Human influenza surveillance in areas with animal flu epidemics and China visitors in Taiwan

Abstract

Background: This study investigates the changes in human flu viruses in areas where unique animal flu viruses or epidemics were isolated in Taiwan and Kinmen islet. Materials and methods: Sentinel physicians obtained throat swabs from patients presenting with flu-like illness and two-step RT-PCR, using five sets of primers for matrix (M) and HA2, to detect all the animal influenza viruses and then typing/subtyping for human flu viruses. Questionnaires included travel history, animal contacts and occupations. Results: One flu B and eight flu A H3N2 isolates were identified in the flu season of 2002–2003, including 1, 2, 2 and 3 H3N2 in Taoyuan, Yilan, Tainan and Kinmen, respectively. Amino acid sequences of HA of human isolates revealed that Pro (P) at position 227 among most of the Kinmen isolates (2/3) replaced Ser (S) in the Taiwanese isolates, including one mutant from Gln (Q) to His (H) at position 156 of the HA gene for five out of eight H3N2 Taiwan isolates. Phylogenetic analysis demonstrated that all of the H3N2 viruses were of human origin (belonging to the lineage of A/Fujian/411/2002), with 80–90% homology in HA, NA and M gene segments of A/Swine/PingTung/Taiwan/199.2/02 (H3N2) and 75–77% homology in HA gene segment of A/Wild Bird/Taiwan/243/02(H3) and A/Mallard Duck/Taiwan/3.3/03 (H3). Conclusions: Residents in Kinmen islet frequently traveling from China need to monitor their flu A viruses that might be different from those obtained on the main Taiwan island.