Interestingly, the HA sequence from sample 5250Jan02 clusters closely with those from samples 5251Jan02 and 5267Jan03 (Figures S1 and S3), but its NA sequence lies some distance away on a separate branch (Figures S2 and S4 ). This may suggest a possible reassortment event, either with its HA or NA gene segment. Further full genome sequencing and analysis may resolve this issue.