Tanzania is a malaria zone and therefore you will be at risk of contracting the disease. We recommend that you take malaria tablets.
While there are no mosquitoes above 2,000m on the mountain itself, they are present in Moshi, in the safari parks and on Zanzibar. Some of the hotels provide mosquito nets but you are still safer to take the tablets as well.
We recommend consulting your doctor or travel clinic to get advise on the best anti-malarial medication.
In addition to taking anti-malarial medication, we would recommend you take every precaution to prevent mosquito bites by wearing long-sleeved trousers and shirts and using a DEET based mosquito repellent.