Prevalence and Modes of Transmission of Hepatitis C Virus Infection: A Historical Worldwide Review

Hepatitis C virus infection affects over 58 million individuals and is responsible for 290,000 annual deaths. The infection spread in the past via blood transfusion and iatrogenic transmission due to the use of non-sterilized glass syringes mostly in developing countries (Cameroon, Central Africa Republic, Egypt) but even in Italy. High-income countries have achieved successful results in preventing certain modes of transmission, particularly in ensuring the safety of blood and blood products, and to a lesser extent, reducing iatrogenic exposure. Conversely, in low-income countries, unscreened blood transfusions and non-sterile injection practices continue to play major roles, highlighting the stark inequalities between these regions. Currently, injection drug use is a major worldwide risk factor, with a growing trend even in low- and middle-income countries (LMICs). Emerging high-risk groups include men who have sex with men (MSM), individuals exposed to tattoo practices, and newborns of HCV-infected pregnant women. The World Health Organization (WHO) has proposed direct-acting antiviral (DAA) therapy as a tool to eliminate infection by interrupting viral transmission from infected to susceptible individuals. However, the feasibility of this ambitious and overly optimistic program generates concern about the need for universal screening, diagnosis, linkage to care, and access to affordable DAA regimens. These goals are very hard to reach, especially in LMICs, due to the cost and availability of drugs, as well as the logistical complexities involved. Globally, only a small proportion of individuals infected with HCV have been tested, and an even smaller fraction of those have initiated DAA therapy. The absence of an effective vaccine is a major barrier to controlling HCV infection. Without a vaccine, the WHO project may remain merely an illusion.