Transmission of hepatitis B, hepatitis C and human immunodeficiency viruses through unsafe injections in the developing world: model-based regional estimates

Abstract

Thousands of millions of injections are delivered every year in developing countries, many of them unsafe, and the transmission of certain bloodborne pathogens via this route is thought to be a major public health problem. In this article we report global and regional estimates of the number of hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections that may occur from unsafe injections in the developing world. The estimates were determined using quantitative data on unsafe injection practices, transmission efficiency and disease burden of HBV, HCV and HIV and the prevalence of injection use obtained from a review of the literature. A simple mass-action model was used consisting of a generalized linear equation with variables accounting for the prevalence of a pathogen in a population, susceptibility of a population, transmission efficiency of the pathogen, proportion of injections that are unsafe, and the number of injections received. The model was applied to world census data to generate conservative estimates of incidence of transmission of bloodborne pathogens that may be attributable to unsafe injections. The model suggests that approximately 8-16 million HBV, 2.3-4.7 million HCV and 80,000-160,000 HIV infections may result every year from unsafe injections. The estimated range for HBV infections is in accordance with several epidemiological studies that attributed at least 20% of all new HBV infections to unsafe injections in developing countries. Our results suggest that unsafe injections may lead to a high number of infections with bloodborne pathogens. A major initiative is therefore needed to improve injection safety and decrease injection overuse in many countries.

PIP: This paper reports global and regional estimates of the prevalence of hepatitis B virus (HBV), hepatitis C virus (HBV), and HIV infections that may occur as a result of unsafe injection practices in the developing countries. The estimates were determined using quantitative information on unsafe injection practices, transmission efficiency of pathogen, and disease burden of hepatitis B and C viruses, as well as HIV and the prevalence of injection usage as observed in the literature reviews. A simple mass-action model was utilized in the study and was applied to world census data to generate the conservative estimates of interest. The model showed that about 8-16 million HBV, 2.3-4.7 million HCV, and 80,000-160,000 HIV infections may result from unsafe injections each year. It was also noted that the estimated range of HBV infection is consistent with a number of epidemiological studies that attribute at least 20% of all new cases of HBV infection to unsafe injections in the developing world. Given that unsafe injections may contribute to a high number of infections with bloodborne pathogens, a major effort is necessitated to improve injection safety and reduce injection overuse in many countries.