Bloodborne infections are diseases caused by pathogens present in human blood that can be transmitted to another person through contact. Transmission primarily occurs through direct exposure, such as sharing needles or occupational exposure in healthcare settings. Understanding the most common infection is crucial because many people remain unaware they are infected for years, leading to significant long-term health consequences. While Human Immunodeficiency Virus (HIV) and Hepatitis B Virus (HBV) are well-known, the pathogen causing the highest number of chronic infections in the US is often overlooked.
Identifying the Most Prevalent Bloodborne Infection
The most common chronic bloodborne infection in the United States is the Hepatitis C Virus (HCV). HCV targets the liver; while initial exposure may cause an acute illness, 75% to 85% of infected individuals progress to a chronic, lifelong infection. This high rate of chronicity distinguishes HCV from Hepatitis B, which most adults successfully clear. Between two and four million people in the U.S. are currently living with chronic HCV. This makes it a leading cause of severe liver disease, cirrhosis, and liver cancer, and the most common reason for liver transplantation in the country.
How the Infection Spreads
Transmission of the Hepatitis C Virus occurs primarily when infected blood enters the bloodstream of an uninfected person. Today, the most frequent mechanism for transfer in the U.S. is sharing contaminated equipment used to inject drugs, which accounts for roughly 60% of all HCV infections. Historically, poorly sterilized medical equipment and blood transfusions were significant sources, but widespread blood screening implemented in 1992 made transfusion-related transmission rare.
Less common routes include perinatal transmission from mother to child during pregnancy or childbirth. Sexual transmission is also possible but inefficient, usually requiring blood-to-blood contact or high-risk factors like HIV. Importantly, HCV is not spread through casual contact, such as hugging, kissing, or sharing eating utensils.
The Asymptomatic Challenge and Screening Guidelines
A major challenge in controlling HCV is its often asymptomatic nature, allowing it to quietly progress for years or decades. Most people do not experience noticeable symptoms during the acute phase, meaning many are not diagnosed until the virus has caused significant, irreversible liver damage, such as advanced fibrosis or cirrhosis. To combat this silent progression, public health guidelines have shifted toward universal screening.
The Centers for Disease Control and Prevention (CDC) now recommends that all adults aged 18 years and older be screened for HCV at least once in their lifetime. This universal recommendation replaces the previous focus on testing only those born between 1945 and 1965. The CDC also recommends testing for all pregnant women during each pregnancy and for any person with recognized risk factors, regardless of age. Individuals with ongoing risk behaviors, such as current injection drug use, should receive periodic retesting.
Effective Modern Treatment Options
The treatment landscape for Hepatitis C has been dramatically transformed by the introduction of Direct-Acting Antivirals (DAAs). These medications specifically target non-structural proteins within the virus, effectively stopping its ability to replicate. This pharmacological revolution has replaced older, less effective, and often harsh interferon-based therapies.
DAA regimens are typically administered as a simple, all-oral pill taken for a short period, most commonly eight to twelve weeks. These modern treatments are highly effective, achieving a sustained virologic response, or cure, in over 95% of patients across all major genotypes. Achieving a cure eliminates the risk of future liver damage and cancer, and stops the potential for transmission.