Similar, But Different – Hepatitis C Co-Infection and Superinfection
Infecting an estimated 150 million people worldwide, the Hepatitis C virus has proven itself to be a tenacious foe. A leading cause of chronic liver disease, cirrhosis and liver cancer, there is not yet a vaccine to prevent Hepatitis C, and experts believe many are unknowingly infected. Once diagnosis has been made, treatment is arduous and may be ineffective for 10 to 50 percent who begin a cocktail of potent medications. Battling one strain of hepatitis is hard enough, but some people have more than one infection.
As a blood borne virus, Hepatitis C is spread via blood-to-blood contact. This same route of infection can also spread Hepatitis B and HIV – in addition to all genotypes of Hepatitis C. Some people may be infected with more than one virus at the same time or may acquire a different virus later on. Indicating different times of viral acquisition, Hepatitis C co-infection and superinfection mean different things for a person’s prognosis.
Whether referring to co-infection or superinfection, a person can be simultaneously infected with different types of hepatitis viruses (such as Hepatitis B or Hepatitis C) or different genotypes of the same virus (such as Hepatitis C genotype 1 or Hepatitis C genotype 2).
Defined as infection with a second type of hepatitis or a second Hepatitis C genotype after the establishment of:
- Persistent Hepatitis C infection
- Development of an immunologic response to the first virus
Defined as infection with two different Hepatitis C genotypes or two different viruses within a very narrow window period before:
- Infection with the first Hepatitis C resulted in an immunologic response to that virus.
Those with Hepatitis C may also have a co-infection or superinfection with a non-hepatitis virus such as HIV, the virus that causes AIDS. For the HIV population, also being infected with Hepatitis C is relatively common due to similarities of the infection route.
- Experts estimate that about 40 percent of patients with HIV are co-infected with Hepatitis C.
- The exact number of patients co-infected with Hepatitis C and Hepatitis B is unknown. In patients with chronic Hepatitis B, experts estimate the rates of Hepatitis C co-infection vary from 9 to 30 percent.
In general, co-infection symptoms and disease courses are more complex and serious than a single viral infection case. However, this does not seem to be the case for Hepatitis C superinfection.
Researchers from Rockefeller University have found that when the Hepatitis C virus infects cells in the liver, it may be able to block other Hepatitis C variants from infecting the same cell. For this phenomenon to occur there must be a development of an immunologic response to the first virus before being superinfected with the second.
Charles Rice, head of the Laboratory of Virology and Infectious Disease and the Maurice R. and Corinne P. Greenberg Professor explains, “A virus can interfere with a secondary infection in a variety of ways. It can interfere with how a virus attaches to the cell, its penetration, or its access to the cell’s resources.” If both viruses are competing for the same resources in the cell, then the first virus can confiscate them so none are available for the second virus.
The unique characteristic of preventing a new Hepatitis C infection distinguishes Hepatitis C superinfection from co-infection; and has a silver lining. Referred to as superinfection exclusion, the ability to block a new Hepatitis C variant from causing liver infection could generate a potential vaccine in the future.
Although just a matter of timing, Hepatitis C superinfection and co-infection have dramatically different impacts on those infected. Co-infection typically escalates liver disease progression, while superinfection is not much different from a single infection – except for that it may eventually lead to improved Hepatitis C treatment and prevention research.
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