Meeting Abstract
Chikungunya virus (CHIKV) is a rapidly re-emerging global pathogen causing both acute and chronic disabling illness. There is currently no vaccine. An RNA virus, CHIKV is transmitted to humans by the mosquito vector Aedes aegypti and related species. A. aegypti is the same species that transmits Dengue and Zika viruses. Described in 1955, CHIKV existed in two genotypes: West Africa and East, Central, and Southern Africa. Towards the end of the 20th century, CHIKV diversified into a European strain (Indian Ocean Lineage) and an Asian strain that has rapidly spread through Central and South America. This rapid spread has been driven by a) expanding mosquito vector populations as a result of urbanization and climate change and b) increased human global travel. CHIKV was introduced into the Caribbean in 2013, which led to an explosive outbreak in Grenada. Collaborating scientists collected 143 CHIKV samples from acute case symptomatic patients and confirmed positive infection. At the California Academy of Sciences, RNA was extracted from CHIKV positive sera, RNASeq libraries were prepared, and Illumina Miseq sequencing was performed on 12 initial samples. Sequencing reads were parsed, cleaned, and assembled into viral consensus genomes. Phylogenetic analyses were performed using maximum likelihood methods. All of the Grenada samples except for one form a monophyletic group, suggesting a single main introduction of CHIKV into Grenada, as well as a rare importation from Brazil. This reflects human travel among Grenada and other islands in the Caribbean as well as South America. Because viral mutations facilitate emergence and determine disease dynamics, phylogenetic analyses of CHIKV provide a deeper understanding of this pathogen and public health challenges.
