BackgroundAccurate diagnosis of Plasmodium infection is crucial for prompt malaria treatment and surveillance. Microscopic examination has been widely applied as the gold standard for malaria diagnosis in most part of malaria endemic areas, but its diagnostic value has been questioned, particularly in submicroscopic malaria. In this study, the diagnostic performance of microscopic examination and nested polymerase chain reaction (PCR) was evaluated to establish optimal malaria diagnosis method in Myanmar.MethodsA total of 1125 blood samples collected from residents in the villages and towns located in Naung Cho, Pyin Oo Lwin, Tha Beik Kyin townships and Mandalay of Upper Myanmar were screened by microscopic examination and species-specific nested PCR method.ResultsAmong the 1125 blood samples, 261 samples were confirmed to be infected with malaria by microscopic examination. Evaluation of the 1125 samples by species-specific nested PCR analysis revealed that the agreement between microscopic examination and nested PCR was 87.3% (261/299). Nested PCR successfully detected 38 Plasmodium falciparum or Plasmodium vivax infections, which were missed in microscopic examination. Microscopic examinations also either misdiagnosed the infected Plasmodium species, or did not detect mixed infections with different Plasmodium species in 31 cases.ConclusionsThe nested PCR method is more reliable than conventional microscopic examination for the diagnosis of malaria infections, and this is particularly true in cases of mixed infections and submicroscopic infections. Given the observed higher sensitivity and specificity of nested PCR, the molecular method holds enormous promise in malaria diagnosis and species differentiation, and can be applied as an effective monitoring tool for malaria surveillance, control and elimination in Myanmar.

BackgroundPlasmodium vivax apical membrane antigen-1 (PvAMA-1) is a leading candidate antigen for blood stage malaria vaccine. However, antigenic variation is a major obstacle in the development of an effective vaccine based on this antigen. In this study, the genetic structure and the effect of natural selection of PvAMA-1 among Korean P. vivax isolates were analysed.MethodsBlood samples were collected from 66 Korean patients with vivax malaria. The entire PvAMA-1 gene was amplified by polymerase chain reaction and cloned into a TA cloning vector. The PvAMA-1 sequence of each isolate was sequenced and the polymorphic characteristics and effect of natural selection were analysed using the DNASTAR, MEGA4, and DnaSP programs.ResultsThirty haplotypes of PvAMA-1, which were further classified into seven different clusters, were identified in the 66 Korean P. vivax isolates. Domain II was highly conserved among the sequences, but substantial nucleotide diversity was observed in domains I and III. The difference between the rates of non-synonymous and synonymous mutations suggested that the gene has evolved under natural selection. No strong evidence indicating balancing or positive selection on PvAMA-1 was identified. Recombination may also play a role in the resulting genetic diversity of PvAMA-1.ConclusionsThis study is the first comprehensive analysis of nucleotide diversity across the entire PvAMA-1 gene using a single population sample from Korea. Korean PvAMA-1 had limited genetic diversity compared to PvAMA-1 in global isolates. The overall pattern of genetic polymorphism of Korean PvAMA-1 differed from other global isolates and novel amino acid changes were also identified in Korean PvAMA-1. Evidences for natural selection and recombination event were observed, which is likely to play an important role in generating genetic diversity across the PvAMA-1. These results provide useful information for the understanding the population structure of P. vivax circulating in Korea and have important implications for the design of a vaccine incorporating PvAMA-1.

The seasonal abundance of hard ticks that transmit severe fever with thrombocytopenia syndrome virus was monitored with a collection trap method every April to November during 2015-2018 and with a flagging method every July and August during 2015-2018 in Ganghwa-do (island) of Incheon Metropolitan City, Republic of Korea. This monitoring was performed in a copse, a short grass field, coniferous forest and broad-leaved forest. A total of 17,457 ticks (8,277 larvae, 4,137 nymphs, 3,389 females, and 1,654 males) of the ixodid ticks comprising 3 species (<i>Haemaphysalis</i> <i>longicornis</i>, <i>H</i>. <i>flava</i>, and <i>Ixodes</i> <i>nipponensis</i>) were collected with collection traps. Of the identified ticks, <i>H</i>. <i>longicornis</i> was the most frequently collected ticks (except larval ticks) (94.26%, 8,653/9,180 ticks (nymphs and adults)), followed by <i>H</i>. <i>flava</i> (5.71%, 524/9,180) and <i>Ix</i>. <i>nipponensis</i> (less than 0.04%, 3/9,180). The ticks collected with collecting traps were pooled and assayed for the presence of SFTS virus with negative results. In addition, for monitoring the prevalence of hard ticks, a total of 7,461 ticks (5,529 larvae, 1,272 nymphs, 469 females, and 191 males) of the ixodid ticks comprising 3 species (<i>H</i>. <i>longicornis</i>, <i>H</i>. <i>flava</i>, and <i>Ix</i>. <i>nipponensis</i>) were collected with flagging method. <i>H</i>. <i>longicornis</i> was the highest collected ticks (except larval ticks) (99.53%, 1,908/1,917 ticks (nymphs and adults)), followed by <i>H</i>. <i>flava</i> (1.15%, 22/1,917).

hydrogen bonding between PEG and water increases solubility of the MBP. At neutral pH, the increased degree of ionization of the carboxylic acid groups makes the system soluble. In the intermediate pH range of 4±6, where the two opposing forces are balanced, the system seems to have minimal solubility and forms a gel phase. This is similar to the solubility of insulin, which is minimal at pH 4.5±5.5, where ionization of amino groups (positively charged) and carboxylic acid groups (negatively charged) are balanced to give electrically neutral species.[13]The multiblock-copolymer aqueous solution (30 wt.-%) is a low-viscosity sol (g¢~100 Pas) at 37 C at pH 7.4, indicating that the polymer solution can be injected without gelling and blocking a needle. In addition, the adhesive force of the multiblock poloxamer gel at pH 4±6 (about 14±16 Pa) increased by more than ten times from that of the original poloxamer (P85 has an adhesive force of about 1 Pa) by the introduction of the carboxylic acid. The increased adhesion force indicates the stability of the gel at the applied sites. An in-vitro study showed that the gel prepared from a BMP solution (30 wt.-%) persists for two days at pH 4.5 (vaginal pH), which is three times longer than the poloxamer (P85) gel.In conclusion, we are reporting a unique closed-loop sol±gel±sol transition of a multiblock-poloxamer aqueous solution as a function of pH. The counterbalance between the ionization of carboxylic acid groups and the PEG solubility in water seem to be responsible for the phase behavior. The problems of injectability and the small adhesive force of the unmodified poloxamer were significantly improved by our multiblock-copolymer system. ExperimentalThe poloxamer (P85 obtained from BASF, consisting of ethylene glycol (EG) and propylene glycol (PG) blocks in the ratio (EG) 26 -(PG) 40 -(EG) 26 ) was dissolved in toluene, and the solvent was partially removed by distillation in order to remove adsorbed water from the polymer. Terephthalic anhydride (Aldrich) and triethylamine (Aldrich) were added, and the reaction mixtures were stirred at 100 C for 12 h. The product was isolated by precipitation into diethyl ether, and residual solvent was removed under vacuum. The 1 H NMR (CDCl 3 ) spectrum of the multiblock poloxamer shows the ethylene glycol unit (3.6 ppm), propylene glycol unit (1.5 ppm), and aromatic hydrogens (7.2 ppm). Fourier-transform IR (FTIR) spectroscopy shows the ester formation at 1730 cm ±1 by the coupling reaction. For gel permeation chromatography (GPC) analysis, tetrahydrofuran was used as an eluting solvent, and poly(ethylene glycol) standards with molecular weights of 1000 g mol ±1 , 4600 g mol ±1 , 10 000 g mol ±1 , and 30 000 g mol ±1 were used for calibration. Styragel columns (HT3, used in series) were used. The weight-average molecular weight of the multiblock poloxamer was 10 000 g mol ±1 . The sol-to-gel transition of the polymer aqueous solution was investigated using dynamic rheometry (Thermo Haake, Rheometer RS 1) by the method previously de...

BackgroundAfter the re-emergence of Plasmodium vivax in 1993, a total of 31,254 cases of vivax malaria were reported between 1993–2012 in the Republic of Korea (ROK). The purpose of this study was to review Korea Centers for Disease Control and Prevention records to investigate the transmission of malaria from 2010–2012.MethodsReporting of microscopy-diagnosed cases of malaria is mandatory in the ROK. In this study, all available records of malaria cases and malaria vectors collected from 2010 – 2012 in Cheorwon County, Gangwon Province and Ganghwa County, Incheon Metropolitan City, were reviewed.ResultsAlthough the number of cases of malaria peaked a third time in 2010 (1,772 cases) since the re-emergence of P. vivax, the incidence decreased two-fold to 838 in 2011 and three-fold to 555 in 2012. The number of cases decreased 52.7% in 2011 compared with that in 2010 and 33.8% in 2012 compared with that in 2011. However, the number of cases increased in Incheon Metropolitan City (15.3%) and Gyeongnam Province (23.1%) in 2012 compared with 2011. Of the 3,165 cases of vivax malaria in 2010–2012, 798 (25.2%) were in ROK military personnel, 519 (16.4%) in veterans, and 1,848 (58.4%) in civilians. In total, there were 2,666 male patients and 499 female patients, and the ratio of female to male patients increased from 1:7.9 in 2011 to 1:4.1 in 2012.ConclusionsA rapid decrease in the incidence of malaria was observed in most areas from 2010 to 2012, but the incidence increased again in the western part of the demilitarized zone. Therefore, more intensive surveillance is needed throughout high risk areas to identify factors responsible for increase/decrease in the incidence of malaria in the ROK.