Untangling the respiratory disease complex in
small ruminants in Ethiopia
Biruk Alemu, Hiwot Desta, Fasil Aklilu, Matios Lakew, Demeke
Sibhatu and Barbara Wieland
15th International Symposium of Veterinary Epidemiology and
Economics Chiang Mai, Thailand, 12-16 November 2018

Introduction
• Small ruminants serve multiple livelihood roles: food and
nutrition security, income, and providing raw material for
industries
• Diseases are an important constraint for production
• Different production systems in different agro-ecologies:
pastoralist vs. mixed crop-livestock systems

RDC as priority
• Participatory epidemiological studies showed livestock
keepers prioritized respiratory diseases across production
systems
• RDC in Ethiopia: CCPP, PPR, pasteurellosis, lung worm, Maedi
Visna, PI-3, etc….. (unknown)
• Past surveys on pasteurellosis have shown high
seroprevalence with cross-reaction observed between
different serotypes

Objective
The study aimed at:
• Investigating the role of different pathogens involved in the
respiratory disease complex in small ruminant in Ethiopia

Methodology
• Household and sero-survey
• Laboratory analysis of biological samples
• Multivariable logistic regression analysis for
risk factors

Household and sero-survey
• 432 households in 4 regions
• Data on vaccination history, clinical signs observed,
husbandry, health management, and production data
• 2’110 serum samples (1’547 Sheep, 563 goats) were
collected (5-6 per farm)
• Tissue samples were collected from clinically
suspicious animals
• Testing of samples for PPR (Ab and Ag serology), CCPP
(serology), and Pasteurella (culture of samples of
suspicious animals)

Results
Frequency percentage of clinical signs
70
42
27
30
25
68
50
35
35
34
80 60 40 20 0 20 40 60 80
Coughing
Diarrhea
Eye discharge
Circling
LabouredBreathing
LesionsMouth
Hairloss
Salivation
Itching
Mastitis
Lameness
Nodular Skin
Swelling Head
Abortion
SuddenDeath
Ectoparasites
BornDeath
Nasal discharge
Vaginal discharge
Dystocia
Weightloss
Male
Female
Men
Women

• The Ab sero-prevalence level in Tigray vaccinated animals indicate low
herd immunity level
• The relatively high sero-prevalence in unvaccinated animals may be due to
some animals actually having been vaccinated in the past, but reported as
non-vaccinated in this survey
Region
Vaccinated Unvaccinated
Pos (%) 95% CI Pos (%) 95% CI P-Value
Amhara 90.9 85.58 – 94.68 30.9 26.83 – 35.35 0.000
Tigray 58.9 54.39 – 63.22 - - -
Oromia 85.5 79.84 – 90.07 17.4 13.79 – 21.59 0.000
SNNP - - 11.3 8.34 – 15.16 -
Overall 71.4 20.8 0.000
Sero-prevalence of PPR

Sero-prevalence levels of CCPP
• Generally low sero-prevalence level of CCPP observed in unvaccinated
population in all regions
• The Ab sero-prevalence level in vaccinated population indicates low herd
immunity level compared to previous studies
Region
Vaccinated Unvaccinated
Pos (%) 95% CI Pos (%) 95% CI P-Value
Amhara - - 2.2 1.23 – 3.68 -
Tigray - - 0.8 0.26 – 2.2 -
Oromia 52.9 35.1 – 59.5 0.8 0.97 – 3.6 0.000
SNNP - - 1.1 0.35 - 3 -
Overall 52.9 1.3 0.000

Results for animals with clinical signs
• Ag detection for PPRV –
negative result from 29
clinical samples
• 3/55 positive result for
pasteurella culture
(M. hemolytica and B.
trehalosi)

Risk factors for PPR
Term Odds Ratio CI 95% S.E. P-Value
Age (Adult/Young) 1.89 1.2069 2.9595 0.2288 0.0054
Species (Ovine/Caprine) 0.32 0.2101 0.4861 0.2140 0.0000
Sex (Male/Female) 0.64 0.4333 0.9525 0.2009 0.0276
Agroecology
(Highland/Midland)
0.25 0.1479 0.4390 0.2775 0.0000
Flocksize (Medium/Small) 3.22 2.1867 4.7388 0.1973 0.0000
Flocksize (Large/Small) 5.21 0.8455 32.1355 0.9280 0.0752
Region (Oromia/Amhara) 0.21 0.1195 0.3531 0.2763 0.0000
Region (SNNPR/Amhara) 0.23 0.1376 0.3694 0.2519 0.0000
CONSTANT * * * 0.3685 0.0285

Risk factors for CCPP
Term Odds Ratio 95% C.I. S.E. P-Value
Agroecology (Mid
land/Lowland)
0.16 0.0195 1.2621 1.0637 0.0817
Agroecology
(Highland/Lowland)
0.73 0.3112 1.7057 0.4341 0.4655
GrazingHus (Mixed with other
LS/ Sheep and goat
separately)
1.37 0.4608 4.0956 0.5573 0.5688
GrazingHus (Sheep and goat
together/Sheep and goat
separately)
3.22 1.3108 7.9233 0.4590 0.0108
CONSTANT * * * 0.4748 0.0000
Mixed (sheep and goats) raising was identified as a risk factor for
CCPP sero-positivity

Discussion
• Our results provide evidence of ongoing PPR circulation in
lowlands and highlands, but the participatory research
indicated that livestock keepers struggle to identify the
disease
• The PPR sero-prevalence in vaccinated animals was above
80% in some of the study area, indicating sufficient herd
immunity after vaccination
• Targeting agroecology in vaccination may play a key role in
limiting the transmission of PPR infection
• Much less vaccination had been done for CCPP
• In lowland areas that had vaccination, sero-prevalence was
low (low vaccination coverage)

Limitations
• Pasteurella serology unreliable with tests available
• Lungworm testing not done in this study
• Other pathogens not investigated yet

Outlook
To further understand the relative importance of different
pathogens and the role of co-infection, a longitudinal survey is
being conducted
• Follow selected farms over 12 months
• Record morbidity and mortality and other productivity
parameters
• Sample collection and testing for: Pasteurellosis, Maedi-
Visna, caprine arthritis encephalitis virus, parainfluenza,
and bluetongue

This work is financed by
IFAD SmaRT Project, Africa RISING Project, CGIAR Research
Program Livestock
It is implemented in a partnership with
ICARDA, Regional Research Centers
Acknowledgements

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