Lower chronic hepatitis B in South Asia despite all odds: Bucking the trend of other infectious diseases

Abstract

Hepatitis B virus (HBV) infection remains a significant global health problem. As per estimates of the World Health Organization (WHO), approximately 2 billion people have been infected worldwide, which represents one-third of the world population. Of these, more than 350 million (5-7% of the world's population) suffer from chronic HBV infection. 1,2 Approximately 15-40% of the infected patients will develop life-threatening liver diseases (cirrhosis, liver failure and hepatocellular carcinoma) resulting in 600,000 to 1.2 million deaths per year due to HBV. 3,4 Epidemiological data on HBV infection is therefore important for strategies to tackle the spread of the disease. Based on the prevalence of hepatitis B surface antigen (HBsAg), countries are classified as having high (>8%), intermediate (2-7%) or low (<2%) HBV endemicity. Areas of high endemicity (where >8% of the population is HBsAg positive) include SouthEast Asia, China, most of Africa, most of Pacific Islands, the Amazon basin and parts of the Middle East. The areas of intermediate endemicity (2-7%) include South Asia, Eastern and Southern Europe, Russia and Central and South America. On the other hand areas with low endemicity (<2%) include United States, Western Europe and Australia. 5 The South Asian countries, a contiguous block of countries which have been classified together as Global Burden of Disease Regions include Afghanistan, Bangladesh, Bhutan, India, Nepal and Pakistan. 6 People in South Asia are at a higher risk of developing infectious diseases due to poverty and its associated problems of unhygienic living conditions, malnutrition, illiteracy, and poor access to clean water, toilet facilities, and quality health care. Spread of HBV infection in many South Asian countries is attributed to unsafe blood supply, reuse of contaminated syringes, lack of maternal screening to prevent perinatal transmission and delay in the introduction of hepatitis B vaccine. 7 However, it is intriguing that bucking the trend of other infectious diseases, the prevalence of HBV in South Asian countries is lower than some of the more affluent neighbors in the South East Asian countries. Re-emphasizing the lower prevalence of HBV in South Asia is an article by Shrestha et al 8 in this issue of Tropical Gastroenterology, which shows that the prevalence of HBV in Nepal is even lower than that in other countries of South Asia. HBV in India India is the largest nation in the region and by its sheer population bears the bulk of HBV burden in South Asia and accounts for 10-15% of the entire pool of HBV carriers of the world. 9 It has been estimated that India has over 40 million HBV carriers. Of the 25 million infants born every year in India, it is estimated that over one million run the lifetime risk of developing chronic HBV infection. Every year over 100,000 Indians die due to illnesses related to HBV infection. 10

Hepatitis B and hepatitis C in southeast and southern Asia: challenges for governments

“…HBsAg prevalence in pregnant women is estimated to be 0•4% in the rural population and 3•5% in urban regions. 8 HCV prevalence varies considerably, from 0•8% among truck drivers to 24•8% among people who inject drugs. 7 12-18 million people (0•96-1•4% of the population) are thought to be infected with HCV in India, 9 and more than 37 million people (2•55% of the population) have chronic HBV infection 10 -with the highest prevalence in specifi c areas or among tribal populations.…”

Tackling the Hepatitis B Disease Burden in India

“…55 Despite the lower socio-economic status, illiteracy, low immunization rates, regional conflict and high-risk tribal populations, the prevalence of HBV is lower in India and the rest of South Asia as compared to South-East Asia. 56 Despite all the odds, this lower prevalence of HBV in South Asia may be due to the fact that unlike the vertical transmission of HBV in South-East Asia, the predominant mode of transmission is horizontally in South Asia. 57,58 Chronic HBV infection in India is acquired in childhood, presumably before 5 years of age, through horizontal transmission.…”

Seroprevalence and Risk Factors of Hepatitis B and Hepatitis C Virus Infections in Uttarakhand, India

“…9 The overall rate of HBsAg positivity has been reported to range between 2 and 4.7%. 10 The seroprevalence of HBsAg of 2.8% was noted in our tertiary care hospital population. A recent study conducted by Sood and Nalwankar 2 from Jaipur showed seroprevalence of HBsAg to be 0.87%.…”