The World Health Organization currently estimates the global burden of Hepatitis C to be between 130 and 170 million people. Ideally, this figure, as well as stratifications by location, age, and gender, would be more precisely determined based on data from community-based studies. In most countries, however, the utilization of such surveys is lacking and often only accounts for adults in high-risk groups such as blood donors and intravenous drug users instead of the general population. As global efforts to increase HCV surveillance become more prominent, predictive modeling offers valuable insight to both HCV incidence and prevalence around the world. In this installment, we’ll cover current estimates of HCV burden by geographic location, genotype, age, and gender as well as the global burden of HCV morbidity and mortality.
Incidence and Prevalence by Geographic Region and Genotype
The incidence of new global HCV infections has been steadily decreasing in the past 50 years due to increased surveillance and education about HCV risks and transmission. Though these rates are decreasing, hepatitis C remains endemic in many countries. In 2015, the WHO found the global incidence of new HCV infections to be around 1.75 million and has since set a goal of reducing new HCV infections by 80% between 2015 and 2030.
HCV infections can be found in all regions of the world with the highest number of new infections occurring in the European (61.8 per 100,000) and Eastern Mediterranean (62.5 per 100,00) regions. Most new infections in the Eastern Mediterranean are due to unsafe needle practices in healthcare, while injection drug use is the most common mode of transmission in the European region. Following those regions, the African region (31 per 100,000) and South-East Asian region (14.8 per 100,000) have the next highest rates of infections. The lowest incidence rates are in the Americas (6.4 per 100,000) and the Western Pacific region (6.0 per 100,000).
Chronic hepatitis C presents a global burden of about 1% which translates to an estimated 71 million people. Similarly to global incidence, the prevalence of chronic HCV infections is also unevenly distributed around the globe with variations occurring both between and within regions. The Eastern Mediterranean region has the greatest prevalence with 2.3% (15 million people). Followed by the European region with 1.5% (14 million people) and African region with 1% (11 million people). The Americas and Western Pacific both have a 0.7% prevalence with 7 million and 14 million cases respectively. South-East Asian has the lowest prevalence at 0.5% (10 million people). Within regions, China, Pakistan, India, Egypt, Russia, and the United States contributed to 50% of all global infections.
Prevalence by HCV genotype, which can affect the efficacy of hepatitis C treatment, also varies among different geographic regions. Of the 7 different genotypes, type 1 is the most common and accounts for 46% of global infections. It is the most common genotype found in Australasia, Europe, Latin America, and North America. HCV type 3 is the next most common and accounts for 22% of global cases. Genotypes 2 and 4 account for about 13% of global cases each with type 2 comprising an estimated 40% of cases in Asia and type 4 being especially prevalent in the North Africa and Middle East regions.
Incidence and Prevalence by Age and Sex
Though epidemiological data about hepatitis C by age and sex is sparse, studies have shown that incidence and prevalence vary by mode of transmission. Incidence of IV drug contracted HCV, the main mode of transmission in higher income countries, is highest among young men in these regions. Modeling also shows increasing incidence among women of childbearing age due to increased rates of IV drug use. Studies have also found the prevalence of medically contracted HCV infection to be higher among older populations, particularly those born between 1945 and 1965. This applies to most geographic regions and is possibly due to the cohort effect of being born before the implementation of blood screening.
Morbidity and Mortality
Although incidence rates are decreasing, mortality and morbidity continue to rise as older populations with chronic infections age and progress to more advanced stages of liver disease. In 2019, consequences of long-term HCV infection resulted in an estimated 290,000 deaths, most of which can be attributed to the development of liver cirrhosis and hepatocellular carcinoma. These complications also contribute to high rates of morbidity. In 2019 hepatitis C resulted in 15.3 million global Disability-adjusted life years (DALYs) and 0.6% of total global DALYs. Of those DALYs, 79.5% can be attributed to cirrhosis complications, and 18.9% can be attributed to liver cancer complications.
As global efforts to reduce the incidence, prevalence, and mortality of hepatitis C are becoming more widespread, better epidemiological surveillance is still needed to present a more accurate picture of hepatitis C burden and better inform strategies to eradicate the disease.