Infestation and distribution of chiggers on the Anderson's white-bellied rats in southwest China.

As a group of ectoparasites, chiggers (larvae of chigger mites) are the exclusive vector of scrub typhus (tsutsugamushi disease). Rodents are the most important hosts of chiggers. The Anderson's niviventer rat, Niviventer andersoni, is an endemic species of rodent in China. However, few studies have involved this endemic rodent species and its ectoparasites including chiggers. According to the field investigation in five provincial regions of southwest China between 2001 and 2019, this paper retrospectively analysed the infestation and distribution of chiggers on the body surface of N. andersoni in southwest China for the first time. From 77 Anderson's niviventer rats captured, a total of 527 chiggers were collected and they were identified as 39 species and nine genera in two subfamilies of family Trombiculidae. Of 39 chigger species identified, Leptotrombidium deliense and L. scutellare are the most important vectors of scrub typhus in China. The overall infestation indexes were PM = 29.87%, MA = 6.84 and MI = 22.91, and the indexes of chigger mite community were Mf = 39, H' = 2.60, E = 0.71 and D = 0.12. The dominant chigger species are L. wenense, L. xiaguanense and L. fujianense with a total Cr = 51.04%, among which L. wenense is one of the six main vectors of scrub typhus in China. The dominant chigger species are of aggregated distribution among different individuals of the rats.