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. ix 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. x 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
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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
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