“Hepatitis” means “inflammation of the liver”. Those inflammations caused by a virus present a serious problem to public health. As we have seen in Sect. 4.2, acute viral hepatitis in Vietnam had in 2007 an incidence of approximately 11cases per 100,000 inhabitants. This may not appear very high. In fact, among acute infectious diseases viral hepatitis had an incidence below that of dengue fever, varicella, shigellosis and amoebiasis. Its mortality was also fairly low, namely 0.0035 per 100,000 people, that is, only one tenth of the mortality by viral encephalitis (0.0352 per 100,000). Its case fatality (number of deaths per number of cases) was 0.0035/11 = 0.00032 = 0.032% compared with the case fatality of viral encephalitis, which equalled 0.0352/1 = 0.0352 = 3.52%. However, what makes viral hepatitis an important health problem is a trait that it shares with the human papillomavirus infection (see Sect. 22.4): it may lead to cancer. In fact an infection by the virus of the type B or C of hepatitis can turn into a chronic asymptomatic infection, which may entail liver cirrhosis, liver fibrosis, and hepatocellular carcinoma, often only after many years.