Retrospective analysis of febrile patients reveals unnoticed epidemic of zika fever in Dielmo, Senegal, 2000

Background: In Africa, recent malaria controls unveiled a large proportion of febrile illnesses of unknown origin.Few studies have been undertaken to identify these pathogens. Research design and methods:We conducted a retrospective study to determine the seroprevalence of Zika virus (ZIKV) in a malaria endemic village in Senegal.We screened 487 samples collected from febrile individuals in 1999, 2000 and 2001 by using the enzyme-linked immunosorbent assay (ELISA) methods and the 90% plaque reduction neutralization tests (PRNT).Results: Overall ZIKV IgG seroprevalence was 85.82% (218/254) including 82.3% (107/130) in 1999, 59.1% (120/203) in 2000 and 92.2% (142/154) in 2001.Patients aged 15-50 years old and over were the most affected (80% and 91% respectively) in contrast to patients under 15 (54%) (p < 0.01).None of the samples collected in 1999 and 2001 was found positive for ZIKV IgM.In 2000, 8.4% (17/203) samples were positive for ZIKV IgM and 6.9% (14/203) confirmed by PRNT.There was no ZIKV IgM positive in patients over 50 years old.Our analysis showed a strong association between Zika infections and nonmalaria febrile episodes (p < 0.01). Conclusions:Our study revealed serological evidence of Zika epidemic fever in a malaria endemic area.These results highlight the importance of an effective ZIKV surveillance in Senegal.