Hepatitis inflammation of the liver, usually due to infection by several types of viruses, that infect and multiply in liver cells. Some of these viruses have the primary focus of infection in the liver. These are called primary hepatitis virus. Of them, the well-known hepatitis virus is responsible for over 95% of the clinical cases of hepatitis. Viruses that infect liver cells as a consequence of a systemic infection are the secondary hepatitis virus which include yellow fever virus, cytomegalovirus, Epstein-Barr virus, Herpes simplex virus, vericella-zoster virus, and measles, rubella coxsackie B virus, haemorrhagic virus (dengue), and adenoviruses.
Hepatitis virus is responsible for hepatitis in hundreds of millions of individuals every year worldwide. jaundice, characterised by paleness of the body with high levels of billirubin in blood, elevated functions of some liver enzymes and associated vomiting, anorexia and fever, is the end of the sequelae of a full-blown hepatitis virus infection. But there are many cases of hepatitis that do not manifest symptoms of jaundice and can only be recognised by specific tests designed to detect the presence of the virus in the body. These asymptomatic cases, being reservoir of the virus, are also quite considerable in number in the population and play significant role in the transmission of the disease.
Several different types of hepatitis virus have been discovered. These are: Hepatitis A Virus (HAV), Hepatitis B Virus (HBV), Hepatitis C Virus (HCV), Hepatitis D Virus (HDV), Hepatitis E Virus (HEV), Hepatitis G Virus (HGV) and Hepatitis F Virus (HFV, whose role in hepatitis is suspected but not clinically proven yet). Of these HAV, HEV and HFV are transmitted through the enteric (oral) route; the other types are transmitted parenterally, mainly through contaminated blood or body fluid, non-sterile and contaminated syringes and other medical instruments, and also during unprotected sexual intercourse. The latter types are also thus common in intra-venous drug users. Some hepatitis viruses, notably HBV and HCV, cause chronic diseases of the liver and are significantly correlated with cancer of the liver.
The Hepatitis B Virus causes the most severe form of hepatitis, which is a global problem of considerable magnitude. Available data indicate that over 2 billion people world-wide show evidence of past or current infection with this virus and 350 million are chronic carriers of the virus in their liver and blood. The virus accounts for 60-80% of all primary liver cancers throughout the world.
Reliable statistics on hepatitis incidence in Bangladesh are available for some of the hepatitis viruses, particularly HBV. About 7.5% of the population, numbering nearly 10 million, are carriers of Hepatitis B Virus. Some of these carriers do not show any signs of liver disease (asymtomatic), while a fraction of the carriers transit into chronic liver diseases. Asymtomatic carriers can spread the virus to healthy persons through blood contact although they themselves may remain free from diseases throughout life. Because of restricted proliferation of the virus in such persons, however, the mechanism through which this takes place is not known. Acute HBV infection is clinically silent in about 75% of the cases; only 25% acute HBV infections develop clinical jaundice. HBV induced acute hepatitis may be complicated by fulminant hepatic failure in about 1% of cases. Acute illness may progress into chronic carrier states in a certain number of cases.
HAV and HEV Nearly 50% of the children of Bangladesh carry antibodies against Hepatitis A Virus in blood, which suggests that they were infected with the virus at some stage of life. Hepatitis E Virus has been found to be the commonest cause of acute viral hepatitis in Bangladesh. Both of these two viruses, A and E, cause infection through the enteric route with contaminated food and water.
HCV Is next to HBV in importance as a global problem. Approximately 1.8 billion people are infected with HCV, About 170 million people are chronic carriers of the virus and are at risk of developing live cancer. These facts admittedly highlight the gravity of the illness as a major global health problem. In Bangladesh, available data indicate that approximately 3% of hepatitis cases are due to HCV.
Infections by other hepatitis virus types are not routinely detected in Bangladesh as tests are not available but their occurrence will not be negligible. Among patients who have developed clinical jaundice with acute hepatitis, the virus types may vary from time to time. A study carried out recently (year 2000) show a preponderance of cases with HEV infection, followed by HBV, HAV, and HCV.
Blood transfusion and surgery is significantly correlated with infections by HBV and HCV in Bangladesh, which is largely due to poor blood screening and improper sterilisation of surgical instruments. [Zia Uddin Ahmed]
See also jaundice.