Viral Hepatitis

• What are all the different functions of the liver?

  Carbohydrate, fat and protein metabolism

  
  

  Synthesis of coagulation factors

  
  

  Bile secretion- digestion

  
  

  Endocrine- Insulin like GF, angiotensin

  
  

  Cholesterol synthesis and homeostasis

  
  

  Detoxification and urea synthesis

  
  

  Iron and vitamin stores

  
  

  Drug metabolism- benzodiazepines
• What is the significance of hepatitis & liver failure in dentistry?

  Damage to the liver can result in reduced function & so patients with liver failure can show:

  Haemorrhagic tendenciesImpaired drug metabolismCutaneous manifestations (purpura, telangiectasia, finger clubbing)SialadenosisSjögren's syndrome (in primary biliary cirrhosis)Transmission of viral hepatitis is also a concern

  Purpura: small blood vessels leads under skinTelangiectasia: Small red/purple clusters due to dilation of capillaries.Finger clubbing:enlarged fingers
• What are the common liver diseases?

  Alcoholic cirrhosis

  Non alcoholic fatty liver- obesity

  Viral hepatitis

  Drug toxicity

  Liver cancer

  Autoimmune liver disease (primary biliary cirrhosis)

  Can be damaged secondary to bile duct obstruction/gallstones
• How do hepatocytes respond to damage?

  They can demonstrate reversible changes, such as accumulation of fat.

  
  

  However if the injury is too great, they will die-either by necrosis or by apoptosis.
• Can the liver generally respond well to damage?

  Response is limited because you get loss of hepatocytes and fibrosis 'cirrhosis (scar tissue)' (stellate cells convert to fibroblasts).

  
  

  Therefore, hepatocytes are eventually replaced by fibrosis & the liver fails
• Is liver failure acute or chronic?


  It is usually chronic but can result from massive necrosis of hepatocytes
• What are some signs of liver failure?

  Jaundice

  
  

  Encephalopathy - spectrum of Neurological features

  
  

  Bleeding tendency

  
  

  Portal hypertension- ascites (collection of fluid within abdomen), hepatomegaly, arteriovenous shunts

  
  

  Secondary renal failure

  
  

  Anorexia, weight loss, weakness

  
  

  Pruritis - itchy skin
• What is hepatitis A and how can you get it?

  It's a common form of infectious hepatitis and is only an acute infection which is acquired from contaminated food or water via faeco-oral route
• Where is hepatitis A endemic?

  Endemic in developing & hot countries

  
  

  Although in developed countries, consumption of shellfish from contaminated water can give you it
• What is the incubation period for hepatitis A?

  2-6 weeks
• What is the prognosis for hepatitis A?

  Spontaneous recovery in 3 mths is very common

  
  

  There's rarely any complications, it's only fatal 0.2% of the time

  
  

  Vaccine is available for hep A
• Describe the transmission & prevalence of hepatitis E.

  Similar to A,acute infection onlyand is also acquired from contaminated food or water via faeco-oral route

  It's very common in India and is spread from animal reservoirs
• What's the incubation period for hepatitis E?

  4-6 weeks
• What is the prognosis like for hepatitis E?

  It has a 20% mortality rate in pregnant women, but otherwise is similar to hep A
• what does HBV look like?

  HBsAG= Hepatitis B surface antigen

  
• What is the life cycle of hepatitis B?

  Binds sodium/bile acid cotransporting peptide

  
  

  Endocytosed, membranes fuse, core released

  
  

  DNA travels to nucleus, transcribes RNA

  
  

  Viral proteins synthesised

  
  

  Virus assembly in cytoplasm

  
  

  RNA to DNA reverse transcription

  
  

  Reinfection of cell and release of virus and

  incomplete viral particles

  
  

  Released as an 'enveloped' virus like C & D

  
• Why is hepatitis B so transmissible?

  Because minute traces of body fluids can transmit infection since the virus can survive well outside the body for a week at least, possible one month

  
  

  Also the virus is relatively resistant to disinfection
• How high is the risk of getting hepatitis B as a healthcare worker?

  Up to 30% of needlestick injuries from an infected patient can lead to transmission of it to unvaccinated healthcare workers

  
  

  Even in vaccinated individuals, the vaccine is not 100% effective

  
  

  There is also a 0.1% chance of getting it from mucocutaneous exposure

  
  

  The saliva can also be infectious (through the blood content in saliva)
• How much more infectious is hepatitis B in comparison to hepatitis C & HIV?

  10x more infectious than hep C

  100x more infectious than HIV
• Who is infectious with hepatitis?


  Everyone incubating (2-6 months) or with acute infection

  All those with chronic hepatitis

  Often asymptomatic individuals

  0.3% of UK population

  Only 1 in 4 carriers give a positive history

  Particularly those with circulating e-antigen

  
• What is the e-antigen?

  Hepatitis B envelope antigen which lies inside the outer lipid membrane but outside of the protein core containing viral DNA

  
  

  E-antigen is secreted into the blood (unlike the core antigen which stays within the host cell & due to this secretion, it can be used as a marker of infectivity and its level is proportional to the viral load within the individual

  
• What happens in terms of the e-antigen as the infection resolves?

  The host will make antibodies to this e-antigen which will appear as the infection resolves and will these antidotes will persist for several years

  
• What are some examples of high risk individuals for hepatitis B?


  Intravenous drug users and their partners

  
  

  Men who have sex with men

  
  

  Those with frequent changes of sexual partners

  
  

  Babies, family and partners of those infected

  
  

  Anyone with chronic liver or renal disease

  
  

  Those who need regular blood transfusions

  
  

  Male and female sex workers

  
  

  Travellers to endemic areas

  
  

  Prison staff and prisoners

  
  

  Healthcare staff, including dentists

  
  

  Families adopting children from endemic areas

  
  

  Patients and staff of institutions for the handicapped

  
  

  Immunosuppressed patients

  
  

  Patients who have had acupuncture or tattooing, especially in tropical countries
• What are the universal infection control precautions for hepatitis B?

  Vaccination:

  
  

  -3 injections into deltoid muscle

  -6 months required for adequate protection

  -side effects are mild & rare

  -if obese, may need to repeat course

  -antibody levels no longer tested

  -no booster injections

  -protection is >95% but still incomplete
• What is hepatitis D also known as?

  Delta hepatitis
• What is hepatitis D?

  A unique defective RNA virus, related to plant viruses, & it can only infect in the presence of HBsAg which means it's dependent on hep B virus for its life cycle, so it's transmitted with hep B (co-infection)

  
  

  This also means the hep B vaccine helps protect against hep D infection
• Where is hepatitis D endemic to?

  Middle East, Africa, & parts of South America

  In UK, it only really occurs in IV drug users or from overseas transfusions
• What is the mortality rate for hepatitis D?

  Hepatitis rarely resolves, so it has a high mortality

  
  

  Especially when it has occurred via co-infection with hep B, the mortality can be up to 20%
• How serious is hepatitis C and what is it?

  It's a major cause of liver disease & a severe infection; often fatal

  
  

  It's an RNA virus with an incubation period of ~9 weeks

  
  

  There is currently no vaccine for hep C as well

  
  

  Hep C is worse than B and A
• What is the prognosis like for hepatitis C?

  15% develop acute hepatitis, 20% clear infection

  
  

  85% of patients develop chronic hepatitis, cirrhosis and risk of liver failure

  
  

  It's usually diagnosed LATE
• How is hepatitis C transmitted?

  By blood, commonly by:

  
  

  •Needle sharing by IVDU or tattooing

  •Overseas blood transfusions

  It's rare in UK; 2% in USA ; 3% in worldwide

  High in japan, Mongolia, parts of Africa and South America.

  It's common in HIV positive patients

  There is a lower risk of transmission than Hep B on sharps injury