Guide to Hepatitis B for People Living With HIV
One of the most perplexing aspects of HBV infection is its disease progression. In fact, researchers still don't fully understand why some people with HBV have no associated health problems, while others progress to serious liver disease; however, we do know that HBV disease progression is driven by the immune system's ability to control HBV replication, and that damages to the liver result from this dynamic process.
HIV worsens HBV because HIV directly attacks the immune system and gradually suppresses immune function by lowering the CD4 cell count. HIV infection also triggers persistent immune activation, which causes low-level inflammation throughout the body. These immune dysfunctions alter HBV disease progression.
Chronic HBV disease progression varies widely among individuals, but in general there are four distinct disease phases. Not everyone will go through every phase, and there can be fluctuations and reversions.
Phase 1: Immune Tolerant
During this phase, HBV is infecting liver cells and replicating at a very high rate, but the immune system either does not recognize the infection or is incapable of mounting an effective defense -- the immune system is tolerating the virus. Since there is little-to-no immune response, the risk of liver damage is very low, and treatment is not recommended.
Phase 2: Immune Clearance
Researchers are still not sure what triggers the immune system to activate and attempt to control a previously unnoticed HBV infection, but when it does, the immune-clearance phase has begun. During this phase, the immune system and HBV battle for control. The amount of virus in the body will rise and fall in response to the intensity of the immune activation. This phase can last from years to decades, primarily in people younger than 35, during which time liver damage can develop. Because of the risk of liver damage, people in the immune clearance phase are often recommended to go on treatment.
Phase 3: Inactive
When the immune system is able to gain the upper hand, people with HBV will pass into an inactive disease phase. There may still be some very low-level HBV replication, but it will elicit little or no immune response and will not cause liver damage. Chronic HBV is considered to be in remission. In some people, especially those who did not develop liver damage during the immune clearance phase, HBV stays in remission indefinitely; nonetheless, those people still have a low risk of developing liver cancer as they age, possibly because of previous liver damage or other unknown effects of prolonged HBV infection.
Phase 4: Reactivation
Chronic HBV can reactivate in some people after a period of inactivity. This generally starts to occur as men reach the age of 40 and women reach the age of 50 who have been infected at birth, and the likelihood of reactivation increases as they get older. Researchers believe this is caused by the combined effects of the loss of immune function associated with aging, and naturally occurring HBV mutations (in the pre-core or basal-core regions of the viral genome). As the weakened immune system cannot recognize and sufficiently control these HBV mutations, more viral replication follows.
This article was provided by Treatment Action Group.