To investigate the features of various hepatitis virus infection in intravenous drug users （IVDU）, we conducted an epidemiological survey of hepatitis viruses including hepatitis B virus （HBV）, hepatitis C virus （HCV）, hepatitis D virus （HDV） and hepatitis G virus （HGV） in IVDU. The correlation of Tn lymphocyte cytokine and hepatitis virus infection was examined. A. study population of 406 IVDU consisted of 383 males and 23 females. HBV-DNA and HCV-RNA were detected by fluorescence quantitative polymerase chain reaction. HBsAg, HBeAg, anti-HBc, anti-HCV, HDV-Ag and anti-HGV were assayed by ELISA. The levels of cytokines of TH1 and TH2 were measured by ELISA. The similar indices taken from 102 healthy persons served as controls. The infection rate of each virus among IVDU was 36.45% for HBV, 69. 7 % for HCV, 2.22 % for HDV, and 1.97 % for HGV, respectively. The co-infection rate of HBV and HCV was detected in 113 of 406 （27. 83 %）. In contrast, among controls, the infection rate was 17.65% for HBV and 0% for the other hepatitis viruses. The levels of PHA-induced cytokines （IFN-γ and IL-4） and the level of serum IL-2 were obviously decreased in IVDU. On the other hand, the level of serum IL-4 was increased. The IFN-γ level was continuously decreased when the IVDU was infected with HBV/HCV. In conclusion, HBV and HCV infection were common in this population of IVDU and they had led to a high incidence of impaired TH 1 cytokine levels.
