APMEN Vector Control Working Group meeting Kota Kinabalu Malaysia

Transcription

1 APMEN Vector Control Working Group meeting Kota Kinabalu Malaysia May 8 9 9, 2011

2 MALARIA VECTOR CONTROL IN THAILAND by Alongkot Ponlawat, Ph.D. Chief, Vector Biology and Control Section Department of Entomology USAMC-AFRIMS

3 RESEARCH INTERESTS VECTOR BIOLOGY ECOLOGY EPIDEMIOLOGY DISEASE TRANSMISSION SURVEILLANCE VECTOR CONTROL

4 Mae Sot Kamphaeng Phet Sangklaburi Lop Buri Chanthaburi Rayong Field Sites in Thailand Srisaket Surat Thani

5 Malaria Vector Control using Pyriproxyfen We evaluated: 1) The effect of different concentrations and formulations of pyriproxyfen on the emergence and survival rate of malaria vectors. 2) Horizontal transfer of pyriproxyfen by malaria vectors.

6 Pyriproxyfen Pyriproxyfen (4-phenoxyphenyl (RS)-2-(2-pyridyloxy) propyl ether) A juvenile hormone mimic Affects the physiology of morphogenesis, reproduction and embryogenesis of arthropods Pyriproxyfen 0.5% Granule (w/w) pupae not emerged adult not fully eclosed

7 The effect of different concentrations and formulations of pyriproxyfen on the emergence and survival rate of An. epiroticus.

8 Ta Pong Pak Num Phe VBDCC Rayong* Sa Met *VDBCC Rayong : Vector Borne Disease Control Center of Rayong Province

9 Bottom Float

10 Percent of emergence Department of Entomology, Armed Forces Research Institute of Medical Sciences Results Control 1ppb 10ppb 1ppb+float 10ppb+float Week Percent emergence of An. epiroticus in each pyriproxyfen treatment over 12 weeks

11 Horizontal transfer of pyriproxyfen by An. minimus In laboratory experiment, evaluation of the horizontal transfer of pyriproxyfen from treated resting curtain to nontreated ovitrap was conducted by larval bioassay.

12 Results Percent adult emergence between control and treatment are significantly different : 34 replicates (P < 0.05, t-test).

13 Conclusions Our pyriproxyfen treatment method (place pyriproxyfen in the tea bag and float it under the water surface) can effectively inhibit Anopheline adult emergence and potentially be used as the new control technique for malaria vectors. This long term residual effect of pyriproxyfen occurred because of the slow-release pyriproxyfen formulation by gradual solubility. Our results have proved that An. minimus can horizontally transfer pyriproxyfen from the resting site to the breeding site. Efficacy of pyriproxyfen as shown in this study can be applied for the control strategy of malaria vectors in the future.

14 FIELD EXPERIMENTS Insecticide-impregnated bed nets and an insecticide barrier treatment Trap evaluations Spatial repellents Push-Pull strategy

15 Evaluation of Anopheles Control Methods in Malaria Endemic Villages in Thailand Objective To determine the efficacies of both insecticide-impregnated bed nets and an insecticide barrier treatment of vegetation applied around the perimeter of a village, on mosquito vector densities.

16 Evaluation of Anopheles Control Methods in Malaria Endemic Villages in Thailand Treatment Post-treatment : monitoring vector density Larval Survey Distribute Deltamethrin-impregnated bed nets Cow Trap CDC Light Trap Bioassay (Mortality rate): Residual efficacy of insecticide Leaf: Ban Khun Huey Barrier Spray (Bifenthrin) Department of Entomology, Armed Forces Research Institute of Medical Sciences Bed Net: Ban Pa Dae

17 Insecticide impregnated tents Mosquito collected : CDC Light Trap

18 Field Evaluation of Surveillance Devices for Malaria Vectors Objective The efficacy of the BGS and CDC light traps baited with different attractants and different light sources was compared for collecting Anopheline mosquitoes.

19 Experimental Design Study area : A Six trap configurations were evaluated (6 x 6 Latin square design) B C F D E CDC Light Trap BG Sentinel Trap Ban Khun Huay, Mae Sot district, Tak Monitor vector density ID species, counting Test blood-fed status ( Blood-fed, Non Bloodfed, and gravid) Parity status: parous and nulliparous

20 Experimental Design BG Sentinel Trap CDC Light Trap

21 Spatial Repellency Evaluation Hypothesis In a semi-field tunnel study, significantly fewer hostseeking An. dirus are attracted to a human-baited tent with a spatial repellent relative to a human-baited tent without a spatial repellent over the long-term.

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23 Spatial Repellency Evaluation Control Tent # 2, L Sentinel Cup, 15 mosq, 4 days 10 m (4 cups) Treated Tent # 1, R ~ 1.9 m Tunnel # 2 ~ 50 m ~ 2.4 m Treated Ribbons placed outside the tunnel for WHO cone assays and GCs Control ~ 300 m Tent # 4, L Tent # 3, R ~ 1.9 m Tunnel # 1 ~ 50 m ~ 2.4 m

24 Large Mosquito Enclosures Push-Pull control projects

25 Thank you. Vector Biology & Control Section, Dept. of Entomology USAMC-AFRIMS, Thailand Department of Entomology, Armed Forces Research Institute of Medical Sciences