Trombiculid “chigger” mites (Acari) are ectoparasites that feed blood on rodents and another animals. A crosssectional survey was conducted in 7 ecosystems of southern Vietnam from 2015 to 2016. Chigger mites were identified with morphological characteristics and assayed by polymerase chain reaction for detection of rickettsiaceae. Overall chigger infestation among rodents was 23.38%. The chigger index among infested rodents was 19.37 and a mean abundance of 4.61. A total of 2,770 chigger mites were identified belonging to 6 species, 3 genera, and 1 family, and pooled into 141 pools (10-20 chiggers per pool). Two pools (1.4%) of the chiggers were positive for Orientia tsutsugamushi. Ricketsia spp. was not detected in any pools of chiggers. Further studies are needed including a larger number and diverse hosts, and environmental factors to assess scrub typhus.

We collected chigger mites at 7 survey sites in habitats of the national park, mangroves, nature reserves of the Southern on months the rainy season and dry season from 2015 - 2016.Objectives: To determine chigger mites infection rate in rats and species composition, the distribution of chigger mites in rats, and to detect chigger mites of rickettsial infection which is parasitic on rats.Results and conclusions: The common chigger mites infection rate in rats was 23.38% (143/600). In which Suncus murinus and Mus musculus were not infected chigger mites, the highest chigger mites infection rate in Rattus rattus was 36.36% (4/11) and Rattus norvegicus 32.87% (47/143). Collected 2,770 chigger mites individuals from 6 species, 3 genera, 1 family. Among them, Ascoschoengastia was a species of Ascoschoengastia (L.) indica; Leptotrombicula was 2 species of Leptotrombidium (L.)deliense and Leptotrombidium (L.) striatum; Gahrliepia was 3 specie of Gahrliepia (W.) chinensis, Gahrliepia (W.) lupella and Gahrliepia (W.) parapacifica. Total of 123 chigger mites samples (1,781 individual) were tested by PCR. Showed that the overall prevalence of Orientia tsutsugamushi was1.62% (2/123). Where in O. tsutsugamushi in the specie of Ascoschoengastia (L.) indica was 4.67% (1/21) and the species of L. (L.) deliense was 1.85% (1/54). None of chigger mite samples positive with Rickettsia spp.