Bayesian skyline plot inference of the Toscana virus epidemic: a decline in the effective number of infections over the last 30 years.
Toscana virus (TosV), a sandfly fever virus, is one of the main causes of the aseptic meningitis that occurs during the summer in some Mediterranean regions, and whose epidemiology is largely unknown. We used a Bayesian Markov Chain Monte Carlo approach and a relaxed molecular clock to estimate the demographic history of the TosV infection in a series of isolates sampled between 1980 and 2003. The estimated mean evolutionary rate was 2.5 x 10(-4) substitutions per site per year (95% HPD: 0.31-5.44 x 10(-4)subs/site/year). Bayesian skyline plot revealed a sharp decline in the effective number of infections over the last 30 years. In conclusion, our data suggest that continuous and prolonged perturbations of vector/phlebovirus interactions due to the relatively recent climate changes may have contributed to gradually reducing the viral population in endemic areas.
Zehender
Gianguglielmo
G
Department of Clinical Sciences L Sacco, Section of Infectious Diseases, University of Milan, Milan, Italy. gianguglielmo.zehender@unimi.it
Bernini
Flavia
F
Delogu
Mauro
M
Cusi
Maria Grazia
MG
Rezza
Giovanni
G
Galli
Massimo
M
Ciccozzi
Massimo
M
D000818:Animals; D001499:Bayes Theorem; D019143:Evolution, Molecular; D016679:Genome, Viral; D006801:Humans; D008390:Markov Chains; D008582:Meningitis, Aseptic / Q000453:epidemiology* / Q000821:virology; D009010:Monte Carlo Method; D010691:Phlebotomus; D010217:Phlebotomus Fever / Q000453:epidemiology* / Q000821:virology; D010802:Phylogeny; D029301:Sandfly fever Naples virus / Q000235:genetics*; D016415:Sequence Alignment; D017423:Sequence Analysis, RNA