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|Title: ||SERO-EPIDEMIOLOGICAL STUDY OF BRUCELLOSIS IN CAMELS (CAMELUS DROMEDARIUS) IN BORENA LOWLAND PASTORAL AREAS, SOUTHERN ETHIOPIA|
|Authors: ||MEGERSA, BEKELE|
|Advisors: ||Dr. Bayleyegn Molla|
|Keywords: ||Dromedary camels|
|Copyright: ||2004 |
|Date Added: ||16-Apr-2008 |
|Publisher: ||Addis Ababa University|
|Abstract: ||A cross-sectional study was conducted from August 2003 to January 2004, to determine the
prevalence of Brucella species in camels and to identify risk factors for brucellosis infection
in camels (Camelus dromedarius) in two districts of Borena lowland. A total of 3218 camels
in 250 herds were included in the study from Liben (2232) and Yabello (986 animals)
districts. Of these 78.6% (2528 out of 3218) and 21.4% (690 out of 3218) were female and
male camels, respectively. The herd size ranged from 3 to 42 animals with mean herd size of
13.6 + 7.8. A total of 3218 blood samples were collected. All serum samples were initially
screened by RBPT. All RBPT positive reactors were further tested by CFT for confirmation.
CFT confirmed 58 seropositive cases out of 72 RBPT reactors.
The study showed the distribution of Brucella species antibodies in 1.8% (95% CI = 1.4 –
2.3) of the tested samples. Forty herds were found seropositive among the 250 herds included
in the study (16%, 95% CI = 11.6 – 21.1). Seroprevalence rate in those seropositive herds
(within herd prevalence) varied from 2.7% (1 out of 37) to 45.5% (5 out of 11) with average
prevalence of 9.5%. Slightly higher seroprevalence was recorded in Yabello (2.0%, 95% CI =
1.2 – 3.1) than Liben district (1.7%, 95% CI = 1.2 – 2.3), though not statistically differing
from each other (p > 0.05). Female camels had higher prevalence (2.06%, 95% CI = 1.5 – 2.7)
than male animals (0.9%, 95% CI = 0.3 – 1.9).
The effect of sex was observed to be significant for seroprevalence (p < 0.05) with the risk of
infection 2.3 (95% CI = 1.1 – 5.3) times higher in females than male camels. Similarly, there
was significant increase in seropositivity with respect to increasing herd size (p < 0.05) with
chances of disease occurrence 1.4 times higher in herd of 11 – 20 camels and 2.4 times higher
in herd above 20 animals compared to small sized herds (< 11 animals). Immature animals (2
– 4 years) had statistically lower reactors than adult camels (p < 0.05), the odds of infection
being 2.2 (95% CI = 1.1 – 4.6) times lower in immature camels. Conversely, parity and
herding experience did not affect the status of seroprevalence among the respective categories
(p > 0.05). The multivariate analysis of presumed risk factors revealed herd size as the major
risk factors associated with seropositivity (p < 0.05). Advance in age and herd size were also
found to have putative effect on seroprevalence (p < 0.05).
Abortion, stillbirth and birth to weak calf affected 20%, 8.3% and 18.3% of the investigated
herds. Percent of abortion, stillbirth and birth to weak calf were found to be 8%, 3.6% and
7.4%, respectively per females per annum. Live birth, abortion and stillbirth percent were not
significantly different among positive and negative breeding females. This together with low
seroprevalence recorded in this study may not suggest abortion and stillbirth as clinical
manifestation for brucellosis in the study area.
From the questionnaire data it was identified that 95% and 81.3% of herdsmen keep at least
one and more than one ruminant species along side camels, respectively. A household owned
83.3% of the herds while 16.7% belonged to extended families. Accordingly, infection rate
ranging from 1.7 to 1.9% were observed in those camel herds kept with more than one
ruminant while no or less reactor was found in limited numbers of camel herds kept alone or
with one ruminant species.
In spite of knowledge gap about brucellosis herders traditionally do isolation of calving and
aborted dams from the rest of the herd during the day (98.3% and 46.7%) and night (98.3%
and 33.3%), respectively for variable durations. To the contrary, camel pastoralists could be
exposed to infection in several ways including raw milk consumption and close contact with
animals without any protection.
The results of the present study provide the status of seropositivity to Brucella species in
camel in the Borena lowland pastoral areas and the risk factors that contribute to
seropositivity in dromedaries. Habitual consumption of raw milk and close contact with
infected animals signify possible zoonotic importance of brucellosis in the study area.|
|Description: ||A thesis submitted to the Faculty of Veterinary Medicine, Addis Ababa University in
partial fulfillment of Degree of Master of Science in Tropical Veterinary Epidemiology|
|Appears in:||Thesis - Tropical Veterinary Epidemiology|
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