STRONGER-SAFE: Understanding transmission and optimising interventions for an enhanced S.A.F.E. strategy for trachoma elimination (360G-Wellcome-206275_B_17_Z)

Trachoma is the leading infectious cause of blindness worldwide. It is intrinsically linked to poverty in both cause and effect. Preventing blindness from trachoma has broad and profound impact on health and well-being. It is caused by repeated infection with Chlamydia trachomatis (Ct). The WHO-endorsed SAFE-Strategy aims to control infection through annual, single-dose, community-wide azithromycin treatment coupled with Water/Sanitation/Hygiene (WASH) and fly-control measures to suppress transmission. However, particularly in hyperendemic regions, the current approach is not having the anticipated impact. There are two critical issues. Firstly, current azithromycin schedules appear insufficient. Secondly, transmission routes are poorly defined and the very limited evidence-base makes it hard to focus WASH interventions and guide programmatic decisions. We propose the following: 1) Conduct intensive observation of human behaviour and hygiene practice, and fly behaviour, combined with Ct infection mapping, to identify major routes of transmission. 2) Develop and test contextually appropriate, practical, targeted WASH and fly-control approaches to interrupt Ct transmission. 3) Our modelling work indicates double-dose azithromycin two weeks apart is much more effective in controlling Ct. In a cluster-randomised trials we will test whether intensified double-dose treatment coupled with targeted transmission-interrupting strategies can control trachoma more effectively.