Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT02876367 |
| Other study ID # |
OxTREC no. 48-15 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
September 1, 2016 |
| Est. completion date |
December 31, 2018 |
Study information
| Verified date |
September 2021 |
| Source |
University of Oxford |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
This study to collect and identify rodents and mites across transects through diverse
habitats used by the human community from a localised area identified as a scrub typhus 'hot
spot'.
Description:
Study design:
The project will undertake a detailed investigation of one human community, and its
environment, at risk of scrub typhus:
Chiggers, Rodents & Habitat Study:
Transects across diverse habitats determining spatial distribution of species of chiggers and
rodents. This will be performed 3x/year.
High-resolution habitat mapping. Comparison of genomes of O. tsutsugamushi detected in
different environments, using attempted WGS.
Village Cohort Study:
Follow a cohort of villagers over 2 years screening all febrile patients for scrub typhus and
determining seroconversion rates and infecting O. tsutsugamushi genotypes.
Procedures:
- Mites:
Working with ecology/GIS collaborators, the environment of the community will be mapped and
transects laid across the diverse habitats used by the community. Free-living mites will be
collected with black plastic plates and black cloth21, from soil using Berlese funnels and
from rodents. Trombiculid mites will be identified to genus and a subset to species.
DNA will be extracted from individual chiggers, and qPCR screening for O.
tsutsugamushi-positivity performed (real-time PCR targeting 47kDa-gene). A proportion of
confirmed positives will undergo genotyping by attempted whole-genome sequencing (WGS).
- Rodents:
Rodents will be captured alive along transects and identified in collaboration with
University of Montpellier24. All mites will be removed from rodents, the rodents killed and
the rodent spleen and liver collected for O. tsutsugamushi qPCR screening. A proportion of O.
tsutsugamushi-positive samples will undergo genotyping by attempted WGS or extended MLST
analysis.
- Human cohort:
All those in the community (>10 years old) will be approached and asked for consent to
participate. All enrolled will have scrub typhus ELISA/IFA (from finger-prick filter paper
blood spots) performed every 4 months over 2 years to estimate the rates and dynamics of
seroconversion. A brief questionnaire will be administered at each visit to determine whether
the participant had a febrile illness in the preceding 4 months.
Patients presenting with a febrile illness to local healthcare facilities will be clinically
assessed and an on-site scrub typhus IgM rapid diagnostic test (RDT) performed. RDT positive
patients will be recruited into the study, and paired acute/convalescent samples sent to
LOMWRU for ELISA, qPCR and BSL3 culture, followed by genotyping by attempted WGS. A
questionnaire will be administered to recruited patients to determine symptomatology and
vital signs recorded.
Epidemiology & Ecology:
The exact sample collection locations and habitat details will be recorded.
Genomic analyses:
To characterize the relationships between highly diverse O. tsutsugamushi genotypes in
multiple strain/genotype-infected hosts a proportion of qPCR positives (approx. 480 samples)
will be analysed by whole-genome sequencing at WTCHG in Oxford.
