Seroprevalence, Isolation and Molecular Detection of Brucella Species from Camel and Small Ruminants in Tigray and Afar Regional States of Ethiopia
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Date
2020-06
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Abstract
A cross sectional sero- and molecular survellience was conducted in Afar and Tigray
regions of Ethiopia to determine the seroprevalence, isolation and molecular identification
of Brucella species using Real time PCR in small ruminants and camels from November
2019 to May 2020. A total of 2523 serum samples; camel (n= 1625) and small ruminants
(n=898) were collected for the seroprevalence study. In addition, 15 vaginal swab samples
from animals having recent history of abortion were also collected for isolation and
molecular detection of Brucella species. Following serum harvest, the blood clot was
subjected to DNA extraction for detection of Brucella species using PCR. In addition, data
related to risk factors of brucellosis infection were collected to assess the potential
association of risk factors with seropositivity. Multi-species ELISA Kit was used to detect
the presence of circulating antibodies against Brucella species whereas; vaginal swabs
were processed and cultured on Brucella selective media for bacterial isolation and
identification. The seroprevalence of brucellosis was determined as 12.1% (95% CI: 10.1-
14.5%) and 11.5% (95% CI: 8.9-11.8) for small ruminants and camels, respectively.
Multivariate regression analysis revealed that sex, age and parity have significantly
associated (p < 0.05) with Brucella infection in camels (OR 0.42 (95% CI: 0.27-0.64)
P=0.000, OR 0.64(95% CI: 0.44-0.92), P= 0.017and OR 0.61(95% CI: 0.43-0.86), P=
0.004 respectively. Where as, species, abortion history, and herd size were not statistically
significant (P >0.05). Concerning small ruminants, sex, age, parity, abortion history, and
herd size were not statistically significant (P >0.05). Bacterial culture result showed that
Brucella colonies were isolated from 13.3 % (2/15) of vaginal swab samples of caprine and
both isolates were identified as Brucella melitensis using real time PCR. Similarly 295
blood clots from seropositive animals were tested with PCR and the result showed that
seven camel samples were positive for IS711 prmer that indicates Brucella genus. Further
analysis indicated that four of them were B. melitensis whereas three were not amplified
with both B. melitensis and B. abortus specific primers, which indicates they may be other
Brucella species. This study showed relatively higher prevalence of brucellosis in camel
and small ruminants in Tigray and Afar Regions, signaling an urgent need for intervention
to control the disease and prevent zoonotic transmission of brucellosis to the community.
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Keywords
Brucella, Camel Ethiopia, Seroprevalence, Small ruminants