Low Seroprevalence of Aichi Virus Infection in Taiwan

Abstract

Aichi virus (AiV) belongs to the genus Kobuvirus of the family Picornaviridae; it is a single-stranded positive-sense RNA virus without an envelope. AiV causes acute gastroenteritis, abdominal pain, nausea, vomiting, and fever. Low incidence and high seroprevalence of AiV infections have been reported in several regions of the world; however, little was known on the prevalence of AiV infections in Taiwan. This study described the first two cases of AiV infection and analyzed AiV seroprevalence in Taiwan. A total of 700 sera were collected from a single hospital in southern Taiwan. The neutralization assay was employed to assess AiV neutralization antibodies in the serum. The test identified 48 positive cases, with a seroprevalence of 6.86%. Results also showed a gradual increase in AiV seroprevalence rate with age. Compared with other countries, Taiwan had a relatively low AiV seroprevalence, suggesting a low incidence of or sporadic AiV infections.

Keywords: Aichi virus; Taiwan; seroprevalence.

Figure 1

Phylogenetic analysis of AiV by comparison of 518 bp sequences in 3C/3D region using the maximum-likelihood method. The red marks indicate the two AiV isolates from Taiwan. Reference strains were obtained from GenBank, the accession number, strains, geographical origin of detection, and genotype are indicated. The tree with the highest log likelihood (−1569.54) is shown. The percentage of trees in which the associated taxa clustered together is shown next to the branches. Initial tree(s) for the heuristic search were obtained automatically by applying the maximum parsimony method. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site.

Figure 2

Seroprevalence of Aichi virus antibodies in a panel of 700 sera from Taiwan. (A) Number of cases (n) and percentage of positive samples in each age group in the total number of samples are given. (B) Age distribution of the 48 positive cases.