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SERO-PREVALENCE OF HEPATITIS B SURFACE ANTIGEN AMONG ADULT PATIENTS WITH CLINICAL FEATURES OF LIVER DISEASE IN FEDERAL MEDICAL CENTRE OWERRI.
SUMMARY
Hepatitis B viral (HBV) infection has been reported to be one of the etiological agents for hepatitis, liver cirrhosis and hepatocellular carcinoma. This study was therefore carried out to determine the sero-prevalence of hepatitis B surface antigen (HBsAg), a specific marker of HBV infection among adult patients with clinical features of liver disease in Federal Medical Centre, Owerri.
This study was a hospital-based cross sectional study carried out from February 2007 to June 2007. A total of 140 adult patients with clinical features of liver disease met the inclusion criteria and were consecutively selected for the study. The one hundred and forty patients for the study were made up of three groups: 44 patients with clinical features of hepatitis, 62 patients with clinical features of liver cirrhosis and 34 patients with clinical features of hepatocellular carcinoma. These patients were drawn from the general outpatient and internal medicine departments of the hospital and were aged 15 to 80 years. They consisted of 85 males and 55 females. All the patients were screened for HBsAg after obtaining their consent using rapid qualitative immunochromatographic sero-diagnostic test kits. Data were collected using interviewer administered questionnaires and data analysis was done using software Statistical Package for the Social Sciences. The Chi-Square test was used to assess the significance of differences of categorical variables. Fisher’s exact test, Yates continuity correction and logistic regression analysis were employed where appropriate. In all cases, a p-value of <0.05 was considered statistically significant.
The overall sero-positivity rate was 50.71%. The sero-positivity rates for the three groups of patients were: 38.64% for hepatitis, 45.16% for liver cirrhosis and 76.47% for hepatocellular carcinoma. The age group 21-30 years(p-value=0.048) and drivers(p-value=0.019) were significantly infected. Abdominal distension(86.43%) and ascites(67.14%) were the commonest symptom and sign of liver disease among the study population respectively. This study underscores high prevalence of HBV infection among the study population. Routine screening of adult patients with clinical features of liver disease for HBV infection is recommended. Vaccination programmes for persons at risk of HBV infection is advocated.
TABLE OF CONTENTS
Title page………………………………………………………………………i Declaration……………………………………………………………………ii Certification by supervisors……………………………………………….iii Dedication…………………………………………………………………….iv Acknowledgement…………………………………………………………..v Table of contents…………………………………………………………..vi List of abbreviations and acronyms……………………………………vii List of figures………………………………………………………………..ix List of tables…………………………………………………………………x List of appendices…………………………………………………………xii Summary………………………………………………………………………1 Chapter one: Introduction…………………………………………………2 Chapter two: Literature review…………………………………………13 Chapter three: Materials and methods………………………………..33 Chapter four: Results……………………………………………………..42 Chapter five: Discussion………………………………………………….74 References…………………………………………………………………..89 Appendices………………………………………………………………….98
CHAPTER ONE
INTRODUCTION
BACKGROUND
Hepatitis B virus infection is posing a serious challenge to mankind and has remained a global public health problem1-7. In Nigeria, patients with HBV-related liver diseases are increasingly being diagnosed among hospital patients7. Liver diseases globally pose socio-economic and medical challenges3. Liver disease in adult patients can be caused by a wide variety of benign or life threatening disorders. It is caused by viruses, toxins, drugs and other agents. In general, liver disease presents clinically few distinct patterns: hepatocellular disease and cholestatic (obstructive) disease. Hepatitis B virus causes mainly hepatocellular disease1,2.
In acute liver disease, the etiologies are mainly due to hepatitis virus, toxins or drugs1. The global disease burden of hepatitis B virus (HBV) infection is substantial because of the high HBV-related morbidity and mortality. The socio-economic and medical burdens of HBVrelated liver diseases are alarming. The hepatitis B virus–related liver disease constitutes a serious global public health problem due to its attendant complications. Liver disease is common worldwide with variable geographic incidence due to differences in the major etiological agents3. Chronic HBV and hepatitis C virus (HCV) infections are responsible for the majority of cases of liver diseases globally but the highest risks are in South-East Asia and sub-Saharan Africa where HBV infection is highly endemic4,5. However, HCV is the predominant cause in Southern Europe and Japan while alcoholic liver disease is more common in United States of America(USA)5. The increased risk of chronic HBV infection and horizontal transmission serve to sustain a high prevalence of HBV infection and increased incidence of liver cirrhosis and hepatocellular carcinoma in the environment6,7,8. Hepatocellular carcinoma occurs worldwide but it is highly prevalent in countries of SouthEast Asia and sub-Saharan Africa where HBV infection and high dietary aflatoxin intakes are the main etiological agents1,9.
The clinical course of HBV infection is variable. It may be asymptomatic, symptomatic, recovery phase and progressive disease. Clinical illness due to hepatitis B virus infection is
more severe in adults than in children in whom it is typically asymptomatic1,10. Illness due to HBV infection develops insidiously with an incubation period of 6 weeks to 6 months11. The laboratory course of HBV infection is also variable12. Hepatitis B surface antigen can be found in the serum 30 to 60 days after exposure to HBV infection and it is important to document the disappearance of HBsAg. After an acute infection, about 10% of patients with acute HBV infection have HBsAg positive blood at 6 months, 50% of these patients are antigen free after 6 months while 50% will have active viral replication (HBeAg and HBV DNA positive) and 15 to 20% of them may develop cirrhosis within 5 years13,14. The risk of hepatocellular carcinoma in a patient with liver cirrhosis is 3–5% a year15. More so, the younger a person is at the time of acute infection, the more likely the person to be antigen positive10. A neonate who contracts HBV infection at birth has a 90% likelihood of being antigen positive for life unless the neonate receives HBV sero-vaccination11,16. It has been observed that the mechanism associated with the establishment of persistent HBV infection is age related and infants infected with HBV infection have a 90% chance of becoming chronic carriers with this decreasing to 30% at the age of five, while adults have a 10% chance of developing persistent HBV infection17,18.
The prevalence of HBsAg has been the subject of many studies ever since Blumberg and his associates discovered the antigen in 196619. Prevalence of HBV infection, mode of transmission, human behaviour and socio-cultural practices conspire to mould geographical differences in the epidemiological pattern3,20. The prevalence of HBV infection varies geographically throughout the regions of the world, from high (> 8%), intermediate (2–7%) to low (< 2%) prevalence rates and the predominant route of transmission varies according to the endemicity of HBV infection3. In areas with high endemicity, perinatal transmission is the main route whereas in areas with low endemicity, sexual contact among high risk adults is the predominant route3.
The methods of treatment of chronic hepatitis B infection involve the use of antiviral agents, interferon alfa 2b and combination of antiviral agent and interferon alfa 2b11. The nucleoside analogue lamivudine, 100mg orally daily as a single dose can be used1,11. Hepatitis activity may recur when lamivudine is stopped and long term, perhaps indefinite treatment despite a high rate of resistance over time may be required to suppress the disease when HBeAg sero-conversion does not ensue11. Other antiviral agents that can be used include entecavir and emtricitabine1,11.
Patients with chronic hepatitis B can be treated with recombinant human interferon alfa 2b. The pretreatment variables associated with a sustained loss of virus include high transferase levels, HBeAg and HBV DNA in serum, short duration of infection and active hepatitis histologically11. Interferon alfa 2b has antiviral, immunomodulatory and anti-proliferative properties. Treatment with interferon alfa 2b occasionally eliminates the virus but more often causes loss of HBeAg and appearance of anti-HBe which is associated with decrease viral replication and reduced inflammatory activity11. The recommended dose is 5 million units daily or 10 million units three times a week subcutaneously or intramuscularly for 16 weeks with symptomatic and haematological monitoring11. Treatment can also be done using combination of antiviral agents or an antiviral agent and interferon alfa 2b (adefovir
dipivoxil)1,11.
Prevention of HBV infection involves behavior modification to prevent disease transmission, strict universal precaution in healthcare settings, passive immunoprophylaxis and active immunization. Behavior modification involves avoidance of risk factors such as sharing of needles, changes in sexual practices and institutionalization of screening measures in blood banks, human immunodeficiency virus(HIV), antenatal and sexually transmitted infection(STI) clinics. Standard safety precautions in laboratories and hospitals must be strictly enforced to avoid accidental needle punctures and contact with infected body fluids.
Passive immunoprophylaxis involves the use of hepatitis B immunoglobulins (HBIG) which is a sterile solution of ready-made antibodies against HBV and is prepared from human blood from selected donors who already have a high level of antibodies to HBV infection. It is administered intramuscularly at the dose of 0.06 ml per kilogram body weight. It may be protective or may attenuate the severity of illness if given in large doses within 7 days post exposure followed by initiation of hepatitis B vaccine series21.
Active immunization is an important preventive strategy to decrease the risk of HBV infection. It is indicated for at risk groups who are not already immuned as evidenced by anti-HBs in blood in both low endemic and high endemic areas. Vaccines are ineffective in those already infected by hepatitis B infection1. The first generation of hepatitis B vaccine, an inactive plasma-derived vaccine prepared from carriers of HBV infection and consisting of noninfectious subunits of HBsAg became available in 1982. The second generation of HBV vaccine, a DNA recombinant vaccine produced in yeast cells was available for use in 1986.
The third generation HBV vaccine was a DNA recombinant vaccine produced in mammalian Chinese Hamster Ovary (CHO) cells. Three dose regimen for reduced schedule at 0, 1, 6 months or four dose regimen for rapid schedule at 0, 1, 2, 12 is recommended11. Booster doses are recommended every five years11. Sero-vaccination involving passive and active immunizations is indicated in all infants born to HBsAg positive mothers, after needle stick injury, sexual exposure and liver transplantation1,2.
Stakeholders in health should make concerted efforts to overcome the barriers to hepatitis B immunization by a dedicated HB immunization service. The effectiveness of routine infant hepatitis B immunization in reducing the prevalence of HBV infection has been demonstrated
in a variety of countries and settings8,11,22. However, there are still many challenges to achieve the goal of a dedicated HB immunization service such as poor immunization delivery infrastructure, low coverage and lack of financial sustainability. Therefore, to continue to promote access to HBV vaccines worldwide efforts are needed to support countries to ensure sustained funding for immunization programmes.
STATEMENT OF THE PROBLEM AND PROBLEM ANALYSIS
Hepatitis B virus infection has been reported to be a major cause of morbidity and mortality in patients with liver diseases5-9. Hepatitis B(HB) infection greatly worsens the prognosis of
liver disease patients5-7. Prevalence of liver cirrhosis and hepatocellular carcinoma due to HBV infection has been observed to be on the rise in the hospitals6,7,9. Hepatocellular carcinoma reduces quality of life of patients, increases length of hospital stay, bed disability ratio, loss of manpower, work absenteeism and places great burden on the health care facilities, families and communities.
In some developed countries of the world, there is routine HB vaccination of all persons from 0 to 18 years of age11. Pregnant women are also routinely screened for HBV infection3,4. This helps in the identification of infected pregnant women so that preventive measures could be instituted for their sexual partners, their unborn babies and other family and social contacts. Babies born to such HBV positive women routinely receive HBIG within 12 hours of delivery and before their first breastfeed as well as HB vaccination within 7 days of delivery23. In Nigeria, an endemic area of HBV infection6,7,9,14,18, there is neither routine screening of pregnant women for HBV infection nor adequate routine vaccination of their new born babies;
hence no preventive measures are taken to protect babies born to HBV infected women14,23, their sexual and social contacts. Universal screening and vaccination have been acclaimed as major methods of eliminating chronic HBV infection especially in endemic areas1. Vaccination which is required in areas where HBV infection is endemic and hepatocellular carcinoma common is not being pursued with utmost concern and seriousness in Nigeria. Universal vaccination of all infants in the study centre is not yet being practiced adequately. Hepatitis B virus screening protocol is not been practiced in the study centre’s infant welfare clinics, under-five clinics, school clinics, sexually transmitted infection clinics, healthy men and women clinics. In most of these clinics, hepatitis B vaccination is administered without prior investigation to determine the serostatus of the recipients. These contribute to the continued increase in the spread of HBV infection in the environment.
In recent years, there has been increase in the number of HIV infected patients in the study centre. It has also been shown that HIV and HBV infections share similar modes of
transmission and risk factors1,2. The alliance of the dual infectious diseases has become an emerging problem. Hepatitis B infection is not only more prevalent in Nigeria6,7,9,14,18; it is one hundred times more infectious than HIV infection and is more efficiently transmitted
than HIV infection12,19.
In Nigeria, there is no political will on national HBV infection control programme as is presently being done for HIV infection. There is a dearth of information on HBV infection among the Nigerian populace, their early detection, primary prevention compounded by a rather disturbing absence of any government policy or programme on HBV-related liver disease6,14. Half of patients infected with HBV may not be aware of the infection, never develop symptoms, fail to seek appropriate medical attention but become unwitting chronic carriers therefore eventually progressing to liver cirrhosis and hepatocellular carcinoma1,24. This has been observed to pose a great challenge to the screening protocols of family physicians2.
It has also been observed that there is lack of adequate facilities for both routine and specialized laboratory investigations for the diagnosis and monitoring of HBV-related liver diseases8,9,15. This observation results in under-diagnosis and inadequate continuing care of patients with HBV-related liver diseases.
The cost of treatment of chronic hepatitis B infection is astronomical and unaffordable to most Nigerians; hence no treatment is given despite the ugly sequelae of chronic hepatitis B infection (hepatocellular carcinoma) which is incurable. About a million people globally, therefore die each year from complications of HBV infection that is preventable and treatable25.
This type of study has not been done in Owerri. However, reports from different regions of Nigeria have shown that the trend in HBV-related liver disease is on the rise6,7,9,14,18. There is lack of knowledge of HBV infection and HBV-related liver disease burden in the environment6,14. The knowledge of the existing gap will guide in defining interventional programmes to control and prevent HBV infection and its attendant complications as well as plan for adequate facilities for diagnosis, management and continuing care. The continuing care of patients who are chronic carriers of HBV infection is a management protocol of great concern to clinicians in Nigeria6,7. Surveillance for the development of hepatocellular carcinoma by chronic carriers of HBV infection through regular (every six months) alpha-feto protein test and ultrasonography are not being practiced in the hospital.
The direct and indirect costs of caring for patients with HBV infection and HBV-related liver diseases are high; the goal is therefore to minimize morbidity and mortality while at the same time optimize quality of life and medical costs of these patients. This study will provide data on the burden of HBV infection among the study population and identify risk factors of HBV infection.
RELEVANCE OF THE STUDY TO FAMILY MEDICINE
This study will help to determine the sero-prevalence of HBsAg among adult patients with clinical features of liver disease. This will assist us to appreciate the burden of HBV infection among the study population.
This study will emphasize the need for health education of the study population on the epidemiological characteristics of HBV infection in order to reduce the transmission of the HBV infection at home, school, community and workplace through sharing of contaminated razors and toothbrushes, transfusion of infected blood and sexual contacts. This will elucidate the risk of HBV infection for persons at risk.
The study will provide data on hospital-based sero-epidemiology of HBV infection among patients with clinical features of liver disease so as to compare it with similar hospital-based studies in different parts of the country and the world. This will elucidate the risk of HBV infection for population at risk.
This study will highlight the significance of hospital-based care of patients with HBV-related liver disease. The follow up of adult patients who are chronic HBV carriers with ultrasound and alpha-feto protein assay while administering treatment will reduce morbidity and mortality from liver cancer11,26.
The study will highlight the need to institute preventive measures and strategies to reduce the transmission of HBV infection through screening of at risk persons and population. This will help to reduce the risk of HBV infection through behaviour change modification and intervention, behaviour change communication and application of principles of universal precaution at all levels of healthcare, our homes, schools, communities and workplaces.
This study will generate interest among stakeholders in health on the menace of HBV infection among patients with clinical features of liver disease. The need to conduct sentinel study and the importance of national guidelines that recommend vaccination not only for high risk group but ideally everyone that merits vaccination will be elucidated.
In view of the diverse socio-cultural differences in various parts of the country, it is desirable to carry out this study in Owerri and to describe the epidemiological characteristics of HBV infection among the study population.
AIM OF THE STUDY
This study is aimed at determining the sero-prevalence of hepatitis B surface antigen among adult patients with clinical features of liver disease in Federal Medical Centre, Owerri, and forms the basis of programmes aimed at reducing the morbidity and mortality associated with the infection.
OBJECTIVES
- To determine the sero-prevalence of HBsAg among adult patients with clinical features of liver disease in Federal Medical Centre, Owerri, Imo state.
- To describe the socio-economic and demographic characteristics of the affected patients.
- To determine the risk factors associated with hepatitis B infection among the study population.
- To describe the clinical features of liver disease among the study population.
SERO-PREVALENCE OF HEPATITIS B SURFACE ANTIGEN AMONG ADULT PATIENTS WITH CLINICAL FEATURES OF LIVER DISEASE IN FEDERAL MEDICAL CENTRE OWERRI.
