Humanity has been struggling with diseases since it exists on earth. It has always been hard to understand the nature of a disease. Term of a disease could be explained by impairment of normal body functioning. Diseases affected the history of humankind by causing the collapsing economy and brought disasters to people. There have been thousands of people who died because of epidemic disease. Therefore, people have been searched for the treatment of fatality diseases such as Smallpox, Viremia, HIV, Hepatitis A, Hepatitis B, Hepatitis C, Cancer, Rabies, Ebola, etc. Some of these fatality diseases have treatment or vaccines; some do not have treatment or vaccine. Scientists and medical doctors are still working to find vaccines or treatments for fatality diseases whose treatment did not found.

Hepatitis C Infection

The Hepatitis C virus was first fully recognized in 1975. Feinstone et al. showed that there are cases associated with transfusion hepatitis infection reason were not related to hepatitis A virus or hepatitis B virus, and the reason for this disease called non-A, non-B hepatitis. The Discovery of the hepatitis C virus is in 1989, and it is known as a significant reason for chronic liver disease. According to the World Health Organization (WHO)’s estimation, there were 399,000 people died from Hepatitis C in 2016, a major part of deaths caused by cirrhosis and hepatocellular carcinoma.

Transmission Patterns of Hepatitis C

Hepatitis C disease transmission type is blood-borne, which means the virus could be transmitted by injection of drugs, insecure injection methods, insecure healthcare, transfusion of unscreened blood and blood products, and sexual practices that will cause to have contact to blood.

Injection drug use

In developed countries, injection drug use is the primary transmission factor for HCV infection. In the literature, there is much research on injection drug use, which includes many risky behaviors for transmitting the blood-borne virus. The risky behaviors are defined as sharing used needles and other injection equipment. The whole risk is not only sharing needles, but some studies also show that the Hepatitis C virus can transmit by cookers, spoons, and cotton filters, which are called injection paraphernalia.

Injection drug use is the highest mode of transmission among middle-aged people in the USA and Australia, and in these countries, 68 % and 80% of the HCV infection reason is injection drug use, respectively. Recent studies show that young injection drug users with five years or less than five years have 20 – 46% seroprevalence rates. Researchers found that the prevalence of HCV antibody rates is changed from 50 to 90 percent among groups of injection drug users from Australia, Europe, Asia, and North America. This prevalence rate is exceptionally high in transmission routes of HCV. Among transmission routes, injection drug users have the highest prevalence of HCV, and also; another critical point is being a potential reservoir of HCV.

Blood transfusion

The amount of blood products is the crucial factor in obtaining HCV infection via blood transfusion. Transmission of HCV infection by blood transfusion is a potent way. There are some effective procedures that deactivate and destroy HCV for blood products, such as heat treatment, pasteurization, and solvent-detergent treatment; however, these procedures do not totally guarantee the elimination of the HCV [10]. Developed countries in the world have reduced the transmission risk of HCV infection with blood transfusion with the adoption of an all-volunteer donor system, screening blood donations with laboratory tests and HCV nucleic acid testing.

Unsafe therapeutic injections

As a result of being a blood-borne virus, another transmission route of the HCV infection is unsafe therapeutic injections. Unsafe therapeutic injection contributes a really small percentage of the HCV infection transmission in the developed countries and developing countries that use sterilization techniques and infection control practices to prevent HCV. Nevertheless, when we consider developing countries, the risk of HCV infection rate is higher than the developed countries due to the lack of health care conditions, such as supplies sterile syringes, non-hygienic places in the medical setting. In the developing countries, the average number of injections for a person in a year is 3.4, and 39.3% of the injections are reused.

Disease Progression

Acute Hepatitis

Diagnosis of acute hepatitis C is not frequent because the acutely infected patients commonly did not show symptoms. Studies show that between 70% and 80 % of the acute cases were asymptomatic in transfusion settings. The rest of 20% to 30% of the adult acute hepatitis C patients could be shown some symptoms 3 to 12 weeks after exposure to the virus, such as malaise, weakness, anorexia, and jaundice.

Chronic Hepatitis

Chronic hepatitis C is marked by the persistence of HCV RNA in the blood for at least six months after the onset of acute infection. An acute hepatitis C patient who has HCV RNA in the blood for at least six months is diagnosed with chronic Hepatitis C.

Around 75 % of the people who contract acute hepatitis infection will develop chronic hepatitis. The rest of 25 % will cure illness spontaneously, which is called in literature is spontaneous clearance. In the case of persistent hepatitis C chronic infection, the rate of progression of liver fibrosis differs in amount. Fibrosis is a scar that is a result of chronic inflammation in the liver. Fibrosis could grow in time and could advance to forward stages. There are four different kinds of scoring systems, which are the Knodell score/Histological Activity Index (HAI), the METAVIR score, and the Ishak score that measure inflammatory activity and degree of fibrosis.

There is an illustration of the METAVIR scoring system and corresponding’s in Figure 1.

METAVIR Scoring System

According to the METAVIR scoring system, F4 is the final stage, and it is called cirrhosis. If chronic HCV infection is not treated, it could cause severe liver diseases, such as end-stage liver disease, decompensated cirrhosis, hepatocellular cancer.

Treatment of Hepatitis C

There are no vaccines for Hepatitis C, but the treatment of hepatitis C infection is available for Hepatitis C patients. There are two types of treatment for Hepatitis C infection. One of the treatments is interferon therapy, and the other one is direct-acting antivirals treatment. Old therapy, which is interferon-based therapy made of pegylated interferon-alpha (IFN-a) and ribavirin (RBV), applied once a week and once a day for 24 to 48 weeks, respectively. Interferon therapy is a useful tool to prevent morbidity and mortality from Hepatitis C infection. Also, interferon- therapy is known even before the hepatitis C virus is discovered. The sustained virologic response

(SVR) of the old therapy varies from the active substance of the therapy. The virologic response for hepatitis C infection defines in the literature as a virus that is not detected in the blood during treatment. After completing the treatment, if there is no virus in the blood in the 12 weeks and more would be called a sustained virologic response.

IFN and ribavirin combination SVR rate is from 40% to %50. Nevertheless, IFN-a and RBV therapy are not enough to perfect a cure.

In the last decade, the introduction of direct-acting antivirals (DAA) has started a new era for HCV treatment, and the elimination of HCV globally by 2030 became a World Health Organization (WHO) target. New DAA regimes affect the SVR duration and SVR rate of treatment of hepatitis C infection. The SVR rate was increased above 90%, and the duration of the treatment has a decrease to 12 weeks or less.