RESEARCH NOTE

DENGUE VECTOR SURVEILLANCE IN WEST COAST AND DIVISION, ,

Nur Mohd Roslin Elia-Amira1, Chee Dhang Chen1, Koon Weng Lau1, Van Lun Low2, Han Lim Lee3, Yuen Seng Cyril-Tham1 and Mohd Sofian-Azirun1

1Institute of Biological Sciences, Faculty of Science, University of Malaya, ; 2Tropical Infectious Diseases Research and Education Centre (TIDREC), University of Malaya, Kuala Lumpur; 2Medical Entomology Unit and WHO Collaborating Centre for Vectors, Institute for Medical Research, Kuala Lumpur, Malaysia

Abstract. Ovitrap surveillance was conducted to investigate distribution and abundance of Aedes spp in West Coast and Kudat divisions of Sabah, Malaysia. Ovitraps were placed in 21 study sites across six in the West Coast divi- sion (, , Papar, , and ) and two districts in ( and Kudat). Ovitrap indices ranged from 33.3% to 100.0% and mean number of larvae per ovitrap from (mean ± SD) 4.53 ± 3.10 to 78.93 ± 11.77. Generally, Ae. albopictus was the dominant dengue vector in all study sites with a small population of Ae. aegypti in Taman St. Peter, Kudat. High populations of Aedes spp in both divisions should prompt an immediate employment of a strategic integrated vector management program in West Coast and Kudat divisions of Sabah, Malaysia. Keywords: dengue vector, ovitrap surveillance, Aedes, Malaysia

INTRODUCTION ing Malaysia, where as of January 2017, eight confirmed zika cases were reported Dengue has been noted as the world’s (MOH, 2017). In Malaysia, both diseases fastest growing vector-borne disease with are transmitted by Aedes mosquitoes, a 30-fold increment of cases reported specifically Ae. aegypti and Ae. albopictus. over the past 50 years (WPRO, 2015). Endemic peak of dengue and emer- In Malaysia, a total of 101,357 dengue gence of zika are thought to be caused cases were reported in 2016 (MOH, 2016), by escalating population of Aedes spp. and recently, zika virus was reported in Increase in Aedes mosquito population is many Southeast Asian countries, includ- largely contributed by massive urbaniza- tion and climate change, which create favorable breeding opportunities and Correspondence: CD Chen, Institute of Biologi- conditions for mosquitoes (Banu et al, 2011; cal Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia. Mudin, 2015). E-mail: [email protected] Conducting surveillance studies be-

Vol 50 No. 1 January 2019 55 Southeast Asian J Trop Med Public Health forehand are vital in carrying out effective three districts, Kota Marudu, Kudat and vector control measures (Wan-Norafikah Pitas, with only residential areas in Kudat et al, 2010). Through these surveillance and Kota Marudu districts were chosen. studies, improved understanding of Aedes Ovitrap surveillance was conducted in 21 mosquito dynamics can be achieved and residential areas across the eight districts better intervention measures introduced (Fig 1). The surveillance period was from (Lim et al, 2010). In Malaysia, numerous 10 to 20 July 2017. surveillance studies had been conducted Ovitrap surveillance on the distribution of Aedes mosquitoes, Ovitrap was prepared according to but mostly centered in endemic and Lee (1992). In brief, an ovitrap consisted of congested areas, such as Kuala Lumpur, 300-ml plastic container with an opening and (Chen et al, 2006b; of 7.8 cm in diameter, base diameter of 6.5 Saifur et al, 2012; Lau et al, 2013). Surveil- cm and 9.0 cm height, painted black on lance studies conducted in Sabah are the outside with a hardboard oviposition scarce, non-extensive and not up to date. paddle (10 cm × 2.5 cm × 0.3 cm) placed A comprehensive Aedes surveillance in diagonally inside and filled with tap water Sabah covering all divisions, namely, to a level of 5.5 cm. These ovitraps were Interior, Kudat, , , and placed in ≥ 10% of the houses in each West Coast, had been carried out almost study site, outside but within the immedi- 40 years ago and was outdated (King, ate vicinity of the house, ie car porch and 1978). A more updated Aedes surveillance corridor connected to the house entrance was done in 2012, but only focused on one (Chen et al, 2005). All ovitraps were col- study site (Wan-Norafikah et al, 2012). lected after 5 days. Thus, this study surveyed the distri- Identification of larvae bution and abundance of Aedes mosqui- toes in West Coast and Kudat divisions The ovitraps were brought back to of Sabah. the laboratory at Institute of Biological Sciences, Faculty of Science, University of Malaya, where each ovitrap content MATERIALS AND METHODS together with paddles were transferred Study sites into individual plastic container, fresh Sabah is divided into five main water added together with a small piece administrative divisions, namely, Inte- (10 mm in diameter) of fresh beef liver as rior, Kudat, Sandakan, Tawau, and West larval food, the container covered, and Coast, and the two main divisions; West larvae were allowed to breed in the labo- Coast and Kudat, were selected as study ratory for a further 9-day period (Chen sites (Table 1). is et al, 2005). Hatched larvae were counted rd situated in northwest Sabah, with seven and identified at the 3 instar based on districts Kota Belud, Kota Kinabalu, Pa- standard taxonomic keys by Division of par, Penampang, Putatan, , and Medical Entomology, Institute for Medical Tuaran; residential areas located in Kota Research (IMR) Malaysia (2000a, 2000b) Belud, Kota Kinabalu, Papar, Penampang, and Jeffery et al (2012). Putatan and Tuaran were chosen. Kudat Data analysis division is located at the northern tip of Data were analyzed for ovitrap index Sabah, and within the division, there are (OI) (percent positive ovitraps at each

56 Vol 50 No. 1 January 2019 Dengue Vector Surveillance in Sabah, Malaysia Urban Urban Urban Urban Urban Suburban Suburban Suburban Suburban Suburban Suburban Suburban Suburban Suburban Suburban Suburban Suburban Suburban Suburban Suburban Suburban Landscape 8.7 8.1 7.5 7.8 9.0 8.7 7.5 8.0 9.5 11.6 11.9 11.6 11.3 13.4 14.0 18.8 13.4 12.8 14.1 23.2 18.7 Elevation (m a.s.l.) Coordinate Table 1 Table N 5°57’08.845”, E 116°05’18.031” N 6°12’25.800”, E 116°14’04.200” N 6°29’44.169”, E 116°49’00.460” N 6°29’06.036”, E 116°45’38.939” N 6°29’36.780”, E 116°45’44.220” N 6°53’18.900”, E 116°51’03.480” N 5°59’15.430”, E 116°06’13.493” N 6°10’44.547”, E 116°13’48.050” N 6°10’44.701”, E 116°14’00.603” N 5°55’55.531”, E 116°05’28.651” N 5°54’06.946”, E 116°03’22.421” N 5°53’40.222”, E 116°03’10.542” N 5°49’42.473”, E 116°02’26.093” N 5°47’12.871”, E 115°59’38.798” N 6°54’58.941”, E 116°50’00.272” N 6°53’40.452”, E 116°51’14.671” N 5°56’08.700”, E 116°04’19.320” N 6°21’21.870”, E 116°25’48.326” N 6°21’01.285”, E 116°24’31.926” N 6°21’20.100”, E 116°24’56.220” N 5°55’22.433”, E 116°05’02.083” Study site Taman Mutiara Taman Kampung Serusup Pekan Kota Marudu T&G Phase II Taman Jalan Peladang Taman Pakka Taman Jalan Mergastua Jalan Bolong Pekan Tuaran Taman Sindo Taman Kampung Lok Bonu Ceriamas Taman Taman Kampung Beringis Sri Awana Taman St. Peter Taman Taman Selesa Taman Pekan Kota Belud Nikmat Taman Kampung Lebak Moyoh Taman Palm Villa Taman Kota Kinabalu Kota Marudu Tuaran Penampang Putatan Papar Kudat Kota Belud Geographical and ecological features of study sites in West Coast and Kudat divisions, Sabah, Malaysia. Sabah, divisions, Kudat and Coast West in sites study of features ecological and Geographical Division Kudat West Coast West m a.s.l., meter above sea level.

Vol 50 No. 1 January 2019 57 Southeast Asian J Trop Med Public Health

West Coast Division

Kota Belud Kota Kinabalu Putatan (1) Pekan Kota Belud (7) Taman Mutiara (12) Kampung Lok Bonu (2) Taman Nikmat (8) Jalan Mergastua (13) Taman Ceriamas (3) Kampung Lebak Moyoh Taman Selesa Papar Tuaran (9) Penampang (14) Taman Kinarut (4) Pekan Tuaran (10) Taman Sindo (15) Kampung Beringis (5) Jalan Bolong (11) Taman Palm Villa (6) Kampung Serusup Kudat Division

Kudat Kota Marudu (16) Taman Seri Awana (19) Pekan Kota Marudu (17) Taman St. Peter (20) Taman T&G Phase II (18) Taman Pakka (21) Jalan Peladang

Fig 1- Location of study sites in Kudat and West Coast divisions, Sabah, Malaysia.

58 Vol 50 No. 1 January 2019 Dengue Vector Surveillance in Sabah, Malaysia study site) and mean number of Aedes frame and specific location and further larvae per recovered ovitrap (Chen et al, helps to predict dengue and other mos- 2006a). All levels of statistical significance quito-borne burdens (Tham, 2000). were determined with Student t-test and All surveillance sites in this study had performed using a SPSS version 12.0.1 OI values exceeding 10%, with the low- program (SPSS, Chiacago, IL) and a p- est being 33%. OI values >10% indicate value < 0.05 is considered significant. prompt actions need to be taken (Lee, 1992), and higher OI values are positive RESULTS indicators of exceptionally high mosquito breeding and dengue transmission ac- The surveillance was conducted in tivities (Ho et al, 2014). The data collected urban and suburban residential areas in among the surveillance sites in West Coast West Coast and Kudat divisions, Sabah, and Kudat divisions clearly indicate Malaysia. The residential areas were necessary interventions be implemented equipped with proper drainage system immediately by responsible authorities. and had sparse vegetation. Among the surveillance sites in Kudat In all study sites only the presence Ae. albopictus division, Taman St. Peter (93%) and Taman of was found, except at Ta- Ae. Sri Awana (33%) recorded the highest man St. Peter in where albopictus Ae. aegypti and lowest OI, respectively (Table 2). As and (latter at 6% of for West Coast division, Jalan Bolong in the former) were present. Estrada-Franco had the highest OI (100%) and Craig (1995) reported rapid urbaniza- while Jalan Mergastua, Kota Kinabalu tion contributes to the evolution of habitat Ae. albopictus district and Taman Kinarut, , adaptive ability of that can Ae. aegypti both possessed the lowest OI (35%). Ae. co-exist with , thus explaining albopictus was the predominant mosquito the co-existence of both species in Taman species in West Coast and Kudat divisions, St. Peter. However, surveillance studies while a much lower population of Ae. ae- conducted in Alabama, USA in 1991 and gypti was found in Taman St. Peter, Kudat Central African Republic in 2013 found Ae. albopictus Ae. aegypti district, and none in the residential areas totally replacing et al of West Coast division (Table 2). populations (Hobbs , 1991; Kamgang et al, 2013). In a more localized survey, Afizah et al (2015) observed only Ae. al- DISCUSSION bopictus in Malay and Aboriginal villages Surveillance serves as a method to of Carey Island, Selangor, Malaysia, with investigate the geographic distribution apparent absence of Ae. aegypti. All these and density of vectors. It also helps to findings are in line with our findings of evaluate performance of existing vector Ae. albopictus as the sole Aedes spp in the control programs and steers implemen- majority of the study sites. tation of effective intervention strategies Establishment of invasive species of (WHO, 1997). Among various surveillance Ae. albopictus is thought to be the reason methods, ovitrap surveillance remains for Ae. aegypti depletion in number (Hobbs the commonest method used, providing et al, 1991). Ribeiro (1988) and Nasci et information on Aedes and other mosquito al, (1989) hypothesized Ae. albopictus species larval density within a short time compete with Ae. aegypti through asym-

Vol 50 No. 1 January 2019 59 Southeast Asian J Trop Med Public Health 94 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 Ae. albopictus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6 0 0 0 Ae. Percentage (%) Percentage aegypti 6 ± 3 6 ± 2 4 ± 3 9 ± 5 7 ± 7 5 ± 1 Ae. 39 ± 8 23 ± 9 10 ± 3 79 ± 12 30 ± 11 12 ± 5 66 ± 9 32 ± 9 10 ± 3 12 ± 10 17 ± 8 10 ± 3 39 ± 9 31 ± 7 35 ± 12 albopictus

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Ae. 3 ± aegypti of larvae per ovitrap Mean number (± SEM) 68 97 179 546 232 301 445 180 172 986 444 299 178 136 545 262 313 142 430 317 Ae. 1,105 albopictus collected 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 36 Ae. Number of larvae aegypti 57 86 60 57 53 57 36 93 64 52 47 47 47 36 93 33 57 65 71 78 (%) 100 index Ovitrap 6 8 5 9 7 7 7 5 5 7 17 12 17 14 17 14 14 13 17 19 10 of Table 2 Table positive ovitraps Number 9 of 30 14 10 30 14 15 30 14 15 14 27 15 15 15 14 14 15 30 29 14 during 10 - 20 July 2017. July 20 - 10 during ovitraps Number collected of 30 15 15 30 15 15 30 15 15 15 30 15 15 15 15 15 15 30 30 15 15 placed ovitraps Number Study site Kampung Lebak Moyoh Taman Nikmat Taman Pekan Kota Belud Kampung Serusup Jalan Bolong Pekan Tuaran Taman Selesa Taman Jalan Mergastua Taman Mutiara Taman Taman Palm Villa Taman Taman Sindo Taman Taman Ceriamas Taman Kampung Lok Bonu Kampung Beringis Taman Kinarut Taman Taman St. Peter Taman Taman Sri Awana Taman Taman Pakka Taman Jalan Peladang Taman T&G Phase II Taman Pekan Kota Belud Tuaran Kota Kinabalu Penampang Putatan Papar Kudat Kota Marudu Ovitrap index and numbers of mosquito larvae obtained from West Coast and Kudat divisions, Sabah, Malaysia Malaysia Sabah, divisions, Kudat and Coast West from obtained larvae mosquito of numbers and index Ovitrap Division West West Coast Kudat

60 Vol 50 No. 1 January 2019 Dengue Vector Surveillance in Sabah, Malaysia metric mating, where male Ae. albopictus to dwell in areas congested with people mated with female Ae. aegypti to produce (Chen et al, 2005). In addition, residential non-viable hybrid offspring and thereby areas create numerous breeding opportu- eventually eliminating the competing Ae. nities for Aedes spp, ranging from natural aegypti population. This was supported by catchment basins to man-made containers similar findings in Malaysia (Nazni et al, such as flower pot plates (Chenet al, 2005; 2009). Apart from this mating behavior, Ae. Rao and George, 2010). The ovitraps were albopictus larvae are also capable of sup- placed outside the house but within the pressing hatching of Ae. aegypti eggs and immediate vicinity. Despite being placed invading their habitats (Braks et al, 2004). outdoors, there was still a very small Hatching of eggs is usually triggered when population of Ae. aegypti collected (only there is a decline of dissolved oxygen due at Taman St. Peter), thus contradicting to respiration of microbes attached to the the standard belief of Ae. aegypti breed- eggs surfaces (Hawley, 1988). Hatching ing indoors and Ae. albopictus outdoors will cease when Ae. albopictus larvae is (Saleeza et al, 2013). presence, as they will graze the existing In summary, this study highlights microbes coating Ae. aegypti eggs, causing the sensitivity and reliability of ovitraps influx of oxygen level (Gillett et al, 1977). in monitoring Aedes spp population. Our Ae. albopictus is usually more concen- results reveal all residential areas sur- trated in outdoor environment and prefer veyed in Kudat and West Coast divisions breeding in natural catchment basins were infested with Aedes spp and ovitrap such as tree holes and bamboo stumps indices were alarmingly high (≥10%), (Norzahira et al, 2011), whereas Ae. aegypti indicative of urgent and immediate inter- breeds indoor or close to human dwellings vention programs. Integrated vector man- and prefers artificial containers such as agement ranging from vector surveillance, vases and flower pot plates (Nyamah et source reduction, public health education, al, 2010). However, Klowden (1993) noted personal protection and biological and both Ae. albopictus and Ae. aegypti are chemical control should be implemented sympatric species and can occupy similar (Lau et al, 2013). In addition, proper town niche. Increasing human outdoor activity planning and home design could assist is one of the contributing factors of Ae. in eradicating potential breeding sources aegypti changing its breeding preference (Saleeza et al, 2013). to outdoor locations (Saifur et al, 2012). In addition, Ae. albopictus is well known for ACKNOWLEDGEMENTS having a wide range of breeding habitats, rural, suburban and urban (Norzahira The authors thank the University of et al, 2011; Ho et al, 2014). A number of Malaya for funding the study (Project no. reports indicated Ae. albopictus and Ae. RP021A/16SUS and RP021D/16SUS). aegypti are interchanging their normal breeding sites (Chen et al, 2006b; Norza- REFERENCES hira et al, 2011; Saifur et al, 2012). Afizah AN, Mahirah MN, Azahari AH, Asuad In this study, residential areas in MK, Nazni WA, Lee HL. Absence of Aedes towns were selected to be surveillance aegypti (L.) on an ecological island: com- sites as these are places where dengue is petitive exclusion?. Southeast Asian J Trop prevalent owing to Aedes spp preference Med Public Health 2015; 46: 850-6.

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