Hepatitis C virus (HCV) is an important cause of chronic liver disease worldwide. In some areas the prevalence of hepatitis C is extremely high, as in Egypt, Saudi Arabia, the Phillipines and Papua New Guinea. The prevalence of hepatitis C antibody in volunteer blood donors is generally estimated at between 0.4% and 1%.
 
HCV has been described as the "shadow epidemic" because of the insidious nature of the infection which is generally asymptomatic and persists for life in 85% of patients infected with the virus.
HCV has tremendous genetic diversity and this enables it to escape the surveillance of the immune system of infected individual thus leading to chronic infection. In the same light, there are difficulties in vaccine development.

How is HCV transmitted?
HCV is largely transmitted parenterally ie by blood and blood products. Therefore, HCV infections may be acquired via the following means:
Intravenous drug abuse
Tattooing
Body-piercing
Accidental needlestick injury
Hemodialysis in patients with kidney failure
Organ and semen donation from a HCV carrier
HCV can also be transmitted by snorting drugs like cocaine ( blood from damaged nasal mucosa and transmitted by sharing straws).
Vertical transmission ( mother to infant ) during childbirth is possible if the mother has a high HCV viral load, co-infection with HIV (AIDS) and has acute hepatitis C during pregnancy. There is a 6% transmission rate by this method.
Sexual transmission is possible if one engages in promiscuous sexual activity.
Rarely, household ( non sexual ) transmission is possible through the sharing of razors and toothbrushes.

What is the clinical course after a HCV infection?
 
The onset of infection is often unrecognised and the early course is generally indolent. The natural history of HCV infection is dependant upon on geography, alcohol use, viral characteristics ( different genetic types, viral load ), co-infection with other viruses and some as yet unidentified factors.
After exposure to the virus, detectable viral genetic material called HCV RNA is seen in the blood in 1 - 3 weeks. Nearly all patients show evidence of liver injury because blood tests for liver enzymes become elevated. However, only 25% patients manifest symptoms like lassitude, anorexia and some became jaundiced (yellowing of eyes and skin). Rapid progression to liver failure due to fulminant hepatitis is a rare occurrence.
The majority of patients (85%) fail to clear the virus within 6 months and develop chronic hepatitis C. These patients are relatively well in the first 2 decades after acquiring the infection. However in 20% of these carriers, there may be intermittent symptoms of fatigue and malaise.
 
Symptoms
 
Generally, symptoms only appear once advanced liver damage has occurred. These signs and symptoms are features of liver cirrhosis ("hardening of the liver tissue") which results from persistence of the hepatitis C virus. These include ascites (swelling of the abdomen with fluid), jaundice, deterioration of mental state (hepatic encephalopathy), vomiting blood or passing out altered blood in the stools. Of course, there is the dreaded complication of liver cancer. Generally, cirrhosis appears in at least 20% of patients within 20 years of infection. Cirrhosis can be accelerated by concomitant alcohol use. Liver cancer develops after 30 years and occurs only in a background of liver cirrhosis.
 
It is interesting to note that hepatitis C has clinical manifestions beyond the liver. These are as a result of it's effect on the immune system, and are called extrahepatic manifestions. The extrahepatic manifestions include :
Joint swelling and pain ( arthritis )
Eye inflammation ( keratoconjuretivitis sicca )
Skin and oral manifestions ( lichen planus which appears as a characteristic rash and oral inflammation ).
Inflammation of kidneys ( glomerulonephritis )
Essential mixed cryoglobulinemia - this last rare manifestion is in itself a rare disease which affects the blood and various other body systems. Major symptoms may include unusual response to cold, skin abnormalities, weakness and blood problems. There may be joint pain, inflammed blood vessels and kidney problems.