Acute serum samples were collected from suspected dengue cases at the Hospital Infantil Manuel de Jesús Rivera (HIMJR), the National Pediatric Reference Hospital in Managua, Nicaragua, after undergoing informed consent or the informed consent procedure. Patients were enrolled in the study if they presented with fever or history of fever less than 7 days and one or more of the following signs and symptoms: headache, arthralgia, myalgia, retro-orbital pain, positive tourniquet test, petechiae, or signs of bleeding. Patients with a defined diagnosis other than dengue, e.g. pneumonia, were excluded. Suspected dengue cases were tested for dengue virus (DENV) infection at the Centro Nacional de Diagnóstico y Referencia (CNDR) of the Nicaraguan Ministry of Health and were considered laboratory-confirmed if: 1) DENV was isolated, 2) DENV RNA was detected by reverse transcriptase-polymerase chain reaction (RT-PCR), 3) seroconversion was observed by IgM capture enzyme-linked immunosorbent assay (ELISA) of paired acute and convalescent sera, or 4) a $4-fold increase in DENV-specific antibodies was demonstrated by inhibition ELISA in paired acute and convalescent sera [32] . All patients were aged 6 months to 14 years and presented between August 2005 and January 2009.