Multiplex PCR assay for identifying five species of chigger mites in the Republic of Korea

Abstract

Background Molecular date of chigger mites, disease vectors of scrub typhus, are lacking; therefore, they are typically identified morphologically. However, owing to the small size of chigger mites, they are easily damaged. Moreover, factors such as spontaneous mutation and the morphological similarity of adults make accurate classification and identification difficult. Therefore, this study aimed to develop a rapid and accurate molecular method for identifying five chigger mite species (Leptotrombidium pallidum, L. palpale, L. scutellare, L. orientale, and Euschoengastia koreaensis) that transmit scrub typhus in the Republic of Korea. Methods Species-specific primers for multiplex polymerase chain reaction (PCR) were designed using the internal transcribed spacer regions of 106 chigger mite samples from five species. Results Pieces of multiplex PCR products with unique size were created as follows: L. palpale, 933 bp; L. orientale, 747 bp; L. pallidum, 567 bp; E. koreaensis, 487 bp; L. scutellare, 244 bp). Conclusions A multiplex PCR-based molecular method was successfully developed for identifying five chigger mite species (mainly collected from rodents) that transmit scrub typhus in Korea and are distribute nationwide. This multiplex PCR assay will complement morphological classification, providing an accurate species identification method that will be useful for monitoring chigger mites.