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Research on Bio-Molecular Study of Orientia tsutsugamushi
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College of Public Health Sciences_Chulalongkorn University
In Thailand …. Several ongoing research project conduct & 5 Labs work on … Entomology Department, AFRIMS-USAMC [USA.-Personnel]
Analytical Division, AFRIMS-RTA (Royal Thai Army) [Under supervision of Col Dr Wuthikorn Rodkwamtook]
Department of Clinical Tropical Medicine & Wellcome Unit, Faculty of Tropical Medicine, Mahidol University
Entomology Department, Kasetsart University [Under supervision of Prof Dr Theeraphap Chareonviriyaphap]
• PCR amplification of O. tsutsugamushi DNA from whole
blood sample or infected-animal tissue samples
• Multiplex RT-PCR for detection of O. tsutsugamushi
• DNA sequencing to examine the different
strains of O. tsutsugamushi
• Rapid immunochromatography assay for
detection of O. tsutsugamushi
• Other New developing Test-Kit for diagnosis
of O. tsutsugamushi
• Recombinase Polymerase Amplification
assay for detection of O. tsutsugamushi
1st PCR Nested PCR
800 bp
600 bp
700 bp
S: Spleen
L: Liver
K: Kidney
B: Blood
C1: Chigger1
C2: Chigger2
P: Karp
N: No DNA template control
M: DNA marker
M S L K B C1 C2 P N S L K B C1 C2 P N M
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College of Public Health Sciences_Chulalongkorn University
งานวิจยัเก่ียวกบัพาหะ-ตวัอ่อนไร Leptotrombidium
Research on Leptotrombidium Chigger-Mites Vector
Collection of Leptotrombidium Chigger-mites can ONLY be
done by removing them off trapped-animal (rodent)-hosts
• Taxonomy of Leptotrombidium chigger-mite (vector of
scrub typhus) is extremely difficult
[It can ONLY be done on the larval or chigger-mite stage]
Taxonomic Characters
Dorsal/Ventral Aspects of Leptotrombidium deliense (Walch)
Taxonomic characters of Leptotrombidium chigger-mites can only be
accomplished by measuring of key morphological parts & counting
numbers of setae & bristles with (@100x magnification
[objective lens] under the compound microscope) !!!
Maintaining the colonies of scrub typhus-infected Leptotrombidium chigger-mite
is even more difficult with a very tedious & laboring task, required experiencing
technical skill to rear immature-mites
These infected chigger-mite required the “Animal Passage Procedure”
[feeding on lab-mice in order to receive protein source for developing into the next stage]
In Thailand …. No current research project conduct & Only 2 Labs work on ….. Entomology Department, AFRIMS [US-Personnel], Scrub-typhus infected Mite-colonies established in 1984
Entomology Department, Kasetsart University [Under supervision of Prof Dr Theeraphap Chareonviriyaphap]
Scrub-typhus infected Mite-colonies established in 2011
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College of Public Health Sciences_Chulalongkorn University
งานวิจยัเก่ียวกบัโฮสต-์สตัวก์ลุ่มฟันกดัแทะResearch on Rodentia-Hosts
Collecting or Obtaining this animal (rodent)-
hosts can ONLY be done by “Trapping”
In Thailand …. No ongoing research project conduct & Only 3 Labs work on … Entomology Department, AFRIMS-USAMC [US-Personnel]
Analytical Division, AFRIMS0RTA (Royal Thai Army) [Under supervision of Col Dr Wuthikorn Rodkwamtook]
Entomology Department, Kasetsart University [Under supervision of Prof Dr Theeraphap Chareonviriyaphap]
Three trap sites should be designated in trap-areas
1. Town/Residential site
2. Suburb/Village site
3. Scrub Area & nearby Household’s Field
Animal Trapping Trips are costly, very expensive,
man-power required,
no guarantee of catching
high risk from getting bites & diseases
lack of skill rodent taxonomist
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งานวิจยัเก่ียวกบัทางคลีนิคการติดเช้ือ(โรค)
Research on Clinical Infectious Disease
College of Public Health Sciences_Chulalongkorn University
Number of scrub typhus cases have a tendency to
be lower than the actual cases occurred, due to
Lack of experience to diagnose the disease
Nonspecific signs & symptoms
Lack of the unique characteristic of “eschar” as
appeared in scrub typhus patients
Availability & prescription of the antibiotic drugs
Therefore, the actual number of scrub typhus cases would be much higher
In Thailand ... Several ongoing research project conduct & Only 3 Labs work on … Infectious Diseases Unit, Internal Medicine Department, Faculty of Medicine, Siriraj Hospital, Mahidol University
[Prof Dr Yupin Suputtamonkol & Teams]
Department of Clinical Tropical Medicine & Wellcome Unit, Faculty of Tropical Medicine, Mahidol University
Infectious Diease Unit, Internal Medicine Department, Maharat Nakhon Ratchasima General Hospital Hospital
[Dr: Wilawan Thipmontree]
College of Public Health Sciences
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งานวิจยัเก่ียวกบัวคัซีนป้องกนัโรคResearch on Vaccine Development
College of Public Health Sciences_Chulalongkorn University
Scrub typhus vaccine candidates were first developed by the team of the US-Naval
Medical Research Center (NMRC), led by Drs. W.M. Ching & A. L. Richards,[Rickettsial Diseases Division, Viral & Rickettsial Diseases Department, NMRC-WRAIR, USA]
Initial evaluation of scrub typhus vaccine candidates using the
intra-peritoneal (IP) injection [Needle Challenge Procedure] in mice,
Found to provide adequate & satisfactory protection.
Later, those scrub typhus vaccine candidates was assessed &
evaluated for their protection efforts on ICR mice using
“Natural Challenge Procedure”
[using O. tsutsugamushi-(scrub typhus)-infected chigger-mites] {This procedure was conducted by Ectoparasite Laboratory Section, Entomology Department, Armed Forces
Research Institute of Medical Sciences (AFRIMS), United States Army Medical Component, Bangkok, Thailand}
Although the results showed that there were some protection,
But, it failed to reach the level of standard protection as required
Lerdthusnee, et.al., 2007:
AFRIMS-USAMC
In Thailand …. No Study on Scrub Typhus Vaccine
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งานวิจยัการเฝ้าระวงัการแพร่กระจายโรค/งานภาคสนามResearch on Disease Surveillance & Field Surveys
College of Public Health Sciences_Chulalongkorn University
Surveillance survey on wild-caught
rodent serum samples, by province, [with positive detections of specific antibodies
against O. tsutsugamushi by ELISA method]
Lerdthusnee et al., 2002:AFRIMS-USAMC
Global Positioning System (GPS)_Geographical
Information System (GIS) & Coordinate Map [showing trapped-sites with rodents caught & chigger-mite
collection]
Lerdthusnee et al., 2006:AFRIMS-USAMC
POSITIVE RODENT DENSITY
POSITIVE CHIGGER DENSITY
R = Rice Field,
F = Forest,
S = Scrub
V=Village
In Thailand …. No current research project conducted & Only 2 Labs work on this Entomology Department, AFRIMS [US-Personnel], Scrub-typhus infected Mite-colonies established in 1984
Entomology Department, Kasetsart University [Under supervision of Prof Theeraphap Chareonviriyaphap]
Scrub-typhus infected Mite-colonies established in 2011
Routine surveillance &
Field surveys will lead: to define animal reservoirs
and/or insect vectors
to determine locations &
level of disease distribution,
to provide early warning of
disease occurrences,
to report information and
exchange data to the public,
to design & plan further
investigation on livestock,
domestic and wild animals.
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ทิศทางงานวิจยัโรคสครบัไทฟัส & ข้อแนะน า
College of Public Health Sciences_Chulalongkorn University
Using GPS & GIS technology to “Assess-Evaluate” relative risk
in different biotopes within endemic scrub typhus areas
Surveillance of O. tsutsugamushi-infected rodent-populations
& O. tsutsugamushi-infected chigger-mite populations
Development of Rapid diagnostic kit to Diagnose O.tsutsugamushi
Dissemination of O.tsutsugamushi in chigger-mites & rodent-hosts