Detection of Chikungunya Virus from Sera of Dengue-Suspected Patients in the Philippines

Due to the similar symptoms with dengue fever (DF) and dengue hemorrhagic fever (DHF), Chikungunya (CHIK) virus infections were diagnosed as DF or DHF. In this study, we examined more than 300 serum samples collected from dengue-suspected patients in San Lazaro Hospital and St. Luke's Medical Center. Reverse transcriptase-polymerase chain reaction (RT-PCR) and antigen sandwich enzyme-linked immunosorbent assay (ELISA) were applied for CHIK virus detection. IgM-indirect immunofluorescent antibody test (IgM-IFA), IgM capture ELISA, and IgG indirect ELISA were applied for detection of serological evidence of CHIK virus infection. Although we could not detect any Chikungunya virus by RT-PCR, 4.1% of the confirmed samples showed high titer for Chikungunya virus by antigen sandwich ELISA. By IgM-IFA, 15.3% were positive for CHIK virus. Thirteen point seven percent showed positive for CHIK virus by IgM-capture ELISA. Eighteen point five percent showed positive for CHIK virus by IgG indirect ELISA.