Malaria cases on rise in Nairobi
25 April 2013 Last updated at 17:24 BST
Malaria, one of the biggest killers in Sub-Sahara Africa, has recently started spreading to places that were previously known to be free from the disease.
Scientists say that as high altitude areas get warmer, the malaria-causing parasite is able to survive there and cause infection.
Nairobi is one of the places to be reporting more and more cases of malaria.
Anne Soy reports.