False-positive dengue non-structural protein 1 in pregnancy

Dengue is a vector-borne infection, which contributes to significant morbidity and mortality in endemic areas. It manifests rapidly within 2 wk from febrile, critical to recovery phase. The point-of-care test (POCT) comprises the non-structural protein 1 (NS1) antigen, IgM and IgG, which aids rapid diagnosis, leading to timely treatment. Despite the high specificity of various POCTs, a few false-positive NS1 cases have been reported. We report the first case of false-positive NS1 antigen in pregnancy. A 24-y-old female in her second trimester of pregnancy presented with fever and chills for 9 d and a non-productive cough for 3 d. The dengue POCT showed NS1 antigen positive, IgM and IgG negative. Her symptoms were resolved with treatment of urinary tract infection with cefuroxime. Urine culture subsequently yielded Escherichia coli. Her recovery and delivery were uneventful. Her NS1 antigen was persistently positive for 18 d. The confirmatory real time-PCR for dengue and pan-Flaviviruses was negative.