Virions consist of an envelope and a nucleocapsid. During their life cycle, virions have not been observed outside a cellular environment and have a cell-associated cycle. Virus capsid is tightly enveloped by a detergent sensitive lipoprotein. Virions are spherical to pleomorphic. Virions measure 70 nm in diameter. Surface projections are distinctive glycoprotein spikes composed of two virus proteins forming heterodimers covering evenly the surface. Capsid/nucleocapsid is round and exhibits icosahedral symmetry (T=4). The nucleocapsid is isometric and has a diameter of 40 nm. Capsids appear round.    

Investigations     The definitive diagnosis can only be made by laboratory means, Viremia will be present in most patients during the first 48 hours of disease and may be detected as late as day 4 in some patients.Virus-specific IgM antibodies are readily detected by capture ELISA in patients recovering from CHIK infection and they persist in excess of 6 months. Haemagglutination inhibition (HI) antibodies appear with the cessation of viremia. All patients will be found positive by day 5 to 7 of illness. Neutralization antibodies parallel HI antibodies.Chikungunya IgM serology test is available in University Malaya.     Although, the National Institute of Virology at Pune, has been of great help in determining the etiology of the outbreak relying on one institute in the country to render diagnostic help for case management would be foolhardy. It would be therefore desirable to ensure that several virology laboratories in the country are enrolled and networked to deliver rapid diagnosis in large outbreaks such as this as well as other emerging viral infections like Chandipura and Avian influenza.