Habitats and Trematode Infection of Bithynia Siamensis Goniomphalos in Udon Thani Province, Thailand
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BITHYNIA SIAMENSIS GONIOMPHALOS HABITAT AND TREMATODE INFECTION HABITATS AND TREMATODE INFECTION OF BITHYNIA SIAMENSIS GONIOMPHALOS IN UDON THANI PROVINCE, THAILAND Jutharat Kulsantiwong1, Sattrachai Prasopdee2, Nipawan Labbunruang1, Monticha Chaiyasaeng3 and Smarn Tesana3 1Department of Biology, Faculty of Science, Udon Thani Rajabhat University, Udon Thani; 2Chulabhorn International College of Medicine, Thammasat University, Pathum Thani; 3Department of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand Abstract. Determination of prevalence of trematode infection in Bithynia siamensis goniomphalos, the first intermediate host of Opisthorchis viverrini, was conducted from May 2014 to December 2015. Snails were collected from seven districts, namely, Kumphawapi, Kut Chap, Mueang Udon Thani, Nong Han, Nong Wua So, Phibun Rak and Prachaksinlapakhom, in Udon Thani Province, Thailand. B. siamensis goniomphalos snails were identified morphologically and examined for trematode infection by cercarial shedding. Seven hundred and sixty-four of 34,667 snails were infected with trematodes. Nine types of O. viverrni cercariae were identified, namely, amphistome, armatae, cystocercous, furcocercous, mono- stome, pleurolophocercous, virgulate, and unknown. The highest prevalent type of trematode infection was virgulate (11.53%), followed by armatae (1.35%). The prevalence of O. viverrini infection in Phibun Rak, Nong Wua So, and Kut Chap District was 0.22%, 0.08%, and 0.02%, respectively. Higher percent trematode infec- tion was in small size snails (2-6 mm) than medium size snails (6.1-10 mm) (73.54% and 26.00%, respectively). Male snails were more infected (82%) than females (17%). Snails were most commonly found in water with pH 7.7 ± 1.0, dissolved oxygen content 3.2 ± 1.7 mg/l, salt concentration 0.09 ± 0.12 ppt, conductivity 1.7 ± 0.1 mS/cm, and total dissolved solids 275.0 ± 0.2 mg/l. The highest prevalence of trematode cercariae was recorded in snails collected in reservoir dam (39.3%), followed by swamp (27.1%), canal (23.2%), rice paddy field (6.0%) and river (4.4%). Keywords: Bithynia siamensis goniomphalos, Opisthorchis viverrini, prevalence, trematode INTRODUCTION the Greater Mekong River sub-region is the infection of freshwater snails, which One of the most critical problems in act as intermediate hosts for asexual multiplication of trematodes, especially Correspondence: Dr Jutharat Kulsantiwong, Department of Biology, Faculty of Science, Opisthorchis viverrini. The latter is an im- Udon Thani Rajabhat University, Udon Thani portant causative agent for cholangiocar- 40002, Thailand. cinoma (CCA) (Haswell-Elkins et al, 1992; Tel: +66 (0) 42 181535, +66 (0) 94 5166869 IARC, 1994; Vatanasapt et al, 2000). The E-mail: [email protected], prevalence of O. viverrini infection shows [email protected] a strong positive correlation with the Vol 48 No. 5 September 2017 975 SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH occurrence of CCA, particularly in the ru- temperature (Suwannatrai et al, 2011). The ral areas of northeastern Thailand (Brock- types of habitat of the snails might be one elman et al, 1986; Srivatanakul et al, 1991; of the factors determining the prevalence Sriamporn et al, 2004; Rangsin et al, 2009; of infection of this parasite in the snail Kaewpitoon et al, 2015), where the high- hosts. Hence, the objective of this study est incidence of CCA in the world occurs was to evaluate the prevalence of trema- at Udon Thani Province (Khuhaprema tode infection, especially of O. viverrini in et al, 2007). B. siamensis goniomphalos in different types The life cycle of O. viverrini requires of water bodies in Udon Thani Province two types of intermediate hosts, namely, to serve as baseline data for future control snails, such as Bithynia siamensis goniom- measures of O. viverrini infection. phalos, B. funiculata and B. siamensis sia- mensis (Brockelman et al, 1986; Sri-Aroon MATERIALS AND METHODS et al, 2005; Kulsantiwong et al, 2015) and fish, such as cyprinids (Sithithaworn Samples and Haswell-Elkins, 2003; Upatham and Bithynia siamensis gonimphalos sam- Viyanant, 2003; Donthaisong et al, 2014; ples were collected from May 2014 to Tesana et al, 2014). Among the intermedi- December 2015 manually for a period of ate host snail species, B. siamensis gonom- 5 minutes/site per person from rocks, soil, phalos is the most important, especially mud and sandy ground and using scoop in hot spots of O. viverrini infection and sieves at locations presenting with grass CCA occurrence. In addition, a field study and leaves on clean or muddy surfaces of O. viverrini infection in bithynid snails or with decaying leaves. The snail col- showed that B. siamensis goniomphalos has lections were conducted at 55 localities a higher prevalence of trematode infec- in 20 rice paddy fields, 20 reservoirs or tion than B. siamensis and B. funiculata dams, 5 swamps, 7 canals and 3 rivers in 7 (Kulsantiwong et al, 2015). The infection in districts in Udon Thani Province, namely, these snails exhibited a higher prevalence Kumphawapi, Kut Chap, Mueang Udon in the dry season than the rainy season Thani, Nong Han, Nong Wua So, Phibun (Brockelman et al, 1986; Ngoen-klan Rak and Prachaksinlapakhom (Fig 1). The et al, 2010; Kulsantiwong et al, 2013). The snails were cleaned, air-dried, separately prevalence of O. viverrini infection in B. labeled according to site and locality, siamensis goniomphalos is low but very stored in plastic bags and transported to high in cyprinid fish (Sri-aroonet al, 2005; the laboratory. Pinlaor et al, 2013). The physicochemical properties of However, there is a lack of evidence water at collection sites were analyzed of cercarial infection in B. siamensis go- using an Extech DO700 Portable Dis- niomphalos in Udon Thani Province. The solved Oxygen instrument (FLIR Com- ecology of water bodies where the snails mercial Systems, Nashua, NH). The prefer to live includes water reservoir, collected snails were identified based on canal and rice paddy field at depths of shell morphology for species following up to 50 cm (Brandt, 1974). In addition, available keys and descriptions (Brandt, freshwater quality optimal for bithynid 1974; Chitramvong and Upatham, 1989; snails is 3 to 420 NTU turbidity, 2.5-5 ppt Chitramvong, 1991, 1992; Kulsantiwong salinity, pH 6.0-8.1, and 21.9-38.6°C water et al, 2013; Tesana et al, 2014). The infected 976 Vol 48 No. 5 September 2017 BITHYNIA SIAMENSIS GONIOMPHALOS HABITAT AND TREMATODE INFECTION Fig 1–Map of Udon Thani Province, Thailand showing snail collection districts and sites. snails were divided into two groups based induced under 25 W electric light bulb on gender and were randomly sampled illumination for 3 to 4 hours at room for measurement of shell size using an temperature (25°C) during the daytime. electronic digital caliper (Tianlun Hard- At night time, black covers were used to ware Tool Manufacture, Zhangjiagang, achieve total darkness. Each snail was Jiangsu, China): small (2.0-6.0 mm) and carefully observed for cercariae under a medium (6.1-10.0 mm) (Kulsantiwong stereomicroscope for daytime and night- et al, 2013; Prasopdee et al, 2015). time shedding. The live cercariae were stained with 0.1% Fast Red B (Sigma, St Trematode collection and identification Louis, MO), then observed under a com- Dechlorinated tap water was used to pound microscope and photographed. clean the snails and then infected trema- The types of cercariae were identified todes were collected using a cercarial based on the available morphological shedding method (daytime and nighttime description (Schell, 1970; Frandsen and shedding). Snails were placed separately Christensen, 1984; Adam et al, 1993). in small plastic cups containing 10 ml of O. viverrini was confirmed using PCR- dechlorinated tap water. Shedding was baed assay employing species-specific Vol 48 No. 5 September 2017 977 SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH Fig 2– Type of cercariae shed from Bithynia siamensis goniomphalos. (A) Furcocercous, (B) amphistome, (C) virgulate, (D) armatae, (E) O. viverrini, (F) cystophorous, (G) parapleurolophocercous, (H) monostome, and (I) unknown. EB, excretory bladder; ES, eye spot; ff, fin fold; OS, oral sucker; VS, ventral sucker. primers OV-6F (5′-CTGAATCTCTCGTTT- Nong Wua So and Kut Chap, had O. viver- GTTCA-3′) and OV-6R (5′-GTTCCAGGT- rini infection of 0.22%, 0.08% and 0.02%, GAGTCTCTCTA-3′) (Wongratanacheewin respectively, all located near Huai Luang et al, 2001). Reservoir. Statistical analysis The highest prevalence (39.3%) of Pearson correlation coefficient was trematode were recorded in snails collect- used to gauge the correlation between ed in reservoir/dam, followed by swamp density of snail population and preva- (27.1%), canal (23.2%), rice paddy field lence of trematode infection (a p-value (6.0%), and river (4.4%). The mean snail <0.05 is considered statistically signifi- density (number/manpower/5 minutes) cant). Descriptive results were expressed of B. siamensis goniomphalos in different as mean ± standard deviation (SD) of localities in the 7 districts surveyed of size, density of snail population from the Udon Thani Province was as follows: in difference habitats and quality of water. the river of Kumphawapi District was 105 Statistical analysis was performed using ± 22, reservoirs/dams of Kut Chap and SPSS version 16.0 software package (SPSS, Nong Wua So District 275 ± 46 and 441 Chicago, IL). ± 37 respectively, canals of Mueang and Prachaksinlapakhom District 355 ± 51 and 75 ± 2, respectively, swamps of Mueang, RESULTS Prachksinlapakhom and Phibun Rak Dis- Seven hundred and sixty-four trict 355 ± 50, 83 ± 22 and 215 ± 69, and (15.08%) of 34,667 B. siamensis goniom- rice paddy fields of Prachaksinlapakhom, phalos were infected with trematodes, Nong Han and Phibun Rak 78 ± 23, 103 ± mainly (3.6%) those in Nong Han Dis- 52 and 167 ± 52, respectively. Of the 378 trict, followed by Nong Wua So District infected snails sampled, 278 (74%) were in (2.98%), Kumphawapi District (2.09%), small size and the remaining in medium Mueang District (2.0%), Prachaksinlapak- size group, with 312 (82%) being females.