Malaria, Malaria, A Re-emerging Health A Re-emerging Health Threat to the Republic Threat to the Republic

of Koreaof KoreaCOL (Ret) Terry A. Klein, PhD

Regional Emerging Infectious Disease Consultant Force Health Protection, 18th Medical Command

Republic of Korea

12 February 2007

Collaborators

• Dr. Heung-Chul Kim, 5th MED DET

• Dr. Won-Ja Lee, Korea NIH

• Dr. Desmond Foley, WRBU

• LTC William Sames, 18th MEDCOM

• Dr. Leopoldo Rueda, WRBU

• Dr. Richard Wilkerson, WRBU

• Commanders/personnel, MED DETs

History of Malaria in Korea1950-53: vivax malaria presented a health threat to US Forces during the Korean War. 1973: Korea declared itself to be malaria free1993: Plasmodium vivax malaria re-emerged and increased exponentially through 1998. 1998-00: overall, malaria stabilized, increasing slightly.2001-04: malaria rates rapidly decreased annually.2005: malaria rates increased, continue to increase in 2006.Chemoprophylaxis:

1997-98: US Forces, increased reliance (>14,000), then decreased usage to 1,300 personnel in 2000 and <500 from 2001-Present.1998-2005: increased reliance by ROK Military (40,000 to >165,000) Evidence that ROK soldiers placed on chemoprophylaxis have higher rates of delayed malaria.2006: ROK Army increases chemoprophylaxis to 200,000

Vivax Malaria – EpidemiologyHealth

• Vivax malaria is a significant health threat.• Vivax malaria is non-lethal. • High Risk Areas - defined only by troop movement

and clinical reporting, not area of transmission.• Once diagnosed and treatment initiated, soldiers lose

about 72--96 hours of duty time. Total recuperation may extend 1 week+.

• Malaria is a significant threat to the blood supply for Korea.

• No vaccine available.

Increased Pressure to put US and ROK soldiers on chemoprophylaxis. – Departing US personnel presents a significant US public

health threat at their new station in the US.– 2004, at least 6 US Soldiers deployed to Iraq from Korea

developed malaria (attributed to exposure in Korea).– Vivax malaria among retiring ROK soldiers pose a threat to

the spread of malaria throughout Korea.

• Hasty reliance on chemoprophylaxis minimizes the doctrinal importance of PPM, vector surveillance and control.

• Potential resistance of P. vivax to chloroquine and/or primaquine.

Vivax Malaria – Epidemiology Chemoprophylaxis

Vivax Malaria - Epidemiology Transmission

• Vector(s)– Zoophilic (?) – Low-survival rates– Low infection rates/

high vector density– Distributions

unknown– Vector status not

well understood

• Environment– Low/moderate endemicity – Epidemic outbreaks– Climate (cold winters,

typhoons) favorable for short periods

• Host – Delayed or immediate

disease manifestation.– Low immunity

Annual Trend of Malaria Cases Diagnosed in the Republic of Korea

YEAR

Chemoprophylaxis initiated

(16,000)

(37,000)

(60,000)

(90,000)

(120,000)

(145,000)

(165,000) (200,000)

As of 31 December 06

Annual Trend of Malaria Cases Among US Soldiers and Attributed to exposure in the Republic of Korea,

1993 – 2006

YEAR

Chemoprophylaxis Initiated

Chemoprophylaxis stopped, except for JSA and Cp

Greaves

Number of Cases of Plasmodium Spp. In US Servicemen Attributed to Exposure in Korea and

Other Countries

Nu

mb

er M

alar

ia C

ases

Month

Latent, Non-latent, and Unknown Forms of Vivax Malaria Diagnosed in Korea and Outside of Korea

Nu

mb

er M

alar

ia C

ases

Month

Month of Diagnosis for Latent and Non-latent Vivax Malaria Forms

Nu

mb

er M

alar

ia C

ases

Month

Distribution of Malaria, USFK, 2002 - 2006

Adult Mosquito Surveillance

CDC Light TrapNew Jersey Light

Trap

Human-Bait Mosquito Magnet RatioAnopheles sp. 2.22 1.09 2.04Aedes sp. 0.31 1.67 0.19Culex sp. 0.03 0.72 0.04

Mean Number of Mosquitoes Collected and Human Biting Propensity - Sept. 03

Species

Anopheles sinensis 1 189.4 n/d 0.1Culex tritaeniorhynchus 2 0 n/d 0Aedes vexans 481.4 n/d 0.4

SEPTEMBERAnopheles sinensis 59.8 1.5 0Culex tritaeniorhynchus 741.9 1 0.25Aedes vexans 320 2.5 0.125

Mosquito Surveillance Trapping Methods - 2000

JUNE

Mosquito Magnet +

Octenol3

New Jersey Light Trap

CDC Light Trap

1 Anopheles sinensis group includes An. lesteri, An. pullusand two undescribed species.2 Culex tritaeniorhynchus are rarely collected in June nearthe demilitarized zone.3 All traps baited with octenol, an artificial attractant, collected more An. sinensis, Cx. tritaeniorhynchus, and Ae.vexans, but fewer Cx. pipiens.

Taxonomy and Distribution of Malaria Vectors

• 5 members of the An. sinensis GroupAn. sinensisAn. lesteriAn. pullusAn. belenraeAn. kleini

• Identify vector species• Identify vector species distributions• Identify vector species habitats

1 Km

Determine Species Distribution

1 Km

KSK-2

An. sinensis s.s. An. kleini

Darker blue indicates areas of greater agreement amongst 10 replicate Ecological Niche models

An. pullus An. belenrae

Geographical Distribution of Four Members of the An. sinensis Group

An. lesteri, 1, 0.8%

An. pullus,

48, 39.3%

An. kleini,

63, 51.6%

An. belenrae 3, 2.5%

An. sinensis , 7, 5.7%

An. sinensis

62, 100.0%

An. sneroides

1, 2.8%

An. belenrae, 1, 2.8% An.

pullus, 3, 8.3%

An. Sinensis, 29, 80.6%

An. kleini, 2, 5.6%

An. sinensis 22, 91.7%

An. belenrae, 2, 8.3% An. pullus,

1, <0.1% An. keini 1, <0.1%

An. belenrae 3, 0.5%

An. sinensis

619, 99.2%

An. sinensis

467, 95.9%

An. belenrae, 1, 0.2%

An. kleini, 15, 3.1% An. pullus

4, 0.8%

An. pullus 8, 26.6%

An. kleini 3, 10.0%

An. belenrae 1, 3.3%

An. sineroides

2, 6.7%

An. sinensis 16, 53.3%

An. sinensis 24, 24.5%

An. belenrae8, 8.2%

An. kleini 50, 51.0%

An. pullus 16, 16.3%

Cp Bonifas

Number/Proportion of Species from of Adult AnophelesMosquitoes Collected by NJ Light Trap, ROK, Jun-Oct 2005

Warrior Base

An. lesteri, 1, 1.4%

An. pullus 2, 2.9%

An. kleini 22, 31.9%

An. belenrae 6, 8.7%

An. sineroides

1, 1.4%

An. Sinensis37, 53.6%

Rodriguez Range

Cp Humphreys

Gunsan AB

Gwangju AB

Cp Long

Cp Eagle

Cp Carroll

An. belenrae8. 0.7% An. kleini

439. 40.0%

An. Pullus33. 3.0%

An. sinensis

617. 56.2%

An. Sineroide1. 0.1%

TongilchonN=1098

Proportion of Anopheles spp. Larvae, Republic of Korea, Mar-Oct 2005

Gimcheon N=45

An. sinensis

730. 62.8% An. Pullus178. 15.3%

An. kleini 212. 18.2%

An. belenrae38. 3.3%

An.lesteri5, 0.4%

Majeong-ri,N=1163

An. belenrae1. 0.5% An. kleini

26. 14.1%

An. Pullus5, 2.7%

An. sinensis

139. 75.1%

An. Lesteri12, 6.5

GimpoN=183

An. belenrae7. 4.5%

An. kleini 4, 2.5%

An. Pullus31, 19.7%An. sinensis

111. 70.7%

An. Lesteri4, 2.5%

IlsanN=157

An. koreicus5. 2.0% An. kleini

23. 9.4%

An. sineroides10. 4.1%An. sinensis

205. 84.0%

An.lesteri1, 0.4%8.2%

CheongpyeongN=244

An. sinensis

28. 100.0%

TaebaekN=28

An. somerpode

s7. 8.1%

An. kleini 2. 2.3%

An. Pullus1, 1.2%An.

sinensis76. 88.4%

JaecheonN=86

An. sinensis

251. 100.0%

Anmyeon-doN=251

Gimcheon N=45

An. kleini 1. 0.9%

An. sinensis107. 99.1%

An. sinensis69. 97.2%

An. kleini 1. 1.4%

An. sineroides1. 1.4%

JeonjuN=108

GwangjuN=99

BoseungN=71

An. kleini 1. 1.0%

An. sinensis98. 99.0%

An. kleini 1. 1.3%

An. sinensis75. 98.7%

Cheongsong N=76

An. sinensis144. 94.7%

An. kleini 5. 3.3%

An. Sineroides3. 2.0%

Busan N=152

An. sinensis7. 100.0%

Geoje Is N=7

An. sinensis40. 97.6%

An. pullus1. 2.4%

Sacheon N=41

An. sinensis43. 100.0%

Jeju Is N=43

Proportion of Anopheles spp. Larvae, Republic of Korea, Mar-Oct 2005

RISK REDUCTION

• Develop and implement efficient and effective vector and disease reduction strategies.– Larval control

• Eliminate water source.• Drain rice paddies

periodically.• Pesticides.

– Adult control• Pesticides.• Repellents.

• Evaluate vector and disease control strategies.

Pre-ULV fogging

Post-ULV fogging

Warrior Base

• Develop, evaluate, and implement efficient and effective vector and disease reduction strategies

Malaria Control

EDUCATION

• Public awareness.– Television– Newspaper– Health related pamphlets– Inform the public of their

responsibilities

• Human surveillance.– Reporting requires a

standardized program

PERSONAL PROTECTIVE MEASURES

PPM is safe and it works!

Personal Protection

1One patient reported DEET use, but didn't know if formulation was civilian or military.2One patient reported using bed nets only when in tents; otherwise they were not used when sleeping on the ground.3Not all respondents answered all questions.4Policy changed to sleeves rolled up while in installations, but down when in the field.

Year 2001 2002 2003 2004 2005 2006

Countermeasure3

Yes (%) Yes (%) Yes (%) Yes (%) Yes (%) Yes (%)

(n=12) (n=19) (n=17) (n=16) (n=9) (n=5)

Permethrin-BDU 2 (17) 3 (16) 8 (47) 3 (20) 1 (11) 0 (0)

Uniform Discipline 9 (75) 8 (42) 144 (100) 12 (80) 9 (100) 5 (100)

DEET 71 (58) 10 (53) 5 (31) 7 (47) 4 (44) 0 (0)

Bed Net 12 (8) 4(21) 1 (6) 2 (13) 1 (11) 0 (0)

QUESTIONS