Dengue Viremia in Kenyan children With Acute Febrile Illness

Abstract

Dengue virus (DENV) remains the most prevalent arboviral infection worldwide, causing an estimated 400 million infections per year. By mathematical modeling, 16% of DENV infections occur in Africa. However due to lack of routine surveillance programs, the burden of DENV infection in many African countries is largely unknown. As a part of an ongoing study on arboviral infection in Kenyan children, we collected blood samples from subjects 1 to 17 years of age who presented with fever of unclear etiology to one of four centers located either in western (Kisumu and Chulaimbo) or coastal Kenya (Ukunda and Msambweni). We tested the samples for the presence of DENV RNA by RT-PCR. DENV RNA positive samples were then serotyped by PCR. Testing is ongoing, however, preliminary results have identifed DENV viremia more frequently in subjects with acute febrile illness in western vs. coastal Kenya (9.2% positive [75 of 814 subjects] vs. 0.9% [4 of 435 subjects], respectively, p<0.001). In western Kenya, all four serotypes were identifed; 51 samples had serotype 1 (DENV-1), two had DENV-2, thirteen had DENV-3, and two had DENV-4. There were also subjects who had dual infection with two DENV serotypes: one subject with DENV-1+3, three with DENV-1+4, and one with DENV-2+3. Only DENV-1 was identifed in samples from coasta Kenya. To investigate the phylogeny of the DENV strains, we performed exploratory next-generation sequence (NGS) on a limited subset of the samples. DENV-1 sequences were over-represented from blood samples of seven subjects from western Kenya (fve from Chulaimbo, two from Kisumu) and mapped to a strain from Thailand (accession AF180818) with 98.5-99.4% homology. Further sequencing experiments will be important for developing a better understanding of the phylogeny of DENV strains currently circulating in Kenya. Together, our preliminary results suggest that DENV may be an important cause of acute febrile illness in Kenyan children, but the incidence and disease burden may differ by geographic location.