The phantom menace

Hepatitis C is a stealthy and deadly disease. Its causative agent, the hepatitis C virus (HCV), is transmitted by blood and slowly destroys the liver. Infection becomes chronic in 80% of cases and leads to cirrhosis, liver cancer, liver failure and eventually death. Hepatitis C is the most prevalent liver disease in the world, the most common cause of liver transplantation in developed countries, and the most frequent blood-borne infection in the USA, where 10,000 people each year die from its complications. There is no vaccine available and current treatments fail in about half of patients. Associated social and healthcare costs on a global scale are incalculable. This is the grim fact sheet of hepatitis C, dubbed ‘the silent killer’ because it may give no sign of its presence for decades, leaving its victims unaware of danger until it is too late for therapy. According to the World Health Organization (WHO; Geneva, Switzerland), 170 million people may be chronically infected with HCV worldwide—around 3% of the world’s population—and millions more are newly infected each year (WHO, 2000). But even these figures are not clear. “Recent CDC estimates indicate that the worldwide prevalence of HCV infection may be closer to 2%, representing approximately 120–130 million persons,” said Joseph Perz, an epidemiologist at the Division of Viral Hepatitis of the US Centers for Disease Control and Prevention (CDC; Atlanta, GA, USA). “These estimates are similar to, but lower than, previous WHO estimates, which did not account for the lack of specificity associated with unconfirmed HCV antibody testing or for lower prevalence among younger age groups that are not well represented in surveys.” Accurate numbers are lacking particularly for developing countries, where most of the world’s population resides, Perz noted, thus global estimates of the prevalence of hepatitis C are difficult to define. The culprit, HCV, was not discovered until 1989, when Michael Houghton and his team at Chiron Corporation (Emeryville, CA, USA) isolated a cDNA clone of the viral agent then known to cause post-transfusion ‘non-A, non-B hepatitis’ (Choo et al, 1989). More than a decade after this discovery, many central questions concerning HCV’s life cycle and host interactions remain unsolved, as does the challenge to develop effective therapies and vaccines. Nevertheless, the silent pandemic is finally receiving attention as a major public health problem and recent advances may help scientists to strike the virus at its weak points.