Effect of Mass Drug Administration with a Single Dose of Albendazole on Ascaris lumbricoides and Trichuris trichiura Infection among Schoolchildren in Yangon Region, Myanmar.

Soil-transmitted helminths, including Ascaris lumbricoides and Trichuris trichiura, are important intestinal parasites mostly affecting younger people in developing countries. In 2014-2015, we performed mass fecal examinations targeting a total of 2,227 schoolchildren in 3 districts (South Dagon, North Dagon, and Hlaing-thar-yar) of Yangon Region, Myanmar, using the Kato-Katz thick smear technique. The egg positive children were subjected to a mass drug administration (MDA) using a single oral dose of 400 mg albendazole. The pre-treatment egg positive rate (EPG/person) of A. lumbricoides averaged 17.2% (15,532); it was 25.2% (21,796), 14.2% (11,816), and 12.8% (12,983) in 3 districts, respectively, and that of T. trichiura averaged 19.4% (1,074), and was 24.1% (1,040), 12.3% (852), and 21.2% (1,330) in 3 districts, respectively. Follow-up fecal examinations performed 4 months post-MDA revealed considerable decreases of A. lumbricoides prevalence (EPG/person) to av. 8.3% (12,429), and 13.7% (17,640), 8.0% (7,797), and 4.5% (11,849) in 3 districts, respectively. However, T. trichiura did not show any recognizable decrease in the prevalence (EPG/person) remaining at av. 18.2% (862), and 18.5% (888), 11.5% (812), and 23.3% (887) in 3 districts, respectively. The results demonstrated difficulty in short-term control of T. trichiura by MDA using albendazole and suggested necessity of either a long-term MDA (>10 years) or changing the albendazole regimen into 2~3-day course (total 800 or 1,200 mg), or using an alternative drug/drug combination.

Low-Grade Endemicity of Opisthorchiasis, Yangon, Myanmar.

We performed an epidemiologic survey of opisthorchiasis in Yangon, Myanmar. The fecal egg-positive rate of residents was 0.7%, and we recovered an adult fluke after chemotherapy and purging of an egg-positive resident. We detected Opisthorchis viverrini metacercariae in freshwater fish. We found the Yangon area to have low-grade endemicity of opisthorchiasis.

Zoonotic Trematode Metacercariae in Fish from Yangon, Myanmar and Their Adults Recovered from Experimental Animals.

A survey was performed to investigate the infection status of zoonotic trematode (ZT) metacercariae in fish from a local market in Yangon City, Myanmar. A total of 264 fish (12 species) were collected through 4 times from December 2013 to June 2015. All collected fish were transferred to our laboratory on ice and examined by the artificial digestion method. More than 7 species of ZT metacercariae, i.e., Haplorchis taichui, H. pumilio, H. yokogawai, Centrocestus spp., Stellantchasmus falcatus, Pygidiopsis cambodiensis, and Procerovum sp. were detected. Metacercariae of H. taichui were collected in 58 (42.3%) out of 137 fish (5 species), and their average density was 42.9 per fish infected. Metacercariae of H. pumilio were detected in 96 (49.0%) out of 196 fish (9 species), and their average density was 23.6 per fish infected. H. yokogawai metacercariae were found in 40 (50.0%) out of 80 fish (5 species), and Centrocestus spp. metacercariae in 91 (50.8%) out of 179 fish (8 species), and their densities were 306 and 25.8 per fish infected, respectively. Metacercariae of S. falcatus and P. cambodiensis were detected only in mullets, Chelon macrolepis. A total of 280 Procerovum sp. metacercariae were found in 6 out of 12 climbing perch, Anabas testudineus. Morphological characteristics of adult flukes recovered from experimental animals were described. It has been first confirmed that fish from Yangon, Myanmar are commonly infected with various species of ZT metacercariae.

Larval Gnathostoma spinigerum Detected in Asian Swamp Eels, Monopterus albus, Purchased from a Local Market in Yangon, Myanmar.

The present study was performed to determine the infection status of swamp eels with Gnathostoma sp. larvae in Myanmar. We purchased total 37 Asian swamp eels, Monopterus albus, from a local market in Yangon in June and December 2013 and 2014. All collected eels were transferred with ice to our laboratory and each of them was examined by the artificial digestion technique. A total of 401 larval gnathostomes (1-96 larvae/eel) were detected in 33 (89.2%) swamp eels. Most of the larvae (n=383; 95.5%) were found in the muscle. The remaining 18 larvae were detected in the viscera. The advanced third-stage larvae (AdL3) were 2.3-4.4 mm long and 0.25-0.425 mm wide. The characteristic head bulb (0.093 × 0.221 mm in average size) with 4 rows of hooklets, muscular long esophagus (1.025 mm), and 2 pairs of cervical sacs (0.574 mm) were observed by light microscopy. The average number of hooklets in the 1st, 2nd, 3rd, and 4th rows was 41, 45, 48, and 51, respectively. As scanning electron microscopic findings, the characteristic 4-5 rows of hooklets on the head bulb, a cervical papilla, tegumental spines regularly arranged in the transverse striations, and an anus were well observed. Based on these morphological characters, they were identified as the AdL3 of Gnathostoma spinigerum. By the present study, it has been confirmed for the first time that Asian swamp eels, M. albus, from Yangon, Myanmar are heavily infected with G. spinigerum larvae.

High Prevalence of Enterobius vermicularis Infection among Schoolchildren in Three Townships around Yangon, Myanmar.

In order to determine the status of Enterobius vermicularis infection among schoolchildren in suburban areas of Myanmar, 761 primary schoolchildren in 3 different townships around Yangon City were subjected to a survey using cello-tape anal swabs. The subjected schoolchildren were 383 boys and 378 girls who were 5-7 years of age. Only 1 anal swab was obtained from each child. The overall egg positive rate of E. vermicularis was 47.2% (359 positives), and sex difference was not remarkable (48.6% in boys and 45.8% in girls). However, the positive rate was the highest in South Dagon (54.6%) followed by Hlaing Thayar (43.8%) and North Dagon (34.8%). This difference was highly correlated with the living standards of the people in each township. Nucleotide sequence of the 5S rDNA from the eggs on the cello-tape (2 children) revealed 99.7% identity with that of E. vermicularis reported in GenBank. The results indicated that E. vermicularis infection is highly prevalent among primary schoolchildren around Yangon, Myanmar.

Laser-induced direct graphene patterning and simultaneous transferring method for graphene sensor platform.

General methods utilized in the fabrication of graphene devices involve graphene transferring and subsequent patterning of graphene via multiple wet-chemical processes. In the present study, a laser-induced pattern transfer (LIPT) method is proposed for the transferring and patterning of graphene in a single processing step. Via the direct graphene patterning and simultaneous transferring, the LIPT method greatly reduces the complexity of graphene fabrication while augmenting flexibility in graphene device design. Femtosecond laser ablation under ambient conditions is employed to transfer graphene/PMMA microscale patterns to arbitrary substrates, including a flexible film. Suspended cantilever structures are also demonstrated over a prefabricated trench structure via the single-step method. The feasibility of this method for the fabrication of functional graphene devices is confirmed by measuring the electrical response of a graphene/PMMA device under laser illumination.

Denaturing gradient gel electrophoresis analysis of bacterial populations in 5-stage biological nutrient removal process with step feed system for wastewater treatment.

Changes in the bacterial populations of a 5-stage biological nutrient removal (BNR) process, with a step feed system for wastewater treatment, were monitored by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S ribosomal DNA fragments. DGGE analysis indicated seasonal community changes were observed, however, community profiles of the total bacteria of each reactor showed only minor differences in the samples obtained from the same season. The number of major bands was higher in the summer samples, and decreased during the winter period, indicating that the microbial community structure became simpler at low temperatures. Since the nitrogen and phosphate removal efficiencies were highly maintained throughout the winter operation period, the bacteria which still remaining in the winter sample can be considered important, playing a key role in the present 5-stage BNR sludge. The prominent DGGE bands were excised, and sequenced to gain insight into the identities of the predominant bacterial populations present, and most were found to not be closely related to previously characterized bacteria. These data suggest the importance of culture-independent methods for the quality control of wastewater treatment.

Estimation of the shadow prices of pollutants with production/environment inefficiency taken into account: a nonparametric directional distance function approach.

This paper deals with the estimation of the shadow prices of pollutants with a nonparametric directional distance function approach, where the inefficiency involved in the production process is taken into account unlike the previous studies. The directional vector, which is critical to the estimation and subject to the criterion for an appropriate efficiency rule proposed here, is calculated by using the annual plans of power plants in terms of production and environment. In the empirical study for Korea's electric power industry during the period of 1990-1995, we find that the average shadow prices of sulfur oxides (SOx), nitrogen oxides (NOx), and total suspended particulates (TSP) are approximately 10% lower than those calculated under the assumption of full efficiency. The methodology we propose and the findings obtained in the empirical study allow us to undertake better decision-making over a broad range of environmental policy issues.

Practical aspects of nitrogen and phosphorous removal with floating media SBBR.

Practical aspect on the application of floating media for the sequencing batch biofilm reactor (SBBR) has not been studied in detail, especially focused on settling step, nutrient removal and temperature effects. Two types of floating media (sponge and plastic) had been examined for SBBR operation with sewage. Based on the observations with various experimental variables including temperature, media volume, operating methods, both SBBR units with sponge and plastic media generally produced a stable nitrified effluent, but depicted unstable phosphorus removal. The sponge media showed better nitrogen removal, while plastic media showed better phosphorus removal. Overall nutrient removal capability for SBBR was better than a typical SBR without media. In addition, SBBR with sponge media was capable to absorb shock loads, but could not effectively nitrify at a lower temperature even with an increased media volume. In order to produce lower SS effluent as well as minimize P release during the settling step, the floating media SBBR systems would require a dual settling stage.

Molecular characterization of microbial community in nitrate-removing activated sludge.

Abstract The microbial community composition and dominant denitrifying populations in high-nitrate-removing (CR-I) and low-nitrate-removing (CR-II) activated sludge from continuous bioreactors were investigated with most probable number (MPN) enumeration, fluorescence in situ hybridization (FISH) and 16S rDNA characterization. MPNs of nitrate-reducing bacteria of sludge CR-I and sludge CR-II were 2.82x10(7) and 2.69x10(4) colony-forming units ml(-1), respectively. Eight denitrifying bacteria and two nitrate-reducing bacteria were isolated from sludge CR-I, and four denitrifying bacteria and three nitrate-reducing bacteria from sludge CR-II. Small subunit rDNA characterization of the isolates showed that the majority belonged to the genus Pseudomonas. By using FISH up to 76% (CR-I) and 52% (CR-II) of total 4,6-diamidino-2-phenylindole cell counts hybridized to the bacterial probe EUB338. Members of beta-Proteobacteria were the most abundant proteobacterial group in both sludges, accounting for up to 41.6% and 37.1% of those detected by EUB338, respectively, whereas a higher number of Cytophaga-Flexibacter cluster members were observed in CR-I sludge compared to CR-II sludge. In contrast with culture-based results, the numbers of rRNA group I Pseudomonads accounted for less than 0.01% of those detected by EUB338 in both sludges. Ribosomal DNA clone library analysis showed that the beta-Proteobacteria were also dominant in both sludges. In CR-I sludge, they were related to Zooglorea ramigera, Alcaligenes defragrans, denitrifying Fe-oxidizing bacteria and Dechlorimonas sp., whereas in CR-II sludge, they were related to Nitrosomonas sp. and Dechlorimonas agitatus. When this reactor was operated under anaerobic and anoxic conditions, nitrifying bacteria could adapt to the anoxic environment. We inferred that anaerobic ammonium oxidation and nitrite oxidation may occur in low-nitrate-removing sludge CR-II and inhibit denitrification.