Scrub Typhus Clinical Trial
Official title:
The Natural Immune Response In Pediatric Scrub Typhus In Chiangrai
This is an observational study of the natural immune response to scrub typhus in patients
recruited from Chiangrai Prachanukroh Hospital, N-Thailand. Febrile patients with a positive
IgM rapid diagnostic test will be asked if they wish to take part in a study to improve the
understanding of how the body responds to scrub typhus. Blood samples will be collected from
each participant ("STP", n=60) at baseline (the day of presentation to hospital), 2 weeks
later in hospital, 12 weeks after baseline at the clinic visit and 1 year later. Data on
clinical presentation and relapses will be recorded. Control subjects are scrub typhus
exposed patients from a rural village in the caption area of Prachanukroh Hospital ("STE",
n=80; approx. 40 children and 40 adults), and healthy adults blood donors from Bangkok ("STH"
n=30) - these subjects will be enrolled for one single blood sample. The study team will also
collect eschar swab specimens from STP group and a non-invasive specimen of the dark crust on
the day of enrollment.
Funder: Li Ka Shing Foundation [Grant C13004]
Primary Objective:
o To measure and characterize the memory and effector T-cell responses, as well as the
humoral response in young patients with acute scrub typhus and to compare theseThese acute
responses will be compared to responses in the convalescent phase of the same individuals at
2, 12 and 52 weeks later, as well as to scrub typhus-exposed controls and to healthy
controls.
Secondary Objectives:
- To establish ELISpot and flow cytometer based immunology assays using human samples
collected in rural areas of high scrub typhus endemicity.
- To set up a prospective cohort study of paediatric scrub typhus in a region of high
endemicity
Description of the Study Sites and Population Chiangrai Prachanukroh Hospital in Chiangrai
province, N-Thailand is ideally suited for this study. We have a well-established
collaboration, due to a previously completed multi-year fever study and an excellent
relationship with local senior doctors, staff and the hospital-based laboratory. There is a
very high rate of scrub typhus cases admitted to the infectious diseases ward and the recent
establishment of a MORU (Mahidol Oxford Tropical Medicine Research Unit) satellite laboratory
within the hospital facilities, make this study site unique and highly suited for performing
this research project. This study will contribute significantly towards the long-term aim of
developing the Chiangrai study site towards an immunogenicity monitoring field site for
vaccine trials.
The 'scrub typhus' patients (STP) are febrile children recruited from the ID and/or pediatric
wards at Prachanukroh hospital during an acute hospitalization due to scrub typhus, and
followed up as described above.
The scrub typhus 'exposed' cohort (STE) will consist of children and adults recruited from
two villages in an area where scrub typhus is reported as a common disease. This cohort has a
high risk of previous contact with scrub typhus, and it is unknown if they had an
asymptomatic or sub-clinical infection in the past, but we expect the presence of some form
of immune memory regarding cellular and/or humoral immunity in a large proportion of these
subjects.
The healthy scrub typhus naïve control group (STH) does not necessarily need to include
children, as the principle is to compare a non-exposed immune response to previously exposed
and/or acute cellular responses. Thus, the 'Healthy Cohort' will be recruited from the staff
at MORU and/or the Faculty of Tropical Medicine in Bangkok.
;
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