Hepatitis B
Hepatitis B(formerly known as “serum” hepatitis) is an acute systemic infection with major pathology in the liver, caused by hepatitis B virus and transmitted usually by the parenteral route. It is clinically characterized by a tendency to a long incubation period and a protracted illness with a variety of outcomes. Usually it is an acute self-limiting infection, which may be either sub-clinical or symptomatic.
Problem statement :
Hepatitis B is endemic throughout the world, especially in tropical and developing countries and also in some regions of Europe. Its prevalence varies from country to country and depends upon a complex mix of behavioral, environmental and host factors. In general, it is lowest in countries or areas with high standards of living.The HBV infection is a global problem, with 66% of all the world’s population living in areas where there are high levels of infection.
More than 2 billion people world wide have evidence of past or current HBV infection and 350 million are chronic carries of the virus, which is harboured in the liver, the virus causes 60-80% of all primary liver cancer, which is one of the three top causes of cancer death in East and SEAR(South- East Asia Region), the Pacific Basin and Sub-Saharan Africa.
Agent Factors:
a) Agent:
Hepatitis B virus was discovered by Blumberg in 1963. Efforts to grow this virus have been so far unsuccessful. HBV is a complex, 42-nm, double standard DNA virus, originally known as the “Dane particle”. It replicates in the liver cells.
b)Reservoir of infection:
Man is the only reservoir of infection which can be spread either from carriers or from cases. The continued survival of infection is due to the large number of individuals who are carriers of the virus, estimated to number over 350 million world-wide.c)Infective material:
Contaminated blood is the main source of infection, although the virus has been found in body secretions such as saliva, vaginal secretions and semen of infected persons.d) Resistance:
The virus is quite stable and capable of surviving for days on environmental surfaces. It can be readily destroyed by sodium hypoclorite, as is by heat sterilization in an autoclave for 30 to 60 minutes.e) Periods of communicability:
The virus is present in the blood during the incubation period(for a month before jaundice) and acute phase of the disease. Period of communicability is usually several months(occasionally years in chronic carriers) or until disappearance of HBsAg and appearance of surface antibody.
Host factors:
a) Age:
In countries in which infection with HBV is relatively uncommon, the highest prevalence of the surface antigen is found in the 20-40 year age group. In countries, where infection with HBV is common, much infection occurs perinatally or during early childhood.b) High risk groups:
Certain groups carry higher risks. For example, in USA., the annual incidence of HBV infection in surgeons is estimated to be 50 times greater than that in the general population, and is more than twice that of other physicians. Other high risk groups comprise recipients of blood transfusions, health care and laboratory personnel, homosexuals, prostitutes, percutaneous drug abusers, infants of HBV carrier mothers and patients who are immuno-compromised.c) Humoral and cellular responses:
Antibodies form in a week or two after onset of jaundice- the order being, first core antibody, then “e” antibody and much later surface antibody.Mode of transmission
a) Parenteral route:
HBV is essentially a blood-borne infection. It is transmitted by infected blood and blood products through transfusions, dialysis, contaminated syringes and needles, pricks of skin, handling of infected blood, accidental inoculation of minute quantities of blood such as may occur during surgical and dental procedures, immunization, traditional tattooing, ear and nose piercing, acupuncture, etc.b) Perinatal transmission:
Spread of infection from HBV carrier mothers to their babies appears to be an important factor for the high prevalence of HBV infection in some regions, particularly China and SE Asia.The mechanism of perinatal infection is uncertain. Infection of the baby is usually anicteric and is recognized by the appearance of surface antigen between 60-120 days after birth.c) Sexual transmission:
The sexually promiscuous, particularly male homosexuals, are at very high risk of infection with hepatitis B.d) Other routes:
Transmission from child to child, often called horizontal transmission. The researchers believe that the spread occur through physical contact between children with skin conditions such as impetigo and scabies, or with cuts or gazes. Often transmission occur when children play together or share the same bed.Phases of HBV infection:
There are three phases of HBV infection:1. The incubation period for HBV is 4 to 10 weeks during which patients are highly infective.
2. This is followed by a symptomatic phase with intermittent flares of hepatitis and marked increases in aminotranferase serum levels.
3. The final phase is seroconversion to anti-hepatitis B core antigen(anti-HbcAg).
• Patients who continue to have detectable hepatitis B surface antigen (HbsAg) and a high serum titer of HBV DNA for more than 6 months have chronic HBV.
Clinical Presentation:
• Easy fatigability, anorexia, anxiety and malaise• Ascites, jaundice, variceal bleeding, and hepatic encephalopathy can manifest with liver decompensation
• Hepatic encephalopathy is associated with hyper-excitability, impaired mentation, confusion, obtundation( altered level of consciousness) and eventually coma
• Vomiting and seizures
Physical Examination:
• lcteric sclera, skin and secretions.• Decreased bowel sounds, increased abdominal girth, and detectable fluid wave.
• Asterixis(flapping tremor or liver flap)
•Spider angioma( collection of small, dilated arterioles clustered very close to the surface of the skin).
Laboratory tests:
• Presence of hepatitis B surface antigen for at least 6 months.• Intermittent elevations of hepatic transaminase(alanine transaminase and aspartate transaminase) and
• Hepatitis B virus DNA>105 copies/mL.
• Liver biopsies for pathologic classification as chronic persistent hepatitis, chronic active hepatitis, or cirrhosis.
Prevention:
• Prophylaxis of HBV can be obtained by vaccination or by passive immunity in post-exposure cases with hepatitis B immunoglobulin.• 2 products are available for prevention of hepatitis B infection:
- Hepatitis B vaccine
- Hepatitis B immunoglobulin (HBIg)
Hepatitis B vaccine
• Engerix- B:
Vaccine indicated for immunization against infection caused by all known subtypes of hepatitis B virusDosage and administration:
• IM administration
• Persons from birth through 19 years of age: A series of 3 doses(0.5ml each) on a 0-,1-,6-month schedule
• Persons 20 years of age and older: A series of 3 doses(1ml each) and a 0-,1-,6- month schedule
• Adults on hemodialysis: A series of 4 doses(2ml each) as a single 2 ml dose or as two 1ml doses on a 0-,1-,6-month schedule
Dosage form and strength:
• 0.5ml(10mcg) single-dose vials and prefilled syringes
•1ml(20mcg) single-dose vials and prefilled syringes
Hepatitis B immunoglobulin:
Used only for post-exposure for HBV for• Perinatal exposure of infants of HBV- carrier mothers
• Sexual exposure to HBsAg positive persons
• Percutaneous or permucosal exposure to HBsAg-positive blood
• Exposure of an infant to a care giver who has acute hepatitis
Brands available in Pakistan:
• BEHRIN• HEP-GLOBIN
•HEPATECT and
• HEPUMAN
TREATMENT :
Treatment of chronic HBV with cirrhosis• Compensated cirrhosis: Treat with Adefovir or entecavir
• Decompensated cirrhosis: Lamivudine+ adefovir or Entecavir + adefovir
Also Read
What is hepatitis a? hepatitis a vaccine schedule?
What is hepatitis c? hepatitis c vaccine schedule?
What is hepatitis d? hepatitis d vaccine?Hdv virus?
What is hepatitis e? hepatitis e vaccine? hev virus?