Study Identifies Most Common Genotype of Hepatitis C Infection

Hepatitis C genotype 1 is the most common of half a dozen genotypes of the virus and accounts for nearly half of all cases, according to results from global analysis conducted by researchers in the United Kingdom.

The liver-damaging hepatitis C virus (HCV) has a high degree of genetic diversity which is characterized by regional variations in genotype prevalence, according to Jane Messina, PhD, University of Oxford, lead coauthor of a study published in Hepatology. Messina and her research team reviewed studies published from 1989 — when the virus was discovered – to 2013 to determine national HCV genotype prevalence and they combined the information with overall estimates from the World Health Organization’s Global Burden of Disease project.

“While the HCV infection rate is decreasing in developed countries, deaths from liver disease secondary to HCV will continue increasing over the next 20 years,” Messina said in a news release. “Understanding the global trends in the genetic makeup of HCV is the focus of our study and imperative in developing new treatment strategies that may save millions of lives around the world.”

Hepatitis C is a blood borne virus that can inflame the liver and lead to cirrhosis, cancer of the liver and a need for transplants in some patients. It is one of the most prevalent diseases globally and health officials estimate that about 3 million people in the US and up to 150 million worldwide have chronic HCV infection. The World Health Organization reports that 350,000 to 500,000 deaths each year are caused by HCV-related liver diseases.

Researchers included 1,217 studies in the analysis, which represented 117 countries and 90% of the world population. For countries that lacked genotype data, researchers generated regional and global genotype prevalence estimates.

Results from what the authors say is one of the largest prevalence studies to date indicate that some 83.4 million people with HCV have genotype 1infection type, amounting to 46.2% of cases worldwide. Study authors note that approximately one-third of that group live in East Asia.

Among the six different subtypes, genotype 3 is the second most prevalent globally with 54.3 million people or just over 30% of the population with hepatitis C. In most countries, HCV genotypes 1 and 3 dominate over the other genotypes among all economic ranks, but the largest proportions of people with HCV genotypes 4 and 5 live in lower-income countries, according to the study.

People with genotypes 2, 4, and 6, comprise a total of 22.8% of all hepatitis C cases, while a smaller share of less than 1% were found to be from genotype 5.

The authors conclude that though genotype 1 is the most common, other HCV genotypes are less well served by advances in vaccine and drug development.

“The testing of new therapeutics is still dependent upon knowledge of viral genotype,” coauthor Eleanor Barnes, PhD, University of Oxford, stated in the release. “Non-genotype 1 HCV comprises more than half of all HCV cases. Our study provides evidence of genotype prevalence for specific countries and regions that will help improve access to new viral therapies to combat HCV.”