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. 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. 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 ( 8% of the population is HBsAg positive) include South-East 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. 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. 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. 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 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.