PREVALENCE AND CHARACTERISATION OF FASCIOLA SPECIES FROM SNAILS, SLAUGHTERED CATTLE AND SHEEP FROM MAIDUGURI, GOMBE AND JOS ABATTOIRS, NIGERIA
PREVALENCE AND CHARACTERISATION OF FASCIOLA SPECIES FROM SNAILS, SLAUGHTERED CATTLE AND SHEEP FROM MAIDUGURI, GOMBE AND JOS ABATTOIRS, NIGERIA
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Date
2017-12
Authors
LUKA, Joshua
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Abstract
The prevalence, morphometry and molecular characterisation of Fasciola species from
slaughtered cattle and sheep, and snails from Maiduguri, Gombe and Jos were investigated.
Prevalence of Fasciola spp. was studied by determination of eggs of the parasite in both faeces
and bile, while morphometric description was done using standard keys and descriptions. For
molecular characterisation, the first internal transcribed spacer (ITS-1) of nuclear ribosomal
DNA (rDNA), 28S rDNA and NADH dehydrogenase subunit 4 (NAD4) respectively were
amplified from individual Fasciola isolated from bile duct by polymerase chain reaction (PCR).
All collected snails were subjected to morphological identification using standard keys. The
DNA of Fasciola spp. was similarly characterised in Lymnaea natalensis by the use of 28S
rDNA, while the Lymnaea (Radix) natalensis was characterised by the use of 18S rDNA.
Representative amplicons of both Fasciola spp and Lymnaea natalensis were sequenced, and
NCBI databases were used for sequence homology analysis using BLAST and ClustalW
programs, while phylogenetic analysis was done in ApE and Molecular Evolutionary Genetics
Analysis (MEGA). Combined location prevalence rate was 27.52% for cattle and 11.97% for
sheep. For cattle, sex, age or breed had no significant (p≥0.05) impact on prevalence rate, while
for sheep, only age had an impact, as more adult than young sheep were infected (12.62%
compared to 2.63%). Jos, had a significantly (p<0.05) higher prevalence of 35.43% followed by
Gombe (26.99%), while Maiduguri had the lowest (19.63%). In cattle, there was a negative
association between the number of positive animals and egg per gram of faeces and bile (EPG),
with Maiduguri having a mean EPG of 65.85±13.2 followed by Gombe 45.48± 10.8 and Jos the
least (14.4± 1.34). For sheep, Jos had significantly (p<0.0.010) higher prevalence rate (24.35%)
than both Maiduguri (6.16%) and Gombe (5.52%). Actual mean EPGs were 19.71, 36.34 and
14.47 for the respective locations. For both cattle and sheep, mean EPG were significantly
(p<0.05) higher by the bile sedimentation method than by faecal analysis. For cattle, values were
41.12±5.8 versus 15.72± 3.8, while for sheep values were 50.88±15 versus 8.36±1.9 for bile and
faeces respectively. Month of sampling had a significant (p≤0.05) influence on infection rate
with most animals infected in January - Febuary, being the months with highest infections.
Morphological differences were observed in linear measurements and ratios. Three useful
morphological parameters (BL, CL, CW) and one ratio (BW/BL) showed significant (p<0.05)
variations among samples from the locations, and may therefore be relevant for phenotypic
differentiation of species. The molecular identification using ITS-1, 28S rDNA and NAD4 and
the sequencing revealed the presence of both F.hepatica and F.gigantica in the study areas.
Analaysis of the overall genetic sequence data showed that 64.7% of the sequences of Fasciola
isolates were F. gigantica, while 35.3% were F. hepatica. Of the F.hepatica isolates, 66.6% were
from Jos. The phylogenetic tree constructed based upon the ITS-1 sequences revealed a close
relationship (95-98%) with isolates of F. gigantica from Bukina Faso and South Africa, while
the F. hepatica isolate had 84% identity with that from Iran. The 18S rRNA of Lymnaea
natalensis was identified molecularly at 450bp. The sequences had between 99-100% similarities
among themselves and 98-100% with other deposited reference Lymnaea natalensis sequences.
All our Lymnaea (Radix) natalensis sequences formed a clade different from the clade formed by
other reference sequences. Lymnaea (Radix) natalensis sequences from Nigeria seem to clade
separately from deposited sequences from GenBank. Conclusively, the prevalence of Fasciola
spp indicates a high morbidity in the sampled animals. The study had shown that, a well defined
relationship exists between egg counts in bile and faeces of cattle, but not sheep in this study.
This study also confirmed the presence of F.gigantica and strongly suggests the existence of
F.hepatica for the first time, to the best of our knowledge, using molecular tools. The findings of
the two species of Fasciola (F. hepatica and F.gigantica) may have implications for livestock
and human infections and vaccine types to be developed in the control of fasciolosis in the study
locations and Nigeria.The findings also confirmed the existence of Lymnaea (Radix) natalensis
and its role as intermediate host of Fasciola spp in the study areas. In addition, experimental
infection of different breeds of cattle and sheep with Fasciola spp, complete sequence of the
ITS-1, 28S rDNA, NAD4 of Fasciola spp and 18S rDNA of Lymnaea (Radix) natalensis and
investigation of snails such as Melanoides tuberculata and Biomphalaria pfeifferei as potential
intermediate hosts of Fasciola spp are recommended for further studies.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POST GRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF DOCTOR OF PHILOSOPHY DEGREE IN VETERINARY HELMINTHOLOGY DEPARTMENT OF VETERINARY PARASITOLOGY AND ENTOMOLOGY, FACULTY OF VETERINARY MEDICINE,
AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
Keywords
PREVALENCE,, CHARACTERISATION,, FASCIOLA SPECIES,, SNAILS,, SLAUGHTERED,, CATTLE,, SHEEP,, MAIDUGURI,, GOMBE,, JOS ABATTOIRS,, NIGERIA,