum weight (PPWT), birth type, birth year and precipitation variables were associated with (p-value < 0.05) kid mortality rate. Pure Boer kids compared with Central Highland goat cross with Boer goats were 2.505 times at a higher probability of mortality (p-value < 0.001). A 1-kg increase in kid birth weight and dam PPWT reduces mortality probability by 32.5% (p-value = 0.000) and 6.4% (p-value < 0.001), respectively. Twin birth kids had a 1.512 times higher rate of mortality (p-value = 0.001) than single-born kids. A 1-ml increment of 15 days of average precipitation significantly reduced kid mortality by 7.8% (p-value < 0.001). CONCLUSION: Vaccination, extensive control of ticks and the use of proper comfortable housing to reduce the stress of goats are recommended. Scheduling a mating programme (May to early July) to match the kidding period to the less kid mortality seasons (end of the long rainy season) of flocks is also important to reduce kid mortality.

The magnitude of calf morbidity and mortality and risk factors in smallholder farms across livestock production systems in central Ethiopia.

BACKGROUND: Calf morbidity and mortality are major constraints in Ethiopian cattle production that severely limit available replacement stock. Calf morbidity and mortality reports in Ethiopia mostly focus on market-oriented dairy production systems. A cross-sectional study was undertaken in central Ethiopia with the objectives of estimating the magnitude of calf morbidity and mortality across three production systems and contributing risk factors. METHODS: A cross-sectional study was conducted at pastoral, mixed-crop livestock, and dairy farms in central Ethiopia from February 2019 to June 2019 to collect 1-year retrospective and cross-sectional data on calf morbidity and mortality from smallholder farmers using a structured questionnaire. RESULTS: A total of 293 smallholder farmers were involved in the study. Among the households interviewed, 83% of respondents encountered feed shortages in the year prior to this study. The overall annual calf morbidity prevalence and mortality rate were 6.49% (95% CI: 4.87-8.44) and 10% (95% CI: 8.28-11.93), respectively. Morbidity was higher in Dalocha and Sululta districts in mixed crop-livestock and peri-urban production systems, respectively. Logistic regression analysis of potential risk factors indicated that calf morbidity was associated with the calf and dam body condition score (BCS). Calves with BCS of 3 (medium) were less likely to be morbid (odds ratio [OR]: 0.20 [95% CI: 0.07-0.56]) than calves with BCS of 1 (emaciated), and calves born from dams with a body condition score of 2 (thin) were also at lower risk (OR: 0.25 [95% CI: 0.07-0.95]) than calves born from emaciated dams. The odds of calf mortality in Awash Fentale district were higher (OR: 6.19 [95% CI: 2.09-18.32]) compared to Sululta district. CONCLUSIONS: The study results revealed that the production system and management affect the magnitude of calf morbidity and mortality. We recommend improving water and feed access and resources for livestock owners to reduce calf morbidity and mortality.

Serological Evidence of Caprine Arthritis Encephalitis in North Shewa Zone, Ethiopia: Clinical Case Analysis.

Introduction: Caprine arthritis encephalitis (CAE) is a chronic debilitating and economically important viral disease of goats. It is mainly manifested as encephalitis in kids and polyarthritis in adult goats. The present study was conducted to determine the rate of morbidity and mortality due to clinical diseases attributed to infection by Caprine arthritis encephalitis virus (CAEV) and to determine the serological status of CAEV in goat in North Shewa, Ethiopia. Methods: A cross-sectional serological study and a longitudinal clinical case study were conducted. A total of 257 serum samples have been collected from apparently health and clinical cases attributed to CAE infection and tested with the usage of indirect enzyme-linked immunosorbent assays to screen antibodies against CAE. Records have been statistically analyzed by using the chi-square test. Results: During five consecutive years of longitudinal clinical study, a total of 195 clinical diseases of chronic pneumonia, nerve problems, clinical mastitis, and arthritis occurred with prevalence of 99 (50.8%), 57 (29.2%), 27 (13.9%), and 12 (6.2%), respectively. Chronic pneumonia was the highest cause of goat morbidity (50.8%) and mortality (100.0%). Of the total samples tested from clinical cases, 7 (58.3%) were sero-positive for the presence of antibodies against CAEV. The overall seroprevalence of CAE was 4.7%. There has been a significant difference (p < 0.05) in sero-positivity among management system, breeds, and age groups of goats. However, there was no significant variation in sero-positivity between the sexes (p > 0.05) of goats. Conclusion: This finding indicates that CAEV infection exists in the goat flocks in examined localities in Ethiopia. This disease poses serious animal health problems that constrain production with the presence of apparent clinical signs. Further investigations need to be done to explore the seroconversion of CAEV in small ruminants and the associated factors to plan an appropriate eradication program and prevent transmission.

Survival Analysis of Clinical Cases of Caseous Lymphadenitis of Goats in North Shoa, Ethiopia.

Caseous lymphadenitis (CLA) is a bacterial disease of small ruminants causing abscesses in lymph nodes of the body and internal organs. A longitudinal study from 2011 to 2019 was undertaken at Ataye site of Debre Birhan Research Center to estimate the prevalence and incidence, identify associated risk factors, and characterize the causative bacteria. 1025 goats were followed up for the CLA study. Survival analysis was done using SAS 9.4 software program. Biochemical tests and Biolog microbial identification system were used to characterize the bacteria. In the recurrent survival data analysis, there were 1,138 clinical observations and 214 CLA cases (18.8% prevalence) based on clinical diagnosis. The incidence rate was 0.14 cases per animal year. From a total of 214 cases, 130 have occurred once and 84 cases are recurrent cases following first cases. The cumulative failure rates were 68% for newborn and 64% for yearling age groups. The parotid lymph node was the most frequently affected site. Proportional hazard analysis results showed that sex, age, and breed were associated (p < 0.05) with CLA incidence. Females, newborn age group, Boer, and Boer × Central Highland Goat (CHG) were at higher risks compared to males, yearling age group, and CHG goats, respectively. The present study indicated that a high incidence rate of CLA in the goat farm is difficult to control and prevent because of its poor response to clinical treatment. Thus, control and prevention should focus on the spread of the disease such as isolation of clinically sick animals, culling, and vaccination of flocks.