Characterization of Dengue Virus Infections Among Febrile Children Clinically Diagnosed With a Non-Dengue Illness, Managua, Nicaragua.

We sought to characterize dengue virus (DENV) infections among febrile children enrolled in a pediatric cohort study who were clinically diagnosed with a non-dengue illness ("C cases"). DENV infections were detected and viral load quantitated by real-time reverse transcription-polymerase chain reaction in C cases presenting between January 2007 and January 2013. One hundred forty-one of 2892 C cases (4.88%) tested positive for DENV. Of all febrile cases in the study, DENV-positive C cases accounted for an estimated 52.0% of patients with DENV viremia at presentation. Compared with previously detected, symptomatic dengue cases, DENV-positive C cases were significantly less likely to develop long-lasting humoral immune responses to DENV, as measured in healthy annual serum samples (79.7% vs 47.8%; P < .001). Humoral immunity was associated with viral load at presentation: 40 of 43 patients (93.0%) with a viral load ≥7.0 log10 copies/mL serum developed the expected rise in anti-DENV antibodies in annual samples versus 13 of 68 (19.1%) patients with a viral load below this level (P < .001). Antibody responses to DENV-positive C cases differ from responses to classic symptomatic dengue. These findings have important implications for DENV transmission modeling, immunology, and epidemiologic surveillance.