Hepatitis B Virus is a potentially life-threatening liver infection. It is a major global health problem and the most serious type of viral hepatitis (WHO, 2012).
In 2004, an estimated 350 million individuals were infected worldwide. National and regional prevalence ranges from over 10% in Asia to under 0.5% in the United States and northern Europe. Routes of infection include vertical transmission, early life horizontal transmission (bites, lesions, and sanitary habits), and adult horizontal transmission (sexual contact, intravenous drug use) (Custer et al., 2004).
The primary method of transmission reflects the prevalence of HBV infection in a given area. In low prevalence areas such as the continental United States and Western Europe, injection drug abuse and unprotected sex are the primary methods, although other factors may also be important (Redd et al., 2007).
In moderate prevalence areas, which include Eastern Europe, Russia, and Japan, where 2-7% of the population is chronically infected, the disease is predominantly spread among children. In high prevalence areas such as China and South East Asia, transmission during childbirth is most common, although in other areas of high endemicity such as Africa; transmission during childhood is a significant factor (Alte, 2003).
The prevalence of HBsAg in Egypt is of intermediate endemicity (2-8%) (Attia, 1998). Nearly 2-3 million Egyptians are chronic carriers of HBV. In Egypt, it appears that HBV transmission is a mixture of perinatal and horizontal transmission. However, the majority of HBV infection is acquired by horizontal transmission (Hyams et al., 1998).
HBV genotype D is the prevalent genotype in Egypt. The clinic impact of HBV genotype D has been studied less extensively, however, initial studies have found that it may be associated with lower rates of sustained remission and HBsAg clearance and more severe liver disease compared with genotype A (Asnchez et al., 2002).
Emerging evidence suggests that patients with genotype D infection may develop fulminant hepatitis with high frequency (Wai et al., 2005). A study from India indicated that genotype D is more often associated with HBeAg-negative chronic hepatitis (CHB), more severe disease and may predict the occurrence of hepato-cellular carcinoma (HCC) in young patients (Thakur et al., 2002).
Hepatitis B Virus is a member of the Hepadnavirus family (Zuckerman, 1996).
The virus is transmitted by exposure to infectious blood or body fluids such as semen and vaginal fluids (Coopstead et al., 2010). Other risk factors for developing HBV infection include working in a healthcare setting, transfusions, and dialysis, acupuncture, tattooing, extended overseas travel and residence in an institution (Sleisenger et al., 2006 and Kidd-Liunggren et al., 2010).
Vertical transmission is a major source; investigations in Taiwan estimated that 40% to 50% of HBsAg carriers became infected in the perinatal period (Stevens et al., 1975 and Beasley et al., 1982). The potential for vertical transmission of HBV at birth is significant. Most of infants born to carrier mothers are HBsAg-negative at birth experience seroconversion in the first 3 months after delivery, suggesting acquisition of the virus at birth (Lee et al., 1978).
Mothers positive for both HBsAg and HBeAg are at highest risk for transmitting the virus; 85% to 100% of their offspring become infected, with 70% to 90% becoming chronic carriers. Mothers who are HBsAg-positive but HBeAg-negative, presumably indicating lower levels of replicating virus, do have a lower risk of transmitting the virus, but up to 35% of their children still will become carriers in the absence of neonatal therapy (Biswas et al., 1989).
A positive HBsAg result in early pregnancy should be followed-up by tests for liver functions, as well as HBeAg and HBeAb ; HBcAb is not helpful in distinguishing acute from chronic disease, and HBsAb rarely is present if HBsAg is still circulating. Repeating the tests for HBsAg and liver function later in pregnancy, however, does help to make the diagnosis and guide the need for perinatal prophylaxis of the neonate. (Lin et al., 1987).
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