What is hepatitis C and what causes it?
Hepatitis C (HCV) is a virus that causes liver disease in a significant number of the U.S. and world population. In the United States, about 4 million people are infected, whereas worldwide it is 120 million. Majority of people who are infected remain undiagnosed. Infection from HCV virus causes inflammation of liver, and this may lead to scarring and cirrhosis. Cirrhosis may lead to liver failure and liver cancer.
The transmission is through blood, and common sources are contaminated needles (drug use in many countries), blood transfusion (uncommon in the United States), tattoos and other contaminated medical instruments (more in the developing world). Rarely, it can be transmitted by sex, from mother to child, or possibly by other sharp objects (pedicure, beauty parlors or hairdressers).
How is it different from hepatitis A and B?
Hepatitis A is transmitted by contaminated food or water. Hepatitis A is not uncommon in this country, but it is more common in developing countries. Hepatitis also causes acute liver disease, but it gets better without any specific treatment. It does not lead to chronic liver disease, cirrhosis or liver cancer. In a very small minority (less than 0.1 percent), it may cause acute liver failure. Those with pre-existing liver disease are more likely to develop severe liver disease after an acute hepatitis A infection. Those with chronic liver diseases, therefore, should be vaccinated to prevent hepatitis A infection.
Hepatitis B (HBV) is similar to HCV, and also transmitted in a similar fashion as HCV. About 1 million to 2 million people in the United States are infected with HBV. Worldwide, about 400 million people carry the virus and about 2 billion had exposure to HBV. It is very common in some parts of world, including China, East Asia and Africa. In those countries, mother passes the virus to the children (known as vertical transmission). In the United States, those who are born in those countries and whose parents are from these countries have a high prevalence of HBV. HBV is highly infectious (several times higher than HIV or HCV) and could be transmitted easily by body fluids that may contain blood.
For HBV, there is no cure, but it can be controlled. HBV is a DNA virus, and the memory stays in the nucleus of liver cells the rest of the infected person's life. There are effective treatments for controlling HBV, and they will reduce the risk of cirrhosis and cancer. Like HVC, HBV is a common cause of cirrhosis and liver cancer.
Like, HAV, the HBV infection could be prevented by vaccination.
If so many people have hepatitis C, when does it become a problem?
About 4 million people in the U.S. have HCV. In one out of three infected with HCV, it can cause cirrhosis. Initially, it causes inflammation, and gradually scar tissue forms and this leads to cirrhosis. Those who drink are more likely to develop cirrhosis and cancer. Therefore, it is important that those with HCV abstain completely from drinking.
Past therapies have been time-consuming and ineffective in many cases. Is this still the case?
There are different sub-types of HCV. Most people (75 percent) in the United States have genotype 1. This is more difficult to treat compared to genotype 2 or 3.
HCV treatment in early 1990s with interferon alone was ineffective. Until recently, HCV was treated with interferon and ribavirin. The cure rates varied from 40 percent to 50 percent for genotype 1. Recently, protease inhibitors were approved by the Food and Drug Administration. With the three-drug regimen, in genotype 1, the cure rate has gone up to 79 percent in those without cirrhosis and 62 percent in those with cirrhosis. The cure rate is also lower (62 percent) in African-Americans.
Are there even new therapies in the works?
Many new clinical, research trials are using three or four drugs, and some trials are being done without interferon. Early results are very promising, pushing the cure rates to almost 90 percent. New therapies without interferon are very exciting as they have fewer side effects. The progress in the last five years in this field has been very impressive.
Future trials will focus on a combination of oral medications to treat hepatitis C in a short period. Already, trials are in progress to reduce the treatment duration to three months. Trials are also being done with medication with fewer side effects.
Another area that has seen less progress is the development of effective vaccines to prevent HCV infection. Unlike HAV and HBV, there is no vaccine to prevent HCV infection.