STUDIES IN CATTLE OF BRUCELLA INFECTIONS, CONVENTIONAL AND MOLECULAR IDENTIFICATION OF THE ISOLATES FROM KACHIA GRAZING RESERVE AND JOS PLATEAU, NIGERIA
STUDIES IN CATTLE OF BRUCELLA INFECTIONS, CONVENTIONAL AND MOLECULAR IDENTIFICATION OF THE ISOLATES FROM KACHIA GRAZING RESERVE AND JOS PLATEAU, NIGERIA
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Date
2014-08
Authors
BERTU, WILSON JAMES
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Abstract
Brucellosis is an infectious disease of domestic animals and wildlife and one of the
commonest human Zoonosis caused by slow-growing, small, Gram negative, cocobacilli
and intracellular bacteria of the genus Brucella. The prevalence of brucellosis is high in
sub-Saharan Africa. In Nigeria, brucellosis is endemic and wide- spread. Several
serological studies carried out in various parts of the country indicated that brucellosis is
prevalent, with prevalence rates ranging from low to high. A few studies on cultural
isolation of Brucella organisms have also been conducted, all of which reported Brucella
abortus biotype 1 as the species circulating in Nigeria. However, few or no studies have
been done on brucellosis in the study areas. There has also been little or no work on the
molecular identification of Brucella isolates from Nigeria. A cross-sectional study was
carried out in Fulani cattle herds in Kachia Grazing Reserve (KGR) and the Jos Plateau to
determine the prevalence of brucellosis, isolate Brucella strains and carry out conventional
and molecular identification of the isolates from the two study areas along with some
isolates from field submissions and from the archive. A total of 1,982 and 2,880 serum
samples were collected from cattle from KGR and on the Jos Plateau respectively and
tested for Brucella antibodies by standard RBPT and modified RBPT. A total of 229
samples made up of vaginal swabs, milk and hygroma fluids were collected from the two
study areas and cultured for Brucella isolation according to standard methods. Classical
biotyping was carried out on all the isolates in this study and those in the archive. Bruceladder
multiplex polymerase chain reaction (PCR) was used to identify the isolates to
species level. Geographic information system was used to map out the study areas. Based
on standard RBPT, the individual animal prevalence and herd prevalence of brucellosis in
KGR were 0.5% and 17. 5% respectively while the individual and herd prevalence of
brucellosis on the Jos Plateau were 1.0% and 30.0% respectively. Fifty eight (2.9%) individual animal prevalence and 21(52.5%) herd prevalence were recorded in KGR while
91(3.2%) individual animal prevalence and 23(63.9%) herd prevalence were recorded on
the Jos Plateau respectively using the modified RBPT. Due to its higher sensitivity, the
modified RBPT was used to determine the prevalence rates based on blocks, villages, sex,
age and herd sizes. The prevalence of brucellosis was higher on the Jos Plateau compared
to KGR but the difference was not statistically significant (P>0.05). Seropositivity was
higher in larger herds compared to smaller herds, and this was statistically significant
(P<0.05). The prevalence rates were significantly higher in females compared to males and
in adults compared to the young (P<0.05). Three Brucella abortus isolates were obtained
from KGR while four Brucella abortus isolates were obtained from the Jos Plateau.
Classical biotyping of all the isolates including field submissions and those from the
archive revealed that they were all Brucella abortus biotype 3. Molecular identification of
all the isolates by Bruce-ladder multiplex PCR showed that they were all Brucella abortus.
This is the first molecular identification of Brucella isolates from Nigeria to their species
level and the first use of the Bruce-ladder multiplex PCR. This study may be the first to
establish that Brucella abortus biotype 3 is the predominant Brucella biotype circulating in
Nigeria. These findings are very significant as they established the endemicity of Brucella
infection due to Brucella abortus biotype 3 in KGR and on the Jos Plateau. GIS enabled
the spatial presentation of Brucella prevalence on the map of each study areas and
provided a better understanding of the spread of the disease. There is urgent need for the
institution and implementation of brucellosis control in these areas. Genotyping of the
isolates should be carried out to determine their phylogenetic position in relationship with
those in the data bases.
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE
STUDIES, AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD
OF DOCTOR OF PHILOSOPHY DEGREE IN VETERINARY PUBLIC HEALTH
AND PREVENTIVE MEDICINE
DEPARTMENT OF VETERINARY PUBLIC HEALTH AND PREVENTIVE
MEDICINE, FACULTY OF VETERINARY MEDICINE,
AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
Keywords
STUDIES,, CATTLE,, BRUCELLA,, INFECTIONS,, CONVENTIONAL,, MOLECULAR,, ISOLATES,, GRAZING,, RESERVE,, JOS PLATEAU,, NIGERIA.