CamScanner Created

CamScanner Created

Hepatitis B is an infectious disease caused by the hepatitis B virus, primarily characterized by liver damage. It is quite prevalent in China and poses serious health risks. According to surveys conducted in some provinces and cities, the infection rate of the hepatitis B virus is as high as 54.8%, of which 10% may develop symptoms. Furthermore, 10%–15% of hepatitis B patients may develop cirrhosis within five years, and a small portion may eventually progress to primary liver cancer. This disease is widespread globally, with higher prevalence in regions with lower economic development and poorer sanitary conditions. How does the hepatitis B virus transmit to humans? Any blood or bodily fluids containing the hepatitis B virus (saliva, breast milk, amniotic fluid, semen, vaginal secretions) can directly enter the body or penetrate through broken skin and mucous membranes, leading to transmission. (1) Blood transfusion transmission. Blood transfusions, plasma, and various blood products, including gamma globulin, can all transmit hepatitis B. In recent years, strict screening procedures have been implemented for hepatitis B virus testing of blood donors, significantly reducing the incidence of hepatitis B after blood transfusion, but it has not yet been completely eliminated, so further attention is still needed. (2) Iatrogenic transmission. Infections can occur during treatment using various medical devices, and sometimes hepatitis B may be transmitted through medical personnel as intermediaries. (3) Mother-to-child transmission. Among newborns born to mothers who test positive for hepatitis B surface antigen, 20%–40% will be infected. This is because during delivery, the placenta separates and breaks, allowing maternal blood containing the hepatitis B virus to directly enter the newborn’s bloodstream; alternatively, it may also be due to the rupture of the fetal membrane during childbirth, allowing maternal blood to seep into the fetal circulation.

CamScanner Created

Hepatitis B is an infectious disease caused by the hepatitis B virus, primarily characterized by liver damage. It is quite prevalent in China and poses serious health risks. According to surveys conducted in some provinces and cities, the infection rate of the hepatitis B virus is as high as 54.8%, of which 10% may develop symptoms. Furthermore, 10%–15% of hepatitis B patients may develop cirrhosis within five years, and a small portion may eventually progress to primary liver cancer. This disease is widespread globally, with higher prevalence in regions with lower economic development and poorer sanitary conditions. How does the hepatitis B virus transmit to humans? Any blood or bodily fluids containing the hepatitis B virus (saliva, breast milk, amniotic fluid, semen, vaginal secretions) can directly enter the body or penetrate through broken skin and mucous membranes, leading to transmission. (1) Blood transfusion transmission. Blood transfusions, plasma, and various blood products, including gamma globulin, can all transmit hepatitis B. In recent years, strict screening procedures have been implemented for hepatitis B virus testing of blood donors, significantly reducing the incidence of hepatitis B after blood transfusion, but it has not yet been completely eliminated, so further attention is still needed. (2) Iatrogenic transmission. Infections can occur during treatment using various medical devices, and sometimes hepatitis B may be transmitted through medical personnel as intermediaries. (3) Mother-to-child transmission. Among newborns born to mothers who test positive for hepatitis B surface antigen, 20%–40% will be infected. This is because during delivery, the placenta separates and breaks, allowing maternal blood containing the hepatitis B virus to directly enter the newborn’s bloodstream; alternatively, it may also be due to the rupture of the fetal membrane during childbirth, allowing maternal blood to seep into the fetal circulation.

<!-- translated-chunk:2/15 -->

The infant becomes infected by inhaling maternal blood or vaginal secretions containing the hepatitis B virus during passage through the birth canal; this mode of transmission is most infectious in mothers who are positive for the e antigen (so-called "big three positives").
(4) Contact transmission. Close contact among family members and the general population is an important mode of transmission, known as horizontal transmission. The aforementioned transmission from parents to children is called vertical transmission, which involves certain genetic factors. It is often observed that when the mother is infected, several of her children develop hepatitis B, whereas when the father is infected, only a few of his children do so—hence the saying, "If the mother is sick, the whole brood gets sick; if the father is sick, only one does." This indicates that the mother plays a greater role than the father in vertical transmission.
Hepatitis B can be classified into three main types: acute hepatitis, chronic hepatitis, and severe hepatitis. Acute hepatitis can be further divided into acute icteric hepatitis and acute non-icteric hepatitis; chronic

CamScanner created

hepatitis can be divided into chronic persistent hepatitis and chronic active hepatitis (some experts classify chronic hepatitis into mild, moderate, and severe degrees); severe hepatitis can be divided into acute severe hepatitis, subacute severe hepatitis, and chronic severe hepatitis (severe hepatitis will be discussed in detail in later chapters).
Diagnosis of hepatitis B: ① Acute hepatitis B. There is a history of contact with a hepatitis B patient or a history of blood transfusion or use of blood products. Symptoms include fatigue, loss of appetite, nausea, aversion to fatty foods, abdominal distension, and possibly jaundice. Liver function tests show elevated alanine aminotransferase and aspartate aminotransferase, with normal or elevated bilirubin levels. Serum hepatitis B surface antigen (HBsAg) is positive, serum hepatitis B virus DNA is positive, or hepatitis B virus DNA polymerase is positive, and serum hepatitis B core antibody IgM is positive. ② Chronic hepatitis B. There is a history of acute hepatitis, with symptoms such as fatigue, poor appetite, and pain in the liver area (right hypochondrium), which may be mild, moderate, or absent altogether. The hepatitis B surface antigen (HBsAg) remains positive for more than six months. In chronic persistent hepatitis, liver function impairment is relatively mild, and the prognosis is relatively good; in chronic active hepatitis, clinical symptoms are more severe, liver function is also more severely impaired, the albumin-to-globulin ratio is abnormal or inverted, and splenomegaly is often present, making it difficult to distinguish from early cirrhosis, resulting in a relatively poorer prognosis.
The significance of the "three systems" (also called "two-and-a-half") in the diagnosis of hepatitis B:
(1) Hepatitis B surface antigen (HBsAg) is a specific marker of infection with the hepatitis B virus. Its presence indicates that the body has been infected with hepatitis B, but the level of HBsAg is not directly correlated with the severity of the disease; rather, it is closely related to the degree of infectivity.
(2) Hepatitis B surface antibody (anti-HBs, HBsAb) is a protective antibody, indicating that the individual has previously been infected with the hepatitis B virus. Regardless of whether there are clinical manifestations of hepatitis, it signifies that the patient has now recovered and has immunity against the hepatitis B virus. If the body produces this antibody after receiving the hepatitis B vaccine, it means that the body has developed immunity.
(3) Hepatitis B e antigen (HBeAg) is a fragment of the core antigen, and its positivity and titer often reflect the replication status of the hepatitis B virus and the strength of its infectivity. In acute hepatitis B, HBeAg is briefly positive; if it remains positive, it suggests a transition to chronic hepatitis. In chronic hepatitis B infection, positive HBeAg often indicates active viral replication within hepatocytes. When HBeAg turns negative and is accompanied by the appearance of hepatitis B e antibody (anti-HBe), it usually indicates that viral replication has stopped. Precisely because of this characteristic of HBeAg, CamScanner created

people often refer to its positivity as "big three positives" and its negativity as "small three positives."
(4) Hepatitis B e antibody (anti-HBe, HBeAb) appears during the recovery phase of acute hepatitis B and can persist for a long time. In chronic hepatitis B infection, if anti-HBe is positive, HBeAg is often negative, indicating that the hepatitis B virus is not actively replicating and that infectivity is relatively low.
(5) Hepatitis B core antibody (anti-HBc, HBcAb) appears during the acute phase of hepatitis B and can persist for several years or longer after recovery, with its titer gradually decreasing. In patients with chronic hepatitis B, the core antibody remains positive. A single positive core antibody indicates a possible past infection with the hepatitis B virus. It is more meaningful to test anti-HBc-IgM and IgG separately. In acute hepatitis B patients, anti-HBc-IgM is highly positive, especially for those whose surface antigen has already turned negative; a positive anti-HBc-IgM can diagnose acute hepatitis B. The rate at which anti-HBc-IgM declines is related to the patient's condition: a rapid decline indicates a good prognosis, while if it does not return to normal within a year or shows fluctuating levels, it suggests the possibility of transitioning to chronic hepatitis. During the active phase of chronic hepatitis B, anti-HBc-IgM is moderately positive and can help distinguish between the active and inactive phases. Anti-HBc-IgG appears later than anti-HBc-IgM and is mainly seen during the recovery phase and in chronic infections.
In the examination of the three systems for hepatitis B, clinicians commonly refer to individuals who test positive for all three indicators—hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and hepatitis B core antibody (anti-HBc)—as "big three positives." Among them, a positive HBsAg indicates infection with the hepatitis B virus, but a positive HBsAg alone cannot fully diagnose hepatitis B, because some people are merely carriers of the virus. A positive HBeAg indicates viral replication and significant infectivity; if it remains positive, hepatitis is likely to recur frequently, leading to a poorer prognosis. A positive anti-HBc indicates that the person has either been infected with or previously infected with the hepatitis B virus, so "big three positives" means that the patient has been infected with the hepatitis B virus, and the virus is actively replicating and multiplying in the patient's liver, exhibiting strong infectivity, thus requiring prompt treatment and isolation. In the examination of the three systems for hepatitis B, clinicians also commonly refer to individuals who test positive for all three indicators—hepatitis B surface antigen (HBsAg), hepatitis B e antibody (anti-HBe), and hepatitis B core antibody (anti-HBc)—as "small three positives." Clinically, when acute hepatitis B presents as "small three positives," it often indicates slower viral replication during the acute phase, a tendency toward improvement, and a possible near-term recovery. However, when "small three positives" appear in the chronic phase, there are usually two meanings: ① Non-mutated strain infection transitions from "big three positives" to "small three positives," indicating reduced or halted viral replication, decreased or eliminated infectivity, and a milder or stabilized condition. ② When the virus mutates or a mutated strain infects, the hepatitis B e antigen (HBeAg) expression is lost, often accompanied by recurrent illness, rapid progression, and even the potential development of cirrhosis and liver cancer, or the occurrence of severe hepatitis. This situation is relatively rare in clinical practice and typically only occurs after a significant worsening of the condition.
In summary, the fundamental difference between "big three positives" and "small three positives" lies in whether HBeAg is positive or negative: those with positive HBeAg are "big three positives," while those with negative HBeAg are "small three positives."
Section 3: Hepatitis C Hepatitis C, abbreviated as HCV, is an infectious disease caused by the hepatitis C virus, primarily characterized by liver damage. Although the incidence of hepatitis C in China is lower than that of hepatitis B, the positive rate for anti-HCV antibodies in the healthy population can still reach 0.7%–3.1%, and in some regions, it even exceeds 10% among blood donors. In 1989, Choo et al. in the United States were the first to successfully clone HCV-DNA, thereby establishing the name of the disease. The primary mode of transmission is through blood. In the United States and Japan, the detection rate of anti-HCV antibodies among blood donors is 1.2%–1.4%, in Italy it is 0.99%, while survey results in various regions of China vary. For example, in Wuhan, a survey was conducted on 589 qualified blood donors—those who tested negative for HBsAg—and 9.35% were found to be anti-HCV positive. PCR testing confirmed the presence of HCV-RNA, indicating that most of these anti-HCV-positive individuals are infectious. Such blood donors can also be referred to as asymptomatic HCV carriers. Individuals who are frequently exposed to blood, such as hemophiliacs, obstetricians and surgeons, operating room staff, patients undergoing extracorporeal circulation, kidney transplant recipients undergoing hemodialysis, and cancer patients, are particularly susceptible to hepatitis C if they receive large amounts of stored blood. Intravenous drug users are also a high-risk group for HCV infection. Among hepatitis C patients, many have a history of sexual contact or household contact with hepatitis C, and it has also been found that the incidence of hepatitis C is significantly associated with having multiple sexual partners. Some researchers followed up on 25 infants born to anti-HCV-positive mothers, and among them, 14 had their anti-HCV antibodies disappear 2–4 months after birth, but by 6–12 months, 11 infants again tested positive for anti-HCV, with some developing clinical hepatitis C, indicating that HCV may be transmitted from mother to child. Although bloodborne transmission is the most effective way for hepatitis C to spread, at least 15%–30% of sporadic hepatitis C cases have no history of blood or extra-intestinal exposure, suggesting that sexual contact and daily life contact may also transmit HCV, though the probability is lower. Currently, hepatitis C has not yet been formally classified, and both domestically and internationally, it still uses the classification standards for hepatitis B, dividing it into acute hepatitis, chronic hepatitis, and severe hepatitis. Acute hepatitis is further divided into acute icteric hepatitis and acute non-icteric hepatitis; chronic hepatitis is divided into mild, moderate, and severe degrees; severe hepatitis is divided into acute severe hepatitis, subacute severe hepatitis, and chronic severe hepatitis.
The vast majority of hepatitis C patients have a history of blood transfusion, use of blood products, or contact with hepatitis C patients. Symptoms include fatigue, loss of appetite, nausea, abdominal distension, and possibly jaundice. A considerable number of patients are asymptomatic, and liver function tests often show isolated elevation of ALT, with normal or elevated bilirubin levels, and positive anti-HCV. The clinical course is generally milder than that of hepatitis B, often presenting as subclinical non-icteric hepatitis. Hepatitis C infection is more likely to become chronic than hepatitis B infection. According to observations, about 40%–50% of hepatitis C patients may develop chronic hepatitis, and 25% may develop cirrhosis.
Although the general course of hepatitis C is milder, acute outbreaks of hepatitis C and subacute courses, as well as chronic late-onset liver failure and other severe manifestations, can still occur. During the acute phase, patients may also exhibit extrahepatic symptoms, such as arthritis, rash, glomerulonephritis, and nodular polyarteritis.
Given the high rate of chronic hepatitis C, the incidence of cirrhosis reaching 25%–30%, and the fact that some patients often present with severe symptoms, the negative impact of this disease on individuals and society is no less than that of hepatitis B. CamScanner created