Myanmar Health Sciences Research Journal
Original Article:
The Korean Journal of Parasitology 2020; 58(3): 217-227.
Published online: June 26, 2020
DOI: https://doi.org/10.3347/kjp.2020.58.3.217

Vector Bionomic Study in Kayah State and Kachin State

Aye Aye Myint,Thiha, Ohmar Nyo, Abraham, Aung Thi & Nay Yi Yi Lin

Myanmar Health Sciences Research Journal, Vol. 32, No. 1, 2020

Abstract

Malaria is still one of the most important public health problems in Myanmar. National Malaria Control Programme (NMCP) has implemented malaria prevention and control activities based on national malaria control strategies. One of the strategies is selective and sustainable vector control measures with integrated vector management approach which includes distribution of Long Lasting Insecticide Treated Nets (LLINs), Insecticide Treated Nets (ITN) and Indoor Residual Spray (IRS) whenever and whatever necessary. As the country scale up distribution LLIN and ITN programme, insecticide selection pressure on the vector mosquito populations is increased. Susceptibility status of insecticides could depend on population migration and environmental changes and ecology factors in relation to human behavior. Therefore, malaria vector bionomic and insecticide sus-ceptibility status study should be investigated in these malaria endemic areas. The present study was conducted in Kayah State and Kachin State. In Nankit Village, Kayah State, nineteen Anopheles species were collected and An. minimus was primary vector. In the whole night collection, peak biting time of An. minimus was 9 to 10 pm in first peak and 2 to 3 am in second peak. The highest density of An. minimus was observed in November. An. minimus was susceptible to 0.05% deltamethrin and 0.5% ectofenprox. In Tanphae and Ngwepyaw Sampya villages, Kachin State, more than 20 Anopheles species were collected and An. minimus and An. dirus were primary vectors in these areas. The density of the An. minimus was highest in June, and An. maculatus was also highest in June, but An. annularis which were higher density in December. Peak biting time of An. minimus was 20:00 to 21:00 and that of An. maculatus was 19:00 to 20:00. An. kochi was susceptible to 0.05% deltamethrin with 100% mortality.

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INTRODUCTION

INTRODUCTION

 

Malaria is still one of the important public health problems in Myanmar. National Malaria Control Programme (NMCP) has implemented malaria prevention and control activities based on national malaria control strategies. One of the strategies is selective and sustainable vector control measures with integrated vector management approach which includes distribution of LLINs, ITN and IRS whenever and whatever necessary.

As the country scale up distribution LLINs  and ITN programme, insecticide selection pressure on the vector mosquito populations is increased. The success of any vector control program relies on knowledge of vector species and their bionomics which is very  important  to get update knowledge and information on primary and secondary vectors, distribution is related to environmental changes. Monitoring level of resis-tance is an essential tool in enabling to make a decision. Resistance to insecticides  is concerned due to population migration and changes of environment and ecology factors in relation to human behavior.1, 2 Thus, the vector bionomic and insecticide resistance susceptibility status survey should be investigated in this region.
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MATERIALS AND METHODS

MATERIALS AND METHODS

 

Localities and survey period

Vector bionomic survey was conducted in Nankit village, Phasaung Township, Kayah State during October, November and December, 2016. Nankit village is situated in latitude 18.89613ºN and longitude 97.30016ºE. Vector bionomic survey was also conducted in Tanphae and Ngwepyawe Sampya villages, Myitkyina Township, Kachin State during the period of March, June, September and December 2017. Tanphae village is situated in 25.71536ºN, 97.49098ºE, 633 feet above sea level and 27 miles far from Myitkyina and side of the Myitkyina-Putao highway road. Ngwe-pyawe Sampya village is about 14 miles far from Myitkyina, at the latitude 25.56707ºN and longitude 97.35565ºE with above sea level of 564 feet.

Entomological parameters

Entomological survey include: human land-ing indoor and outdoor collection, animal bait net trap collection, light trap collection, morning resting indoor and outdoor hand collection, spray sheet collection, larval collection, susceptibility test, bio-assay test and sporozoite detection with ELISA test.3

DISCUSSION

DISCUSSION

 

Entomological surveillance in sentinel sites was conducted annually by Entomology team of the NMCP. Both in Phasaung Township, Kayah State and Myitkyina Township, Kachin State, primary vectors of An. minimus, An. dirus and other secondary vectors were observed in entomological survey. Entomological surveillance and vector control is an important component in malaria elimination programme. In Kayah State, the primary vectors of
An. dirus, An. minimus, and 17 anopheles species were observed. The An. minimus biting density of human landing indoor collection is higher than outdoor. The peak biting time of An. minimus was 21:00 to 22:00 in first peak and 2-3 am in second peak. An. minimus, An. maculatus and An. philippinenesis were susceptible to pyrethroid and An. annularis was susceptible to organophosphate. According to the efficacy of the local LLINs, WHO optimal effective was observed.

In Kachin State, An. minimuswas observed in all entomological collection methods. Peak biting time of An. minimus was 20:00 to 21:00 and An. maculatus was 19:00-20:00. An. kochi is susceptible to pyrethroid. Biting habit of the Anopheles vector was assessed by human bait and cattle bait. Zoophilics nature of both vector species was observed as 72% of An. minimus vs. 58% of  An. maculatus. There was reduction in number of cows and buffaloes in the village that could deviate the feeding of mosquitoes from animal to man. According to the efficacy of the local LLINs, WHO optimal effective was also observed. According to ELISA test, five positives were found in Kachin State.

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ACKNOWLEDGMENT

ACKNOWLEDGEMENT

 

We would like to express our special gratitude to the National Malaria Control Program for permission to conduct this research. Thanks are also due to the staffs from Regional and Township Health Departments in Kayah State and Kachin State for collaboration. Special thanks to Global Fund for funding support.

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CONFLICT OF INTEREST
CONFLICT OF INTEREST

Competing interests

The authors declare that they have no competing interests.

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REFERENCES

REFERENCES

 

1.      Bradley J, Matias A, Schwabe C, Vargas D, Monti F, Nseng G & Kleinschmidt I. Increase risks of malaria due to limited residual; life of insecticide and outdoor biting versus protection by combined use of nets and indoor residual spraying on Bioko Island, Equatorial Guinea. Malaria Journal 2012; 11: 242. Available from: doi: 10.1186/ 1475-2875-11-242

2.     Corbel V, Akogbeto M, Damien GB, Djenontin A, Chandre F, Rogier C, et al. Combination of malaria vector control interventions in pyre-throid resistance areas in Benin: A cluster randomized controlled trial. Lancet Infectious Diseases 2012 Aug; 12(8): 617-626. Available from: doi:10.1016/S1473-3099(12) 70081-6 Malaria Policy Advisory Committee Meeting -Background Document Session 3 (12 March 2014)/13.

3.    World Health Organization. Malaria Ento-mology and Vector Control: Guide for Participants: Training Module for Malaria Control. Geneva, WHO, 2013.


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