As a member of the Human Enterovirus species A (genus
Enterovirus, family
Picornaviridae), Enterovirus 71 (EV71) is a small, non-enveloped, positive-stranded RNA virus. Based on the VP1 coding region, the worldwide circulation of EV71 can be divided into seven genotypes designated A to G, where the two major genotypes B and C are classified into 14 subgenotypes, respectively, designated B0 to B7 and C1 to C6 [
1]. The sub-genotype C4 has been identified as the most dominant sub-genotype circulating in the Chinese mainland since 1998. The circulation situation of EV71 before 1998 is not well established due to insufficient experimental data [
2]. It is reported that the sub-genotype C1 of EV71 circulated only in the Western Pacific, Europe, and the United States before 2000. After 2000, it was reported that the C1 genotype was prevalent in Southeast Asia, such as Malaysia, Thailand, Hong Kong. However, the sub-genotype C1 of EV71 has not been reported in the Chinese mainland by now [
3]. China established the AFP (Acute Flaccid Paralysis, AFP) surveillance system to monitor acute onset cases, decreased muscle tension, decreased muscle strength, and weakened or disappeared tendon reflex. Based on the AFP surveillance system of the mainland of China, this study performed a retrospective study of AFP cases for 1985–1999: A strain of EV-A71 C1 sub-genotype was found.