Hepatitis C

Hepatitis C is an infectious disease caused by the hepatitis C virus, often called HCV. This virus primarily attacks the liver, which is a vital organ in the human body.

HCV is a small, enveloped, single-stranded, positive-sense RNA virus. It belongs to the genus Orthohepacivirus within the family Hepaciviridae. Scientists have identified seven major genotypes of the virus, labeled one through seven. In the United States, genotype 1 is the most common, causing about 70% of cases. Genotype 1 is also the most frequent type found in Europe and South America.

When a person is first infected, they enter an acute phase. About 20% of people develop symptoms during this initial period. These symptoms usually appear between 4 and 12 weeks after infection, though the window can range from 2 weeks to 6 months. Common signs include fever, fatigue, nausea, vomiting, and abdominal pain. Some people experience jaundice, which is a yellowing of the skin or eyes, in about 25% of cases. Other symptoms include muscle pain, weight loss, dark urine, and clay-colored stools. For many, the infection may resolve spontaneously, which happens in 10% to 50% of cases. This spontaneous recovery is more common in females and young people.

For many others, the virus becomes a chronic infection. This is defined as the presence of detectable viral replication for at least six months. About 70% of people exposed to HCV develop this chronic state. While many people feel few symptoms for decades, the virus can cause long-term damage. In about half of those infected, fatty changes occur in the liver. These changes usually affect less than one-third of the liver and often appear before cirrhosis develops. Over 30 years, about 10% to 30% of infected individuals will develop cirrhosis.

Cirrhosis is a serious condition involving permanent scarring of the liver. This scarring can lead to dangerous complications like liver failure or liver cancer. Those with cirrhosis face a 20-fold greater risk of developing hepatocellular carcinoma, which is a type of liver cancer. This transformation occurs at a rate of 1% to 3% every year. Other complications include portal hypertension and ascites, which is the accumulation of fluid in the abdomen. Ascites occurs in more than half of those with chronic infection. Patients may also experience varices, which are enlarged veins in the stomach and esophagus, or hepatic encephalopathy, a syndrome of cognitive impairment.

Transmission occurs mainly through blood-to-blood contact. In the developed world, injection drug use is the primary route. In developing nations, unsafe medical procedures and blood transfusions are more common. The virus can also spread from an infected mother to her baby during birth. However, HCV is not spread through breast milk, food, water, or casual contact like hugging or kissing.

In the United States, universal screening of blood supplies began in 1992. This has lowered the risk of infection from transfusions to between one in 10,000 and one in 10,000,000. In healthcare settings, a needlestick injury from an HCV-positive person carries about a 1.8% chance of transmission.

History shows how much our understanding of the virus has grown. Scientists first suggested the existence of a "non-A, non-B" hepatitis in the 1970s. It was not officially proven to be a specific virus until 1989.

Today, we can diagnose the infection using blood tests to find antibodies or viral RNA. While there is no vaccine to prevent infection, modern treatments are highly effective. Older treatments like peginterferon and ribavirin were successful in less than 50% of cases and had many side effects. Newer antiviral medications, such as sofosbuvir or simeprevir, can cure more than 95% of chronic infections.

Global health data highlights the scale of this issue. In 2019, an estimated 58 million people were living with hepatitis C worldwide. That same year, approximately 290,000 deaths occurred, mostly due to cirrhosis and liver cancer. Because the virus is so closely linked to liver health, it remains one of the leading reasons for liver transplants. However, the virus often recurs even after a successful transplant. As medicine advances, the cost of new treatments has dropped significantly due to generic versions, helping more people in low-income countries access care.