World Hepatitis Day is observed on July 28 every year to raise awareness of the problem of viral hepatitis. Let’s learn more about how hepatitis impacts people and how to prevent this viral disease.
The liver is the largest substantial organ of the human body and the largest digestive organ in the digestive system. Hepatitis, a group of infectious diseases known as hepatitis A, hepatitis B, hepatitis C, hepatitis D, and hepatitis E, affects millions of people worldwide, causing both short-term and long-term liver diseases.
Any kind of hepatitis that develops for a long time will cause serious damage to the body and can even present a threat to life. Hepatitis B and hepatitis C cause relatively more harm in China. About one tenth of the population in China is afflicted with hepatitis B. Long-term sufferance from hepatitis B and hepatitis C will cause liver cirrhosis, with the potential of leading to liver cancer through the malignant transformation of liver cirrhosis nodules.
How viruses attack the liver
Hepatitis A: When the hepatitis A virus infects the body, they self-replicate in liver cells. The body will have a series of immune responses, such as liver cell necrosis and an inflammatory reaction, which in turn causes liver cell damage. The Hepatitis A virus can be eliminated by the immune responses of the body, and will not develop into chronic hepatitis, cirrhosis or viral state.
Hepatitis B: When the hepatitis B virus infects the body, they self-replicate in liver cells, which does not directly cause liver cell disease, but the gene of hepatitis B virus can be integrated into the host's liver cell chromosome, resulting in long-term liver disease. The liver cell damage of hepatitis B is caused by a series of immune responses of the body, which can not only eliminate the virus, but also cause liver cell damage, and can even make the hepatitis B virus mutate.
The immune regulation function of the body and the strength of immune responses are closely related to the clinical type and prognosis of hepatitis B.
(1)Acute hepatitis: In a body with a normal immune response, the liver cells infected by the hepatitis B virus are destroyed by the immune response attack, which eventually die and cause no further infection, but appear as acute hepatitis. Depending on the amount of the virus present, the degree of liver cell damage is different, and acute hepatitis is divided into acute icteric and acute non-icteric hepatitis.
(2)Chronic hepatitis: If the immune function of the body doesn’t work well and fails to eliminate the hepatitis B virus, the body may become an asymptomatic chronic hepatitis B virus carrier. Some patients' liver function suffers from continuous and mild damage, resulting in chronic hepatitis.
Hepatitis C and E: At present, there is little research on the pathogenesis of hepatitis C and E. Some results suggest that the pathogenesis of hepatitis C and E is also related to the immune response of the body.
Hepatitis D: Studies have shown that the hepatitis D virus has direct destructive effects on hepatocytes. The overlapping infection of hepatitis D and hepatitis B can lead to mass replication of the hepatitis D virus, significantly aggravating the damage to liver cells and easily developing into chronic hepatitis or severe hepatitis.
How Hepatitis spreads
The most common form of transmission for hepatitis A virus is the fecal-oral route, also known as the intestinal route, that is, contaminated food and water enter the digestive tract to cause a hepatitis A infection.
Aquatic crustaceans are likely to be contaminated by the hepatitis A virus. When people eat undercooked oysters, clams, and other aquatic products, there is a higher risk of the hepatitis A virus infection.
Hepatitis B and C
Hepatitis B and C can be transmitted through blood, mother-to-child transmission, close contact and iatrogenic transmission.
(1) Blood transmission: A very small amount of blood or blood products containing hepatitis B or hepatitis C virus can cause infection after entering the human body. Blood transfusion, hemodialysis and organ transplantation can all spread the viruses.
(2) Mother-to-child transmission: If the mother is a carrier of the hepatitis B or hepatitis C virus, there is a certain probability of transmission to the fetus upon delivery.
(3) Sexual transmission: When there is unprotected sexual contact with patients infected with the hepatitis B virus, the virus can be transmitted through damaged skin mucosa.
(4) Latrogenic transmission: Use of contaminated or poorly disinfected needles can cause the infection of hepatitis B or hepatitis C virus.
The Hepatitis D virus has the same route of transmission as hepatitis B, which is through blood, sexual contact and mother-to-child transmission. However, hepatitis D rarely infects the host alone; it mostly co-infects the host with hepatitis B and other DNA viruses.
Hepatitis E, like hepatitis A, is also transmitted through the fecal-oral route. Most of the patients are young and middle-aged. Pregnant women can be easily infected with hepatitis E and can develop into severe cases, with a high mortality rate.
Daily contacts, such as working with patients with hepatitis B/C, shaking hands and hugging, living in the same room, even having meals together and sharing toilets, will not have people infected.
However, for those will be engaged in intimate contacts, it is recommended to carry out hepatitis virus tests first.