CHAPTER ONE

INTRODUCTION

Hepatitis B virus (HBV), a DNA virus of the family hepadnaviridae is the causative agent of hepatitis B infection [1].  HBV infects humans and is highly contagious, more so than HCV or human immunodeficiency virus (HIV).  HBV is transmitted by parenteral or mucosal exposure to infected blood and serous fluid, where its concentration is the highest, and body fluids such as semen and vaginal fluid. Common routes of infection include mother to infant, child to child, unsafe injection practices, sexual contact, and blood transfusions [2].  The global burden of HBV remains high, with about 2 billion people exposed worldwide and about 350 million individuals with chronic infection who may be at risk for complications of liver cancer or progressive liver disease. Hepatitis B is estimated to be the cause of 30% of liver cirrhosis and 53% of hepatocellular carcinoma (HCC) worldwide, with an estimated 600,000 deaths each year can be attributed to acute or chronic HBV infection [3].

Hepatitis B virus (HBV) infection is a global public health problem affecting millions of people every year and causing disability and death [52]. Globally, it is estimated that approximately 257 million people are infected, particularly in low-income and middle-income countries [53]. About 1 million people die each year (~2.7% of all deaths) from causes related to viral hepatitis, mostly liver disease including liver cancer and cirrhosis [54]. Hence, it is considered the tenth leading cause of death worldwide [55]. Despite the increasing seroprevalence, there is no routine screening of high risk groups in most countries because of lack of public awareness, inadequate funding for health care settings, and the expensive nature of the test [56] . Though the lifetime risk of contracting HBV in the general population is 4.8%, this can be reduced significantly through vaccination. For example, infant vaccination reduces this value by 68%, while adolescent vaccination reduces it by 45% [57]. Health care personnel (including Medical and Paramedical students) are at an unavoidable higher risk of contracting blood borne pathogens like HBV due to their interaction with patients [58]. Fortunately, Hepatitis B virus vaccine has been present for over three decades to prevent this well-known occupational disease [55]. Immunization is achieved in 95% of the population following the administration of three doses of HBV vaccine at zero, first and the sixth month respectively.

This vaccine is meant to prevent HBV infection and its associated liver complications [60]. all those vaccinated need a booster dose of the vaccine after 10-15 years since the antibody titer declines with time [59]. The vaccine is produced following the purification of HBsAg obtained from the plasma of persons with chronic HBV infection [60]. To achieve this, the vaccine must trigger an immune response which would produce anti-HBs at a concentration of >10 IU/mL at least 1 month and at most 2 months after the 3rd dose [61]. About 5% – 15% of vaccines may not develop the expected immune response following the complete dose administration of the vaccine [62]. Usually, about 30% – 50% of people who do not respond to a primary 3-dose vaccine series with anti-HBs concentrations of >10 IU/mL, may respond to an additional vaccine dose or to a 3-dose revaccination series [63]. Vaccination coverage of healthcare personnel (HCP) and the general population against this virus remains low especially in some developing countries. For example; research to determine the prevalence and vaccination coverage against HBV among HCP
in Cameroon of a seroprevalence survey, only 199 (11.4%) of the 1747 participants were fully vaccinated [64].

1.1. Problem Statement

Hepatitis B virus (HBV) infection is a global public health problem [19,20]. Worldwide estimates suggest that more than 2 billion people have been infected with HBV, and that 248 million of these people are chronically infected (defined as hepatitis B surface antigen [HBsAg] positivity) [21] About 15% to 25% of persons with chronic HBV infection die from cirrhosis or liver cancer [21]. The Global Burden of Disease study estimated that there were 686,000 deaths caused by hepatitis B in 2013 and a 5.9 per 100,000 age-standardized death rate globally [22], of which 300,000 deaths were attributed to liver cancer and 317,400 deaths to cirrhosis of the liver secondary to hepatitis B [22] Infectious diseases are commonly transmitted from person to person by direct indirect contact. Transmission occurs when an infected person touches or exchanges body fluids with an uninfected person and this can happen when the infected person is asymptomatic.

 In 1991, the Global Advisory Group of the Expanded Programme on Immunization (EPI) recommended integration of hepatitis B vaccination into national immunization programs by 1995 in countries with an HBV carrier prevalence of 8% or higher, and by 1997 in countries with a lower prevalence [46] By the end of 2014, hepatitis B vaccine had been introduced worldwide in 184 countries [47].

The policy in Cameroon requires HBV vaccination of children at 6 weeks, 10 and 14 weeks of age and the vaccine has a lifespan of about 15 years. Hence, people above 15 years of age are liable to having the infection.

To eliminate HBV transmissions, specific efforts to create awareness of the infection and to vaccinate populations will have to be made such as health education campaigns, the solicitation of government assistance for the provision of vaccines and high levels of vaccination coverage need to be sustained or even increased. Many people are not vaccinated as seen in research to determine the prevalence and vaccination coverage against HBV among HCP in Cameroon of a seroprevalence survey, only 199 (11.4%) of the 1747 participants were fully vaccinated [64], and are risk of contracting the infection.

1.2. Research Question

• What is the know Knowledge and the degree of Awareness of Risk factors of hepatitis B Virus infection amongst adults in Nitob 1 community, Mankon-Bamenda?
• What is the Knowledge and the degree of Awareness of vaccination against hepatitis B Virus infection amongst adults in Nitob 1 community, Mankon-Bamenda?
• What is the Vaccination Status of adults in Nitob 1 community, Mankon-Bamenda?
• What is the prevalence of Hepatitis B virus infection amongst adults in Nitob 1 community, Mankon-Bamenda?

1.3. Hypothesis

There is low vaccination coverage and a high risk of hepatitis B Virus infection amongst adults in Nitob 1 community, Mankon-Bamenda

1.4. General Objectives

To determine Vaccination coverage and the risk of hepatitis B Virus infection amongst adults in Nitob 1 community, Mankon-Bamenda

1.4.1. Specific Objectives

1. To determine the prevalence of hepatitis B Virus infection amongst adults in Nitob 1 community, Mankon-Bamenda
2. To assess the Knowledge and the degree of Awareness of Risk of hepatitis B Virus infection amongst adults in Nitob 1 community, Mankon-Bamenda
3. To assess the Knowledge and the degree of Awareness of vaccination against hepatitis B Virus infection amongst adults in Nitob 1 community, Mankon-Bamenda?
4. To evaluate the Vaccination Status of adults in Nitob 1 community, Mankon-Bamenda