MOLECULAR EPIDEMIOLOGY OF ROTAVIRUSES, ASTROVIRUSES AND ADENOVIRUSES ASSOCIATED WITH GASTROENTERITIS IN CHILDREN IN NORTHWESTERN NIGERIA
MOLECULAR EPIDEMIOLOGY OF ROTAVIRUSES, ASTROVIRUSES AND ADENOVIRUSES ASSOCIATED WITH GASTROENTERITIS IN CHILDREN IN NORTHWESTERN NIGERIA
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Date
2006-10
Authors
AMINU, MARYAM
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Abstract
ABSTRACT
Rotaviruses are associated with ~ 610,000 deaths worldwide and with 33,000 deaths in
Nigeria in children < 5 years of age annually. A study of the epidemiology of rotavirus,
astrovirus and adenovirus infection in children 0-5 years old with gastroenteritis was
therefore undertaken in Northwestern Nigeria where there is little or no information. A
total of 1063 (869 diarrhoeic and 194 non-diarrhoeic) stool specimens were collected
from children attending clinics in Kaduna, Kebbi, Sokoto and Zamfara States from July
2002 to July 2004. Viral antigens were detected by enzyme immunoassay (EIA) and the
different patterns of rotavirus genomic RNA by polyacrylamide gel electrophoresis.
Rotavirus VP7 (G) and VP4 (P) genotyping was carried out by reverse transcriptionpolymerase
chain reaction (RT-PCR). Rotavirus group A antigen was detected in 18%
of the diarrhoeic and in 7% of the non-diarrhoeic specimens. Rotavirus infection
occurred throughout the study period with slightly higher peaks in the dry season.
Children < 2 years old were more vulnerable to rotavirus infection (p < 0.01). There
were statistically significant associations between vomiting (p<0.01), feeding regimen
(p<0.05) and rotavirus infection. There were, however, no statistically significant
associations between sex of the child, type of stool, a child’s socio-economic status and
parents’ level of education, type of drinking water and rotavirus infection.
Sixteen electrophoretic patterns were detected with the ‘long’ predominating (78%).
Three strains exhibited the unusual combination of a VP6 Subgroup I specificity with a
‘long’ electropherotype. VP6 subgroup I + II strain predominated (36%) in this study.
Only 54 (32%) of the 170 rotavirus strains could be assigned a single sero- and
genotype. Of these, the predominant strain was G1 P[8] (46.3%). Six (3%) other strains
could be assigned a single G or P type. Of the remaining 110 rotavirus strains, 47 (28%)
could not be typed and 63 (37%) were mixed infections consisting of 37 different strain
combinations. The most prevalent mixed combination was G1G8 P[6] (15.9%).
Genotypes G9 and G4 occurred only as mixed infections. The most prevalent VP4
genotype was P[6]. Genotypes P[10] and P[14], detected for the first time in Nigeria as
mixed infections, were found in 8.8% and 2.4% of cases respectively.
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A further 282 specimens were randomly selected from the 1063 stool specimens and
screened for astroviruses and adenoviruses using EIA kits. Astroviruses and
adenoviruses were detected in 19% and 22.3% of the specimens respectively. Further
analysis of the adenovirus EIA positive specimen detected Ad40/41 in 8% of the
specimens. Astrovirus infection was more frequent among children 0-24 months old
while adenovirus infection predominated in children 25-36 months old.
The present study indicates that the diversity of strains in Nigeria is much greater than
was previously recognized. The detection of novel unusual VP4 genotypes (P[10] and
P[14]) and the presence of unusual genotypes and mixed infections in this study
underscores the need for a surveillance system for the detection of new rotavirus strains
in Nigeria and in Northwestern region in particular. There is a further need to design
primers specifically for the rotaviruses in Nigeria.
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TABLE OF CONTENTS
Page
Title page i
Declaration ii
Certification iii
Dedication iv
Acknowledgement v
Abstract viii
Table of Contents x
List of Tables xv
List of Figures xix
List of appendices xxi
CHAPTER ONE
1.0 INTRODUCTION 1
1.1 Background Information 1
1.2 Rotavirus: A Leading Agent of Infantile Diarrhoea
Description
A DISSERTATION SUBMITTED TO THE POSTGRADUATE
SCHOOL, AHMADU BELLO UNIVERSITY, ZARIA,
NIGERIA, IN PARTIAL FULFILMENT FOR THE AWARD OF
DOCTOR OF PHILOSOPHY IN MICROBIOLOGY
Keywords
MOLECULAR, EPIDEMIOLOGY, ROTAVIRUSES,, ASTROVIRUSES, ADENOVIRUSES, ASSOCIATED, GASTROENTERITIS, CHILDREN IN NORTHWESTERN