Rapid spread of hepatitis C virus among injecting-drug users in the Philippines:: Implications for HIV epidemics

From the trends of human immunodeficiency virus (HIV) epidemics in South and Southeast Asia, it was postulated that an HIV epidemic would start as a blood-borne infection among injecting-drug users in the Philippines. In 2002, 560 individuals were recruited in Metro Cebu, Philippines and tested for HIV, hepatitis C virus (HCV), and hepatitis B virus (HBV) infections. The seroprevalence of anti-HCV among injecting-drug users (70.1%, 61/87) was significantly higher than those among inhalation drug users (16.3%, 7/43; P= 0.00; OR= 12), sex workers (0%, 0/130; P= 0.00; OR = infinity), antenatal clinic attendees (0%, 0/100; P = 0.00; OR = infinity), and students/health care workers (2%, 4/200; P= 0.00; OR = 115). The seroprevalence of HBsAg among injecting-drug users (10.3%, 9/87) was significantly higher than those among sex workers (2.3%, 3/130; P= 0.01; OR = 4.9), and antenatal clinic attendees (3% 3/100; P= 0.04; OR = 3.7), but was not statisticaliy different from those among inhalation drug users (9.3%, 4/43; P=0.9) and students/health care workers (4.5%, 9/200; P= 0.06). None of the study population was reactive to anti-HIV antibody. The HCV strains obtained from the injecting-drug users belonged to either genotype 1 a or 2b and the strains in each genotype clustered closely to each other. There was no dual infection with genotype la and 2b. These results suggest that the HCV infection in injecting-drug users may be emanating rapidly from limited number individuals in Metro Cebu, Philippines.