Epidemiologic assessment of risk of yellow fever and dengue transmission and outbreaks in Kenya

The recent increase in frequency and magnitude of yellow fever (YF) and dengue virus outbreaks in East Africa is unusual and of great concern to public health authorities in the region. It calls for a roll out YF vaccination programs and vector control plans against dengue region. However, we have little understanding of the ecology of the viruses which is vital for evaluating risks which will facilitate cost-effective vaccination and vector control programs. Yellow fever vaccines are expensive and often not available in adequate doses. It is costly to vaccinate the entire population.

It is more prudent to identify risk areas for focused vaccination. We would like to focus on parts of Kenya bordering countries that have experienced YF outbreaks recently, including Ethiopia, South Sudan and Uganda. There has been a similar recent increase in frequency of dengue virus (DENV) outbreaks in the region with reports of Dengue fever (DF) outbreaks reported in Tanzania, Somalia, Djibouti, Eritrea and Sudan (Sang 2006).

Dengue which is now considered the most important re-emerging arbovirus worldwide with over 2.5 million people being at risk caused an outbreak in Kenya in 1982 by a lull until September 2011 when an outbreak of dengue was detected in Mandera, North Eastern Kenya and subsequently in March 2013 when another outbreak was detected in Mombasa, Kenya (currently ongoing) with three serotypes circulating hence the potential for dengue to spread through much of Kenya is increasingly worrying.

We are investigating the ecologic and epidemiologic risk for Yellow Fever and Dengue virus transmission in the at risk border regions of West Pokot and Turkana in Northern Rift regions of Kenya and also in the major cities of Nairobi, Kisumu and Mombasa. Our findings will help in decision making concerning cost effective vaccination and vector control programs to combat both diseases.


  • United States National Institute of Health (NIH)