Malaria is endemic in Rwanda. If you stay in Kigali, there is significantly less risk but you should familiarize with your local health authority advice.
All travelers coming from Yellow Fever-endemic countries and/or where active Yellow Fever outbreaks exist must to produce proof of vaccination at border posts or be immunized at the airport clinic at their own cost.
First aid and emergency services will be available at the Kigali Convention Centre (KCC). There are also several large hospitals near the KCC.
It is advisable to have medical insurance that covers yourself while in Rwanda.