There is very limited data of HDV in Thailand. As both HDV and HIV can accelerate the HBV course and increased the risk of death, particularly, among those with low CD4 cells/count, therefore, HDV burden in this special population is unmet need. Therefore, this study plans to perform a nationwide survey of the prevalence and predictor of HDV among people uses drugs (PWID) with and without HIV, HBV/HIV (MSM vs non MSM), HBV related cirrhosis. Findinds from this study will provide the scientific community to understand how important HDV is among HBV patients, this could be used to develop strategies for HDV screening and treatment