Malaria aside, the biggest danger you will encounter in Sengerema, as well as the rest of Tanzania, is the traffic. Watch out when the dallas and especially the off-roads come swirling in from Kamanga. The Tanzanians themselves make a run for it and literally jump off the road. In the beginning I found this quite hilarious, but after having seen a couple of these buses tilt or furniture falling off the roof of the buses because of the speed, I quickly started doing the same thing. When you hear the buses coming, walk a couple of metres away from the road and wait until the bus has passed you.
Walking out at night
Stay inside after it gets dark. This really applies to all of Tanzania, so it can't come as a big surprise. You risk getting robbed or attacked if you walk outside after dark, so avoid it at all costs. There is no risk of getting robbed in Sengerema at day time - it is probably one of the most safe places I have been due to the fact that everyone knows everyone, so you can't get away with a thing like that in a small town like Sengerema. Nevertheless, at nighttime no one can see anything and people are drunk, so stay inside. Only go out if you're with a local. If so, you should be fine.