Risk Factors for Reproductive Disorders and
Major Infectious Causes of Abortion in Sheep
in the Highlands of Ethiopia
Gezahegn Alemayehu, Azeb Gebretensay, Mourad Rekik, Fasil
Aklilu, Biruk Alemu, Barbara Wieland
ISVEE 15, Thailand, Nov. 12-16, 2018

Introduction
• Sheep play an important role for food security and food self-
sufficiency in the highlands of Ethiopia
• Sheep population estimated 30.7 million (CSA, 2017).
• Sheep production mostly a low input agricultural activity
• Various efforts have been made to improve the productivity of
indigenous sheep
• Community-Based Breeding Programs (CBBPs)-to improve
productivity and income of small-scale resource-poor sheep
producers.

Introduction
• Regardless of these interventions, diseases and poor herd-health
management practices remain a bottleneck, resulting in low flock
productivity
• Sheep often encounter complex disorders that hinder optimum
offspring production
• Pregnancy wastage in the form of abortion, stillbirth and perinatal
lamb mortality remain significant issues

Introduction
• Infectious agents are the most plausible causes of abortion
• Most of them are zoonoses, but causes remain largely undiagnosed
• Reducing reproductive diseases is crucial to improve reproductive
performance
 To design intervention strategies, information on magnitude of
reproductive failures and their possible causes is needed

Objectives
To investigate and estimate the prevalence of reproductive
failures
To determine its association with infectious agents and risk
factors

Material and methods
Map of study sites

Material and Methods
• Cross-sectional study: 120 households/farms from six villages
• Blood was randomly taken from 3-4 animal from each flock
ELISA RBT
445 samples collected and
tested

Study population

Study population

Mixed crop-livestock production system

Feeding
Some flocks were supplemented

Data analysis
• Descriptive statistics
• Logistic regression model
• Standard Poisson and Zero-inflated Poisson regression model
• A mixed-effects logistic regression model

Results
Reproductive
failures
Menz Gera
(n=41)
Horro
(n=39)
Bonga
(n=40)
Total
(n= 120)
P-value
Abortion 12.20% 41.03% 7.5% 20% 0.000
Stillbirth 2.44% 17.95% 10% 10% 0.069
Dystocia 4.88% 10.26% 0.0% 5% 0.112
Neonatal
losses
65.85% 74.36% 55% 65% 0.195
Flock level prevalence of reproductive failure

Factors associated with reproductive
failure
Exposure variables
• District
• Flock size
• Membership of CBBP
• T. gondii positive
• C. burnetii positive
• Chlamydia spp. positive
• Presence of cats
• Presence of dogs
• Communal grazing
• Feed supplementation
• Housing type
• Presence of goats
• Presence of cattle
Outcome variables
Presence of Abortion in the flock
Number of abortion in the flock
Presence of neonatal lamb loss in flock
Number neonatal loss in the flock

Results
Factors associated with abortion
Variables Categories Multivariable
IRR
(95%CI) P-value
District Menz Gera 1
Horro 3.41 1.35 8.64 0.01
Bonga 0.82 0.22 3.03 0.76
Flock size <15 1
>15,<30 0.35 0.14 0.83 0.02
> 30 0.27 0.11 0.62 0.00
multivariable Poisson regression

Results
Factors associated with neonatal loss
Variables Categories Multivariable
IRR
95%CI P-Value
District MenzGera 1
Horro 2.17 1.53 3.08 0.00
Bonga 1.74 1.10 2.75 0.02
Flock size <15 1
>15,<30 0.88 0.62 1.25 0.48
> 30 2.01 1.43 2.81 0.00
Coxiella positive No 1
Yes 1.80 1.15 2.81 0.01
Multivariable Zero-Inflated Poisson regression

Seroprevalence of major infectious causes
Agents Menz Gera (41) Horro (39) Bonga (40) Total (120) p-value
C. abortus 82.9% 84.6% 100% 89.2% 0.025
C.burnetii 90.2% 79.5% 35% 68.3% 0.000
T. gondii 51.2% 87.2% 75% 70.8% 0.001
Mixed
infection
85.4% 92.3% 77.5% 85% 0.182
None of the flocks testing positive for Brucella
spp. or border disease virus
Flock prevalence

Animal level sero-prevalence
41.8
37.98
39.78
58.2
0 10 20 30 40 50 60 70
Mixed infection
C. burnetii
T. gondii
C. abortus

Conclusions
• Importance of reproductive failure in sheep and possible role of
multiple pathogens shown
• Multiple agents likely involved in reproductive failure- carful
investigation and isolation of pathogens in abortion cases needed to
show causality (longitudinal studies to determine incidence)
• Consider breeding ram certification through health and serological
testing for major diseases to use in CBBP
• Most agents found pose zoonotic risk for farmers and their families
• Targeted interventions are needed: control programs, targeted
feeding of pregnant ewes, improved husbandry (shade, water)

This presentation is licensed for use under the Creative Commons Attribution 4.0 International Licence.
better lives through livestock
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better lives through livestock
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