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Diarrhoeal disease is one of the leading causes of mortality and morbidity globally. Non-biting synanthropic flies are of public health importance due to their habit of flying between faecal matter and households, potentially transmitting pathogenic bacteria by regurgitation, defecation or mechanical transmission via legs or wings. Lymphatic filariasis (LF), caused by Wuchereria bancofti and transmitted by Culex quinquefasciatus, affects approximately 120 million people in Asia. Controlling the mosquito vector can have a significant impact on LF incidence rates. It is assumed that increasing the coverage of latrines will reduce the amount of open defecation and environmental faecal contamination resulting in a healthier population. However, few studies have measured the impact of building latrines on human health and even fewer have demonstrated its impact on synanthropic fly populations or their bacterial carriage and associated diarrhoeal disease. Similarly, although Cx. quinquefasciatus has long been associated with pit latrines, the resulting impact through the construction of improved pour-flush latrines on population densities has yet to be explored. Initial experiments were conducted to determine the best methodology for trapping both synanthropic flies and Cx. quinquefasciatus, to inform the design of the entomological component of a cluster randomised control trial (cRCT). Thereafter, the focus was on determining the impact of latrine construction on the exposure of households to populations of flies and the bacteria that they carry, and on Cx. quinquefasciatus densities and W. bancofti prevalence. Results indicate that latrine construction had no impact on the density of flies within households or on the carriage of bacteria. There was no statistical difference between control and intervention arms in the population density of synanthropic flies (IRR=0.89; 95%CI=[0.76-1.03]; p=0.131). There was a significant correlation between fly numbers and rainfall. Data were analysed by season for between arm differences; in the monsoon season 40% fewer flies were caught in the intervention arm compared to the control arm (p= |
