Explanation of some abbreviations
Literature review of HBsAg
1. To study the occurrence of HBsAg among pregnant women in this locality.
2. To study the possibility of implementing routine HBsAg screening among pregnant women.
3. To study the classification of HBsAg of this locality into high, intermediate or low carrier status according to World Health Organization classification of HBsAg.
Limitations: α-fetoprotein assay, HBeAg and ultrasound scanning were not done.
Keywords: Epidemiology, Hepatitis B surface antigen, Pregnancy,
A total of 83 pregnant women of Porto Novo were studied for HBsAg infectivity within the time period of 26th July to 30th August, 2012, during their first visit to the antenatal section- Hospital of Porto Novo. The age of the pregnant women studied range from 15 years to 46 years old.
The results of 1.2% were reported for HBsAg positivity among pregnant women of multigravid. They values of transaminase recorded at various stages were not statistically significant.
In conclusion, immunization of all infants, education of the general public and healthcare providers, and more research studies, among others, were advised for the elimination of hepatitis B virus infectivity in this region.
Keywords: Seroepidemiology, Hepatitis B surface antigen, Pregnancy,
Explanation of some of the Abbreviations used in this project
HBV: Hepatitis B virus, a double-shelled DNA virus of the Hepadnaviridae family.
HCC: Hepatocellular carcinoma or primary liver cancer- a major complication of chronic HBV infection; usually fatal.
Hep B3: The third and final dose of Hepatitis B vaccine three doses are recommended for full protection.
Perinatal transmission: Transmission from mother to child at the time of birth.
Seroprevalence: Percentage of a population whose sera are positive for a specific marker such as an antibody, for example; anti-HBs or anti-HBc or an antigen, for example; HBsAg or HBeAg.
RNA: Ribonucleic Acid
DNA: Deoxyribonucleic Acid
MHC: Major Histocompatibility complex
IFFCC: International federation of Clinical chemistry
Anti HBc: Antibodies against Hepatitis B core antigen
Anti HBs: Antibodies against Hepatitis B surface antigen, the presence of which indicates protection (either following infection or immunization)
Cirrhosis: Chronic infection and scarring of the liver as a result of chronic inflammation of the liver.
Chronic carrier: Person with long-term HBV infection defined as persistence of HBsAg in the blood for more than six months.
Hep B: A liver inflammation caused by the Hepatitis B virus.
HBcAg: Hepatitis B core antigen, a protein found in the core of HBV.
HBeAg: Hepatitis B e antigen, the presence of which implies active viral replication, thus making it a marker of greater infectivity in chronic infection.
HBsAg: Hepatitis B surface antigen; a protein from the virus coat. Its presence in the blood indicates current infection (acute or chronic).
BCG: Bacillus Calmette Guerin (Vaccine).
DTP: Diphtheria-Tetanus-Pertussis (Vaccine).
EPI: Expanded Program on Immunization.
FIC: Fully Immunized Child.
HBIG: Hepatitis B immune Globulin.
Hib: Haemophilus Influenzae type b (Vaccine).
OPV: Oral Polio vaccine
SIGN: Safe injections Global Network.
VVM: Vaccine vial monitor.
to Hepatitis B surface Antigen
Hepatitis is a general term which means inflammation of the liver and this inflammation could be caused by different types of hepatitis; A, B, C, D and E. Of the many viral causes of human hepatitis, hepatitis B and hepatitis C are of global medical importance, Hollinger, FB et al (2001). The development of jaundice is a significant feature of liver disease; a laboratory diagnosis could be made by testing the patients´ sera for the presence of specific anti- viral antigens or antibodies. Hepatitis B is a serious and common infectious disease of the liver affecting millions of people worldwide, Chisari, FN et al (1997). The severe pathological consequences of persistent HBV infections include; the development of chronic hepatic insufficiency, cirrhosis, and hepatocellular carcinoma. Furthermore, HBV carriers can transmit the disease for many years, Robinson, WS (1994).
Every year, there are over 4 million acute clinical cases of HBV, and about 25% of carriers, a million people a year dies from chronic active hepatitis, cirrhosis or primary liver cancer, World Health Organization (2001). Hepatitis B has been correctly called type B hepatitis, Serum hepatitis, Homologous serum Jaundice, Mahoney FJ Kane M (1999).
Causes of Hepatitis B
Hepatitis B is caused by hepatitis B virus (HBV), an enveloped virus containing a partially double stranded, circular DNA genome and fall into the family, Hepadnavirus. The virus interferes with the functions of the liver while replicating in hepatocytes. The immune system is then activated to produce a specific reaction to combat and possibly eradicate the infectious agent. As a consequence of pathological damage, the liver becomes inflamed. HBV may be responsible for about 80% of all cases of hepatocellular carcinoma worldwide, only second to tobacco among known human carcinogens, (Viral Hepatitis Prevention Board, 1996).
Spreading of Hepatitis B Virus
The majority of the people infected looks perfectly healthy and have no symptoms at all. HBV is transmitted through percutaneous or parenteral contact with infected blood, transmission associated with injection and blood transfusion, body fluids, child to child, and by sexual intercourse, Gitlin N (1997). HBV is able to remain on any surface it comes into contact with, for about a week, example, table tops, razorblades, blood stains, blades used in local circumcision, used needles, without losing its infectivity. HBV is a large virus and does not cross the placenta; hence it cannot infect the fetus, unless there is a breakage in the maternal- fetal barrier. Still, pregnant mothers who are infected with HBV can transmit their disease to their fetus at birth. If these fetuses were not vaccinated at birth, many of them will develop life-long HBV infections and yet many will develop liver failure or liver cancer later in life. Sexual intercourse with multiple partners makes the person prone to a danger of contamination and HBV is the only sexually transmitted infection for which there is a protective vaccine, Mahoney FJ & Kane M (1999). All persons who are HBV positive are potentially infectious. The many millions of people around the world who become HBV carriers are a constant source of new infections for those who have never contracted the virus.
Perinatal Transmission of HBV
Perinatal transmission from mothers infected with HBV to newborn infants is a major way of HBV infection in some countries, Okada K et al (1976). This happens at the time of birth; in-utero transmission is relatively rare, accounting for up to 2% of perinatal infections in most research studies, Wong VC et al (1984). The danger of perinatal transmission depends on the presence of hepatitis B e antigen (HBeAg) in the blood of mothers infected with HBV. The risk of chronic HBV infection is in the approximate range of 70% to 90% from such mothers, who are HBeAg positive and about 5% to 20% from those who are HBeAg negative, Margolis et al (1997).
Child to child transmission
The spread of HBV from child to child accounts for most HBV infections, Martinson FE et al (1998). Transmission usually happens in household settings but could also happen in child day care centers and in schools. The mechanisms of child to child spread include; contact of skin sores, small breaks in the skin, mucous membrane with blood or skin sore secretions. HBV may also spread due to contact with saliva by bites or other breaks in the skin, Beasley & Hwang (1983).Furthermore, the virus may spread from inanimate objects such as shared towels or toothbrushes.
Transmission associated with injection and blood transfusion
Unsafe injection practices are a major source of transmission of HBV and other blood borne pathogens in many countries, Simonsen L et al (1999). Blood transfusion is a major source of HBV transmission in countries where the blood supply is not screened for HBsAg due to financial restraints. However, in many developing countries, up to 50% of injections are administered with needles and syringes that are reused without adequate sterilization. A substantial proportion of therapeutic injections, accounting for approximately 90% of the estimated 12 billion injections administered each year throughout the world are really unnecessary. Injectable medications given in primary care settings can be administered via oral, stated by Drs. Hutin & Chen (1999). Unsatisfactory injection control practices including the reuse of contaminated medical or dental equipment, failure to use appropriate disinfection and sterilization practices for equipment and environmental surfaces, and improper use of multidose medication vials can result in the transmission of HBV and other blood borne pathogens. Finally, the injection of illicit drugs is a common mode of HBV transmission in some countries.
HBV is efficiently transmitted by sexual contact, which can account for a high proportion of new hepatitis B infections among adolescents and adults in countries with low and intermediate endemicity of chronic HBV infection reported by Drs. Alter MJ & Margolis HS (1990). In countries where HBV infection is highly endemic, sexual transmission does not account for a high percentage of cases because persons are already infected during childhood.
Persons at risk
The general public is at risk. Only persons who have been vaccinated successfully or those who have developed anti-HBs antibodies after HBV infection are immune to HBV infection. Persons with congenital or acquired immunodeficiency, including HIV infection, and those with immunosuppression, including those with lymphoproliferative disease, and patients treated with immunosuppressive drugs and patients on hemodialysis are more likely to develop persistent infection with HBV. Following acute HBV infection, the risk of developing chronic infection varies inversely with age. Chronic HBV infection occurs among about 90% of infants infected at birth, 25 to 50% of children infected at 1 to 5 years of age and about 1 to 5% of persons infected as older children and adults, Robinson WS (1995).
Globally, the world can be divided into three areas where the prevalence of chronic HBV infection is high (≥8%), intermediate (2 to 8%), and low (≤2%), Mahoney FJ & Kane M (1999). High prevalence areas are South- East Asian and the pacific Basin (excluding Japan, Australia and New Zealand), Sub-Sahara Africa, the Amazon Basin, parts of the Middle East, the Central Asian Republics and some countries in Eastern Europe. In these areas, about 70 to 90% of the population becomes HBV infected before aged 40 and 8 to 20% of people are HBV carriers, Hollinger FB (2001).
China, Senegal, and Thailand, infection rates are very high in infants. In some countries such as Panama, Papua New Guinea, Solomon Islands and Greenland, infection rates in infants are relatively low, but increase rapidly during early childhood. Low endemicity areas include; North America, Western and Northern Europe, Australia and parts of South America. The carrier rate here is less than 2% and less than 20% of the population is infected with HBV, Hollinger FB (2001). The rest of the world falls into intermediate range of HBV prevalence, with 2 to 8% of a given population being HBV carriers.
Life Cycle of Hepatitis B Virus
The HBV binds to a receptor at the surface of the liver and other receptors include, transferring receptors, the asialoglycoprotein receptors and liver endonexin. Although, the mechanism is not known, viral nucleocapsids enter the cell and reach the nucleus where viral genome is attached. In the nucleus, second strand DNA synthesis is completed and the gaps in both strands are repaired to yield a covalently closed circular supercoiled DNA molecule that serves as a template for transcription of RNAs.