J. of Advancement in Medical and Life Sciences Volume 6 / Issue 1 ISSN: 2348-294X 1 JOURNAL OF ADVANCEMENT IN MEDICAL AND LIFE SCIENCES Journal homepage: http://scienceq.org/Journals/JALS.php Review Open Access A Review of Pathogenesis, Transmission, Diagnosis and Prevention of Hepatitis B infection Lord Tertese Angahar Department of Microbiology, Federal University of Agriculture P. M. B 2373 Makurdi, Nigeria *Corresponding author: Lord Tertese Angahar, Email: lordlegs365@gmail.com Received: November 12, 2017, Accepted: December 10, 2017, Published: December 10, 2017. ABSTRACT: Hepatitis B infection is caused by the hepatitis B virus (HBV). A double-stranded virus of the hepadnaviridae family. It infects the liver, causing hepatocellular necrosis and inflammation. HBV infection can be either acute or chronic, and the associated illness ranges in severity from asymptomatic to symptomatic, progressive disease. Over two billion people are known to be infected with Hepatitis B virus. Hepatitis B disease is ranked among the ten top killer diseases, with over a million deaths recorded annually from chronic HBV infection and its complications: cirrhosis or primary liver cancer. Liver injury occurs through immune-mediated killing of infected liver cells. Hepatitis B disease has huge health, mortality and economic burden. This review was aimed at contributing to global knowledge on Hepatitis B infection with the objectives of controlling its spread through prevention and vaccination. The review was on the burden and epidemiology of HBV, it’s Pathogenesis, Transmission modes, Signs and symptoms, Risk factors for Hepatitis B, Diagnosis, Drugs approved for the treatment of chronic hepatitis B and prevention of HBV infection. This review noted that HBV vaccination is very effective and remains the best way to prevent Hepatitis B infection. Vaccination should be administered to everyone, but especially those who are at risk. Infants should be vaccinated within 24 hours of delivery. The review noted that avoiding risky behaviours through the practice of safe sex, use of protective hand gloves when handling blood or other body fluids, not sharing personal items like nail cutter, clippers, razors, or toothbrushes, single use of only sterilized disposable needles or body piercing objects, and screening of pregnant women before child delivery are very significant in HBV prevention. Keyword: Acute Hepatitis B, Chronic Hepatitis B, Risk factors, Symptoms, Transmission, Prevention. INTRODUCTION “Hepatitis” means inflammation of the liver. Hepatitis B is a contagious and potentially life threatening liver disease that results from infection with a pathogenic agent; the Hepatitis B virus. The enveloped DNA virus belongs to the family hepadnaviridae [1], its virions are double-stranded particles, measuring 40 to 42 nm in diameter [2]. With a genome of only 3200 base pairs, HBV is one of the smallest DNA viruses known. It has an outer lipoprotein envelope that contains three related envelope glycoproteins (or surface anti-gens) [3]. Hepatitis B virus (HBV) infection may develop to: chronic hepatitis, hepatic cirrhosis, or primary hepatic cancer. Infection with hepatitis B virus (HBV) is a worldwide problem. Over a million deaths are recorded annually from chronic HBV infection and its complications: cirrhosis or primary liver cancer [4]. Liver injury occurs through immune-mediated killing of infected liver cells. The body’s immune response tries to get rid of the virus by killing the infected cells. It is this self-defence mechanism that does most of the damage to the liver over time [5]. HBV is a recognized oncogenic virus that confers a higher risk of developing Hepatocellular Carcinoma Cancer (HCC) [6]. Hepatitis B is a disease of significant health importance. Over two billion people are known to be infected with Hepatitis B virus. Hepatitis B disease is ranked among the ten top killer diseases [7]. Ott et al. [8], reported that more than 2 billion people alive today have serologic evidence of past or present HBV infection, while 250 million are chronically infected and are at risk of developing HBV-related liver disease. It was also reported that 15-40% of chronically infected patients will develop cirrhosis, progressing to liver failure and/or HCC during their lifetime [9]. The prevalence of hepatitis B virus infection is relatively high in Africa, having the second highest number of chronically HBV-infected individuals. Poynad [10], observed that HBV infection varies epidemiographically with Africa, Asia and the Western Pacific accounting for higher infection rates of ≥ 8%, Southern and Eastern Europe with 2 - 7.9 % infection rates, while Western Europe, North America and Australia infection rates lowest (< 2 %). The health and economic burden of hepatitis diseases in Nigeria is enormous, with high mortality. Nigeria is endemic for HBV infection with about 18 million known infected people [11]. Pathogenesis of HBV infection Host–virus interaction, mediated by the adaptive immune response all together determines the outcome of HBV infection [12]. WGO [13], noted that the virus-specific T cell response is one of the key factors in the pathogenesis of HBV infection. The course and outcome of the disease may be influence by viral variants. Hollinger and Liang [14], observed that the effect of host factors on the progression of disease is not well understood. Hepatitis B virus infections rarely become directly cytopathic, except in cases of extreme immune suppression [15]. There is no age specificity in the infection and development of the disease [16]. Acute (self-limiting) infection, fulminant hepatic failure, inactive carrier state, and chronic hepatitis with chances of progression to cirrhosis and hepatocellular carcinoma are the clinical course (but not necessarily sequential) of HBV infection [17]. Adults that acquire acute infection usually recover or can be managed by supportive therapy, but the chronic type is ultimately fatal [18]. The average incubation period of Hepatitis B is 60 to 90 days (range is 40 to 160 days)[19]. HBV replicates in the hepatocytes of humans and other higher primates but does not grow in artificial cell cultures. Kapoor et al.[20], observed that in acute hepatitis B, the disease may last from one to six weeks but may be prolonged and can be fulminate. The