Global burden of hepatitis D virus infection underestimated
Hepatitis D virus infection (HDV) is highly prevalent in subgroups of individuals with intravenous drug use (IVDU) and those with high-risk sexual behaviour (HRSB), study has reported. Its prevalence has also increased twofold over time in patients infected with hepatitis B virus (HBV).
“The trend of HDV infection is not as optimistic as we imagined, suggesting further implementation of international guidelines of HDV screening and HBV vaccination programme,” researchers said.
In a systematic review and meta-analysis of 182 articles from 61 countries representing about 40 million individuals (0.54 percent of the global population), pooled data showed that HDV prevalence was 0.98 percent (95 percent CI, 0.61–1.42) in the general population and 14.57 percent in the pooled HBsAg-positive population. [Gut 2018;doi:10.1136/gutjnl-2018-316601]
HDV seroprevalence in the general population differed widely among countries, from 0 percent in France to 8.03 percent in Mongolia. The greatest disease burden was observed in China (8.68 percent), with the numbers attributed to its large population base.
In the HbsAg-positive population, HDV seroprevalence was 37.57 percent among individuals with IVDU, 17.01 percent among those with HRSB, and 10.58 percent among those without IVDU and HRSB. HDV seroprevalence was significantly associated with IVDU and HRSB (p=0.00).
Based on the current estimates, HDV prevalence was extremely high in several countries located in Africa and Oceania, including Niger, Mongolia, Australia, Kiribati and Nauru, among others. HDV genotype 1 remains ubiquitous all over the world, and the geographical distributions of genotypes 3, 4 and 8 have been consistent. [Hepatology 2017;66:1826-1841]
However, genotype 2, which was previously confined to Asia (especially Southeast Asia), has now emerged in Egypt and Iran. Meanwhile, genotypes 5–7, which were first reported from Africa, have surfaced in the UK, France and Switzerland, in the last 5 years. This emergence might be attributed to population migration from Africa to Europe. [J Med Virol 2016;88:837-842; Jundishapur J Microbiol 2015;8:e14908; J Clin Virol 2015;66:33-37; J Clin Virol 2014;59:126-128; J Hepatol 2017;66:297-303]
“Our study substantiates the findings published by previous studies that the Africa, the Amazon Basin, the Eastern and Mediterranean Europe, the Middle East and parts of Asia have the highest rates of HDV carriage,” researchers said.
Reports from previous systematic reviews have shown that about 5 percent of chronic HBV carriers worldwide are coinfected with HDV. In comparison, the current estimates indicate that the prevalence of HDV among HBsAg carriers has climbed up to 10.58 percent. [J Hepatol 2003;39(Suppl 1):212-219]
Taken together, the data show “that the global burden of HDV infection is not abated and has been underestimated … [as well as] stress on the need for the international guidelines of HDV screening in HBsAg-positive individuals, especially in the IVDU and HRSB population,” researchers pointed out.
Given that HBV vaccine has a defensive action against infection by HDV, researchers recommended pushing the implementation of HBV vaccination programmes further in poor-resourced countries. Moreover, vaccination priority should be given to all susceptible IVDUs.