Hepatitis C virus is an RNA virus that is found worldwide. It is the causative agent of hepatitis C.
What is the hepatitis C virus?
Hepatitis C virus (HCV) is an enveloped virus with one strand of RNA. It belongs to the Flaviviridae family and the hepacivirus genus. The virus with positive polarity is the only known RNA virus, with the exception of retroviruses, that can cause chronic infectious disease. The virus was first mentioned in 1974 as a non-A non-B hepatitis virus. However, it was not until 1989 / 1990 that the sequencing of the pathogen, which was henceforth referred to as hepatitis C virus, was achieved. The entire genome frequency of the virus is subject to patent protection. The patent holder is currently the pharmaceutical company Novartis. Together with Epstein-Barr virus, the causative agent of Pfeiffer’s glandular fever, hepatitis B virus and human herpesvirus 8, HCV is one of the viruses responsible for most cancers worldwide. Approximately 10 to 15 percent of all cancers are due to infection with these human viruses.
Occurrence, distribution, and characteristics
Humans are the only natural host of the hepatitis C virus. Monkeys are equally infectable, but chronic infection develops in them extremely rarely. The virus has a worldwide distribution. The World Health Organization (WHO) estimates that there are more than 170 million virus carriers. Not all carriers develop the disease, so the number of people with the disease is somewhat lower. Prevalence is highest in countries such as Japan, Egypt and Mongolia. In Egypt, for example, the high prevalence rate is due to contaminated needles used in the treatment of schistosomiasis. Schistosomiasis is a worm disease that is further spread in warm inland waters by intermediate hosts. In Europe and the U.S., the prevalence rate is less than 0.02. While subtypes 1a, 1b, and 3a are predominant in Europe and the Americas, subtype 1b is dominant in Asia. In Africa, genotype 4 predominates, and in Hong Kong and Vietnam, genotype 6. Genotypes 2 and 3 are found worldwide, but are represented to a lesser extent. Hepatitis C virus is transmitted parenterally. Parenteral means “bypassing the intestine.” Infection usually occurs through contaminated blood products or blood. Sexual transmission is extremely rare. Risk factors for hepatitis C virus infection include intravenous drug abuse, piercings and tattoos. Dialysis is also a risk factor. This is especially true for dialysis performed before 1991. Before 1991, the virus had not been sequenced, so it could not be detected. In one-third of patients, the route of transmission is unknown.
Diseases and symptoms
In the acute phase, hepatitis C is usually asymptomatic or associated with few symptoms. Therefore, in 85 percent of all cases of infection, the disease is not diagnosed in the early stages. After an incubation period of two weeks to two months, those affected suffer from fatigue, tiredness or loss of appetite. The joints may ache or the infected person may experience a feeling of tension or pressure in the right upper abdomen. In a few affected individuals, jaundice develops. Due to liver damage, urine may be dark and stools clay-colored. In the absence of these liver-typical symptoms, the disease is perceived by most sufferers in the acute phase merely as a mild flu-like infection. In more than 70 percent of all cases, however, hepatitis C takes a chronic course after the acute phase. If the infection remains untreated in the chronic stage, it leads to liver cirrhosis in 25 percent of patients. Liver cirrhosis is characterized by chronic degeneration of liver tissue. This results in a nodular tissue structure of the liver that severely limits the function of the organ. In addition, connective tissue increasingly forms in place of liver function cells. Liver function may be impaired with respect to its synthesis function of albumins and/or clotting factors. The result is an increased tendency to bleed and the formation of edema. Typical symptoms of liver cirrhosis also include abdominal dropsy, splenomegaly, redness of the palms, a red lacquer tongue and caput medusae, a distinct vascular marking on the abdomen. Liver cirrhoses are also so-called facultative precancerous lesions.This means that a malignant cancer can develop at the base of cirrhosis. This malignant tumor of the liver tissue is called hepatocellular carcinoma (HCC). In the course of hepatitis C, other antibody-mediated diseases may also develop. These include cryoglobulinemia, for example. This is a vascular inflammation (vasculitis) associated with joint pain, muscle pain, and neuropathies. Polyarteritis nodosa is also a vasculitis that can develop on the hepatitis C floor. Affected individuals experience nonspecific symptoms such as fever, night sweats, and weight loss. A large proportion of those affected also suffer from nerve disorders. CNS (central nervous system) involvement with [stroke|strokes]] is also possible. Hepatitis C can also cause Sjögren’s syndrome. Sjögren’s syndrome belongs to the group of collagenoses. In this disease, immune cells attack the lacrimal glands and salivary glands, causing inflammatory changes in the central nervous system and internal organs. There are also proven causal links between hepatitis C and insulin resistance, diabetes mellitus and depressive symptoms. Standard therapy for hepatitis C is a combination of different antivirals. Different drugs are used depending on the genotype. Severe side effects are to be expected with treatment of hepatitis C.
