dengue in thailand worskop 2012/diaden... · aedes albopictus vector /a secondary vector of viruses...

Theeraphap Chareonviriyaphap

Department of Entomology

Kasetsart University Bangkok, Thailand

DENGUE IN THAILAND

Dengue is a mosquito-borne viral disease

Viruses can be transmitted to humans by the bite of

infective female mosquitoes

Transmission by Aedes mosquitoes: Aedes aegypti &

Ae. albopictus

TRANSMISSION CYCLE

Transmission of Dengue Virus

1. Virus is transmitted to

human from mosquito saliva

2. Virus replicates in target

organs

3. Virus infects white blood cells and lymphatic tissues

4. Virus released and circulates in blood

www.cdc.gov/.../slideset/set1/i/slide05.htm

World distribution of dengue viruses, 2008

DISEASE POP AT POP ENDEMIC MORTALITY MORBIDITY

RISK INFECTED COUNTRY

(MILLION) (MILLION)

MALARIA 2400 >500 90 1.5-3 300-500

M/Y M/Y

CHAGAS 90 18 21 45000/Y 3 M

SCHISTO

SOMIASIS 600 200 74 20,000/Y 20 M

FILARIA 750 75 70

DENGUE 2000 MILLION >100 1-5% MILLIONS

DHF cases and case fatality rate in Asia, 2006-2008

Morbidity Rate of DF and DHF in Thailand (2003-2009)

0

10

20

30

40

50

60

70

80

90

2003 2004 2005 2006 2007 2008 2009

Year

Mo

rbid

ity R

ate

/ 100,0

00 P

op

.

DF

DHF

Morbidity Rate of DHF by region in Thailand (2003-2009)

0

20

40

60

80

100

120

140

2003 2004 2005 2006 2007 2008 2009

Year

Mo

rbid

ity R

ate

North

Central

Northeast

South

1 5 10 15 20 25 30 35 40 45 50

2009

Number of DHF cases by week of onset and region in Thailand, 2009

Rainy season Cool season

Hot season Cool season

0.01-10

>10-25

>25-50

>50-100

>100-200

Province:

Samutprakan, Chonburi,

Nakhonpathom, Rayong , Samutsakhon.

Morbidity Rate

Distribution of DHF in Thailand in 2009

Mosquitoes in Thailand (2006) Anopheles 73 species Aedes 164 species Culex 144 species Toxorhynchites 12 species Uranotaeniini 45 species

Dengue Vectors

http://www.cdc.gov/ncidod/dvbid/dengue/slideset/spanish/set1/i/slide07.htm

http://www.wbrcouncil.org/CatSubCat/CatSubCatdisplay.asp?p9=CSC1&p1=119&p7=36

Aedes aegypti Aedes albopictus

Aedes aegypti Ae. albopictus

2-3 days

2-3 days

7-12 days 4-6 weeks

Aedes aegypti A primary vector of dengue & chikungunya

Originated from Africa, spread around the word ,

mainly in urban area

Likely to rest and feed indoor / around human dwelling ( esp. dark area)

Primarily a daytime feeder

Lays eggs and produces larvae preferentially in artificial containers

Adult resting area

Larval breeding site in town

Larval survey in village

Larval breeding site in rural

Aedes albopictus Vector /a secondary vector of viruses such as dengue

viruses, Chikungunya, etc.

Origin in the forests of Southeast Asia mainly occurs in rural & suburban areas.

Exophagic and exophilic mosquito

The larval breeding sites of Ae. albopictus are very broad and range from natural sites to artificial containers

Tree hole

Bamboo stump Banana pedal

Palm plantation

Waterfall

Orchard

Public park

Rubber plantation

MOSQUITO CONTROL

Chemical Control

Physical control

Biological Control

Trap Technology

Repellent

Chemical control

Physical control

Biological control

Trap technology

Repellent

References

Bureau of Epidemiology, Department of Disease Control, Ministry of Public Health.

http://www.cdc.gov/ncidod/dvbid/dengue/slideset/spanish/set1/i/slide07.htm http://www.wbrcouncil.org/CatSubCat/CatSubCatdisplay.asp?p9=CSC1&p1=119&p7=36

KASETSART UNIVERSITY