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Viral Hepatitis – Which Virus?
Interview with Prof David Mutimer
OK, so hepatitis refers to inflammation or irritation of the liver, and there are lots of different causes of hepatitis. I guess in Western society, the main cause would be alcohol, so alcoholic hepatitis causing liver damage. But on a global basis, the main cause of liver inflammation and liver damage is actually viral infection of the liver. And there are a number of different hepatitis viruses. And conveniently, they’re called hepatitis A, B, C, D, and E. Now the symptoms of hepatitis depend upon whether you have an acute hepatitis or whether it’s a chronic hepatitis. And by acute hepatitis, I mean that the person or the patient has acquired the infection quite recently.
Now under those circumstances, there is frequently associated an illness where patients develop nausea and sometimes vomiting and diarrhoea. And then the telltale sign that it’s a hepatitis which is causing their problems is the development of jaundice, or a yellow discoloration.
Over a period of decades usually, and frequently without any symptoms during that long period, you can have established chronic liver damage which leads to scarring and eventually to a cirrhosis of the liver, and sometimes to liver cancer.
So anybody can get viral hepatitis, of course, unless they’ve been vaccinated against the specific viruses. But in answering that question, it’s probably best to look at the five different hepatitis viruses and the way that they’re transmitted. So hepatitis A and hepatitis E viruses are very similar. They’re both what we call fecal-oral transmission, which basically means that you’ve managed somehow to ingest somebody else’s faeces. And that’s usually by contamination of the water supply, of course.
A hepatitis B virus has a different epidemiology. And globally, most people who’ve got hepatitis B virus have acquired the infection from their mother. So if mum is a carrier of hepatitis B virus, then unless the baby gets vaccinated at birth, then most infants will end up being infected by hepatitis B virus. They’ll get it from their mother. In Western society, the main way that you come into contact with hepatitis B is via sexual transmission. I think that’s often forgotten, but hepatitis infection– particularly hepatitis B virus infection– in adults is principally sexually transmitted.
It can be transmitted in other ways– for instance, by injecting drug use, so it’s common to find that long term injecters have come into contact with hepatitis B that way.
A hepatitis C virus, again, is quite different from the others in terms of transmission and who’s at risk. If you’ve got hepatitis C virus, then usually you’ve got somebody else’s blood directly into your own bloodstream. So in Western society, that means that most often that you’ve injected drugs and shared needles or shared the paraphernalia that goes with drug injection. And the trouble with hepatitis C infection is that it’s frequently completely asymptomatic in the acute stage, so the people may not be aware that they’ve been infected with the virus. The other trouble with hepatitis C is that the outcome is nearly always chronicity, so that spontaneous clearance of the virus by the immune system is really most uncommon.
And hepatitis C then infects a person, they become a carrier, and of course they become a potential source for infecting other people without even knowing that they’re a carrier themselves. Now the other ways that you can get blood into your own bloodstream would include blood transfusion, of course, but that’s, again, quite uncommon in Western society. In fact, it’s exceedingly rare now because we can screen blood products for hepatitis C. Hepatitis D virus is an unusual virus. It’s a defective virus in some ways because it can only infect people who are already infected or simultaneously infected with hepatitis B virus. It probably affects about 10% of hepatitis B carriers in the UK and figures not much greater than that across Europe.
But in some parts of the world, it’s very prevalent– Central Africa and some parts of Eastern Europe. And the characteristic of hepatitis D virus infection is the severity of the damage that it does to the liver. It tends to damage the liver very quickly so that instead of taking three or four decades to go from infection to cirrhosis, you often see that process condensed into 10 to 20 years, for instance. The hepatitis D transmission then historically has been transmitted in the same way as hepatitis B because the two viruses have tended to travel together.
Your task: watch this short video in which Professor David Mutimer discusses the various viruses that can cause liver disease.
Professor Mutimer is an Honorary Consultant Hepatologist at the Queen Elizabeth Hospital Liver and Hepatobiliary Unit. He is a fellow of the Royal College of Physicians of England and Australasian College of Physicians. He acts as adviser to the Department of Health on issues related to viral hepatitis and liver transplantation, and is a founder and trustee of the charity, Hepatitis B Foundation UK.
If you would like to find out more information about how alcohol and drugs cause liver damage, please follow the links at the bottom of this step.
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