Viral hepatitis is the inflammation of the liver caused by viruses A, B, C, D or E. These viruses can be distinguished depending on the predominant mode of transmission — water or blood — and show significant differences in their epidemiology, presentation, prevention and control.
Viral hepatitis has been recognized as a serious public health problem in India by the World Health Organisation (WHO) with over 52 million people infected with chronic hepatitis in the country. This is placing a huge disease, social and economic burden on the affected families as well as the health system. Nearly 119,000 cases of allcause viral hepatitis were reported in India in 2012. The Integrated Disease Surveillance Programme of the NCDC received notification of 290,000 cases of acute viral hepatitis in 2013.
Latest assessment by WHO shows that in India, 40 million people are chronically infected with Hepatitis B and 6 to 12 million people are chronically infected with Hepatitis C. Besides, Hepatitis E virus (HEV) is the most important cause of epidemic Hepatitis, whereas Hepatitis A virus (HAV) is more common among children. Most acute liver failures diagnosed are attributable to HEV.
Disease burden and sero-prevalence of hepatitis A and E. Globally, an estimated 1.4 million cases of hepatitis A virus (HAV) infection occur annually. The proportion of young adults at risk for HAV infection is very low in India. The Indian population is showing a recent upward shift in the average age at first HAV infection, among the socio-economically developed population resulting in pockets of susceptible populations. Hepatitis E prevalence is highest in the East and South Asia regions, accounting for 60% of hepatitis E global incidence and 65% of global deaths. Despite the high endemnicity of hepatitis E virus (HEV) in the South Asian region (Figure 1), the sero-prevalence of antibody to HEV is only 25% in young adults. Among the Indian population, there is low sero-prevalence until age 15, reaching 40% in young adults. HEV is the most important cause of epidemic hepatitis, though HAV is more common among children.
Most Acute Viral hepatitis is most commonly seen due to acute Hepatitis A or Hepatitis E virus infection. Globally, an estimated 1.4 million cases of hepatitis A virus (HAV) infection occur annually. The proportion of young adults at risk for HAV infection is very low in India. The Indian population is showing a recent upward shift in the average age at first HAV infection, among the socio-economically developed population resulting in pockets of susceptible populations.
Hepatitis E prevalence is highest in the East and South Asia regions, accounting for 60% of hepatitis E global incidence and 65% of global deaths. HEV is the most important cause of epidemic hepatitis though HAV is more common among children. Most acute liver failures diagnosed in India are attributable to HEV, and HEV is the most common cause of hepatitis during pregnancy.
Transmission. Both HAV and HEV are transmitted through the fecal–oral route, due to ingestion of contaminated water — sewage-contaminated and inadequately-treated water. Consistent with previous reports from India unsafe drinking water was the most commonly reported cause of hepatitis A and E outbreaks, highlighting the need for improved access to clean drinking water and improved sanitation. Mixing of contaminated soil into wells and rivers during rains or floods has also been associated with HEV outbreaks in India. Person-to person transmission or through food route is relatively less common in HEV than in HAV.
Laboratory diagnosis. Recent infections are detected by the presence of IgM antibodies in the serum and acute increase in liver enzymes. IgG antibodies remain detectable for life in HAV infected persons but persist for only 15 years in those with HEV infection.
Prevention and control. Prevention and control of HAV and HEV transmission can be achieved by (1) improvements in sanitation and sewage disposal, measures for water and food safety, and health education on hygiene practices, and (2) use of effective inactivated and live attenuated HAV vaccines for controlling outbreaks. Routine immunization against HAV has not been warranted in India considering the high sero-prevalence, and lower cost of antibody assay compared to that of the HAV vaccine. However, the recent epidemiological transition presents a need to develop an immunization strategy for susceptible populations. HEV recombinant protein vaccines are being studied.
Hepatitis viruses B (HBV), D (HDV) and C (HCV), which predominantly transmit through the parenteral route, pose a serious “silent epidemic” challenge to India. Infected persons are unaware of their chronic carrier status, and continue to infect others for decades and eventually burden the society with loss of productive workforce, and the health care system with expenses of treating liver failures, chronic liver diseases, and cancers. Disease burden and sero-prevalence. HBV and HCV together are estimated to have led to 500 million chronically infected persons and one million deaths annually (Figures 2 and 3 present global HBV endemnicity and HCV endemnicity, respectively). In the South-East Asia region, the estimated burden of chronic HBV infection is 100 million and the estimated burden of chronic HCV infections in South Asia is 50 million. HBV is the second most common cause of acute viral hepatitis after HEV in India. With a 3.7% point prevalence, that is, over 40 million HBV carriers, India is considered to have an intermediate level of HBV. endemnicity. Every year, one million Indians are at risk for HBV and about 100,000 die from HBV infection. The population prevalence of HCV infection in India is 1%. HDV infection is not very common in India and is observed in 10% to 20% of HBV positive patients.
Transmission. HBV, HDV, and HCV infections are commonly caused by exposure to infected blood. Infections also occur as a result of iatrogenic exposures (transfusion/ transplantation/dialysis of infected blood/ blood products or organs/tissues), and use of contaminated injections/equipment. Epidemics due to unsafe injection practices have been documented in India (hepatitis B carriage and C infection is 46% and 38%, respectively), such as among injecting drug users and healthcare workers caring for infected people. Transmission through unsafe sexual intercourse and transmission from mothers to infants is well-established, though less frequent for HCV infection. Perinatal transmission is about 10% if the mother is hepatitis B surface antigen (HBsAg) positive only and about 90% when the mother is positive for both HBsAg and hepatitis B e-antigen (HBeAg). HCV accounts for most of the post transfusion hepatitis cases. HDV exclusively super-infects or co-infects those infected with HBV and transmits through both iatrogenic and sexual routes. The ability of HBV and HCV to survive for prolonged periods in the external environment increases their infectivity. Though HBV is the major cause of chronic liver disease, cirrhosis and liver cancers in India, about 20% of them are also associated with HCV infection. Dual infection of HDV and HBV has more serious presentation of liver failures in acute infections and liver cancers in chronic infections. HBV and HCV co-infection and their coinfection with HIV is another area of concern.
Laboratory diagnosis: Presence of HBsAg determines infectivity of the HBV infected case. Presence of HBeAg suggests increased viral replication in the infected case. Appearance of anti-HBs implies immunity to HBV infection either by natural infection or vaccination. Acute infection is identified by the presence of IgM hepatitis B core antigen (anti-HBc). Presence of anti-HBc in the absence of IgM anti-HBc and persistence of HBsAg indicates chronic infection. Presence of anti-HCV and anti-HDV suggest exposure to HCV and HDV, respectively. HCV-RNA detection is necessary for verification of current HCV infection. Liver disease activity is evaluated on clinical imaging, blood biochemistry, liver enzymes, and histo-pathological findings along with viral load studies.
Prevention and control: Prevention and control can be achieved through safe and effective HBV vaccines. WHO recommends routine infant vaccination along with catch-up immunization for adolescents and high risk populations. India introduced universal immunization against hepatitis B in 10 states in the year 2002, and in 2011, scaled up this operation countrywide. Recently a pentavalent vaccine, which also protects against HBV, has been introduced in some states. The HBV vaccine also protects from HDV infection. There is no vaccine against HCV. Screening and immunization of high-risk groups, such as those with history of exposure, risky practices, and occupational risk; specific measures for prevention of mother-to-child transmission and promoting safe blood supply, safe injections and safe sex are other recommended preventive measures.
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