The incidence and spread of dengue virus (DENV) have increased rapidly in recent decades.Dengue is underreported in Africa, but recent outbreaks and seroprevalence data suggest that DENV is widespread there.A lack of ongoing surveillance limits knowledge about its spatial reach and hinders disease control planning.We sought to add data on dengue distribution in Kenya through diagnostic testing of serum specimens from persons with an acute febrile illness (AFI) attending an outpatient clinic in rural western Kenya (Asembo) during rainy seasons.Patients with symptoms not likely to be misclassified as dengue (e.g., diarrhea and anemia), those with a positive diagnostic laboratory results which explained their febrile illness, or those with serum collected more than 5 days after fever onset were excluded.However, febrile patients with a positive malaria smear were included in the study.We used reverse transcription polymerase chain reaction (RT-PCR) to test for DENV and IgM anti-DENV to test for recent infection.Of the 615 serum specimens available for testing, none were dengue positive by either RT-PCR or IgM anti-DENV testing.Dengue did not appear to be a cause of febrile illness in this area of western Kenya, although our relatively small sample size may not have identified DENV infections occurring at low incidence.A more widespread AFI surveillance system that includes dengue diagnostic testing by RT-PCR and antibody-based methods is required to more definitively gauge the size and geographic distribution of DENV infection in western Kenya.

Dengue appears to be endemic in Africa with a number of reported outbreaks. In February 2013, several individuals with dengue-like illnesses and negative malaria blood smears were identified in Mombasa, Kenya. Dengue was laboratory confirmed and an investigation was conducted to estimate the magnitude of local transmission including a serologic survey to determine incident dengue virus (DENV) infections. Consenting household members provided serum and were questioned regarding exposures and medical history. RT-PCR was used to identify current DENV infections and IgM anti-DENV ELISA to identify recent infections. Of 1,500 participants from 701 households, 210 (13%) had evidence of current or recent DENV infection. Among those infected, 93 (44%) reported fever in the past month. Most (68, 73%) febrile infected participants were seen by a clinician and all but one of 32 participants who reportedly received a diagnosis were clinically diagnosed as having malaria. Having open windows at night (OR = 2.3; CI: 1.1-4.8), not using daily mosquito repellent (OR = 1.6; CI: 1.0-2.8), and recent travel outside of Kenya (OR = 2.5; CI: 1.1-5.4) were associated with increased risk of DENV infection. This survey provided a robust measure of incident DENV infections in a setting where cases were often unrecognized and misdiagnosed.