Molecular epidemiology of Chikungunya virus in Vellore district, Tamilnadu, India in 2006

The present study was carried out with the aim of evaluating the epidemiology of Chikungunya virus (CHIKV) in Vellore district and also to identify the most susceptible sex and age group to CHIKV infection.

About 100 positive blood samples were collected from various localities Vellore, Katpadi, Thiruvallam, Sathuvachari and Gudiyatham in Vellore district and analysed. The total RNA was isolated from these infected blood samples and transcribed into its cDNA. The E1 gene of CHIKV was amplified and subsequently sequenced. A Phylogenetic analysis was carried out with the resultant sequence. Also the RNA secondary structure and restriction sites in the E1 gene of CHIKV were predicted using the softwares Genebee and NEBCutter, respectively. A survey on the outbreak of Chikungunya fever in and around Vellore district was carried out with the aim of identifying the most susceptible sex and age group to Chikungunya viral infection.

The results of the present study based on the phylogenetic analysis and BLAST studies revealed that the E1 gene sequence of CHIKV under investigation showed 87% similarity with that of the sequence of the CHIKV strain AR18211.

This study has thus revealed that the major strain responsible for the outbreak of Chikungunya fever in Vellore district was "AR18211" strain, an African genotype. Also the survey on CHIKV fever revealed the most susceptible age group to be between 20-40 years and the infection to be predominant among the male population.