Viral Hepatitis

Question 1

What are all the different functions of the liver?

Answer 1

-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

Question 2

What is the significance of hepatitis & liver failure in dentistry?

Answer 2

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

-Haemorrhagic tendencies
-Impaired drug metabolism
-Cutaneous manifestations (purpura, telangiectasia, finger clubbing)
-Sialadenosis
-Sjögren’s syndrome (in primary biliary cirrhosis)
-Transmission of viral hepatitis is also a concern

Purpura: small blood vessels leads under skin
Telangiectasia: Small red/purple clusters due to dilation of capillaries.
Finger clubbing: enlarged fingers

Question 3

What are the common liver diseases?

Answer 3

-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

Question 4

How do hepatocytes respond to damage?

Answer 4

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.

Question 5

Is liver failure acute or chronic?

Answer 5

It is usually chronic but can result from massive necrosis of hepatocytes

Question 6

Can the liver generally respond well to damage?

Answer 6

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

Question 7

What are some signs of liver failure?

Answer 7

-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

Question 8

What is hepatitis A and how can you get it?

Answer 8

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.

Question 9

Where is hepatitis A endemic?

Answer 9

Endemic in developing & hot countries

Although in developed countries, consumption of shellfish from contaminated water can give you it

Question 10

What is the incubation period for hepatitis A?

Answer 10

2-6 weeks

Question 11

What is the prognosis for hepatitis A?

Answer 11

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

Question 12

Describe the transmission & prevalence of hepatitis E.

Answer 12

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

It’s very common in India and is spread from animal reservoirs.

Question 13

What’s the incubation period for hepatitis E?

Answer 13

4-6 weeks

Question 14

What is the prognosis like for hepatitis E?

Answer 14

It has a 20% mortality rate in pregnant women, but otherwise is similar to hep A

Question 15

What is the life cycle of hepatitis B?

Answer 15

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

Question 16

what does HBV look like?

Answer 16

HBsAG= Hepatitis B surface antigen

Question 17

Why is hepatitis B so transmissible?

Answer 17

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

Question 18

How high is the risk of getting hepatitis B as a healthcare worker?

Answer 18

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)

Question 19

How much more infectious is hepatitis B in comparison to hepatitis C & HIV?

Answer 19

10x more infectious than hep C
100x more infectious than HIV

Question 20

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

Answer 20

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.

Question 21

Who is infectious with hepatitis?

Answer 21

-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

Question 22

What is the e-antigen?

Answer 22

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

Question 23

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

Answer 23

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

Question 24

What are the universal infection control precautions for hepatitis B?

Answer 24

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

Question 25

What is hepatitis D also known as?

Answer 25

Delta hepatitis

Question 26

What is hepatitis D?

Answer 26

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.

Question 27

Where is hepatitis D endemic to?

Answer 27

Middle East, Africa, & parts of South America

In UK, it only really occurs in IV drug users or from overseas transfusions.

Question 28

What is the mortality rate for hepatitis D?

Answer 28

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%.

Question 29

How serious is hepatitis C and what is it?

Answer 29

• 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

Question 30

What is the prognosis like for hepatitis C?

Answer 30

-15% develop acute hepatitis, 20% clear infection

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

-It’s usually diagnosed LATE

Question 31

How is hepatitis C transmitted?

Answer 31

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