A collaborative study involving several research institutes and hospitals in Taiwan recently revealed that individuals infected with the human immunodeficiency virus (HIV) or individuals who use injectable illicit drugs are at a higher risk of becoming infected with hepatitis D virus (HDV). The study was published in the journal Hepatology and is entitled “Changing hepatitis D virus epidemiology in a hepatitis B virus endemic area with a national vaccination program.”
Hepatitis corresponds to a medical disorder characterized by liver inflammation, leading to jaundice, poor appetite and malaise. Hepatitis can heal on its own or progress to cirrhosis, an irreversible advanced liver disease characterized by fibrosis (scarring) and nodules in liver tissues. There are five main viral strains of hepatitis (A, B, C, D and E), where hepatitis D virus (HDV) infection occurs only in concomitant infection with HBV. Patients co-infected with HBV and HDV usually have a poorer response to therapy and experience a more severe liver disease, rapidly progressing to cirrhosis, and an increased risk of developing liver cancer.
“Nearly 20 million people worldwide have HDV, with prevalence varying between geographic regions,” said the study’s lead authors Dr. Lin and Dr. Jaw-Ching Wu in a news release. “HBV is endemic in Taiwan, but with HBV vaccination and sustained health education to general public to interrupt HDV transmission routes we have witnessed a decrease in acute HDV superinfection from 24% of chronic hepatitis B with acute exacerbation in 1983 to 4% in 1995.” The impact of the vaccine against HBV on modern HDV prevalence is, however, poorly elucidated.
In this study, researchers analyzed HDV epidemiology in low- and high-risk populations in Taiwan between 2001 and 2012, after an outbreak of HIV and HCV among injection drug users. In total, 2,562 HBV patients were enrolled in this prospective, multicenter study. The team assessed the genotype, prevalence and risk factors linked to HDV infection.
Researchers found that the prevalence rate of HDV was 75% among HIV-positive injection drug users, 44% in HIV-negative injection drug users, 11.4% in HIV-positive homosexual men, 11.1% in HIV-positive heterosexual men and 4.4% in the general population infected with HBV. Among HIV-positive injection drug users, a significant increase was found in the trend of HDV prevalence from 38.5% to 90%. The risk factors found to be linked to HDV infection were HBV surface antigen blood levels equal or higher than 250 IU (international units)/mL, injection drug use, the duration of drug use, HIV infection, HCV infection, and an older age. The most prevalent genotype was HDV IV among injection drug users (72.2%) and HDV II among non-injection drug users (73.3%).
The research team concluded that in the current period of widespread HBV vaccination, injection drug users and HIV-positive individuals have emerged as high-risk groups for HDV infection, acting as a virus reservoir. “Our findings indicate that injection drug users, especially those infected with HIV, are the highest risk group for HDV infection in Taiwan, despite a 30-year hepatitis B vaccination program,” concluded Dr. Wu. “New strategies, such as methadone maintenance therapy and clean syringe exchange, to inhibit injection drug use are needed to control the spread of HDV.” The research team also suggests that a HBV vaccination booster could be considered in these high-risk groups.