A retrospective report on chiggers at a focus of scrub typhus on the China-Vietnam border in Yunnan of southwest China.

IMPORTANCE

Chiggers are the exclusive vector of scrub typhus. Jinping County, located along the China-Vietnam border in southwest China, is a focus of scrub typhus. It is of medical and veterinary importance to study chiggers in this area.

OBJECTIVE

The present study made a retrospective analysis aiming to report chiggers on small mammals (hosts) in Jinping County on the China-Vietnam border, Yunnan of southwest China.

METHODS

The indexes of chigger infestation and chigger community were routinely calculated. The niche width and overlap were calculated for analyzing chiggers' host selection. The sample completeness was determined through coverage index (CI).

RESULTS

A total of 7,718 chiggers from 274 small mammal hosts were identified as 52 species, 10 genera, three subfamilies and two families, including nine vector species. The CI of chigger species reached 99.84%. The genus Leptotrombidium accounted for 94.86% of 10 chigger genera. The majority of chiggers (constituent ratio [Cr] = 95.35%) came from rodents (Rodentia). The four dominant chigger species (Cr = 89.88%, 6,937/7,718) included Leptotrombidium deliense, the most important vector of scrub typhus in China.

CONCLUSIONS AND RELEVANCE: The abundant L. deliense in Jinping, together with other vector chigger species and their low host specificity, increases the potential transmission risk of scrub typhus in China-Vietnam border areas.