The Status of Bovine Tuberculosis in Selected Areas of North Gondar Administrative Zone, Ethiopia
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Date
2006-06
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Addis Ababa University Faculty Of Veterinary Medicine
Abstract
Mycobacterium bovis CM. bovis) is one of the members of Mycobacterium tuberculosis
complex, which infects both animals an d man causing mamma li an tuberculosis. A cross
sectional and case contr ol studies were co nducted in Dembia and Gond ar d istricts of North
Gondar from September 2005 to April 2006 to detennine the prevalence of bovine
tuberculosis (BTS) and associated risk factors and assess the sources of infection of human
tuberculosis (HTS). In the cross sectional study, cattle from extensive (310) and semi
mtenslve (31 5) production systems were tested with the comparative intradermal tuberculm
test (CI O). In the case control study design, 50 human tuberculous patients (cases) and a
similar number of patients visiting the hospilal for some other health problems other than
tuberculosis were intetyiewed about their hyglemc practices. feeding habits and cattle
management practices that would contribute to the transmission and maintenance of the
disease. From each of the cases and control groups, 200 cattle owned or auended by them
were tested with the CID test. Ofall 1025 ammals cxammed,21% were POSill\'e. In the cross
secuonal S dy, assuming doubtful reactors as negati\'c, prevalence was higher ( 16 ,8~-'o) 10
semi-lOtenslve producti on system than extenSive (11.6%) and thiS difference was significant
(p<0.05). Herd Je\'C1 pre\"3ience was 37.7% and 56.3% 10 extensive and semi intensive
production systems. respectively. It was also Significant (p<0.001) between poor and good
cattle management pracllces: cattle under poor management were 3,4 times more hkely to be
IOfected wllh BTB than those under good management. Other factors which were ",gnificantly
(p<0.05) associated with pre\ alencc were production system, breed, age, sex and body
candillon. In the muhi\anate logistic regressIOn analYSIS, production system and management
were slgmficant (p<0.05). In the case-control study, out of the 200 animals tested that are
0\\ ned by tuberculous human pall ems . ..\ 0 (20%) and from the same number of ammals owned
by non-tuberculous comrol groups, 22 (II %) were posui\'e for the tuberculin test. The
differences 10 prevalence of BTB 10 cattle owned by human TB cases and control group wcre
sigmficant (X 2=98,90, p<O.OO 1). Of 50 TB cases, 66% and 3~% were diagnosed as pulmonary
and extra pulmonary tub erculosis, respectively. About 6% of the patIents consume raw milk
and milk products. The majority (58%) of HTB patients are between the ages 15 and 45 while
24% and 18% were below 15 and above 45 years, respectively. Cattle owners who consumed
raw milk were at higher risk (O R = 1..\.33) of being infected with tuberculOSIS than those who
consumed balled milk. From the questionnalTe survey, Significant associations (p<O,05) with
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cases were found when patients had physical cont act with other c lini cal cases, drinks raw milk
(X 2 =32.18j P<O.OO I) and are farmers compared to similar variabl es in the control group
(X 2=25.0 I ; P<O.OO I). In the bacteri ological examinati on, Mycobacterium specIes were
isolated from 26 (47.3%) spu tum, 2 (15. 4%) fin e·need le aspirates (FNA) and 1( 14.3%)
peritoneal fluid of humans and 7 (7. J %) of 99 milk sampl es. The majority (88.5%) of sputum
isolates were M. tuberculosis , and on ly one isolate (3.8%) was M. bovis while one isolate
from milk was M. tuberculosis. Atyp ical mycobacteria were isolated from sputum (2), fNA
( I) and milk (2). Amo ng the isolates, 79 .4% (23 / 29) and 10,3 % (3 /29) of th e human isolates
were M. Ill berculosis and M. bovis, respectively. Th e rest 10.3% (3/29) were oth er
mycobacte ri al species. On the other hand, 14.3% (117) and 57.1% (417) of the cattle isolates
indicates were M. tuberculosis and M. hovis, respecti ve ly . Th e rest 28.6% (217) were ot her
mycobacteria l spec ies. The findings in thi s study demonstrate th e imp ortance of BTB as a
major health risk and cattle being one of the most important sources of infection. The finding s
of the present study using comparative intradennal tubercu lin test and cu ltu ral examination of
samples from humans and animals have shown that cau lc may be important sou rc es of
infection to humans particularly of AI. bods infection.
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Keywords
My cobacTerium bovis; Bovi ne TB: Cattle; Prevalence; North Gondar; Cross- sectional; Case-control.