I lived for three years in a place and time (rural Bangladesh in the 1980's) where humanure was commonly simply deposited wherever the urge overtook people on the roadsides, or in designated "open latrines" often near or even directly over bodies of temporary or permanent water. Diseases of various sorts were inevitable and widespread, even for those very careful of their own hygeine. The stuff would dry out in the dry season and blow around in the wind so one could actually inhale the germs! But by far, the majority of diseases were spread through three means....1. contaminated water 2. contaminated hands and 3. flies. An ordinary pit latrine, enclosed to exclude flies or with each deposit covered with even a small amount of soil or mulch, would prevent the vast majority of cases. Even moreso if water for handwashing were provided nearby. One advantage is that most of the soil there is clayey, and so transport of bacteria through the soil, to the water table or elsewhere, is minimal. Another danger common there, and to beware of elsewhere, is flooding, which would enter pit latrines and liberate their contents broadscale. Humanure used in any way in a flood prone area complicates things hugely.