Epidemiology of Hepatitis C Genotype 6 and its Management
Background Hepatitis C virus (HCV) genotype 6 is common among patients from Southeast Asia and the surrounding regions, where HCV prevalence is also high. HCV genotype 6 has great genetic diversity and different response to antiviral therapy compared with the more commonly known genotype 1.
Aim Our goal was to provide a systematic review of the current literature on the epidemiology, classification and treatment of HCV genotype 6.
Methods A search using PubMed for 'hepatitis C' AND 'genotype 6' produced a total of 47 articles, of which 33 articles were found to be relevant and included in this review. Additional articles were identified using the reference lists of these 33 primary articles.
Results The prevalence of HCV genotype 6 is estimated to be as high as 50% in some regions of Southeast Asia with demonstrated significance among intravenous drug users and thalassemia major patients. Although previous line probe assays may have misclassified HCV genotype 6 as genotype 1, newer line probe assays can more accurately and reliably determine HCV genotype. Patients infected with HCV genotype 6 respond better to interferon-based therapy compared with those infected with genotype 1, although patient baseline clinical characteristics and side effect profiles are similar between HCV genotype 6 and other HCV genotypes.
Conclusions Future studies should seek to clarify issues regarding early predictors for treatment response in patients with HCV genotype 6, and the impact of ethnic and genotypic factors to treatment response in HCV genotype 6 patients.
Hepatitis C virus (HCV) is one of the leading causes of chronic liver disease and hepatocellular carcinoma (HCC) and currently infects approximately 3% of the world's population. Of the estimated 170 million people who suffer from chronic hepatitis C (CHC) worldwide, 62 million – more than one-third – are from the Western Pacific region. In particular, there are approximately 32.2 million people with CHC in Southeast Asia alone. In the United States, approximately 3.2 million people suffer from CHC, making it the most common chronic blood-borne infection in this country with an estimated 8000–10 000 deaths annually. In some countries in Southeast Asia, HCV prevalence (approximately 6–7%) far exceeds the prevalence seen in the US (1.8%).
In many developing countries such as those found in Southeast Asia, nosocomial transmission of HCV through re-use of inadequately sterilized needles and other unsafe medical and dental practices may account for the majority of the infection. Southeast Asian countries are reported to have among the highest rates of needle reuse in the world. A recent study by Nguyen et al. of risk factors for HCV in 290 Southeast Asians reported that close to half of these patients could not recall an exposure to HCV with the vast majority of the remaining patients identifying exposure risks related to medical care such as prior surgery (34%), blood transfusion (25%), acupuncture (13%) and exposure to contaminated needles (7%). Studies by Dev et al. of Southeast Asians and Caucasians in Australia and by Ho et al. of Caucasians and Asian-Americans in the United States also suggest that unsanitary medical practices are probably the major cause of HCV infection in Asians, whereas injection drug use is responsible for the majority of HCV infection in Caucasians.
Recent studies have also shown that the incidence of HCV-related HCC and HCV-associated HCC deaths is rising in several Asian countries. In the United States, Asian & Pacific Islander (API) populations continue to grow rapidly and report the highest incidence of HCC at 7.8 per 100 000 – more than double the national average of 3.2 per 100 000 – according to the most recent data published by the Center for Disease Control in 2010. Besides infection with hepatitis B virus, infection with HCV is also probably a major contributing factor to this high HCC incidence rate in API. Prevalence studies of HCV among Asian-Americans are limited, but one population-based study in Los Angeles, California reported an 8% HCV prevalence.
Despite implementation of successful hepatitis B screening programs, the rising worldwide incidence of HCC suggests an increasing role of HCV as a cause of underlying liver disease in addition to chronic hepatitis B. In 2000, the World Health Organization estimated a 2.2% prevalence of infection with HCV across Southeast Asia. Certain country-specific prevalence studies have revealed a significant variation in the distribution of HCV infection among countries in Asia, ranging from 0.5% in Singapore and Hong Kong to 11.6% in Myanmar. With 2–3% of its population suffering chronic infection, the Republic of China is home to approximately 30 million people with infection with HCV and is the Asian country with the largest number of people infected with HCV. Table 1 summarises the prevalence of HCV infection in several countries in Asia.
The aim of this review was to provide a comprehensive review of the current literature on the epidemiology, classification and treatment of HCV genotype 6. Using PubMed and the search criteria: 'hepatitis C' AND 'genotype 6', a total of 47 articles were identified, reviewed and assessed for relevance. A total of 33 articles were found to be relevant and included in this review. The reference lists of these 33 articles were also reviewed to identify additional relevant articles.
Abstract and Introduction
Abstract
Background Hepatitis C virus (HCV) genotype 6 is common among patients from Southeast Asia and the surrounding regions, where HCV prevalence is also high. HCV genotype 6 has great genetic diversity and different response to antiviral therapy compared with the more commonly known genotype 1.
Aim Our goal was to provide a systematic review of the current literature on the epidemiology, classification and treatment of HCV genotype 6.
Methods A search using PubMed for 'hepatitis C' AND 'genotype 6' produced a total of 47 articles, of which 33 articles were found to be relevant and included in this review. Additional articles were identified using the reference lists of these 33 primary articles.
Results The prevalence of HCV genotype 6 is estimated to be as high as 50% in some regions of Southeast Asia with demonstrated significance among intravenous drug users and thalassemia major patients. Although previous line probe assays may have misclassified HCV genotype 6 as genotype 1, newer line probe assays can more accurately and reliably determine HCV genotype. Patients infected with HCV genotype 6 respond better to interferon-based therapy compared with those infected with genotype 1, although patient baseline clinical characteristics and side effect profiles are similar between HCV genotype 6 and other HCV genotypes.
Conclusions Future studies should seek to clarify issues regarding early predictors for treatment response in patients with HCV genotype 6, and the impact of ethnic and genotypic factors to treatment response in HCV genotype 6 patients.
Introduction
Hepatitis C virus (HCV) is one of the leading causes of chronic liver disease and hepatocellular carcinoma (HCC) and currently infects approximately 3% of the world's population. Of the estimated 170 million people who suffer from chronic hepatitis C (CHC) worldwide, 62 million – more than one-third – are from the Western Pacific region. In particular, there are approximately 32.2 million people with CHC in Southeast Asia alone. In the United States, approximately 3.2 million people suffer from CHC, making it the most common chronic blood-borne infection in this country with an estimated 8000–10 000 deaths annually. In some countries in Southeast Asia, HCV prevalence (approximately 6–7%) far exceeds the prevalence seen in the US (1.8%).
In many developing countries such as those found in Southeast Asia, nosocomial transmission of HCV through re-use of inadequately sterilized needles and other unsafe medical and dental practices may account for the majority of the infection. Southeast Asian countries are reported to have among the highest rates of needle reuse in the world. A recent study by Nguyen et al. of risk factors for HCV in 290 Southeast Asians reported that close to half of these patients could not recall an exposure to HCV with the vast majority of the remaining patients identifying exposure risks related to medical care such as prior surgery (34%), blood transfusion (25%), acupuncture (13%) and exposure to contaminated needles (7%). Studies by Dev et al. of Southeast Asians and Caucasians in Australia and by Ho et al. of Caucasians and Asian-Americans in the United States also suggest that unsanitary medical practices are probably the major cause of HCV infection in Asians, whereas injection drug use is responsible for the majority of HCV infection in Caucasians.
Recent studies have also shown that the incidence of HCV-related HCC and HCV-associated HCC deaths is rising in several Asian countries. In the United States, Asian & Pacific Islander (API) populations continue to grow rapidly and report the highest incidence of HCC at 7.8 per 100 000 – more than double the national average of 3.2 per 100 000 – according to the most recent data published by the Center for Disease Control in 2010. Besides infection with hepatitis B virus, infection with HCV is also probably a major contributing factor to this high HCC incidence rate in API. Prevalence studies of HCV among Asian-Americans are limited, but one population-based study in Los Angeles, California reported an 8% HCV prevalence.
Despite implementation of successful hepatitis B screening programs, the rising worldwide incidence of HCC suggests an increasing role of HCV as a cause of underlying liver disease in addition to chronic hepatitis B. In 2000, the World Health Organization estimated a 2.2% prevalence of infection with HCV across Southeast Asia. Certain country-specific prevalence studies have revealed a significant variation in the distribution of HCV infection among countries in Asia, ranging from 0.5% in Singapore and Hong Kong to 11.6% in Myanmar. With 2–3% of its population suffering chronic infection, the Republic of China is home to approximately 30 million people with infection with HCV and is the Asian country with the largest number of people infected with HCV. Table 1 summarises the prevalence of HCV infection in several countries in Asia.
The aim of this review was to provide a comprehensive review of the current literature on the epidemiology, classification and treatment of HCV genotype 6. Using PubMed and the search criteria: 'hepatitis C' AND 'genotype 6', a total of 47 articles were identified, reviewed and assessed for relevance. A total of 33 articles were found to be relevant and included in this review. The reference lists of these 33 articles were also reviewed to identify additional relevant articles.
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