This link will give you some factual information specifically about Tanzania and the most common diseases found there:
International Association for Medical Aid for Travellers - Tanzania
This link exposes some of the common malaria myths:
Dispelling the Myths - Malaria
This is what the Center for Disease Control has to say:
CDC Destinations - Tanzania
In my 30+ years I've been lucky to have had malaria only 3 times and not very badly and I've treated it with Coartem (Artemether/lumefantrine). I've usually used doxycycline as my chemo-prophylaxis although as I am fair-skinned this may have contibuted to a few small rodent ulcers which I've had to have treated with cryotherapy. I always carry Coartem when I go on leave and I've printed up and laminated a small card saying that I work in West Africa and if I'm found unconscious suspect falciparum malaria.