Laboratory diagnosis of chikungunya virus: do we really need it?

Chikungunya (CHIK) fever is a re-emerging Aedes mosquito-transmitted viral disease caused by CHIK virus belonging to the Togaviridae family of genus Alphavirus. The disease is almost self-limiting, occurs with characteristic triad of sudden onset fever, rash and arthritis. During the recent outbreak CHIKV was also found to cause long-term arthralgia, severe neurological disease and even fatalities. Although there are no antiviral or vaccines available for CHIKV, still there are several advantages to diagnose the infection. The present article provides an overview of various diagnostic modalities available and its significance by searching PubMed MeSH terms "Chikungunya virus" and "Diagnosis" for recent articles. The gold standard of CHIKV diagnosis is culture, yet requires facilities and skills. Highly sensitive and specific PCR assays for CHIKV have been developed, but the reagents and equipment are costly for widespread use. Serological diagnosis by detecting IgM antibody is most widely used as it is relatively cheaper and easier to perform. Disadvantages of antibody testing are cross-reactivity with other alpha viruses, cannot differentiate between recent past and acute infection, and its sensitivity varies in clinical settings. When tested for diagnosing acute CHIKV disease, sensitivities were just 4 to 22% and after 1 week rose to more than 80%. As most acutely infected patients seek medical attention within the first few days of illness, the ideal test should detect RNA or antigen. Therefore, the more realistic aim would be to develop a reliable antigen detection assay that could be used in rural areas, where CHIKV infection often occurs.