Surachart Koyadun

Border malaria associated with multidrug resistance on Thailand-Myanmar and Thailand-Cambodia borders: transmission dynamic, vulnerability, and surveillance.

This systematic review elaborates the concepts and impacts of border malaria, particularly on the emergence and spread of Plasmodium falciparum and Plasmodium vivax multidrug resistance (MDR) malaria on Thailand-Myanmar and Thailand-Cambodia borders. Border malaria encompasses any complex epidemiological settings of forest-related and forest fringe-related malaria, both regularly occurring in certain transmission areas and manifesting a trend of increased incidence in transmission prone areas along these borders, as the result of interconnections of human settlements and movement activities, cross-border population migrations, ecological changes, vector population dynamics, and multidrug resistance. For regional and global perspectives, this review analyzes and synthesizes the rationales pertaining to transmission dynamics and the vulnerabilities of border malaria that constrain surveillance and control of the worlds most MDR falciparum and vivax malaria on these chaotic borders.

Ecologic and Sociodemographic Risk Determinants for Dengue Transmission in Urban Areas in Thailand

This study analyzed the association between household-level ecologic and individual-level sociodemographic determinants and dengue transmission in urban areas of Chachoengsao province, Thailand. The ecologic and sociodemographic variables were examined by univariate analysis and multivariate logistic regression. In the ecologic model, dengue risk was related to households situated in the ecotope of residential mixed with commercial and densely populated urban residential areas (RCDENPURA) (aOR = 2.23, P = 0.009), high historical dengue risk area (aOR = 2.06, P < 0.001), and presence of household window screens (aOR = 1.62, P = 0.023). In the sociodemographic model, the dengue risk was related to householders aged >45 years (aOR = 3.24, P = 0.003), secondary and higher educational degrees (aOR = 2.33, P = 0.013), household members >4 persons (aOR = 2.01, P = 0.02), and community effort in environmental management by clean-up campaign (aOR = 1.91, P = 0.035). It is possible that the preventive measures were positively correlated with dengue risk because these activities were generally carried out in particular households or communities following dengue experiences or dengue outbreaks. Interestingly, the ecotope of RCDENPURA and high historical dengue risk area appeared to be very good predictors of dengue incidences.

Thailand Momentum on Policy and Practice in Local Legislation on Dengue Vector Control

Over a past decade, an administrative decentralization model, adopted for local administration development in Thailand, is replacing the prior centralized (top-down) command system. The change offers challenges to local governmental agencies and other public health agencies at all the ministerial, regional, and provincial levels. A public health regulatory and legislative framework for dengue vector control by local governmental agencies is a national topic of interest because dengue control program has been integrated into healthcare services at the provincial level and also has been given priority in health plans of local governmental agencies. The enabling environments of local administrations are unique, so this critical review focuses on the authority of local governmental agencies responsible for disease prevention and control and on the functioning of local legislation with respect to dengue vector control and practices.

Current Bancroftian Filariasis Elimination on Thailand-Myanmar Border: Public Health Challenges toward Postgenomic MDA Evaluation

From regional and global perspectives, Thailand has progressed toward lymphatic filariasis transmission-free zone in almost entire endemic provinces, being verified by WHO by the end of 2012 after the 5-year implementation of mass drug administration (MDA) with diethylcarbamazine and albendazole as part of the National Program to Eliminate Lymphatic Filariasis (PELF) (2002–2006) and a 4-year expansion of post-MDA surveillance (2007–2010). However, Thai PELF has been challenging sensitive situations of not only border crossings of local people on Thailand-Myanmar border where focal distribution of forest- and forest fringe-related border bancroftian filariasis (BBF) is caused by nocturnally subperiodic Wuchereria bancrofti in local people living in pockets of endemic villages, but also intense cross-border migrations of Mon and Tanintharyi workers from Myanmar to Thailand who harbor nocturnally periodic W. bancrofti microfilaremic infection causing the emergence of imported bancroftian filariasis (IBF). Thus, this paper discusses the apparent issues and problems pertaining to epidemiological surveillance and postgenomic MDA evaluation for 2010–2020 convalescent BBF and IBF. In particular, the population migration linked to fitness of benzimidazole-resistant W. bancrofti population is a topic of interest in this region whether the resistance is associated with pressure of the MDA 2 drugs and the vulnerabilities epidemiologically observed in complex BBF or IBF settings.

Molecular Diagnosis and Monitoring of Benzimidazole Susceptibility of Human Filariids

Adisak Bhumiratana1,2,3, Apiradee Intarapuk3, Danai Sangthong3, Surachart Koyadun4, Prapassorn Pechgit1 and Jinrapa Pothikasikorn5 1Department of Parasitology and Entomology, Faculty of Public Health, Mahidol University, Bangkok 2Center for EcoHealth Disease Modeling and Intervention Development Research, Faculty of Public Health, Mahidol University, Bangkok 3Environmental Pathogen Molecular Biology and Epidemiology Research Unit, Faculty of Veterinary Medicine, Mahanakorn University of Technology, Bangkok 4Ministry of Public Health, Department of Disease Control, Office of Disease Prevention and Control 11 Nakhon Si Thammarat 5Department of Microbiology, Faculty of Science, Mahidol University, Bangkok Thailand

OL-013 Imported bancroftian filariasis: diethylcarbamazine response and benzimidazole susceptibility of Wuchereria bancrofti in dynamic cross-border migrant population targeted for the national program to eliminate lymphatic filariasis in Southern Thailand

Background: Imported bancroftian filariasis (IBF) caused by Wuchereria bancrofti (Wb) in crossborder Myanmar migrant workers has been targeted for multidose diethylcarbamazine (DEC) mass treatment as part of the lymphatic filariasis elimination program at different health settings in permitted provinces. Regarding their healthseeking behaviors and migration patterns, the IBF was scrutinized for a 300mg single-dose DEC response and benzimidazole-susceptible parasite inhabiting Myanmar carriers in southern Thailand. Methods: Of the 1,133 Myanmars: DEC experienced long-termmigrants significantly outnumbering those shortterm migrants were examined for microfilaremia (WbMf) and antigenemia (WbAg), parasite loads of 14 DEC-treated antigenemic cases: the same 7 microfilaremic and amicrofilaremic were monitored at month 0, 1, 2 and 3 to signify DEC treatment effects on infection intensity reduction. PCR and sequencing of βετα-tubulin gene retained in 7 WbMf isolates were performed to analyze two discrete exons linked with benzimidazole selection: 141bp (Phe167Tyr) and 174bp amplicons (Phe200Tyr). Results: Significant 3-month antigen load reduction between the groups was pronounced (Table 1). In microfilaremic group, Mf density rebounded up to pretreatment level whereas parasite load (WbMf and WbAg) reduction did not correlate with time. Sequence analysis revealed homology of the fragments (Fig. 1) against filarial homologs deposited in genome databases, which neither point mutation was detected in all isolates. Conclusion: The IBF predominantly susceptible to benzimidazole was sensitive to DEC that is still a best-buy public health in-