SURVEY OF BOVINE TUBERCULOSIS IN SLAUGHTERED CATTLE IN GUSAU ABATTOIR, ZAMFARA STATE, NIGERIA

SURVEY OF BOVINE TUBERCULOSIS IN SLAUGHTERED CATTLE IN GUSAU ABATTOIR, ZAMFARA STATE, NIGERIA

Abstract:

Bovine tuberculosis (bTB) is a wide spread disease of cattle and other animals with both economic and public health significance, but it has received little attention in Nigeria; particularly in some parts such as Zamfara State. This study aimed at detecting and speciation of Mycobacteria in cattle slaughteredin Gusau abattoir Zamfara State, Nigeria. The study was a cross-sectional abattoir-based which examined atotal of 3690 cattle slaughtered between the months of April to June 2014. The samples of lesions suggestive of bTB collected during participatory meat inspection were processed and examined for the presence of acid-fast bacilli (AFB) Mycobcateria by using microscopic technique (Ziehl-Neelsen staining and microscopy: ZN). Detected Mycobacteriawere identified to species level using region of difference (RD) deletion typing, a multiplex polymerase chain reaction (PCR)-based method (involving RD1, RD4, RD9 and RD12 loci). Of the 226 animals observed with lesions compatible with bTB, 37 (16.4%) turned out to be acid-fast bacilli (AFB) positive.15 (6.6%) of the lungs samples were AFB positive out of which 14 (37.8%) were further tested positive for RD deletion typing. Animal level data on age, sex and breed were recorded. The individual animal prevalence was significantly affected by both age (ZN: χ2 = 8.324, p= 0.004; RD deletion typing: χ2 = 6.68, p= 0.010) and sex (ZN: χ2 = 3.46, p= 0.063; RD deletion typing: χ2 = 3.63, p= 0.057).Moreover, there was weak statistical association between age groups (OR= 0.254, p= 0.004) in ZN positive samples, and for RD deletion typing positive samples amongst ages (OR= 0.287, p= 0.010). While no statistically significant association was recorded between sex (OR= 4.58, p= 0.063) of the cattle positive for ZN, and sex groups (OR= 0.432, p= 0.057) in cattle positive for RD deletion typing. Based on RD deletion typing, 37 tissue samples were analyzed for molecular characteristics:band-patterns of 30 samples were identified to be M. bovis, 3 were M. viii caprae and 1 was M. tuberculosis.Breed prevalence rates of the disease by ZN and RD deletion typing were found to be 25 (67.6%) and 22 (64.7%) for White Fulani, 8 (21.6%) and 8 (23.5%) Sokoto Gudali, and 4 (10.8%) and 4 (11.8%) Red Bororo respectively.Risk factors for transmission and exposure of bovine tuberculosis were assessed, 101 (67.3%) of 150 questionnaires administered were retrieved for analysis. Butchers made up of most of the respondents 34 (33.7%) compared to cattle traders 25 (24.8%), cattle handlers 21 (20.8%), meat sellers 8 (7.9%), cleaners 5 (5.0%), animal health scientists 3 (3.0%) and veterinarians 3 (3.0%).In conclusion, this study has for the first time recorded prevalence of bTB in the study area, and molecular identification of three different Mycobacteria species from thirty four 34 (92%) slaughtered cattle with caseous lesions suggests the presence of same or more species of Mycobacteia in circulation among other domestic animals in the State. These findings have raised concerns for both animal and public health considering the predominant extensive livestock production system (which is mixed: cattle, goat, sheep and camels combined), in-contact of humans with cattle, and the level at which unpasteurized milk and poorly processed meat are being consumed in the study area. This study approves of RD deletion typing to be useful for confirmation of bTB and an efficient tool in differentiatingMycobacterium tuberculosis complex (MTC) members, while it also considered Ziehl-Neelsen staining and microscopy as useful and accessible diagnostic method for detecting AFB from clinical specimen. Further research is needed to better understand bTB prevalence, genetic diversity of MTC and transmission in an extensive livestock production system of Zamfara State.

SURVEY OF BOVINE TUBERCULOSIS IN SLAUGHTERED CATTLE IN GUSAU ABATTOIR, ZAMFARA STATE, NIGERIA