The influence of HIV on STI epidemics : the re-emergence of lymphogranuloma venereum

• Main Author: Ronn, Minttu Minna-Maarit
• Other Authors: Ward, Helen : White, Peter
• Published: Imperial College London 2013
• Subjects: 614
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.634081

Lymphogranuloma venereum (LGV) is a re-emerging sexually transmitted infection (STI) in men who have sex with men (MSM). The emergence of LGV has occurred in parallel to an increase in STIs in MSM. It represents a public health problem and an added burden in the control of STIs. This thesis aims to identify factors that have contributed to the persistent high levels of HIV prevalence among LGV cases. I use surveillance data to explore the re-emergence of LGV through statistical analyses. I then perform a literature review to better understand the social epidemiological context in which seroadaptive behaviours in HIV-positive MSM occur, a hypothesised cause for the re-emerging STIs. I finally look at the dynamics of HIV and LGV through a deterministic mathematical model where the effect of serosorting is investigated in more detail. Through statistical analyses I demonstrate that there is a strong behavioural component in explaining the association between the two infections. In the LGV Enhanced Surveillance HIV-positive LGV patients were more likely to report unprotected receptive anal intercourse compared to HIV-negative/unknown LGV patients. In a subsequent analysis I show that individuals with reported LGV re-infection were more likely to be HIV-positive, visit a clinic in London and have concurrent hepatitis C and gonorrhoea on their first recorded LGV episode. However, the data also suggests there is a diagnostic bias in favour of HIV-positive men who present with shorter duration of symptoms. I propose a conceptual framework of seroadaptive behaviours in HIV-positive MSM based on a literature review. The mathematical model demonstrates that infections with the same mode of transmission will be associated, but it provides further support to the hypothesis that serosorting can explain the particularly high HIV prevalence in those who acquire LGV. This work cannot exclude the possibility of a biological interaction but the current evidence points to behavioural, and likely network-level, differences between HIV-positive and -negative MSM as the main driver in LGV re-emergence. This has implications for surveillance and control of LGV. Rare STIs, such as LGV, may benefit from a more detailed and qualitative investigation of cases using a periodic sentinel model as well as from health promotion targeted specifically to the small subpopulation affected.