Abstract
Background:
Hepatitis B is a liver infection caused by the Hepatitis B Virus (HBV). Sri Lanka is considered a country of low endemicity, with an HBV infection prevalence estimated at less than 2%. However, there is a high risk of HBV transmission among family members and close contacts of infected patients. Preventing intra-familial transmission is crucial in managing Hepatitis B.

Aim:
This study aimed to evaluate the HBV infection status among family contacts of HBV-infected patients followed up at the National Hospital, Kandy, Sri Lanka.

Methods:
Laboratory data on serological markers from 148 family contacts of 42 index cases were analyzed. All index cases were followed up at the Department of Virology at the National Hospital, Kandy, after being referred from gastroenterology, STD, and medical clinics. Serum samples from the close contact of family members of these index cases were tested for HBV serological markers between March 2017 and February 2021.

Results:
Out of the 148 family members, 25 (16.89%) showed evidence of exposure to HBV (reactive anti-HBc) at the time of screening. Six family members (4.1%) were positive for HBsAg. Among these, two had evidence of active infection (reactive HBeAg/non-reactive anti-HBe) and four had seroconverted to anti-HBe. Among exposed contacts, 19/25 (12.8%) were non-reactive for HBsAg, indicating past infection, of whom 13/25 (8.7%) were positive for anti-HBs indicating immunity following infection.
Among 32 spouses, six (18.75%) showed evidence of exposure to HBV infection. In two index cases, all family members had evidence of HBV infection. Thirty-six (24.3%) family members had taken the HBV vaccine prior to screening. Among them, 26 (17.6%) showed adequate immunity against Hepatitis B (anti-HBs antibody titer > 10 mIU/ml), and all were negative for anti-HBc, indicating immunity following vaccination.

Conclusion:
The HBV infection rate among family members (16.9%) is significantly higher than in the general population (<2%). A proper understanding of the transmission dynamics of intra-familial HBV infection is important for preventing HBV infection among family contacts.

Key words: Hepatitis B Virus (HBV), Intra-familial, transmission. Hepatitis B infection