Molecular and serological diagnosis of Chikungunya virus infection.

INTRODUCTION: In 2005-2006, during the Chikungunya virus outbreak in La Réunion (Indian Ocean), we urgently established the molecular and serological methods for the diagnosis of Chikungunya virus (CHIKV) from various types of samples.
METHODS: CHIKV RNA was detected using a highly sensitive real-time RT PCR assay. A co-extracted and co-amplified internal control RNA was used to identify RT PCR inhibitors. Depending on their nature samples were pretreated before nucleic acid extraction. Viral loads were measured using a synthetic RNA calibrator. CHIKV immunoglobulin (Ig) G and M antibodies were detected by ELISA either from sera or from blood absorbed on filter paper.
RESULTS: CHIKV RNA was found in various types of samples such as plasma, cerebrospinal fluid, and placenta, but was not found in some samples including maternal milk and synovial samples. Detection of IgG from filter paper absorbed blood is specific and sensitive. Routine data showed that maternally transferred IgG and naturally acquired IgM persist at least 12 and 18 months, respectively. DISCUSSION: The techniques enabled the diagnosis of chikungunya in known and newly described forms of the disease. They are used for routine diagnosis and large scale surveys.