Effect of preventive and curative interventions on hepatitis C virus transmission in Egypt (ANRS 1211): a modelling study

Abstract

Background: Most hepatitis C virus (HCV) transmission in Egypt is related to medical injections and procedures. To control the spread of HCV, the Egyptian Ministry of Health initiated awareness and education campaigns, strengthened infection control in health-care facilities, and subsidised anti-HCV treatment. We aimed to investigate the effect of these interventions on the spread of HCV by mathematical modelling. Methods: We developed a mathematical model of HCV transmission in Zawyat Razin, a typical rural community. Our model assumes that each individual has two distinct types of medical procedures: injections and more invasive medical procedures. To quantify the severity of the spread of HCV, we used the notion of the basic reproduction number R0, a standard threshold parameter signalling whether transmission of an infectious disease is self-sustained and maintains an epidemic. If R0 is greater than 1, HCV is self-sustained; if R0 is 1 or less, HCV transmission is not self-sustained. We investigated whether heterogeneity in the rate of injection or invasive medical procedures is the determinant factor for HCV transmission and whether most iatrogenic transmission is caused by a small group of individuals who receive health-care interventions frequently. We then assessed whether interventions targeted at this group could reduce the spread of HCV. Findings: The R0 of the spread of HCV without treatment was 3·54 (95% CI 1·28–6·18), suggesting a self-sustained spread. Furthermore, the present national treatment programme only decreased R0 from 3·54 to 3·03 (95% CI 1·10–5·25). Individuals with high rates of medical injections seem to be responsible for the spread of HCV in Egypt; the R0 of the spread of HCV without treatment would be 0·64 (95% CI 0·41–0·93) if everybody followed the average behaviour. The effect of treatment on HCV transmission is greatly enhanced if treatment is provided a mean of 2·5 years (95% CI 0·1–9·2) after chronic infection and with drug regimens with more than 80% efficacy. With these treatment parameters, preventive and curative interventions targeting individuals with high rates of medical injections might decrease R0 below 1 for treatment coverage lower than 5%. Interpretation: Targeting preventive and curative interventions to individuals with high rates of medical injections in Egypt would result in a greater reduction the spread of HCV than would untargeted allocation. Such an approach might prove beneficial in other resource-limited countries with health-care-driven epidemics. Funding: Agence Nationale de Recherche sur le SIDA et les Hépatites Virales (ANRS 1211), ANR grant Labex Integrative Biology of Emerging Infectious Diseases.