Hepatitis B virus infection
Hepatitis B virus infection is a leading cause of chronic hepatitis, liver cirrhosis, and liver cancer in Thailand. Nearly half of the patients with chronic hepatitis in the country are due to infections with hepatitis B virus (HBV). The country prevalence of the disease is about 5 - 7%.
Causes, risk factors, and transmission
HBV transmits through bodily fluids and blood. Mother-to-child transmission is the most common route and source of chronic HBV infection. Sharing a needle or sharp instrument, transfusion of HBV-contaminated blood or blood products (rarely encountered due to screening of all donor blood units for hepatitis B and C viruses), and sexual activity are other avenues of transmission.
Symptoms and complications
Acquiring HBV infection in adulthood with a fully matured immune system, the body can control and eliminate the virus with mild or no symptoms. Very few people may present with acute hepatitis, accompanied by fever, nausea, vomiting, weakness, loss of appetite, and possibly yellowing of the skin and the eyes, known as jaundice. Patients with preexisting liver disease may develop fulminant hepatitis; and acute liver failure with symptoms of mental obtundation and confusion due to toxic waste products buildup. Secondary infection may ensue, leading to death. Most adults recovering from acute hepatitis develop immunity against HBV and will be free from future chronic hepatitis B.
On the contrary, HBV acquired in infancy from mother-to-child transmission during childbirth; most will become chronic HBV carriers. The viruses remain in the body for decades into their adulthood. Chronic HBV infections are categorized into various phases based on the rate of viral replication and the extent of liver inflammation resulting from the immune cells' response to HBV, causing liver damage. Though most are asymptomatic, the liver will sustain ongoing damage with excessive scar tissue build-up, or fibrosis, leading to liver cirrhosis and liver cancer. Some patients are unaware of their HBV infections because of the asymptomatic nature until advanced-stage liver cirrhosis when jaundice, ascites, gastrointestinal bleeding secondary to portal hypertension, or palpable liver cancer mass become obvious.
In chronic HBV patients, the quiescent stage, generally referred to as HBV carriers, may incorrectly insinuate that the virus is simply hitching a ride and not causing any damage. Asymptomatic, apparently inactive HBV carriers are at risk of developing liver cirrhosis and cancer, as well as the risk of HBV reactivation.
When to see doctor
Everyone who tests positive for HBV should see a doctor to evaluate the degree of liver damage and fibrosis, the phase of infection, HBV viral load, and screen for liver cancer.
In addition, married couples whose spouse harbors HBV; and people with a family history of liver cirrhosis or liver cancer of unknown causes should test for HBV. Since Thailand is a high-prevalence country for HBV infection, everyone should be tested for HBV at least once as a baseline.
Diagnosis
Appropriate blood tests can help confirm a diagnosis of HBV infection. Hepatitis B surface antigen will be tested first, followed by a viral load test if the surface antigen test is positive.
Treatment goals
The treatment goals are to prevent liver cirrhosis complications, liver cancer and decrease the risk of viral spread, specifically through perinatal transmission.
Additional tests
Though current anti-HBV medications are very effective in suppressing viral replications, achieving complete eradication is rare. Additional tests are necessary to identify patients who need to take antiviral drugs through quantitative liver fibrosis assessment for liver damage and measurement of HBV viral load.
Transient elastography (FibroScan®) can determine the degree of liver fibrosis. It is a painless procedure transmitting ultrasound through the skin and measuring the reflected sound waves from the liver or through blood tests to calculate the degree of hepatic fibrosis.
Treatment
Patients with a clinical indication for treatment include those with liver cirrhosis, significant hepatic fibrosis, high viral loads, or liver cancer. The primary treatment is an oral antiviral – one-pill-a-day – to decrease the viral load and prevent further liver damage. The oral antivirals are very effective in reducing the viral load, but their efficacy in eradicating HBV is limited. Patients may need to take oral antivirals for many years or lifelong.
In patients with favorable features predicting beneficial responses to parenteral antivirals, consider prescribing the drugs on a case-by-case basis. Even though injected antivirals have the advantage of the finite duration of treatment, not lifelong, their downsides are more severe side effects and the successful elimination of HBV is low.
Outcome and expectation
The objectives of HBV treatment are to prevent and limit liver damage from becoming full-blown liver cirrhosis, decrease the risk of liver cancer, and prevent the reactivation of HBV. Take the medication regularly to forestall the emergence of HBV drug resistance and to bring out the best efficacy from the antivirals.
HBV patients with incipient liver cirrhosis should have regular liver cancer screening with alpha-fetoprotein (AFP) tumor marker determination and upper abdominal ultrasound every six months. HBV patients without liver cirrhosis who are males over 40 years old, females over 50 years old, or persons with a family history of liver cancer should be screened with the same investigations.
HBV reactivation is something you must guard against as it may erupt with no warning and can be fatal if severe. The risk of HBV reactivation depends on baseline liver function. If significant hepatic fibrosis is present, the reactivation can lead to severe inflammation and eventual liver failure. Before starting immunosuppressive therapies with high-dose steroids, chemotherapy, or immunotherapy, chronic HBV patients should take HBV antivirals to prevent virus reactivation.
