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144 results on '"Tan, Tiong Kai"'

12. Detoxification Enzymes: A Cornerstone of Rampant Insecticide Resistance in Aedes Albopictus (Diptera: Culicidae) from Sabah, Malaysia

Author

Mohd Roslin, Nur Elia Amira, primary, Chen, Chee Dhang, additional, Low, Van Lun, additional, Lau, Koon Weng, additional, Rashid, Amirah Haziqah, additional, Yap, Amelia Zheng Hua, additional, Tan, Tiong Kai, additional, Lim, Yvonne Ai Lian, additional, Lee, Han Lim, additional, and Azirun, Mohd Sofian, additional

Published
2023
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15. First Report of Rickettsia Asembonensis in Small Ruminants

Author

Low, Van Lun, primary, Azhar, Siti Sarah, additional, Tan, Tiong Kai, additional, Bathmanaban, Premaalatha, additional, AbuBakar, Sazaly, additional, Chandrawathani, Panchadcharam, additional, Nizamuddin, Hassan Nizam Quaza, additional, Hanim, Mohd Saeid Faizah, additional, Akma, Ngah Hamid, additional, Norlizan, Mohd Noor, additional, and Lim, Yvonne Ai Lian, additional

Published
2022
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19. Bioefficacy of mosquito mat vaporizers and associated metabolic detoxication mechanisms in Aedes aegypti (Linnaeus) in Selangor, Malaysia: A statewide assessment

Author

Taib, Azratul Hizayu, Chen, Chee Dhang, Lau, K. W., Abdul Wahid, Noor Azrizal, Tan, Tiong Kai, Lim, Yvonne Ai Lian, Azirun, Mohd Sofian, Low, Van Lun, Taib, Azratul Hizayu, Chen, Chee Dhang, Lau, K. W., Abdul Wahid, Noor Azrizal, Tan, Tiong Kai, Lim, Yvonne Ai Lian, Azirun, Mohd Sofian, and Low, Van Lun

Abstract

This study aims to examine the efficacy of mosquito mat vaporizers on Aedes aegypti and their associated metabolic detoxication mechanisms. For this purpose, Aedes aegypti (Linnaeus) was collected from nine districts in Selangor, Malaysia and tested with mosquito vaporizing mat bioassays. The same populations were also subjected to biochemical assays to investigate activities of detoxifying enzymes, namely non-specific esterase (EST), glutathione-S-transferase (GST) and mixed function oxidase (MFO). The efficacy of Ae. aegypti on the active ingredients tested in decreasing order were d- allethrin > dimefluthrin > prallethrin with PBO > prallethrin. The results further indicated significant enhancement mean levels of EST, GST and MFO in pyrethroid-resistant populations. The mortality rate of Ae. aegypti in response to pyrethroid active ingredients was associated with MFO activity, suggesting it is an important detoxification enzyme for the populations tested. In view of the presence of resistance against household insecticide products, pyrethroid efficacy on Ae. aegypti populations needs to be monitored closely to ensure the implementation of an effective vector control program in Malaysia.

Published
2021

20. Identification of potential vectors of Dirofilaria immitisand Brugia pahangi(Spirurida: Filariidae): First observation of infective third-stage larva of B. pahangiin Culex quinquefasciatus(Diptera: Culicidae)

Author

Vinnie-​Siow, Wei Yin, Low, Van Lun, Tan, Tiong Kai, Wong, Meng Li, Leong, Cherng Shii, Ahmad, Nazni Wasi, and Lim, Yvonne Ai Lian

Abstract

ABSTRACTInformation on the mosquito species that transmit canine filariosis is scanty. Hence, an experimental study was conducted to identify the potential vectors responsible for the transmission of D. immitisLeidy and B. pahangiBuckley & Edeson. A total of 367 mosquitoes belonging to six species containing both laboratory and field strains (i.e. Aedes togoiTheobald, Aedes aegyptiLinnaeus, Aedes albopictusSkuse, Culex quinquefasciatusSay, Culex vishnuiTheobald and Anopheles dirusPeyton & Harrison) were used in this study. All mosquitoes were artificially fed on either D. immitisor B. pahangi microfilariae (mfs) infected blood by using the Hemotek™ membrane feeding system. Out of 367 mosquitoes, 228 (64.9%) were fully engorged. After feeding on D. immitis(20%) and B. pahangi(33%) mfs positive blood, the mortality rates for Cx. quinquefasciatuswere found to be slightly lower than that of other species of mosquitoes. On the other hand, majority of An. diruswere found to be incapable to withstand the infection of mfs as the mortality rates were relatively high (D. immitis = 71.4%; B. pahangi = 100.0%). Brugia pahangiwas detected in Ae. togoiand Cx. quinquefasciatuswith infection rates of 50% and 25%, respectively. Aedes togoiwas the only species infected with D. immitiswith an infection rate of 69%. Our results showed that Ae. togoiwas an excellent experimental vector for both D. immitisand B. pahangi. This study also documented the observation of B. pahangi, for the first time in the head region of Cx. quinquefasciatus under a laboratory setting.

Published
2022
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26. Sexually anomalous individuals of the black fly Simulium trangense (Diptera: Simuliidae) infected with mermithid parasites (Nematoda: Mermithidae).

Author

Ya'cob, Zubaidah, Low, Van Lun, Tan, Tiong Kai, Noor-Izwan, Anas, Lourdes, Emmanuel Y., Ramli, Rosli, Takaoka, Hiroyuki, and Adler, Peter H.

Subjects
SIMULIIDAE, DIPTERA, NEMATODES, FEMALE reproductive organs, MALE reproductive organs
Abstract

Sexually anomalous individuals, typically intersexes or gynandromorphs, bear a mixture of male and female traits. Twelve sexually anomalous individuals of the black fly Simulium (Gomphostilbia) trangense Jitklang, Kuvangkadilok, Baimai, Takaoka & Adler were discovered among 49 adults reared from pupae. All 12 sexually anomalous adults were parasitized by mermithid nematodes, although five additional parasitized adults had no overt external anomalies. Sequence analysis of the 18S rRNA gene revealed that the mermithids, possibly representing a new species, are related to Mesomermis spp., with genetic distances of 5.09–6.87%. All 12 anomalous individuals had female phenotypical traits on the head, thorax, forelegs, midlegs, and claws, but male features on the left and right hind basitarsi. One individual had mixed male and female genitalia. The findings are in accord with the trend that mermithid infections are associated with sexually anomalous adult black flies. [ABSTRACT FROM AUTHOR]

Published
2021
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28. Pyrethroids Use: Threats on Metabolic-Mediated Resistance Mechanisms in the Primary Dengue Vector Aedes aegypti (Diptera: Culicidae)

Author

Amelia-Yap, Zheng Hua, primary, Sofian-Azirun, Mohd, additional, Chen, Chee Dhang, additional, Suana, I Wayan, additional, Lau, Koon Weng, additional, Elia-Amira, Nur Mohd Roslin, additional, Haziqah-Rashid, Amirah, additional, Tan, Tiong Kai, additional, Lim, Yvonne Ai Lian, additional, and Low, Van Lun, additional

Published
2019
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37. Contrasting evolutionary patterns between two haplogroups of Haematobia exigua (Diptera: Muscidae) from the mainland and islands of Southeast Asia

Author

Low, Van Lun, primary, Tan, Tiong Kai, additional, Prakash, Batah Kunalan, additional, Vinnie-Siow, Wei Yin, additional, Tay, Sun Tee, additional, Masmeatathip, Roungthip, additional, Hadi, Upik Kesumawati, additional, Lim, Yvonne Ai Lian, additional, Chen, Chee Dhang, additional, Norma-Rashid, Yusoff, additional, and Sofian-Azirun, Mohd, additional

Published
2017
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39. DNA Barcoding of Simulium asakoae(Diptera: Simuliidae) From Northern Thailand

Author

Low, Van Lun, Srisuka, Wichai, Saeung, Atiporn, Tan, Tiong Kai, Ya’cob, Zubaidah, Yeong, Yze Shiuan, and Takaoka, Hiroyuki

Abstract

Previous studies suggested the presence of species complex in the so-called Simulium asakoaeTakaoka & Davies (Diptera: Simuliidae) in Thailand due to its high morphological variability and genetic divergence. To investigate whether the true S. asakoaeis present in Thailand, we performed a detailed morphological identification of S. asakoaeand compared its DNA barcodes with the morphospecies S. asakoaefrom Myanmar and the typical S. asakoaefrom Malaysia. Phylogenetic analysis revealed the Thai materials analyzed in this study were indeed genetically similar with those from Myanmar and Malaysia, though genetic distances 0–2.27% were observed. We tentatively regard this divergence as intraspecific variation, and the automatic barcode gap discovery analysis further supports them as a single species.

Published
2020
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42. A New Black Fly Species of the Simulium(Gomphostilbia) duolongumSubgroup (Diptera: Simuliidae) From Vietnam, and Molecular Comparisons With Related Species Using the COI Barcoding Gene

Author

Takaoka, Hiroyuki, Low, Van Lun, Tan, Tiong Kai, Ya’cob, Zubaidah, Sofian-Azirun, Mohd, Dhang Chen, Chee, Lau, Koon Weng, and Da Pham, Xuan

Abstract

Simulium(Gomphostilbia) yvonneaesp. nov. is described based on adults, pupae, and mature larvae from Vietnam. This new species belongs to the Simulium duolongumsubgroup in the S. batoensespecies-group of the subgenus GomphostilbiaEnderlein. It is distinguished by having a relatively larger number of male upper-eye facets in 16 vertical columns and 16 horizontal rows and a pupal gill with eight filaments arranged as 3+(1+2)+2 from dorsal to ventral, of which two filaments of the ventral pair are 1.8 times as long as the longest filament of the middle and dorsal triplets. Morphological comparisons are made to distinguish this new species from all 22 related species. The genetic distinctiveness of this new species in the S. duolongumsubgroup is also presented based on the DNA barcoding COI gene.

Published
2019
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43. Molecular identification of human hookworm infections in economically disadvantaged communities in Peninsular Malaysia

Author

Muhammad Aidil Roslan, Lee Soo Ching, Romano Ngui, Tan Tiong Kai, and Yvonne A. L. Lim

Subjects
Adult, Male, Veterinary medicine, Ancylostoma, Adolescent, Necator americanus, education, Helminth genetics, Biology, Feces, Hookworm Infections, Young Adult, Dogs, Virology, parasitic diseases, DNA, Ribosomal Spacer, RNA, Ribosomal, 28S, Animals, Humans, Internal transcribed spacer, Child, Hookworm infection, Ancylostoma ceylanicum, Aged, Aged, 80 and over, Sequence Analysis, RNA, Malaysia, Sequence Analysis, DNA, Articles, Ribosomal RNA, DNA, Helminth, Middle Aged, biology.organism_classification, Infectious Diseases, Socioeconomic Factors, Child, Preschool, Host-Pathogen Interactions, Parasitology, Female
Abstract

Species identification of human hookworm infections among eight communities in rural areas of Peninsular Malaysia was determined during 2009-2011. Fecal samples were examined by microscopy and subsequently, the internal transcribed spacer 2 and 28S ribosomal RNA region of Necator americanus and Ancylostoma spp. were sequenced. Overall, 9.1% (58 of 634) were identified positive by microscopy for hookworm infection, and 47 (81.0%) of 58 were successfully amplified and sequenced. Sequence comparison found that N. americanus (87.2%) was the most predominant hookworm identified, followed by Ancylostoma ceylanicum (23.4%). No A. duodenale infection was detected in this study. Detection of A. ceylanicum in humans highlighted the zoonotic transmission among humans living near dogs. Thus, implementation of effective control measures for hookworm infections in future should seriously consider this zoonotic implication.

Published
2012

45. Molecular characterisation of the tick Rhipicephalus microplus in Malaysia: new insights into the cryptic diversity and distinct genetic assemblages throughout the world

Author

Low, Van Lun, primary, Tay, Sun Tee, additional, Kho, Kai Ling, additional, Koh, Fui Xian, additional, Tan, Tiong Kai, additional, Lim, Yvonne Ai Lian, additional, Ong, Bee Lee, additional, Panchadcharam, Chandrawathani, additional, Norma-Rashid, Yusoff, additional, and Sofian-Azirun, Mohd, additional

Published
2015
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46. Co-infection of Haemonchus contortus and Trichostrongylus spp. among livestock in Malaysia as revealed by amplification and sequencing of the internal transcribed spacer II DNA region

Author

Tan, Tiong Kai, Panchadcharam, Chandrawathani, Low, Van Lun, Lee, Soo Ching, Ngui, Romano, Sharma, Reuben Sunil Kumar, Lim, Yvonne Ai Lian, Tan, Tiong Kai, Panchadcharam, Chandrawathani, Low, Van Lun, Lee, Soo Ching, Ngui, Romano, Sharma, Reuben Sunil Kumar, and Lim, Yvonne Ai Lian

Abstract

Background: Haemonchus contortus and Trichostrongylus spp. are reported to be the most prevalent and highly pathogenic parasites in livestock, particularly in small ruminants. However, the routine conventional tool used in Malaysia could not differentiate the species accurately and therefore limiting the understanding of the co-infections between these two genera among livestock in Malaysia. This study is the first attempt to identify the strongylids of veterinary importance in Malaysia (i.e., H. contortus and Trichostrongylus spp.) by amplification and sequencing of the Internal Transcribed Spacer II DNA region. Results: Overall, 118 (cattle: 11 of 98 or 11.2%; deer: 4 of 70 or 5.7%; goats: 99 of 157 or 63.1%; swine: 4 of 91 or 4.4%) out of the 416 collected fecal samples were microscopy positive with strongylid infection. The PCR and sequencing results demonstrated that 93 samples (1 or 25.0% of deer; 92 or 92.9% of goats) contained H. contortus. In addition, Trichostrongylus colubriformis was observed in 75 (75.8% of 99) of strongylid infected goats and Trichostrongylus axei in 4 (4.0%) of 99 goats and 2 (50.0%) of 4 deer. Based on the molecular results, co-infection of H. contortus and Trichostrongylus spp. (H. contortus + T. colubriformis denoted as HTC; H. contortus + T. axei denoted as HTA) were only found in goats. Specifically, HTC co-infections have higher rate (71 or 45.2% of 157) compared to HTA co-infections (3 or 1.9% of 157). Conclusions: The present study is the first molecular identification of strongylid species among livestock in Malaysia which is essential towards a better knowledge of the epidemiology of gastro-intestinal parasitic infection among livestock in the country. Furthermore, a more comprehensive or nationwide molecular-based study on gastro-intestinal parasites in livestock should be carried out in the future, given that molecular tools could assist in improving diagnosis of veterinary parasitology in Malaysia due to its high sensitiv

Published
2014

48. Mitochondrial DNA Markers Reveal High Genetic Diversity but Low Genetic Differentiation in the Black Fly Simulium tani Takaoka & Davies along an Elevational Gradient in Malaysia

Author

Low, Van Lun, primary, Adler, Peter H., additional, Takaoka, Hiroyuki, additional, Ya’cob, Zubaidah, additional, Lim, Phaik Eem, additional, Tan, Tiong Kai, additional, Lim, Yvonne A. L., additional, Chen, Chee Dhang, additional, Norma-Rashid, Yusoff, additional, and Sofian-Azirun, Mohd, additional

Published
2014
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49. First molecular characterization of Giardia duodenalis from goats in Malaysia

Author

Lim, Yvonne A. L., Mahdy, Mohammed A. K., Tan, Tiong Kai, Goh, Xiang Ting, Jex, Aaron R., Nolan, Matthew J., Kumar Sharma, Reuben Sunil, Gasser, Robin B., Lim, Yvonne A. L., Mahdy, Mohammed A. K., Tan, Tiong Kai, Goh, Xiang Ting, Jex, Aaron R., Nolan, Matthew J., Kumar Sharma, Reuben Sunil, and Gasser, Robin B.

Abstract

In the present study, 310 faecal samples from goats from eight different farms in Malaysia were tested for the presence of Giardia using a PCR-coupled approach. The nested PCR for SSU amplified products of the expected size (∼200 bp) from 21 of 310 (6.8%) samples. Sixteen of these 21 products could be sequenced successfully and represented six distinct sequence types. Phylogenetic analysis of the SSU sequence data using Bayesian Inference (BI) identified Giardia assemblages A, B and E. The identification of the ‘zoonotic’ assemblages A and B suggests that Giardia-infected goats represent a possible reservoir for human giardiasis in Malaysia.

Published
2013

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