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All content in this area was uploaded by Oluwawemimo Adebowale on Feb 10, 2018
Content may be subject to copyright.
94
Alexandria Journal of Veterinary Sciences 2016, July. 50 (1): 94-98
www.alexjvs.com 2047,-1110 ISSN 10.5455/ajvs.222912 DOI:
Potential Bacterial Zoonotic Pathogens Isolated from a Major Abattoir and its Receiving Surface
Water in Abeokuta, Nigeria
Adebowale, O. Oluwawemimo1, Jayeola Adedamola1, Adeyemo Olanike2, Kperegbeyi Eniola1
1Department of Veterinary Public Health and Reproduction, College of Veterinary Medicine, Federal University of Agriculture Abeokuta,
Abeokuta, 2Department of Veterinary Public Health and Preventive Medicine, University of Ibadan, Ibadan
ABSTRACT
Key words:
Bacteriology;
Abattoir; Water
waste; Surface
water; Public
health
The rapid pace and scale of urbanization in Nigeria has led to large volumes of domestic, agricultural
and industrial wastes, which pose threats to the environment and public health. Currently, in Nigeria,
there seems to be neither sufficient measures nor facilities to treat such wastes to ensure environmental
safety or recovery of usable energy and material. This study was conducted to determine the microbial
status of the Lafenwa abattoir effluent and its receiving nearby surface water. The various waste disposal
methods at the abattoir were also assessed. The Total viable and Coliform counts (TBC and TCC) using
surface plating techniques were performed. The mean TBC and TCC for waste water during and after
slaughtering were 5.2x107, 4.9x107 and 4.26x107, 3.06x107 cfu/ml respectively. Meanwhile, the receiving
surface water during and after slaughtering had mean TBC and TCC of 4.15x107, 3.83x107, and
3.89x107, 2.87x107 cfu/ml respectively. Waste disposal at the abattoir was by open dumping of solid
wastes while effluent was discharged into a nearby Ogun River, which is also used by butchers for meat
processing. Bacterial organisms isolated from abattoir effluent included Enterobacter aerogenes,
Hafnia alvei, Erwinia mallotivora, Edwardsiella ictaluri, Enterobacter amnigenus and Escherichia coli
O157strains. Meanwhile, Proteus miriabilis, Staphylococcus spp, Pseudomonas aeruginosa,
Enterobacter intermedius, Yersinia aleksiciae, Serratia odorifera, Enterobacter cloacae, Enterobacter
aerogens and Eschericia coli O157 were isolated from the surface water. The high microbial load and the
isolation of pathogenic organisms of public health importance especially Escherichia coli O157 strains
further demonstrates the need for adequate waste disposal and treatment. Also, the current methods of
waste disposal at the abattoir greatly reduces the quality of the surrounding environment and portends a
risk to public health and food safety.
Corresponding Author: Adebowale Oluwawemimo, oluwawemimo1@yahoo.com
1. INTRODUCTION
The abattoir is a specialized facility approved and
registered by regulatory authority for inspection of
animals, hygienic slaughtering, processing and
effective preservation and storage of meat products for
human consumption (Alonge, 2002). Adequate
facilities to ensure safe disposal of abattoir wastes in a
manner that will not constitute a potential hazard to
public, animal and environmental health is considered
very essential. Most abattoirs in Nigeria have no
facilities for waste treatment; wastes are either
disposed on open dumps or are discharged into nearby
streams, hence constituting an environmental menace
(Adeyemo et al., 2002).
Effluents generated from abattoirs are characterized by
the presence of a high concentration of whole blood of
slaughtered food animals and suspended particles of
semi-digested and undigested feeds within the stomach
and intestine of slaughtered and dressed food animals
(Coker et al., 2001). Abattoir effluent contains several
million colony forming units (cfu) of total aerobic
bacteria count and fecal coliforms. In addition, there
may also be the presence of pathogenic
microorganisms, such as Salmonella, Eschericia coli
(including serotype O157:H7), Shigella, parasite eggs
and amoebic cysts (Bull et al., 2001). Several past
studies have reported the isolation of pathogenic
bacteria and fungi species such as Staphylococcus
aureus, Streptococcus, Salmonella spp, Eschericia
coli, Aspergillus, Muccor, Saccarhomyces. spp and
Penicillium spp from abattoir wastewater (Coker et al.,
2001; Adesomoye et al., 2006 and Adebowale et al.,
Adebowale et al., / Alexandria Journal of Veterinary Sciences 2016, July. 50 (1): 94-98
95
2010). Pathogens isolated might threaten public health
by migrating into ground or surface water, or vectors
like animals, birds and arthropods which can help in
the dissemination (Gauri, 2004).
Zoonoses from abattoir wastes are yet to be fully
controlled in more than 80% public abattoirs in
Nigeria (Cadmus et al., 1999). This may be linked to
the absence or inadequate abattoir waste management
facilities, which has consequently led to large solid
wastes and untreated effluents being common sites
(Adeyemo, 2002). The risk of epidemics, water
contamination and pollution, annihilation of biotic life,
global warming and soil degradation by waste
materials are real problems confronting developing
countries where issues concerning waste management
have been grossly neglected (Adedipe, 2002; Adeyemi
and Adeyemo, 2007).
This study was conducted to examine the different
methods of waste disposal in the largest abattoir in
Abeokuta, Ogun State. We also performed
microbiological investigation to determine the
bacterial load of the abattoir effluent and receiving
surface river.
2. MATERIALS AND METHODS
2.1. Study Area
Lafenwa abattoir is located in a commercial district of
Abeokuta North Local Government Area of Ogun
State, South-Western Nigeria. It is located on
geographical map reference Latitude 30 20’E and
Longitude 70 10’N. Lafenwa abattoir is a major
slaughtering facility in Ogun state where a total
number of 150-200 heads of cattle are slaughtered
daily for public consumption. The slaughtering
activities commences from 6. 00a.m to 12.00 noon
every day, except on Sundays.
2.2. Sample collection
Waste water samples from the major channel for
effluent outflow and water samples from the receiving
surface water, (which is also used for meat processing)
were collected for microbial investigation using
sterilized 250ml bottles. Sampling was carried out
during and post slaughtering twice a week for 3months
November 2009 to January 2010. Overall, 50 samples
were collected. After collections, samples were
transported to the laboratory in ice boxes for microbial
analyses in the Microbiology and Public Health
Laboratory of the College of Veterinary Medicine,
FUNAAB.
2.3. Microbiological Analysis
The waste water and water samples were plated and
cultured to determine the TBC and TCC using
Nutrient and MacConkey agars, respectively. Media
were prepared according to the manufacturer’s
instruction. Sterile Nutrient and MacConkey agar
plates were inoculated aseptically in duplicates with
0.1 ml aliquot of serial dilutions 10-7 and 10-8 of
samples using surface plate technique, and plates
incubated at 37°C for 24 hours (Boulter et al., 2002).
After incubation, plates were observed and distinct,
visible colonies were counted; total bacteria and total
coliforms were estimated and recorded as colony
forming units per ml.
For detection and identification of E. coli O157,
samples were inoculated on Sorbitol MacConkey-
BCIG Agar (Oxoid) supplemented with cefixime-
tellurite selective supplement (Oxoid). Plates were
incubated for 24 hours at 37oC. Straw colored
colonies suspected to be E. coli O157 were subjected
to biochemical test for E. coli identification and further
confirmed E. coli O157 using dry spot Eschericia coli
O157 test kits (Oxoid, UK).
Furthermore, identification of bacteria isolates was
performed. Briefly discrete bacterial colonies plates
were subcultured onto fresh sterile corresponding
plates and subjected to colonial characterization, Gram
staining and microscopy as well as biochemical tests
according to Cappucino and Sherma 1998. Isolates
characteristics were interpreted with an online bacteria
identification software system (ABIS 7.0) to determine
the identity of the isolates.
2.4. Methods of Abattoir waste disposal.
Information on different methods of abattoir waste and
effluent disposal were gathered by investigators
through visual observations and personal interview
with Veterinarians on duty at the abattoir.
Investigators moved round the abattoir and ways of
disposal observed, recorded and images captured using
a camera.
2.5. Data Analysis
The Mean TBC and TCC are represented as charts.
Ordinary 2-way ANOVA was performed to determine
if there were difference in the mean TBC and TCC of
abattoir effluent and receiving surface water. In all
analysis, differences were statistically significant at p
≤0.05. Graphical representations and analysis were
performed using Graphpad Prism 6.0
Adebowale et al., / Alexandria Journal of Veterinary Sciences 2016, July. 50 (1): 94-98
96
3. RESULTS
The results of the mean values of the TBC and TCC
are presented in Fig. 1. The mean TBC and TCC for
waste water during and after slaughtering were
5.2x107, 4.9x107 and 4.26x107, 3.06x107 cfu/ml
respectively. The contaminated receiving surface
water had mean TBC and TCC of 4.15x107, 3.83x107,
and 3.89x107, 2.87x107 cfu/ml respectively. Analysis
of variance indicated there was no difference between
the TBC and TCC estimated for Abattoir effluent and
surface water/river (P=0.27), and during and after
slaughter (p= 0.39). Bacteria isolated from both
effluent and the receiving surface water were Bacillus
spp, Staphylococcus aureus, Pseudomonas,
Enterobacter, Hafnia alvei, E. coli, Erwinia, Proteus
and Klebsiella. Table 1. represents the various bacteria
isolated from abattoir effluents and receiving surface
water. From the total 50 samples analyzed,
Escherichia coli O157 was detected in 16% (Table 2).
The types of wastes generated at the Lafenwa abattoir
included solid and liquid wastes. Solid wastes included
ruminal contents, horns, hooves, fat, meat trimmings
and most importantly, animal faeces are disposed on
open dumps around the abattoir. Condemned organs
and parts of carcasses were disposed into pits and
covered with chemicals such as formaldehyde and
lysolR. Liquid wastes including blood, urine and water
used for various activities in the abattoir were
discharged without pre-treatment into nearby surface
water, the Ogun River. As shown in Fig. 2 open dumps
were situated in and around the abattoir. Abattoir
effluents discharged into the Ogun River is represented
in Fig. 3.
Fig. 1. Bacteria and coliform counts estimated for
Abattoir effluents and receiving Surface River.
Fig. 2. Open dumps observed within and around the
Abattoir.
Fig. 3. Abattoir liquid waste discharged nearby surface
water, Ogun River.
Table 1. Bacteria isolated from Abattoir Effluent and
the receiving Surface Water/River.
Abattoir
Effluents
Receiving surface
river/water
Bacteria
isolates
Bacillus spp
Staphylococcus
aureus
Pseudomonas spp
Enterobacter
aerogens
Enterobacter
cloacae
Hafnia alvei
Escherichia coli
Enterobacter
intermedius
Staphylococcus
aureus
Erwinia carotovora
Pseudomonas spp
Erwinia
chrysanthesis
Enterobacter
aerogens
Proteus miriabili
Enterobacter
cloacae
Klebsiella oxytoca
Hafnia alvei
Escherichia coli
Klebsiella
pneumoniae
Bacillus spp
Adebowale et al., / Alexandria Journal of Veterinary Sciences 2016, July. 50 (1): 94-98
97
Table 2. Percentage of E coli O157 isolated from
abattoir effluents and receiving water body.
Sample
Frequency of E coli O157
positive samples (n=50)
( %)
Effluent
4(8.0)
Contaminated Surface
water
4(8.0)
4. DISCUSSION AND CONCLUSIONS
The study revealed that abattoir waste disposal at the
Lafenwa abattoir were observed as open dumps within
and around the abattoir. There were no structured and
adequate drainages. Consequently, effluents were
discharged into the nearby surface Ogun River. Most,
if not all abattoirs in Nigeria uses these methods of
disposal (Adeyemo, 2002). These methods are
currently prohibited in most developed countries
because it provides no safeguard against risks to
human health and the environment. Unfortunately,
improper disposal of domestic or agricultural wastes is
still a huge problem in most developing countries. The
primary food safety risk associated with these methods
of disposal is the potential for pathogen, chemical
contaminants being transferred to humans directly or
through other animals. Scavengers flies, vermin, and
wild birds that feed on these wastes enhance
transmission of diseases such as Lassa fever,
Leptospirosis, Cholera, Salmonellosis (Ekugo, 1998).
The microbial analyses of the waste water and
receiving surface water showed that the mean total
bacteria and total coliform counts exceeded the
Federal Environmental Protection Agency
(FEPA,1999) and World Health Organization (W.H.O,
2004) maximum recommended and permissible limits
of 400cfu/ml and 200cfu/ml, respectively. Previous
studies conducted had shown that the receiving surface
water does not meet international standards and unfit
for meat processing (Adebowale et al., 2010). This
result serves as legible indicator of the extent of the
pollution of the water body used for meat processing at
the abattoir. The presence of Eschericia coli O157 in
both waste water from the abattoir and receiving water
body as well as other pathogens especially the
Enterobacteriaceae (many of which are associated
with gastroenteritis and opportunistic infections in
humans), indicate the need for waste water treatment
before discharge into water bodies after complying
with international limits. Detection of E coli O157
from abattoir effluents was not surprising since, it is
well documented that cattle is the chief reservoir of E.
coli O157 (Zhao et al., 1993., Renter et al., 2003;
LeJeune et al., 2004). E coli O157 is particularly
important giving the low infectious dose of this
pathogen (Prince et al., 2000). E coli O157 has been
recognized as a significant human enteric pathogen
causing sporadic cases and outbreak of infection
(Mead and Griffin, 1998). It is also the cause of life
threatening hemolytic uremic syndrome and
thrombocytopenia in children and the elderly
respectively (Padhye and Doyle, 1997). The risk is
further amplified because the receiving surface water
is also used for recreational activities including
swimming and fishing as well as a source of water for
domestic use by people living around the abattoir. The
prevalence of E coli O157 strains (8%) from the
abattoir waste water and the contaminated river (8%)
in this study poses a major concern as other studies by
various authors in Nigeria, reported lower prevalence
of 0.5 -2% (Agbogu et al., 2005 and Luga, 2006). On
the other hand, a study conducted in Egypt by El-
Gamal and EL-Bahi, 2016 reported 0% E coli O157
from abattoir environmental samples investigated.
The results obtained from the investigation showed
that effluents from the abattoir may constitute potential
hazards to the environment. The use of contaminated
surface water for meat processing by butchers may
portends serious challenges to public health and food
safety. There is therefore an urgent need to encourage
availability of adequate and clean water for meat
processing for the butchers. In addition, on the part of
the government, improvements are needed on
slaughterhouse and abattoir structures and
installations; waste and effluent treatment, potable
water supply and monitoring of abattoir workers to
ensure compliance with best practices. Better waste
disposal methods and modern technology such as
recycling and biogas technology should be adopted to
solve the issues of unhygienic waste disposal methods
that are currently being practiced at the abattoirs.
Policies that prohibit discharge of untreated animal
wastes into water bodies are suggested. Encouraging
and implementing good waste management practices
in abattoirs are important to avoid wastes constituting
persistent environmental, animal and human health
hazards.
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