Modelling the force of infection for hepatitis B and hepatitis C in injecting drug users in England and Wales.

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Title: Modelling the force of infection for

hepatitis B and hepatitis C in injecting drug users in

England and Wales.

 

Author: Sutton AJ Gay NJ Edmunds WJ Hope VD Gill

ON Hickman M

 

Source: BMC Infect Dis, 6(1): 93 2006

 

Abstract: ABSTRACT: BACKGROUND: Injecting drug

use is a key risk factor, for several infections

of public health importance, especially hepatitis

B (HBV) and hepatitis C (HCV). In England and

Wales, where less than 1% of the population are

likely to be injecting drug users (IDUs),

approximately 38% of laboratory reports of HBV, and 95% of

HCV reports are attributed to injecting drug use.

METHODS: Voluntary unlinked anonymous surveys

have been performed on IDUs in contact with

specialist agencies throughout England and Wales. Since

1990 more than 20,000 saliva samples from current

IDUs have been tested for markers of infection

for HBV, HCV testing has been included since 1998.

The analysis here considers those IDUs tested for

HBV and HCV (n=5,682) from 1998-2003. This study

derives maximum likelihood estimates of the force

of infection (the rate at which susceptible IDUs

acquire infection) for HBV and HCV in the IDU

population and their trends over time and injecting

career l

ength. The presence of individual heterogeneity

of risk behaviour and background HBV prevalence

due to routes of transmission other than injecting

are also considered. RESULTS: For both HBV and

HCV, IDUs are at greatest risk from infection in

their first year of injecting (Forces of infection

in new initiates 1999-2003: HBV=0.1076 95% C.I:

0.0840-0.1327 HCV=0.1608 95% C.I: 0.1314-0.1942)

compared to experienced IDUs (Force of infection

in experienced IDUs 1999-2003: HBV=0.0353 95% C.I:

0.0198-0.0596, HCV=0.0526 95% C.I: 0.0310-0.0863)

although independently of this there is evidence

of heterogeneity of risk behaviour with a small

number of IDUs at increased risk of infection. No

trends in the FOI over time were detected. There

was only limited evidence of background HBV

infection due to factors other than injecting.

CONCLUSIONS: The models highlight the need to increase

interventions that target new initiates to

injecting to reduce the transmission of blood-borne

viruses. Al

though from the evidence here, identification of

those individuals that engage in heightened

at-risk behaviour may also help in planning effective

interventions. The data and methods described

here may provide a baseline for monitoring the

success of public health interventions.

Language: ENG

Unique Identifier: 16762050

 

 

 

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