Hepatitis C Prevalence and Genotype Distribution Worldwide

Researchers recently conducted a comprehensive review of recently published literature to estimate anti-hepatitis C virus (HCV) prevalence, the viraemic rate (HCV-RNA positive), and genotype distribution in order to create a global estimate of hepatitis C disease burden.

The systematic study published in the World Journal of Gastroenterology is representative of one of the most comprehensive efforts to quantify global HCV epidemiology. Recent estimates have shown an increase in HCV seroprevalence over the last decade to 2.8%, which equates to 185 million infections globally.

For the study, a comprehensive review of literature from 2000 to 2015 was conducted in order to gather country-specific prevalence. The regions included in the analysis were defined by the Global Burden of Diseases, Injuries, and Risk Factors 2010 (GBD) study.

The GBD study defined 21 regions that were “epidemiologically homogenous as possible so that information from detailed studies in 1 country can plausibly be extrapolated to other countries in the region to create burden estimates that are useful to individual countries in planning for health sector activities.”

To calculate the average HCV prevalence for each continent, researchers divided the sum of data reported from each region to the total number of countries within the region. Studies that used a third generation immunoassay test were selected for the study to estimate the country’s HCV prevalence, while studies that used first- and second generation tests were not included.

This is because first- and second generation tests usually provide false-positive results overestimating the total infect population.

The results of the study showed that the total global anti-HCV prevalence was 2.5%, which was equal to 177.5 million infected adults, and ranged from 2.9% in Africa and 1.3% in America. The total viraemic rate was 67%, and varied from 64.4% in Asia to 74.8% in Australia.

Globally, the most prevalent genotype was genotype 1 (49.1%), followed by genotype 3 (17.9%), genotype 4 (16.8%), and 2 (11%). Genotypes 5 and 6 accounted for the remaining <5%. Although genotypes 1 and 3 are common worldwide, the largest proportion of genotypes 4 and 5 was found in lower-income countries, according to the study.

Some limitations to the study was the lack of available information from some extended regions (Africa and Asia), which forces researchers to use regional estimates that sometimes came from high populated countries. Authors noted that data from additional countries in the future would be helpful in minimizing this bias.

A second study limitation was the lack of robust epidemiology studies at the national level. According to researchers, only 21% of the 138 countries included in the analysis showed a sample size > 1000, selected by multiple cities or regions, and a random sampling strategy, while the majority are generally conducted in a select population within one setting.

The study’s findings suggest that HCV prevalence and the viraemic rate has decreased from 2005 to date. Furthermore, researchers believe that more precise knowledge of HCV genotype distribution will be helpful to best inform national health care models to improve access to new hepatitis treatments.