Researchers identify the worldwide prevalence of specific hepatitis C virus genotypes in their new study, finding that genotype 1 is the most dominant.
Hepatitis C is an infection caused by the hepatitis C virus (HCV). It is primarily spread through contact with blood from an infected person. The infection can become chronic and cause liver diseases, such as cirrhosis, liver cancer and liver failure.
According to the World Health Organization (WHO), approximately 130-150 million people worldwide have chronic hepatitis C infection, and 350-500,000 people die each year from hepatitis C-related liver diseases.
Lead co-author of the study, Dr. Jane Messina of the University of Oxford in the UK, notes that although the rate of HCV infection is declining in developed countries, deaths from HCV-related liver diseases are set to rise over the next 20 years.
With this in mind, Dr. Messina and colleagues set out to gain a better understanding of the prevalence of HCV genotypes - information she says is "imperative in developing new treatment strategies that may save millions of lives around the world."
More than 83 million people worldwide infected with HCV genotype 1
To reach their findings, the team analyzed 1,217 studies that reported on the six HCV genotypes between 1989 - the year that saw the discovery of HCV - and 2013. They say their study included 117 countries and represents approximately 90% of the worldwide population.
The researchers then looked at HCV prevalence estimates from the WHO Global Burden of Disease Project and combined the two sets of information to determine the global prevalence of specific HCV genotypes.
Results of their analysis revealed that HCV genotype 1 - the most difficult to treat - is the most prevalent. They found it accounts for 46% of all HCV cases, meaning it is present in around 83.4 million individuals worldwide.
HCV genotype 3 was found to be the second most prevalent, accounting for 30% of all HCV cases (representing more than 54.3 million people), followed by genotypes 2, 4 and 6, which collectively accounted for 23% of all HCV cases. Genotype 5 accounted for the remaining 1% of cases.
When taking economic status into account, the researchers found that HCV genotypes 1 and 3 remained the most dominant. However, lower-income countries were found to have a higher prevalence of genotypes 4 and 5 when taking this factor into consideration.
Dr. Messina and colleagues note that although HCV genotypes 1 and 3 are the most prevalent, the prevalence of the remaining genotypes can still increase if they find efficient transmission routes.
They note, for example, that the high prevalence and dominance of subtype 4a in Egypt is believed to have become widespread as a result of unsafe injections while past anti-schistosomal campaigns were taking place.
"These observations suggest that under the right circumstances, most, if not all, HCV genotypes have epidemic potential," the researchers add. "They also suggest that social, behavioral, and demographic factors (including international migration) are more important than viral genetic variation in determining the global prevalence of different genotypes."
Commenting on their findings, study author Dr. Eleanor Barnes, also of the University of Oxford, says:
"The testing of new therapeutics is still dependent upon knowledge of viral genotype. 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."
Last year, Medical News Today reported on a study published in the journal Gastroenterology, which revealed that adding the drug danoprevir to standard treatment for hepatitis C patients led to higher rates of remission.