LAUSR

Introduction There is considerable uncertainty as to the effectiveness and optimal timing of Neisseria gonorrhoea (NG) screening in Men who have Sex with Men (MSM). NG has evolved resistance to a wide range of antibiotics, which makes it particularly important to ensure that NG screening in this population does not lead to excessive consumption of antibiotics. We use a mathematical model to evaluate the effectiveness of different NG screening strategies on NG prevalence in an MSM population. Methods Separable Temporal Exponential Random Graph Models are used to model the sexual relationships network in MSM. Two networks of sexual relationships with main and casual partners are modelled, where the number of casual partners depends on having a main partner or not and vice versa. Next the transmission of NG is simulated on this dynamic network. We have adapted the standard model to include different infection statuses per person for the pharynx, urethra and rectum. Accordingly, different possible transmission routes (anal sex, oral sex and rimming, both active and passive) with their own act and transmission rate have been implemented. Furthermore, a different recovery rate for symptomatic and asymptomatic infections was specified. The model was used to compare different screening programmes in terms of NG prevalence. Our models simulate day-by-day evolution of a population of 10,000 MSM. Each scenario is simulated 20 times for 10 years. Behavioural data was taken from Belgian MSM participating in the European Men who have sex with men Internet Survey (EMIS). Results If one half of MSM is screened once a year, the prevalence of NG infection at pharynx decreases from 13% to 10% (urethral), 8% to 6% (rectal) and 16% to 12% (pharyngeal), as compared to no screening. When only one third is screened, prevalence decreases to 11%, 7% and 13%, respectively. Conclusions The achieved prevalence reduction might not outweigh the larger risk of development of antibiotic resistance.