ABSTRACT

This research work was undertaken to determine the seroprevalence of hepatitis B

virus infection in pregnant women in Kaduna, Kaduna state, Nigeria. The study

population was randomly drawn from women attending antenatal clinics in the three

general hospitals in Kaduna metropolis i.e. Barau Dikko Specialist Hospital, Yusuf

Dantsoho Memorial Hospital and Gwamna Awan General Hospital. Blood specimen

and personal data were obtained from two hundred and seventy four pregnant women

attending the clinics. For this study, three Hepatitis B Virus infection serological

markers : anti-HBs, anti- HBc and HBeAg, were employed using ELISA. The three

assay kits used were AutoBio Anti-HBs Plus, AutoBio Anti-HBc Plus and AutoBio

HBeAg all manufactured by AutoBio Immundiagnostics U.S.A. From the study

population of 274 pregnant women screened for the HBV serological markers, 77

(28.1%) were seropositive for anti-HBs, and 57(20.8%) and 6(2.2%) were seropositive

for anti-HBc and HBeAg respectively. There was no statistical association between

the presence of the hepatitis B virus infection markers and marital status, educational

status, age and number of sexual partners. The seroprevalence rate for the HBV

infection markers increased with increase in educational status, the tertiary group did

not follow this trend. The distribution across age revealed that the frequency of the

anti-HBs infection markers was highest (35.3%) in the 20-24 years age group, and for

anti-HBc the peak was recorded in the 15-19 years age group, this is likely due to the

sexual activity of this age range. Married women accounted for all the 6 (2.4%) that

were seropositive to HBeAg. This survey confirms the presence of hepatitis B virus

infection markers in Kaduna and also illustrates the percentage that lacks the

serological markers which makes them susceptible to HBV infection. This study

provided a baseline for further research on the transmission, surveillance and

intervention strategies of HBV in Kaduna and Nigeria as a whole. Vaccination of all

children against hepatitis B virus irrespective of the serological status of their mothers

and routine screening of pregnant women for these HBV serological markers are

recommended.

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TABLE OF CONTENTS

PAGE

Cover Page i

Fly Page ii

Title Page iii

Declaration iv

Certification v

Dedication vi

Acknowledgement vii

Abstract viii

Table of contents ix

List of figures xiii

List of Tables xiv

List of Appendices xv

CHAPTER ONE INTRODUCTION 1

1.1 Background Knowledge 1

1.2 Statement of Research Problem 4

1.3 Justification 5

1.4 Aims and Objectives 6

1.5 Research Question 7

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CHAPTER TWO LITERATURE REVIEW 8

2.1 Hepadnaviridae 8

2.2 Virologic Features 9

2.2.1 Hepatitis B Virus Structure 9

2.2.2 Viral genes and protein 10

2.3 Viral Replication cycle 11

2.4 Pathogenesis of Hepatitis B 12

2.5 Natural History 14

2.6 Primary infection 15

2.7 Persistent infection 19

2.8 Hepatocellular carcinoma 22

2.9 Transmission of Hepatitis B virus 23

2.10 Prevention of Hepatitis B transmission 24

2.11 Hepatitis B laboratory diagnostic tests 25

2.11.1 HBsAg and Anti-HBs 26

2.11.2 HBcAg and Anti-HBc 26

2.11.3 HBeAg and Anti-HBe 26

2.11.4 HBV DNA 27

2.12 Management of chronic Hepatitis B virus infection 31

2.12.1 Drugs/Agents used in chronic HBV treatment 32

2.12.2 Lamivudine 33

2.12.3 Adefovir 34

2.13 Hepatitis B Vaccine 34

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2.14 Liver transplantation 35

CHAPTER THREE MATERIAL AND METHOD 36

3.1 Area of study 36

3.2 Data Collection 37

3.2.1 Sample size 37

3.2.2 Study Design 38

3.3 Questionnaire administration 38

3.4 Collection of samples 38

3.5 Reagents 39

3.6 Equipment and Materials 39

3.7 Kit components (Anti-HBs) 39

3.7.1 Principle of Assay (Anti-HBs) 40

3.7.2 Test Procedure (Anti-HBs) 41

3.8 Kit Components{Anti-HBc) 42

3.8.1 Principle of Assay (Anti-HBc) 43

3.8.2 Test Procedure (Anti-HBc) 44

3.9 Kit components (HBeAg) 45

3.9.1 Principle of Assay ((HBeAg) 46

3.9.2 Test Procedure ((HBeAg) 46

3.10 Precautions 48

3.11 Data Analysis 49

3.12 Determinations of Cut-off Values and Interpretation of samples’ results 49

3.13 Ethical Consideration 49

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CHAPTER FOUR RESULTS 50

4.1 Results of HBV assays 50

CHAPTER FIVE DISCUSSION 64

CHAPTER SIX SUMMARY CONCLUSION AND RECOMMENDATION 68

References 69

Appendices 78

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LIST OF FIGURES

FIGURES Page

2.1 Typical Serological Course of Acute HBV Infection with Recovery 17

2.2 Typical Serological Course of Progression to Chronic HBV Infection 20

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LIST OF TABLES

TABLES PAGE

2.1 Interpretation of Hepatitis B `laboratory Diagnostic tests 28

2.2 Classic 4 stages of HBV infection 30

4.1 Prevalence by hospitals of Hepatitis B virus infection markers among

pregnant women attending Antenatal Clinics in Kaduna Metropolis 51

4.2 Distribution by educational status of HBV infection markers among

pregnant women attending Antenatal Clinics in Kaduna Metropolis 53

4.3 Marital Status Distribution of HBV infection markers among pregnant

women attending Antenatal Clinics in Kaduna Metropolis 55

4.4 Age Distribution of HBV infection markers among pregnant

women attending Antenatal Clinics in Kaduna Metropolis 57

4.5 Number of Sexual Partners Distribution of HBV infection

markers among pregnant women attending antenatal Clinics

in Kaduna Metropolis 59

4.6 Statistical Association between Anti- HBs and some

Subjects’ Parameters 61

4.7 Statistical Association between Anti- HBc and some

Subjects’ Parameters 62

4.8 Statistical Association between HBeAg and some

Subjects’ Parameters 63

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LIST OF APPENDICES

APPENDICES PAGE

A - Letter requesting permission to collect samples

and data from pregnant women attending ante-natal

Clinics in State-owned hospitals 78

B - Consent to collection of samples and data from

pregnant Women 79

C - A sample of the questionnaire used for data collection 80

D. - Data obtained from HBV analysis and Questionnaire 83

E-G - Determination of Cut-off Values and Interpretation 94

H - Statistical Data Analysis 101

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Chapter 1 INTRODUCTION

1.1 Background Knowledge

Clinical and epidemiologic studies began to differentiate among various types of acute

hepatitis in the decades following world war ll. The groundbreaking studies of

Krugman and colleagues in 1967 firmly established the existence of at least two types

of hepatitis, one of which (then called serum hepatitis, and now called hepatitis B) was

parenterally transmitted. Blumberg and colleagues (1965) while searching for serum

protein polymorphisms linked to diseases identified an antigen (termed Au) in serum

from patients with leukemia, leprosy and hepatitis. Prince and coworkers (1964)

independently identified an antigen (termed SH), while systematically studying

patients with transfusion-associated hepatitis. Further work established that AU and

SH were identical. The antigen represented the hepatitis B surface antigen (HBsAg).

These studies made possible the serologic diagnosis of hepatitis B and opened up the

field to rigorous epidemiologic and virologic investigations (Prince et

al.,1964.,Blumberg et al.,1965.,Prince, 1968., Krugman et al.,1970.,Ganem and

Prince, 2004).

Hepatitis B virus (HBV) is transmitted mainly by the percutaneous routes (e.g., needle

sharing, acupuncture, ear piercing, tattooing) and through very close personal contact

involving the exchange of blood or secretions (e.g., sexual contact, childbirth). It is

also transmitted through other body fluids including semen and saliva. The virus starts

to replicate within three days of its acquisition, symptoms may not be observed for 45

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days or longer, depending on the infectious dose, the route of infection, and the person

(Kao and Chen, 2002). The virus replicates in hepatocytes with minimal cytopathic

effects, after which infection proceeds for a relatively long time without causing liver

damage (i.e., elevation of liver enzyme levels) or symptoms (Blum et al;1989., and

Murray et al.,1998).

The clinical course of hepatitis B virus infection is complex and is influenced by

several factors classified into viral factors and host factors. The viral factors include

level of hepatitis B virus replication (viral load), hepatitis B virus genotype, and

mutations in viral genome. The host factors include age of acquisition of infection,

immune status, concurrent infection with other hepatotropic viruses, and alcohol

intake (Aggarwal and Ranjan, 2004). Overall, chronic hepatitis progresses to end stage

liver disease in 15 to 40 percent of patients (Liaw et al; 1988).

For a successful infection, Hepatitis B virus requires an infectious source, a

susceptible host, and an established route of transmission (Kao and Chen, 2002). The

predominant routes of transmission in various locations vary according to the

endemicity of HBV infection. The virus is 100 times more infectious than human

immunodeficiency virus (HIV) and unlike HIV, it can live outside the body in dried

blood for longer than a week (Ott, 1999; Kirchner and Lin, 2004).

The most efficient way to control hepatitis B is to prevent individuals from contracting

it rather than treat the infections. Two main approaches lead to achieving this goal:

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interrupting the virus at the various routes of transmission and immunizing susceptible

host. Although immunization is more effective, public health measures should include

both approaches. Prevention strategies must include Hepatitis B vaccination of high

risk groups and all new born infants, screening of blood and blood products before

transfusion, using universal precautions in healthcare settings like avoid sharing

needle among injecting drug users and promote safe sexual practices (Chen, 2005).

In the early 1980s, vaccination against hepatitis B became available, first with plasmaderived

vaccines and then with recombinant DNA vaccines. All these vaccines are

safe and have a protective efficacy of approximately 95%. Despite this success, the

duration of protection afforded by hepatitis B vaccination is unknown (Chen, 2005).

Detecting persistent antibody is the easiest but not necessarily the most accurate way

to measure persistent protection ( West et al; 1996.,Chen, 2005).

The implications of hepatitis B in pregnancy cannot be over emphasized. Hepatitis B

virus can be transmitted from mother to child in utero. The sequelae of infection in

children can be phenomenal (Owusu-Boateng, 2002). The exact mechanism of

perinatal transmission is not clear. It is unusual for infants to be infected in utero, cord

blood is usually negative for hepatitis B markers; however occasional intrauterine

infection does occur (Ko et al;1994).

The serological markers that define the state of hepatitis B infection include Hepatitis

B surface antigen (HBsAg), antibody to hepatitis B surface antigen (anti-HBs),

hepatitis B core antigen (HBcAg), antibody to hepatitis B core antigen (anti-HBc),

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hepatitis B e antigen (HBeAg), antibody to hepatitis B e antigen (anti-HBe). The

presence of anti-HBs indicates past infection and immunity to HBV, it also means

presence of passive antibody from hepatitis B immunoglobulin (HBIG), immune

response from HBV vaccine. Antibody to hepatitis B core antigen (anti-HBc) indicates

infection with HBV at some undefined time in the past, they could be asymptomatic

carriers. Hepatitis B e antigen is associated with the nucleocapsid; it circulates as

soluble antigen and indicates ongoing viral replication (Brooks et al;2004). These

markers when assayed for in pregnant women will assess the possibility of

transmission to neonates. Women who are HBsAg negative may be vaccinated safely

during pregnancy (Lin et al;2004) . No current evidence supports the use of cesarean

delivery to reduce vertical transmission of HBV (Lin et al; 2004). Vaccination of

hepatitis B carrier mothers, which is standard practice in many endemic areas of the

world has prevented more than 90% of this transmission (Brooks et al;2004, Lin et al;

2004).

1.2 Statement of Research Problem

Hepatitis B virus infection is a global public health problem with approximately 400

million people chronically infected (Lin et al; 2004). An estimated one third of the

world’s population has serologic evidence of past infection, and the virus causes more

than I million deaths annually (Zuckerman and Zuckerman, 1999).

In Sub-Saharan Africa HBV, infection usually is acquired through maternal-fetal

transmission or in early childhood leading to a high prevalence of chronic infection

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(Aggarwal, 2004).A proportion of people infected with hepatitis B Virus (5%-10%)

among adults progress to chronicity, defined as persistence of infection for more than

six months (Aggarwal and Ranjan, 2004). The rate of chronicity is much higher

among neonates born to hepatitis B infected mothers and children because they have

an immature immune system. Ninety percent of infants infected perinatally progress to

chronic infection. Progression to chronic HBV infection occurs in 25 to 30 percent of

persons infected before five years of age, and in 3 to 5 percent of those infected later

in childhood or as adults (Lok, 2001). Once the infection becomes chronic, HBV or

part of the viral genome usually persists a lifetime in the liver of the carrier. The

carriers are not only reservoirs of the virus but also victims of chronic liver diseases

themselves (Kao, 2002; Chen, 2003 ). Thus, control of HBV infection, especially in

terms of preventing chronic carrier status of the virus, is extremely important (Ganem

and Prince, 2004).

Moreover, the higher prevalence of chronic infection due to maternal-fetal

transmission also translates into higher rates of cirrhosis and cancer in these areas.

Treatments are not curative because they rarely produce permanent remission of the

disease (Lin et al; 2004).

1.3 Justification

Transmission of HBV from mother to child, (vertical transmission), is associated with

a greater probability of generating carrier status and consequently of maintaining the

chronic infection in the population. Some authors observed that the proportion of

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carriers among children born to mothers with a history of HBsAg seropositivity can

range between 70% and 90% (Saenz-Gonzalez, 2001; Vazquez-Martinez et al; 2003).

In 1981, the prevalence rate of HBsAg carrier state in Nigerian pregnant women was

determined to be 11.2% (Ayoola et al; 1981). Recent studies that describe the

magnititude of the problem in Nigeria are limited. Seroepidemiologic studies for

pregnant women carried out revealed a wide range of prevalences for HBV infection

markers ranging from 15.8% to 22.0% in Maiduguri (Harry et al;1994 and Baba et

al;1999), 2.19% for Benin city (Onakewhor et al; 2001), 9.3% for Anambra State

(Agbonlahor et al; 2004), 10.4% for Gombe (Mustapha and Jibrin, 2004). Screening

for hepatitis B virus infection serological markers in all pregnant women bases

prevention of perinatal transmission on seroprevalence studies which provide direct

outcome measure of program effectiveness (AJPH, 1999).

Seroprevalence studies help to identify those at greatest risk of infection and therefore

assist in effectively targeting prevention strategies (AJPH, 1999).

Kaduna, the commercial and industrial centre of Northern Nigeria with a population of

approximately 1,580,000 has no prevalence of HBV infection markers.

1.4 Aims and Objectives

The objective of this study is to:

1. To determine the seroprevalence of hepatitis B infection in pregnant women in

Kaduna, as well as the risk factors associated with its occurrence.

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1.5 Research Question

This work was therefore designed to answer this question:

1. What is the baseline hepatitis B seroprevalence rate among pregnant women in

Kaduna, Kaduna state?

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