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Hepatitis B and C viruses - some issues

<p>Sean R. Hosein</p>


June 1, 2013

Hepatitis B virus

In high-income countries such as Canada, hepatitis B virus (HBV) can be spread when a person comes into contact with the blood from someone who has HBV. This can happen in the following ways:

  • unprotected intercourse (anal or vaginal sex)
  • sharing equipment for substance use, including syringes, needles, straws and rolled-up currency notes
  • exposure to unsterilized equipment used for tattooing and body piercing
  • from an infected mother to child during birth
  • sharing personal items such as razors and toothbrushes

According to the U.S. Centers for Disease Control and Prevention (CDC), HBV is not spread in the following ways: “Through food or water, sharing eating utensils, breastfeeding, hugging, kissing, hand-holding, coughing or sneezing.”

Hepatitis C virus

Hepatitis C virus (HCV) is most commonly spread in Canada and other high-income countries in the following ways:

  • sharing equipment for substance use, including needles, syringes, straws, rolled-up currency notes
  • exposure to unsterilized equipment used for tattooing or body piercing
  • among HIV-positive men who have sex with men (MSM) – having unprotected anal intercourse particularly when blood or sexually transmitted infections are present, sharing unsterilized sex toys, and not using a new condom with each new partner
  • HIV-positive women who engage in unprotected anal intercourse are likely also at risk for HCV

Some newcomers to Canada can also be at high risk for infection with HBV and HCV if they come from countries or regions where these viruses are relatively common, if they were exposed to mass vaccination campaigns where needles were reused, if they received contaminated blood or blood products (such as clotting factors) or if they were exposed to unsterile equipment during medical procedures.

Infection with HBV or HCV can be associated with symptoms similar to a flu-like illness or there can be no symptoms at all. Due to mild or no symptoms with initial HBV or HCV infection, few people infected with these hepatitis-causing viruses are aware of their infection. The Public Health Agency of Canada (PHAC) estimates that there are approximately 600,000 Canadians infected with HBV or HCV.

A busy organ

The liver is an important organ that performs many functions, including filtering waste from the blood, storing nutrients, breaking down drugs, making proteins and hormones, and playing an important role in maintaining the health of the immune system.

HCV and the liver

Once HBV or HCV has established itself in the liver, it causes inflammation, which slowly degrades this vital organ. In a process called fibrosis, healthy tissue is gradually replaced by useless scar tissue. If left untreated, HCV- or HBV-related liver damage can spread to the entire organ over a period of years. The speed at which the liver is damaged by fibrosis varies from one individual to another and this is why regular medical monitoring is important in people with these viruses. In addition, quitting smoking, reducing alcohol intake and maintaining a healthy weight are all important steps for liver health.

As fibrosis spreads and healthy tissue is lost, the liver becomes increasingly dysfunctional and complications can appear. Initially, such complications may be mild, but eventually more severe symptoms arising from liver or other organ dysfunction can appear, including the following:

  • intense fatigue
  • internal bleeding
  • build-up of fluid in the abdomen
  • recurring infections
  • kidney dysfunction
  • problems with memory and difficulty thinking clearly

In cases of extensive liver damage (cirrhosis), the risk of liver failure is high. Both HBV and HCV can be responsible for transforming infected liver cells into cancers, increasing the risk of death.

HCV screening and other steps

As there is currently no vaccine to prevent HCV infection and due to the serious consequences associated with this virus and the fact that many infected people may not be aware that they carry it, testing for HCV is very important. If HCV test results are negative, people need to engage in behaviours that protect them from the risk of future infection. People who are HCV positive need swift referrals for medical evaluation and monitoring. Also, discussion about treatment options should be a part of subsequent medical appointments.

HBV screening

People who are not infected with this virus can receive a vaccine to protect them from infection with HBV. People who are infected can be referred for medical evaluation and care. Treatment for HBV can stabilize the course of the disease and, in some cases, partially reverse liver damage.

HCV treatment

There are many strains, or genotypes, of HCV (genotypes 1 through 6 and subtypes within genotypes such as 1a, 1b and so on). In Canada, the most common genotype is type 1. The standard treatment for this is as follows:

  • boceprevir (Victrelis) + peginterferon (a long-lasting form of interferon) + the broad-spectrum antiviral drug ribavirin

OR

  • telaprevir (Incivek, Incivo) + peginterferon + ribavirin

For other genotypes, standard therapy is a combination of peginterferon + ribavirin. However, that will change in the years ahead as many new anti-HCV drugs become available. In the short-term, the drugs most likely to be licensed in Canada between 2013 and 2015 are as follows:

  • sofosbuvir
  • simeprevir
  • faldaprevir
  • daclatasvir

Initially, these drugs—particularly faldaprevir and simeprevir—will likely be approved for use in combination with interferon and ribavirin. However, clinical trials are testing interferon-free combinations of drugs and eventually these combinations will become licensed.

Further information about these and other emerging therapies will appear in TreatmentUpdate 198.

—Sean R. Hosein

REFERENCES:

  1. Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson JL, Loscalzo J. Chapter 304. Acute Viral Hepatitis. In: Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson JL, Loscalzo J, eds. Harrison’s Principles of Internal Medicine. 18th ed. New York: McGraw-Hill; 2012.
  2. Canadian Cancer Society’s Steering Committee on Cancer Statistics. Canadian Cancer Statistics 2013. Toronto, ON: Canadian Cancer Society; 2013.


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