The importance of mobility in sustaining high STI prevalence in remote indigenous communities
An agent-based computer simulation model was developed to study the relationship between mobility rate and the transmission of gonorrhoea and Chlamydia across numerous representative but theoretical Indigenous populations. Population mobility is incorporated using a ‘gravity’ formulation from transport theory.
Simulation results suggest that temporary mobility could be a factor in sustaining a persistent high level of STIs. However, this relationship is unlikely to be of a simple nature. It was found that STIs are unlikely to be sustained at an endemic level if there is no mobility. Interestingly, however, endemic STI levels are also unlikely to be sustained if mobility is very high. For example, in this model the endemic prevalence of gonorrhoea increases rapidly to more than 10% as the maximum mobility rate (MMR) increases from 0 movements per 1000 individuals per day to between 0.2 and 1.2, before gradually decreasing to 0 again as the MMR increases to 3 movements per 1000 individuals per day.
While mobility patterns vary between remote communities, mobility is generally believed to be much higher than for non-remote communities. Our modelling suggests that mobility may be an important factor in sustaining high levels of STIs in remote communities and that simple location-based interventions may not be effective for control and prevention. It is therefore necessary to obtain accurate and specific data on mobility patterns in order to access the potential impact of current and proposed interventions.
