Seroprevalance of selected bacterial and viral diseases of small ruminants in Terengganu, Malaysia
Small ruminant production is an important economic activity for many smallholder farmers in Malaysia. In the past decade, there has been increased demand for sheep and goat products. However, the development of regional livestock meat and milk trade is threated by the continuous threat of many in...
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| Format: | Thesis |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/104778/1/FPV%202020%2021%20IR.pdf |
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| Summary: | Small ruminant production is an important economic activity for many smallholder
farmers in Malaysia. In the past decade, there has been increased demand for sheep
and goat products. However, the development of regional livestock meat and milk
trade is threated by the continuous threat of many infectious diseases of bacterial and
viral origin, which limits the productivity of smallholder flocks. This study
investigated the seroprevalence and risk factors of selected bacterial and viral diseases
of sheep and goats in Terengganu, Malaysia. A cross-section survey was conducted to
collect blood samples and farm management data from the selected farms January and
December 2018. Blood samples were collected from 180 sheep (n=60) and goats
(n=120) from 8 smallholder farms in Terengganu. A structured questionnaire was
completed by individual farmers to furnish management data for the analysis of
possible risk factors associated with seropositivity to bacterial and viral diseases. In
the laboratory, serum was separated from coagulated blood by centrifugation and
preserved for specific ELISA assays at -20 0C. Seroprevalence of SBV was determined
using commercial ID Vet® SBV multispecies cELISA test. Detection of anti-CAEV
antibodies was done using Qayee-Bio caprine arthritis encephalitis virus (CAE)
sandwich-ELISA test kit with a sensitivity of 100% and specificity of 99.6%. A
commercial Sandwich-ELISA kit (Sunlong) with a sensitivity of 100% and a
specificity of 99.6% was used for the direct detection of specific antibody against
Coxiella burnetii, bluetongue and contagious ecthyma virus. Standard Agar gel
precipitation test (AGPT) was used for the detection of antibodies against
Corynebacterium pseudotuberculosis. The Rose Bengal rapid plate agglutination test
was used for the detection of Brucella antibodies. The optical densities (OD) of the
tests were measured at 450nm using ELISA Microplate Reader (Tecan Sunrise®,
Switzerland) and the percentage inhibitions calculated as 100 x [1- (Sample optical
density/Negative control OD)] were interpreted as follows: OD values ≥ 40% =
positive, OD values ≤ 30% = negative and OD values 30%-40% = doubtful. The result
of serological tests indicates 10.6% (95% CI=6.6-16.7) overall seroprevalence of SBV with different (p<0.05) rates of infection between flocks, species, breed, gender, age,
production system and management of small ruminants. The male had 5.26 times
higher risk of exposure to SBV than females and young animals had 4.1 times higher
risk of infection than adults. Serological analysis also revealed 27.2% (95% CI=22.8-
37.3) overall prevalence of contagious ecthyma with different (p<0.05) rates of
infection among the flocks, species, breed, gender, production, and management of
small ruminants. The goats had 3.1 times more risk of orf infection than sheep while
dairy animals had 2.82 times higher odds of orf than the mean and mixed production.
The overall seroprevalence of q fever was 16.7% (95% CI=12.3-24.5) with different
(p<0.05) rates of infection among flocks, species, breed, age, production, and
management system of small ruminants. The species sheep (OR=21.36; 95% CI=2.29-
198.41; p=0.007), especially Barbados black belly (OR=24.35; 95% CI=2.77-213.76;
p=0.004) and Dorper sheep (OR=12.88; 95% CI=1.29-128.59; p=0.029), and the
young age (OR=5.04; 95% CI=1.66-15.31; p=0.004) were risk the factors of q fever
among small ruminants in the study area. The study further revealed 18.3% (95%
CI=13.9-26.6) overall seroprevalence of bluetongue with different rates of infection
among the flocks and breed of small ruminants. Flocks D (OR=5.29; 95% CI=1.16-
24.08; p=0.031), E (OR=8.22; 95% CI=1.46-46.27, p=0.017) and G (OR=18.50; 95%
CI=2.17-16.46; p=0.008) were associated with higher risk of bluetongue in the study
area. This study has also revealed 7.2% (95% CI=3.67-12.32) overall seroprevalence
of CAEV with no difference (p>0.05) in infection rates among various categories of
small ruminants. Our results also showed 5.6% (95% CI=2.3-10.0) overall
seroprevalence of CLA with no difference (p>0.05) in infection rates among different
categories of small ruminants. Serum antibodies against brucellosis were not detected
in this study. This study reports the first occurrence of the novel and emerging
transboundary Schmallenberg virus disease in Malaysia. The presence of anti-SBV
antibodies in Malaysia indicates the potential effects of disease on small ruminant
productivity. This study also revealed an alarming rate of re-emerging bluetongue and
zoonotic q fever infections which need to be kept under control through a one health
approach. We have also seen a high level of circulating antibodies to orf virus infection
among the small ruminant population with a potential to cause a negative impact
towards production. The absence of anti-brucella antibodies in small ruminants
indicates the effectiveness of current control measures. In conclusion, this study
highlights current seroprevalence status of selected bacterial and viral diseases of
small ruminant in East Coast Malaysia and reports the first occurrence of novel and
emerging SBV and also detected existing threats of re-emerging and zoonotic
diseases, which requires a holistic herd health program and biosecurity
implementation for effective control and prevention. |
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