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Hepatitis-B


OVERVIEW OF Hepatitis-B :

It is an liver infection caused by hepatitis B virus(HBV).The infection leads to inflammation of the Liver.Human is the main source of carrier.It is the main cause for chronic liver disease and hepatocellular carcinoma worldwide.


STRUCTURE of Hepatitis-B :

The Nucleocapsid has core envelope embedded with HBsAg in a lipid membrane which it acquires from host cell. Infection with this virus leads to inflammation of the liver.The nucleocapsid comprises of viral genome. Currently 3.5 % population is chronically infected with HBV infections.                                         

You may have acute or chronic hepatitis B based on the duration of HBV in your blood,


EPIDEMIOLOGY :

HBV is more commmon in Asia Pacific and sub Sahara african regions.The lowest prevalence areas include Northren and western europe and north america.


ROUTES OF TRANSMISSION :

Routes of transmission of HBV includes blood an blood products,fluids,parenteral and vertical transmission(from mother to foetus during pregnancy),unsafe medical practices(eg:not using sterilized needles).


COMMON CLINICAL SIGNS AND SYMPTOMS :

Yellowing of skin and sclera (white portion of the eye)-jaundice, dark urine, extreme fatigue, nausea, vomiting, abdominal pain.


DIAGNOSTIC :

Hepatitis B Surface Antigen is the diagnostic marker for  HBV infection and is the first serological marker to appear in acute hepatitis B.The diagnosis is usually done by PCR(polymerase chain reaction using DNA replication).Presence of HBsAG for more than 6 months indicates chronic infection.  Recently, occult HBV infection has been detected in the absence of circulating HBsAg in individuala positive for serum or tissue HBV DNA irrespective of other serological markers.Monitoring the serum HBV DNA level is valuable for assessing the liver disease .Antibodies to HBsAg appears usually within 3 months and persists for a lifetime. Hepatitis core B antigen(HBcAg) is not found in the blood but antibodies to it(Anti HBc) appears early in the illness and rapidly reaches a high titre which subsides gradually but persists for longer time. Chronic hepatitis is marked by the presence of HBsAg and anti HBc in the blood.

VARIOUS METHODS UNDER STUDY :

  •     Rapid immunoassay chromatographic Test
  •     Rapid automated fluorescent Immunoassay


TREATMENT AND PROGNOSIS :

Treatment for acute hepatitis B infection : 

Acute hepatitisis not so severe as chronic hepatitis.boosting the immune system by taking proper nutrition,intake of plenty of fluids is indicated.In severe cases antiviral drugs or a hospital stay is needed to prevent complications.

Treatment for chronic hepatitis B infection :

Treatment helps to reduce the risk of a liver disease and prevents spread of the infection to others.

  • Antiviral medications.
  • Interferon injections. Interferon alfa-2b (Intron A) is a  substance produced by the body to fight against the virus. Interferon must be avoided in pregnancy and for newborn.Side effects may include nausea,vomiting ,breathing and depression,bone marrow suppression..They are contraindicated in cirrhosis(necrosis of liver) patients as it might aacumulates liver failure.
  • Liver transplant. If your liver is damaged severely or necrosis happens ,the doctor must advice for liver transplantation.


PROGNOSIS :

1 in 20 affected adults the infection is chronic and it stays in the body for more than 6 months.About 20% of people who has long term infection will develop liver disease and suffer from scarring or cirrhosis of liver.Mostly there is a higher chance for prognosis aftervaccination and medications.The complication may leads to cirrhosispf liver, Liver cancer,Fulminant hepatitis B(rare complication where our own immune system attacks the liver and leads to severe damage.


PREVENTION :

 Vaccination of HBV:

Human hepatitis B vaccine are made using Hepatitis B surface antigen(HBsAg)that is purified from the plasma of human carriers of hepatitis B virus infection.HBsAg  od subtype adw was produced using recombinant yeast cell culture and this purified antigen in alum formation stimulated the production of antibodies in animals.Thia is the first example of vaccine .obtained from recombinant technology.Nowadys plasma derived hepatitis vaccines are not used widely.

1st dose: In adults it can be given at any times.In case of new borns it  should be given in delivery room to prevent the newborn from Iatrogenic infection(infection acquired from hospital).

2nd dose: At least one month after the first dose.

3rd dose: At least four months of the interval from the first dose and two months of interval from the second dose.

PEOPLE TO BE VACCINATED:

  •   current or recent illegal drug users.
  •   Household contacts of people who are HBsAg positive
  •   Healthcare and public safety workers are at higher risk of exposure of blood and blood products.

Also, Include:

  • Blood safety strategies, screening of donated blood and blood components used for transfusion.
  • Practising safe sex practices.
  • Safe injection or treatment procedures.
  • Using sterilized instruments.
  • Following the good hygiene practice after treating the patients.


Recovery Period :

HBsAg is the hallmark of HBV infection and is the first serological marker to appear in acute hepatitis B. Most patients recovering from acute hepatitis B clear HBsAg within 4-6 months after onset of infection; however, persistence of HBsAg for more than 6 months refers to chronic HBV infection.


Medicines used in the Treatment :

  • Antiviral medications. — including entecavir (Baraclude), tenofovir (Viread), lamivudine (Epivir), adefovir (Hepsera) — can help fight the virus and slow its ability to damage your liver. These drugs are taken orally.

Lamivudine: Effective but longterm treatment leads to the development of rise viral mutants which might occurs after 9 months oftreatment and might leads to rise in viral load.Telibuvidine is more potent but it might rise to viral resistance.

Entecavir and Tenofovir: Both are potent drugs has less chance for viral resistance.But it should be contraindicated in HIV patients since it might leads to HIV viral resistance


REFERENCE :

pubmed.ncbi.in

Davidson practice and principles of General Medicine -22 nd edition.

http://www.cdc.gov

Harrison’s manual of General Medicine-18th edition

http://sciencedirect.com

http://researchgate.net