Hepatitis B is one of the world’s most prevalent infectious diseases today. The disease has been recognized for millennia, but the first actual breakthrough in understanding its etiology came more than 50 years ago, when it was discovered that the serum protein Australia Antigen (first discovered in Australian Aborigines) was in fact the surface antigen (HBsAg) of the hepatitis B virus (HBV). This discovery enabled the development of a successful hepatitis B vaccine in 1981.1
Although the HBV vaccine has been administered routinely at birth in the U.S. since 1991 and despite ongoing population education and awareness efforts, HBV infection remains a global health hazard. It is frequently asymptomatic, so many acutely and chronically infected patients may be unaware they have this disease and so can be the cause of significant mortality and morbidity.
The aim of this article is to update readers on advances in the understanding, treatment, and prognoses for this condition, as well as the underwriting and claims implications for life and health insurers.
About HBV: EpidemiologyThe hepatitis B virus (HBV) is a DNA virus belonging to the hepadnaviridae family. It is considered to be the most complex of the five known forms of viral hepatitis (A, B, C, D, and E). HBV is also a global disease: the World Health Organization (WHO) in 2017 estimated that 325 million individuals worldwide are living with the disease’s chronic form, a 25% increase from 2015’s 260 million estimate. In addition, the Centers for Disease Control and Prevention (U.S.) recently stated that approximately 600,000 individuals worldwide die annually as a direct or indirect consequence of HBV infection.
The disease’s highest prevalence (just over 7%) is in the Western Pacific region (including China and Taiwan) and in Africa. Eastern and Southern Europe, Southeast Asia and Japan have intermediate prevalence levels (2% to 7%), and North America has extremely low prevalence (<2%)2 which is not surprising, as the HBV vaccine has routinely been administered to U.S. newborns for nearly three decades.
The main forms of transmission are via bodily fluids such as blood, semen, and saliva. In areas where HBV is endemic, vertical transmission (i.e., prenatal or perinatal transmission) is its dominant mode of spread. The chances of infection becoming chronic is close to 90% among infected infants, presumably because infant immune systems are immature (immune tolerance phase) whereas among older children and adults, chronicity may vary between <1% to 10%.3 In areas of lower prevalence, the main routes for HBV transmission are unprotected sexual intercourse, intravenous drug use or, for health care workers, direct contact with bodily fluids of infected persons.3
Clinical ManifestationsHBV infections start out as acute and progress either to resolution or to chronicity. The acute phase lasts from one to six months. During this time, infected individuals generally do not have symptoms, but are able to pass the infection to others. However, when symptomatic, individuals with acute hepatitis B can experience anorexia, nausea, low-grade fever, myalgia, changes in the ability to smell or taste, jaundice (icterus), and mild to moderate pain in the right upper quadrant of the abdomen. In rare cases (<3%) fulminant hepatitis B can develop,5 leading to rapid liver failure, encephalopathy, coma, and death.
Those whose hepatitis B has neither spontaneously cleared in six months nor has progressed to fulminant hepatitis are considered to have progressed to chronic hepatitis B (CHB). As noted earlier, risks of chronicity will differ among infants, older children, and adults due to immune response displayed by the host and the virus’s route of transmission.
Patients with chronic infection may remain infected for the rest of their lives. They are generally asymptomatic unless the infection progresses to hepatocellular carcinoma (HCC) or there is a transition from compensated cirrhosis to decompensated cirrhosis. In decompensated cirrhosis, patients may have symptoms including jaundice, ascites, edema, encephalopathy, and variceal hemorrhage.