Transmission of hepatitis B virus infection by iatrogenic intramuscular injections in an endemic area.

The authors followed 95 people from the general and aboriginal population of Taiwan, aged 5 to 69 years for two years. All of subjects studied were susceptible to hepatitis B virus (HBV) infection. In all, 56 of the 95 persons received iatrogenic intramuscular (IM) injections, and 28 of the 95 became newly infected with HBV during the study period. The relative risk of being infected with HBV was higher in people who received an IM injection (IRR = 5.8, 95% CI 1.9-17.9) than in those who did not. New HBV infections were found to correlate significantly with the frequency of injections (Ptrend less than 0.000) and therefore, we concluded that (A) intramuscular injections played an important role in horizontal transmission of HBV, particularly among Aborigines and that (B) the infection was transmitted via inadequately sterilized syringes used for iatrogenic IM injections in a community in which the hepatitis B virus was prevalent and IM injections were common.