H.L by S. SUVASMITA

1. LONGICORNIS​ , VECTORS OF SEVERE FEVER
WITH THROMBOCYTOPENIA SYNDROME
(SFTS) VIRUS IN GYEONGGI PROVINCE,​SOUTH
KOREA​
SUVASHREE
SUVASMITA

2. TABLE OF
CONTENTS
01.INTRODUCTION
02. MATERIALS
03. METHODS
04. RESULTS
05. DISCUSSION
06. CONCLUSION

3. INTRODUCTI
ON
 TICKS SPREAD DISEASE: THESE TINY ARACHNIDS CARRY AND TRANSMIT
BOTH BACTERIAL AND VIRAL PATHOGENS, POSING A
SIGNIFICANT PUBLIC HEALTH THREAT.
 SFTS IS A NEW TICK-BORNE ILLNESS: EMERGING IN EAST ASIA, THIS SEVERE
FEVER WITH THROMBOCYTOPENIA SYNDROME CAN CAUSE SERIOUS
HEALTH COMPLICATIONS.
 HAEMAPHYSALIS LONGICORNIS IS THE MAIN CULPRIT: THIS TICK SPECIES
CARRIES THE SFTS VIRUS AND TRANSMITS IT TO HUMANS, ADDING TO ITS
CONCERN AS AN INVASIVE PEST.
 RESEARCH NEEDED ON THE TICK: DESPITE ITS MEDICAL IMPORTANCE, WE
LACK CRUCIAL KNOWLEDGE ABOUT H. LONGICORNIS' BIOLOGY AND
ECOLOGY, HINDERING CONTROL EFFORTS.

4. 02.MATERIALS & METHODS
I. SAMPLING SITE :
FIG. 1. A THE FOUR SAMPLING SITES
LOCATED IN DIFFERENT VEGETATION
TYPES IN MUGAP-RI, GWANGJU-SI,
GYEONGGI DO, SOUTH KM·EA: B.
MOUNTAIN TRAIL C. SHRUBS D.
GRASSLAND AND E. GRAVE​ ARROW
HEADS INDICATE LOCATIONS OF CO BAIT
TRAPS​.
2-year field study on tick activity and diversity
in Mugap-ri, South Korea.
Four vegetation types
(grassland, grave, trail, shrubs) sampled near
a village.
Trap size varied (1049-2043 m3) to account
for diverse habitats.
Distinct vegetation and wild animals (water
deer) present in each site.
Study aimed to understand tick behaveior
and distribution across environments.

5. II.SAMPLING METHOD:
CO2-bait traps: Used by Korea Disease Control and
Prevention Agency (KDCA) for vector surveillance.
Trap design: White tarpaulin cylinder with dry ice cooler
generating CO2 as an attractant.
Deployment: 3 traps per site, 20m apart, near center.
Collection: Monthly (April-November 2019-2020), set up
10:00-11:00, checked after 24 hours.
Tick analysis: Collected ticks identified in lab, tested for
SFTS virus.

6. III.TICK IDENTIFICATION:
• Chilled ticks identified with stereomicroscope.
• Nymphs/adults: Species level.
• Larvae: Genus level due to difficulty.
• 50% randomly selected for SFTS virus PCR.

7. IV.SFTS VIRUS
DETECTION:
• Ticks pooled by vegetation type, species, and
stage
• Total RNA extracted and one-step PCR conducted
for SFTS virus.
• Nested PCR for increased accuracy.
• Positive samples confirmed by gel electrophoresis
and sequenced.
• Minimum Infection Rate (MIR) estimated to assess
SFTS prevalence (cost-effective for low
prevalence).

8. 03.RESUL
TS
Species​ Stage​ 2019​
No.(%)​
2020​
No.(%)​
Total
No.(%)
Haemaphysalis longicornis Nymph​ 1117​ 649​ 1766​
Adult 445​ 356​ 801​
Subtotal 1562 (59.2) 1005 (53.5) 2567 (56.9)​
Haemaphysalis flava Nymph​ 12​ 5​ 17​
Adult 20​ 18​ 38​
Subtotal 32 (1.2)​ 23 (1.2) 55 (1.2)​
Haemaphysalis sp. Larva• 1043 (39.6) 851 (45.3) 1894 (41.9)
Total 2637 (100)​ 1879 (100)​ 4516 (100)​
Species and Developmental Stage Composition
Dominant species: Haemaphysalis longicornis (>95% of
nymphs and adults).
Haemaphysalis larvae: Peak in August both years, rapid
decrease in September.
H. longicornis nymphs: Increase April-June, peak June 2020,
decrease July-November.

9. a. Species and Developmental Stage Composition
• Dominant species: Haemaphysalis longicornis (>95% of nymphs and
adults).
• Haemaphysalis larvae: Peak in August both years, rapid decrease in
September.
• H. longicornis nymphs: Increase April-June, peak June 2020, decrease
July-November.
• H. longicornis adults: Peak July 2019, June 2020, absent October-
November.
• H. flava: Low numbers, no clear peak in nymphs, slight increase in
adults in Septembe
• SFTS Virus Harboring Rate
• 2019: MIR of 0.43, 1 positive pool from H. longicornis females in
grassland (June).
• 2020: MIR of 1.39-5.88, 18 positive pools detected August-October.
• August: 16 positive pools (6 grassland, 6 grave, 2 mountain trails, 2

10. b.Vegetation Preference
• No significant difference between vegetation types for collected ticks.
• Over 70% of ticks found in grassland and grave.
• H. longicornis adults and nymphs higher in grassland.
• H. flava: no clear pattern due to low numbers.
• Haemaphysalis larvae: highest numbers in grave (80.5% and 59.6% in 2019 and
2020 respectively).
SFTS Virus Harboring Rate
2019: MIR of 0.43, 1 positive pool from H. longicornis females in grassland (June).
2020: MIR of 1.39-5.88, 18 positive pools detected August-October.
August: 16 positive pools (6 grassland, 6 grave, 2 mountain trails, 2 shrubs).

11. 04.DISCUSSION
H. longicornis is the main vector of SFTS in South
Korea, making it a high priority for control strategies.
Expanding tick monitoring periods and employing
diverse sampling methods are crucial for accurate
population assessment.
Managing vegetation in areas like grassland can help
reduce tick density and exposure risk for residents.
Understanding the seasonal dynamics of SFTS virus in
ticks is essential for effective disease management.

12. 05.CONCLUSION
• This study provides valuable insights into tick populations and
SFTS virus prevalence in South Korea. By implementing targeted
control measures, managing vegetation, and raising awareness,
communities can minimize the risk of SFTS and protect public
health.

13. 06.REFFERENCE:
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14. SUVASHREE
SUVASMITA
DT- 16/01/2024