Epidemiology and molecular characterization of chikungunya virus involved in the 2008 to 2009 outbreak in Malaysia

Abstract

Mohd Apandi Yusof, Lau Sau Kuen, Norfaezah Adnan, Nur Izmawati Abd Razak, Liyana Ahmad Zamri, Khairul Izwan Hulaimi and Zainah Saat

The 2008 to 2009 outbreak of chikungunya was considered as the huge and worst outbreak of CHIKV (Chikungunya virus) infections in history of the country affecting all states in both Peninsular and East Malaysia. This was unlike the first outbreak in late 1998, which was only restricted to Klang district in Selangor and six years later the second outbreak which only involved the state of Perak. The objective of the study was to detect the presence of chikungunya antibody and antigen by immunofluorescence technique and RT-PCR from the sera samples. A total of 2,692 sera samples were received in 2008, in which 19.2% were positive by antibody detection and 42.6% were positive by RT-PCR. The following year in 2009, the samples size increased to 3,592, only 16.3% sample were positive by antibody detection and 31.7% were positive by RT-PCR. Majority of the hospitalized cases were adults between 30 to 60 years of age and the highest incidence rate was amongst patients’ age between 40 to 49 year old. In 2008, most of the confirmed CHIKV infection cases were female but the opposite was seen in 2009, where more male cases were reported. In this outbreak, the prominent ethnic group affected was the Malays. CHIKV involved in the 2008 to 2009 outbreaks was the new Central/East African genotype which was found to be similar with strains causing the outbreaks in the India Ocean and main CHIKV genotype circulating in the European countries from 2006 to 2009.