Chikungunya virus, epidemiology, clinics and phylogenesis: A review.

Chikungunya virus is a mosquito-transmitted alphavirus that causes chikungunya fever, a febrile illness associated with severe arthralgia and rash. Chikungunya virus is transmitted by culicine mosquitoes; Chikungunya virus replicates in the skin, disseminates to liver, muscle, joints, lymphoid tissue and brain, presumably through the blood. Phylogenetic studies showed that the Indian Ocean and the Indian subcontinent epidemics were caused by two different introductions of distinct strains of East/Central/South African genotype of CHIKV. The paraphyletic grouping of African CHIK viruses supports the historical evidence that the virus was introduced into Asia from Africa. Phylogenetic analysis divided Chikungunya virus isolates into three distinct genotypes based on geographical origins: the first, the West Africa genotype, consisted of isolates from Senegal and Nigeria; the second contained strains from East/Central/South African genotype, while the third contained solely Asian. The most recent common ancestor for the recent epidemic, which ravaged Indian Ocean islands and Indian subcontinent in 2004 - 2007, was found to date in 2002. Asian lineage dated about 1952 and exhibits similar spread patterns of the recent Indian Ocean outbreak lineage, with successive epidemics detected along an eastward path. Asian group splitted into two clades: an Indian lineage and a south east lineage. Outbreaks of Chikungunya virus fever in Asia have not been associated necessarily with outbreaks in Africa. Phylogenetic tools can reconstruct geographic spread of Chikungunya virus during the epidemics wave. The good management of patients with acute Chikungunya virus infection is essential for public health in susceptible areas with current Aedes spp activity.