Infectious Disease · Public Health · 1 h ago
Viable Orientia tsutsugamushi Isolated from Bat-Associated Chiggers in Japan
A study of chiggers collected from bats on Yonaguni Island, Japan, detected Orientia tsutsugamushi in most tested mites and isolated viable bacteria from four pools. The findings identify a previously undocumented ecological setting for the scrub typhus bacterium, but do not demonstrate transmission to humans or vertebrate hosts.
- O. tsutsugamushi detected in 94% of tested chiggers.
- Viable bacteria isolated from four chigger pools.
- Transmission to humans or vertebrates was not assessed.
Researchers collected 212 Whartonia prima chiggers from 80 Hipposideros turpis bats on Yonaguni Island in 2024 and 2025. They tested 68 mites for Orientia tsutsugamushi using PCR and attempted bacterial isolation from pools of mites collected in 2025. The team assessed isolates through serial passage in L929 cells, microscopy, growth analysis and genetic sequencing.
Of the 68 mites tested, 64 (94%) were positive by real-time PCR and 55 (81%) by nested PCR. Four of 28 chigger pools yielded isolates that were maintained through four passages. Sequences from the isolates clustered within the Karp-related lineage; growth analysis of one isolate showed an increase from 4.19 log10 copies per well at day 1 to 6.93 at day 8.
The results show that bat-associated W. prima chiggers can harbor viable O. tsutsugamushi and expand the known ecological settings in which the bacterium has been identified in the region. However, the study did not establish that these chiggers can transmit the bacterium to vertebrates, that bats are involved as hosts, or that humans are exposed. The article is an early-release report, and the journal notes that it is not yet a final version.
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Emerging Infectious Diseases: Isolation of Orientia tsutsugamushi from Bat-Associated Chiggers, Japan ↗This is an automated AI-condensed summary that has not yet been reviewed by an editor. Always consult the full item at the original source.