Vaccines are available for typhoid fever, hepatitis A and cholera. Anopheles mosquitoes bite only from dusk to dawn. The island of Rodriguez is risk free. Altitudes above 1800 m are risk free. No risk in Harare and Bulawayo.
Most countries require proof of vaccination to enter if travellers have visited an infected area.
Sudan sometimes requires proof of vaccination to exit. The northern boundary of the yellow fever endemic zone of Africa is roughly the southern border of the Sahara. Sao Tome and Principe are also within the infected zone. The London Health Sciences Centre Travel Clinic is a WHO licensed yellow fever vaccination centre. Yellow fever vaccine is not available from family doctors.