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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
Brucellosis,
Serological tests
CFT
RBPT
Epidemiology
Risk factors
Liben
Yabello
Borena lowland
Southern Ethiopia
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 ix 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
URI: http://hdl.handle.net/123456789/539
Appears in:Thesis - Tropical Veterinary Epidemiology

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