High degree of genetic diversity of non-polio enteroviruses identified in Georgia by environmental and clinical surveillance, 2002-2005.

Enterovirus surveillance data are useful for establishing temporal and geographical patterns of circulation and for virus characterization to determine phylogenetic relationships between strains. Almost no information is available on circulating enteroviruses in Georgia and the surrounding region. To describe enterovirus circulation in Georgia, determine relationships with previously characterized strains and assess the role of environmental and clinical enterovirus surveillance, this study analysed a total of 112 non-polio enterovirus isolates identified during 2002-2005 from sewage and human stool samples. Viruses were isolated in cell culture using standard methods and typed by partial sequencing of the VP1 gene. A total of 20 different non-polio enterovirus serotypes were identified over the 4-year period. The most commonly detected enteroviruses included echovirus (E) 6 (21 isolates; 18.8 %), E20, E3 and E7 (11 isolates each; 9.8 %), E11, coxsackievirus (CV) B4 and CVB5 (seven isolates each; 6.3 %), and E13, E19 and E30 (six isolates each; 5.4 %). Phylogenetic analysis showed that many serotypes were represented by more than one genetic lineage. The present study showed a very high degree of enterovirus diversity in Georgia and demonstrated the added value of environmental enterovirus surveillance, particularly in settings with limited clinical surveillance. Several serotypes would not have been detected without having both clinical and environmental surveillance in place. Several serotypes detected in Georgia were among those rarely reported in the USA and Europe (e.g. E3, E20 and E19). As the emergence of new genetic lineages of enterovirus in a particular area is often associated with large-scale outbreaks, continued monitoring of enterovirus strains by both environmental and clinical surveillance and genetic characterization should be encouraged.