There are no mandatory vaccinations required for entry to Kenya unless you are coming from an area infected with Yellow Fever, in which case a Certificate of Inoculation against Yellow Fever is required from travelers older than one year. Visitors coming from other countries in Africa where Yellow Fever may occur, including Tanzania and Zanzibar, require a Yellow Fever certificate.
Other recommended vaccinations are Typhoid, Hepatitis and Polio, and anti-malarial medication is essential. Malaria prophylactics drugs should be taken prior to arrival and should be continued for 4 weeks after leaving Kenya. It is also advisable to try and avoid mosquito bites by using repellent, sleeping under mosquito nets and by wearing suitable cover-up clothes in the evening.
There are good hospitals in the main towns of Kenya while the rural areas have small health centers where one can get basic first aid. There is an excellent Flying Doctor service in Kenya in the event of a medical emergency, while on safari away from the urban centers. Drinking water from the tap is not encouraged. It is advisable to use bottled water which is supplied at all hotels and lodges. Also don’t taste any food from local market stands before you properly wash it or before you are sure that it is properly cooked.