Download Implementation of a National Monitoring System for West Nile Fever

Hopeful Agriculture, Lively Rural Areas, Happy People
Press Release
Release this report after the morning paper on June 3, 2013.
Animal and Plant Quarantine Agency Foreign Animal Disease Division Manager Jo In-su, Research
Officer Jo Yun-sang (+82-31-467-4398)/ Date: May 28 (8 pages)
Implementation of a National Monitoring System
for West Nile Fever in High Risk Areas
《 Key Content 》
◇ A national monitoring system was implemented for mosquitoes
spreading West Nile virus in areas of high risk for exotic infectious
diseases, such as international airports and ports, in order to monitor West
Nile Fever for which risk is spreading due to climate change.
※ Mosquitoes capable of spreading West Nile virus have been identified in 16
international airport and port areas. However, no pathogens have been found.
West Nile Fever is a disease communicable between humans and
animals and is spread through the vector of mosquitoes. The
possibility of West Nile Fever spreading in Korea is increasing due to
climate change, so the Animal and Plant Quarantine Agency (QIA,
Commissioner: Park Yong-ho) announced a national system for
collecting mosquitoes at international airports and ports, areas at high
risk for exotic infectious diseases, has been implemented since May
2012 and that the collected mosquitoes were investigated to reveal
their distribution and determine the existence of any WNV pathogens.
※ West Nile Fever is a disease communicable between humans and animals. It is
spread to humans and horses by Culex pipiens, the common mosquito which have
ingested blood from infected wild birds.
❍ The system was implemented to reinforce monitoring of West
Nile Fever in Korea and take preventative measures at an earlier stage.
Under the system, mosquitoes were collected from 16 international
airport and port areas, and the collected mosquitoes were investigated
to reveal their distribution and determine the existence of any West
Nile Viris pathogens.
❍ In 2012, approximately 180,000 mosquitoes were collected from
international airport and port areas and a distribution of 17 varieties of
mosquitoes was confirmed. Of the mosquitoes collected, species
known to spread WNV, including Culex pipiens, were found.
However, no verifiable WNV was detected.
* (U.S.) West Nile Virus first entered the U.S. in 1999. The disease has since
continued to afflict the country, resulting in the deaths of 286 people and
damage to 690 horses.
QIA also announced a plan to further reinforce national
monitoring on infectious disease vectors in international airports and
ports, given that the possibility for new infectious diseases increases
due to the effects of climate change.
Ref. 1. West Nile Fever Overview
Ref. 2. West Nile Fever Vectors
Ref. 3. Distribution of Mosquitoes Spreading West Nile Fever in
International Airport/ Port Areas
Ref. 1
West Nile Fever Overview
□ Definition
◦West Nile virus (WNV) is a disease communicable to humans and animals that
affects humans, horses, and birds through the vector of blood ingesting mosquitoes.
WNV causes neurological symptoms, such as encephalitis, leading to death.
□ Causative Pathogen
◦Flaviviridae; Flavivirus; West Nile Virus
□ Spread
◦Mosquitoes that have ingested blood from birds infected with West Nile Virus and
spread the disease to humans and horses.
Spread of West Nile Fever
Infection between People
(Blood Transfusions, Organ
Transplants, Placental
Infections, Breast Milk)
Bird vectors
By
Mosquito
Principle
Cycle of
transmission
By
Mosquito
Self-generating Host
Bird vectors
By Mosquito
<Figure> Spread of West Nile Fever (Source: Huhn et al., 2003)
: Recurrent infections from birds and mosquitoes, spread by infected mosquitoes to humans
and horses by blood ingestion
□ Outbreak
◦West Nile Fever outbreaks have been reported in Africa, Europe, Asia, and
America, but not thus far in Korea.
<Figure> West Nile Fever Afflictions in 2012 (Source: World Organization for Animal
Health)
□ Symptoms
◦(Humans) The symptoms of West Nile Fever in people are similar to those of
the flu. This disease causes encephalitis and meningitis in the weak and the
elderly, including other neurological symptoms, and even death.
◦(Horse) Horses affected by West Nile Fever display neurological symptoms
similar to humans, such as fever, ataxia, weakness in the hind legs, astasia,
muscular contractions, paralysis of the lips, facial stiffening, and blindness. In
serious cases, symptoms of encephalitis manifest, leading to death.
◦(Bird) No symptoms are observed in most cases. However, some birds, such as
crows, experience mass mortality.
□ Diagnosis
◦(Antigen Test) WNV separation or checking
- Virus separation
- Virus identification by polymerase chain reaction or immunohistochemical
staining
◦(Antibody Test) Antibody tests on WNV
- Enzyme immunoassay, plaque reduction neutralization test
Suspicious Specimens
↙
↘
Antigen Tests
Antibody Tests
↓
↓
Genetic Tests
Enzyme Immunoassay
↓
↓
Virus Separation
Virus Neutralization Tests
<Figures> / West Nile Fever Diagnosis
(Source: Equine Infectious Diseases Diagnosis Manual, 2009)
□ Prevention
◦Four types of vaccines for horses have been approved by the United States
Department of Agriculture.
- (Inactivated Vaccine) One type of formalin-inactivated vaccine for West Nile
virus
- (Vector Vaccine) Two types of yellow fever or canary pox virus vector +
WNV protein gene recombination vaccines
- (DNA Vaccine) One type of DNA plasmid + WNV protein gene
recombination vaccine
* No approved vaccines for humans
□ Treatment
◦No human or veterinary medicine developed
Ref. 2
West Nile Fever Vectors
□ Medium
◦West Nile virus (WNV) is mainly spread by the common mosquito, or Culex
spp. - C. pipiens, C. quinquefasciatus and C. tarsalis. The species of WNV
spreading mosquitoes vary by continent. (See Table below.)
◦Mosquitoes are mainly found in areas with water, such as rice paddies, streams,
puddles, ponds, drains, and the water pooling in discarded tires.
<Table> WNV Spreading Mosquitoes by Continent
Area
WNV Spreading Mosquitoes
Africa, Middle
C. univittatus, C. poicilipes, C. neavei, C. decens, Aedes albocephalus,
East
Europe
Asia
North America
Mimomyia spp.
C. pipiens, C. modestus, Coquillettidia richiardil
C. quinquefasciatus, C. tritaenirhynchus, C. vishnui
C. pipiens, C. quinquefasciatus, C. tarsalis, C. restuans
(Source: Mackenzie et al., 2004; Artsob et al., 2009; Kilpatrick, 2011)
◦ WNV Spreading Mosquitoes
Culex pipiens Aedes vexans
(Source: National Institute of Infectious Diseases, Japan)
Ref. 3
Distribution of Mosquitoes Spreading West Nile Fever
in International Airport/ Port Areas
□ International Airport/ Port Areas for Mosquito Collection
◦16 areas (2 airports, 10 ports, and 4 ramps)
Classification
Airport (2)
Port (10)
Ramp (4)
Incheon Port,
Pyeongtaek Port,
Incheon International
Sokcho Port, Gunsan
Incheon Ramp,
Airport,
Port, Gwangyang Port, Bullo-dong Ramp,
Jeju International
Ulsan Port, Busan
Busan Ramp,
Airport
New Port, Busan Port,
Jeju Ramp
Area
Jeju Port, Seoguipo
Port
<Figure> Monitoring network for WNV spreading mosquitoes at international airport/ port
areas
1. Incheon Port
2. Pyeongtaek Port
3. Sokcho Port
4. Gunsan Port
5. Gwangyang Port
6. Ulsan Port
7. Busan New Port
8. Busan Port
9. Jeju Port
10. Seoguipo Port
11. Incheon Ramp
12. Bullo-dong Ramp
13. Busan Ramp
14. Jeju Ramp

Incheon International Airport

Jeju International Airport
□ Survey on the Distribution of Mosquitoes and West Nile Fever Outbreaks at
International Airports and Ports in 2012
◦A total of 177,715 mosquitoes were collected from 16 airports and ports
nationwide.
◦The mosquitoes were classified into 17 varieties, including Culex pipiens,
Aedes vexans, and Ochlerotatus dorsalis are capable of spreading WNV. In
particular, 92,590 Culex pipiens were collected, forming the highest distribution.
Ochlerotatus
3%
Aedes
10%
Anopheles
4%
Armigeres
1%
Culex
82%
<Figure> Distribution of Mosquitoes Collected from International Airport/ Port Areas in
2012
◦The results of WNV antigen tests on mosquitoes collected in international
airport and port areas exhibited no WNV positive specimens.