Distribution of Ticks and the Potential Impact of Tick-Borne Disease on United States Forces in Korea

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Distribution of Ticks and the Potential Impact of
Tick-Borne Disease on United States Forces in
Korea

• LTC William J. Sames IV
• Entomology Consultant 18th MEDCOM
• Dr. Terry A. Klein
• Regional Infectious Disease Coordinator
  (Contractor)
• Dr. Hung-Chol Kim
• 5th Medical Detachment (Ento)
• Dr. Joon-Seok Chae
• Seoul University

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Korea
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Tick-Borne Disease and Military Importance in ROK

• Taxonomic knowledge gap identified
• 1971 - Last published collective taxonomic work
  US Army and associates out of Cp Zama, Japan
  Yamaguti, Tipton, Keegan, Toshioka
• 1980s Additional work by Kang and associates
• No published distribution maps out-of-date
  checklists
• Disease knowledge gap identified
• Individual articles on particular diseases, but
  no published list or discussion of importance
• Tick-borne diseases are not reportable by medical
  authorities
• Threat to military forces is currently best guess
  based upon diseases present, tick population,
  exposure rates, mitigation actions, season, etc.

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Knowledge Correction Activities

• Conduct literature search and review
• Compile tick collection data
• Determine tick distributions
• Create tick-borne disease list for Korea
• Estimate prevalence of tick-borne disease in
  Korea
• Conduct surveillance activities for additional
  data to complement the above actions

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Results of Tick Literature Review

• Bibliography of tick literature regarding Korean
  ticks created in MS EXCEL worksheet
• Expanded to include literature regarding ticks
  from Japan, NE China, and SE Russia
• PDF files are being acquired for listed citations
• As of 1 Feb 2007
• 222 citations have been listed
• 151 or 68 of listed files are in PDF
• Intent is to incorporate bibliography and PDF
  files into DPMIAC for future DOD access

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Tick Collection Database

• Created in MS EXCEL worksheet
• Multiple column format to capture as much
  information as possible and to facilitate sorting
  and searches
• Data from literature, non-published military
  collection records, other sources as found
• Potential benefits
• Distribution data by species
• Host association data
• Tick-Disease association
• Seasonality and population estimates

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Ticks of Korea Checklist

• Argas boueti
• Argas japonicus
• Argas vespertilionis
• Boophilus microplus
• Dermacentor coreus
• Dermacentor reticulatus
• Haemaphysalis campanulata
• Haemaphysalis concinna
• Haemaphysalis cornigera
• Haemaphysalis flava
• Haemaphysalis japonica
• Haemaphysalis kutchensis

• Haemaphysalis longicornis
• Ixodes angustus
• Ixodes granulatus
• Ixodes nipponensis
• Ixodes ovatus
• Ixodes persulcatus
• Ixodes ricinus
• Ixodes signatus
• Ixodes turdus
• Ixodes verpertilionis
• Rhipicephalus sanguineus

Checklist from literature sources list has not
been validated work in progress Species
collected during 2006 US Army surveillance.
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Known Tick Distributions

• Under development more confidence as additional
  collection records are acquired
• Adding tick collection data to spreadsheet
• Plot locations of above data to assist in
  determining distributions
• Limited data available from NK can speculate
  based upon NE China and SE Russia collections and
  limited NK data

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Known Tick-Borne Disease in ROK

• Anaplasma equi
• Anaplasma phagocytophila
• Borrelia burgdorferi
• Ehrlichia bovis
• Ehrlichia canis
• Ehrlichia chaffeensis
• Spotted Fever Group Rickettsia
• Theileria sergenti
• Tick-borne encephalitis

Disease list created from literature sources
primarily individual articles about each disease.
List to eventually associate vectors with each
disease.
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Prevalence of Tick-Borne Disease in ROK

• No medical reporting requirements best guess as
  to prevalence
• Most Korean tick-borne diseases treatable with
  antibiotics
• Antibiotics
• Used to be available without prescription
• 2004 law changed requiring prescription
• Some tick-borne diseases are self limiting

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Surveillance Activities

• Sparse surveillance activities in literature
  sources
• Few Army tick surveys reported since 1960s
• Air Force documents no ticks found on military
  working dogs on AFB in Korea (in DPMIAC)
• In 2004-2006, 18th MEDCOM Entomology Consultant
  conducted annual drag/flag tick surveys
• Some tick data from rodent surveys
• Need surveillance which targets host species
• Need peninsula wide collections
• Need entire season collections to show species
  seasonal activity

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Surveillance Activities

• Spring/Summer 2007
• Using degree days to estimate best surveillance
  dates
• Gets warmer in the south, hence earlier season
• Degree day estimates based upon average daily
  temperatures above 32oF beginning on 1 Jan
• Used 7 years of data (1 Jan-30 Jun, 2000-2006)
  for degree day estimates.
• Known that ticks present in good numbers north of
  Seoul around 1 April
• Degree days suggest late-Feb/early-Mar for Jeju
  Island
• Degree days suggest last week of March for Mokpo
  (southern mainland Korea)

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Summary

• Gaps in Korean tick-borne disease knowledge
  identified and being corrected
• Bibliography of literature on Korea ticks
• Spreadsheet of tick collection data
• Checklists for ticks and tick-borne disease
• Distribution and disease prevalence information
  being compiled
• Surveillance activities for additional data

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Questions?