Molecular genome tracking of East, Central and South African genotype of Chikungunya virus in South-east Asia between 2006 and 2009

OBJECTIVE@#To understand the epidemiology of the East, Central and South African (ECSA) genotype of Chikungunya virus (CHIKV) in terms of emerging and re-emerging infections, this study has been aimed at investigating the evolutionary parameters, genomic signatures and molecular tracking of the CHIKV ECSA genotype in South-east Asia and coastal areas of the Indian Ocean between 2006 and 2009 by using phylogenetic analysis and the Bayesian Markov Chain Monte Carlo (BMCMC) evolutionary estimation.@*METHODS@#Nearly complete genome sequences of 53 CHIKV isolates from all genotypes were subjected to phylogenetic analysis and evolutionary parameter estimation. The amino acids of 67 of ECSA genotype during 2006 to 2009 were compared for finding molecular signature tracking. The ECSA genotype signatures were visualized to find the possible transmission root was projected onto a geographic map.@*RESULTS@#Phylogenetic analysis showed the ECSA genotype was divided into 2 groups. The first group comprises viruses from India and Southeast Asian countries. The second group consists of strains typically circulating in Sri Lanka in 2008. The evolutionary parameters of these groups depicted the time of the most recent common ancestor at approximately 7.5 years ago. The genomic signatures revealed the positions of amino acid variation in each group.@*CONCLUSIONS@#The molecular evolution projected onto a geographical map showed the routes of CHIKV transmission from 2006 to 2009. Molecular tracking will assist in understanding transmission routes, epidemiology and molecular evolution of CHIKV.

Novel H1N1 2009 influenza virus infection in Bangkok, Thailand:effects of school closures

Background: Influenza virus is the major cause of respiratory illness, especially in young and older age groups. Since 1918, many subtypes, defined by hemagglutinine (HA) and neuraminidase (NA), have caused global infections or pandemics. The recently isolated swine origin influenza virus (S-OIV) subtype H1N1 has been defined by the World Health Organization (WHO) as the cause of the present influenza pandemic. Objective: To describe and attempt to predict the epidemiology of the novel H1N1 2009 in Bangkok and to evaluate the effects of school closures during the outbreaks. Materials and methods: The first two human cases infected by this S-OIV subtype H1N1 or H1N1 2009 in Thailand have been reported in May 12, 2009 by the Ministry of Public Health. Between May 12 and July 30, 2009, 1212 nasopharyngeal (NP) swabs from four private hospitals and Chulalongkorn Hospital, Bangkok have been sent to a laboratory for Influenza virus diagnosis. The diagnosis was based on real time RT-PCR for seasonal influenza (H1, H3) and H1N1 2009. Results: One thousand two hundreds and twelve specimens of patients with influenza like illness were tested using real time RT-PCR detection. Between mid June and early July, the number of H1N1 2009 increased rapidly with a high prevalence among the 6- to 20-year olds. School closure policy, long public holiday, and additional preventive measures have led to a rapid reduction in the number of H1N1 2009 positive patients. Conclusion: Preventive measures including school closures are important to slow down the outbreak and thus enable health care centers to cope with the large number of patients. Everyone should play a role in delaying the spread of this pandemic.