| Hojong Jun | 11 Articles |
Baseline genetic characterization of malaria vector populations provides critical data for evidence-based surveillance in persistent transmission foci. This pilot study generated preliminary genetic baseline data for Anopheles populations in the Menoreh Hills border region between Central Java and Yogyakarta provinces, Indonesia, addressing a key geographic gap in regional vector research. Adult female mosquitoes were collected from 3 houses with reported malaria cases in Ngadirejo Village using standardized entomological methods, including human landing, animal landing, and resting collections. Specimens were morphologically identified and molecularly characterized via ITS2 gene sequencing. Phylogenetic analyses were assessed using maximum likelihood methods, and genetic diversity indices were calculated to examine population structure. A total of 62 specimens representing 3 species were collected exclusively through animal landing collections: Anopheles vagus (48 specimens, 77.4%), Anopheles maculatus (9 specimens, 14.5%), and Anopheles kochi (5 specimens, 8.1%). An. kochi exhibited high haplotype diversity (Hd=0.709) with low nucleotide diversity (π=0.004), while An. maculatus showed lower haplotype diversity (Hd=0.480) and higher nucleotide diversity (π=0.026). Phylogenetic analysis revealed Purworejo specimens clustered with regional populations: An. kochi grouped within Clade I with Indonesian isolates; An. maculatus distributed across multiple clades; An. vagus formed a cohesive unit with other Indonesian populations. The exclusive success of animal landing collections in the Menoreh Hills highlands provides key methodological insights. This study offers essential baseline reference data, validates cost-effective genetic surveillance approaches, and supports future large-scale population connectivity studies across the Menoreh Hills malaria transmission complex.
As many countries implement different programs aimed at eliminating malaria, attention should be given to asymptomatic carriers that may interrupt the progress. This was a community-based cross-sectional study conducted in Tanzania from December 2022 to July 2023 within 4 villages from each of the 3 regions, Geita and Kigoma, which are high malaria transmission, and Arusha, which is low transmission. Malaria was diagnosed in asymptomatic individuals aged 1 year and older using the malaria rapid diagnostic test and light microscope. A total of 2,365 of 3,489 (67.9%) participants were enrolled from high-transmission villages. The overall prevalence was 25.5% and 15.8% by malaria rapid diagnostic test and light microscope, respectively. Using the respective tools, the prevalence was significantly higher at 35.6% (confidence interval (CI)=23.6–49.9) and 23.1% (CI=16.2–35.1) in the high-transmission regions (Geita and Kigoma) compared with 2.9% (CI=1.1–3.5) and 1.1% (CI=0.7–1.8) in the low-transmission region (Arusha). Children younger than 15 years and males accounted for the greatest proportion of infections. In the study area, the prevalence of asymptomatic cases was higher than that of reported symptomatic cases in health facilities. We hypothesize that these parasite reservoirs may contribute to the persistence of malaria in the country. Therefore, to achieve comprehensive malaria control in the country, the surveillance and screening of asymptomatic malaria cases are vital.
Citations Citations to this article as recorded by
Clonorchis sinensis, which causes clonorchiasis, is prevalent in East Asian countries and poses notable health risks, including bile duct complications. Although praziquantel is the primary treatment for the disease, the emerging resistance among trematodes highlights the need for alternative strategies. Understanding the nutrient uptake mechanisms in trematodes, including C. sinensis, is crucial for developing future effective treatments. This study aimed to characterize the function of C. sinensis glucose transporter 4 (CsGTP4) and determine its role in nutrient uptake employing synthesized cDNA of adult C. sinensis worms. The functional characterization of CsGTP4 involved injecting its cRNA into Xenopus laevis oocytes and analyzing the deoxy-D-glucose uptake levels. The results demonstrated that deoxy-D-glucose uptake depended on the deoxy-D-glucose incubation and CsGTP4 expression time, but not sodium-dependent. The concentration-dependent uptake followed the Michaelis–Menten equation, with a Km value of 2.7 mM and a Vmax value of 476 pmol/oocyte/h based on the Lineweaver–Burk analysis. No uptake of radiolabeled α-ketoglutarate, p-aminohippurate, taurocholate, arginine, or carnitine was observed. The uptake of deoxy-D-glucose by CsGTP4 was significantly inhibited by unlabeled glucose and galactose in a concentration-dependent manner. It was significantly inhibited under strongly acidic and basic conditions. These insights into the glucose uptake kinetics and pH dependency of CsGTP4 provide a deeper understanding of nutrient acquisition in trematodes. This study contributes to the development of novel antiparasitic agents, addressing a considerable socioeconomic challenge in affected regions.
Citations Citations to this article as recorded by
Life cycle stages, including daughter sporocysts, cercariae, and metacercariae, of Parvatrema duboisi (Dollfus, 1923) Bartoli, 1974 (Digenea: Gymnophallidae) have been found in the Manila clam Ruditapes philippinarum from Aphaedo (Island), Shinan-gun, Jeollanam-do, Korea. The daughter sporocysts were elongated sac-like and 307-570 (av. 395) μm long and 101-213 (av. 157) μm wide. Most of the daughter sporocysts contained 15-20 furcocercous cercariae each. The cercariae measured 112-146 (av. 134) μm in total length and 35-46 (av. 40) μm in width, with 69-92 (av. 85) μm long body and 39-54 (av. 49) μm long tail. The metacercariae were 210-250 (av. 231) μm in length and 170-195 (av. 185) μm in width, and characterized by having a large oral sucker, genital pore some distance anterior to the ventral sucker, no ventral pit, and 1 compact or slightly lobed vitellarium, strongly suggesting P. duboisi. The metacercariae were experimentally infected to ICR mice, and adults were recovered at day 7 post-infection. The adult flukes were morphologically similar to the metacercariae except in the presence of up to 20 eggs in the uterus. The daughter sporocysts and metacercariae were molecularly (ITS1-5.8S rDNA-ITS2) analyzed to confirm the species, and the results showed 99.8-99.9% identity with P. duboisi reported from Kyushu, Japan and Gochang, Korea. These results confirmed the presence of various life cycle stages of P. duboisi in the Manila clam, R. philippinarum, playing the role of the first as well as the second intermediate host, on Aphae-do (Island), Shinan-gun, Korea.
Citations Citations to this article as recorded by
Knockdown resistance (kdr) mutations in the voltage-gated sodium channel (VGSC) of mosquitoes confer resistance to insecticides. Although insecticide resistance has been suspected to be widespread in the natural population of Aedes aegypti in Myanmar, only limited information is currently available. The overall prevalence and distribution of kdr mutations was analyzed in Ae. aegypti from Mandalay areas, Myanmar. Sequence analysis of the VGSC in Ae. aegypti from Myanmar revealed amino acid mutations at 13 and 11 positions in domains II and III of VGSC, respectively. High frequencies of S989P (68.6%), V1016G (73.5%), and F1534C (40.1%) were found in domains II and III. T1520I was also found, but the frequency was low (8.1%). The frequency of S989P/V1016G was high (55.0%), and the frequencies of V1016G/F1534C and S989P/V1016G/F1534C were also high at 30.1% and 23.5%, respectively. Novel mutations in domain II (L963Q, M976I, V977A, M994T, L995F, V996M/A, D998N, V999A, N1013D, and F1020S) and domain III (K1514R, Y1523H, V1529A, F1534L, F1537S, V1546A, F1551S, G1581D, and K1584R) were also identified. These results collectively suggest that high frequencies of kdr mutations were identified in Myanmar Ae. aegypti, indicating a high level of insecticide resistance.
Citations Citations to this article as recorded by
Mosquitoes are globally distributed and important vectors for the transmission of many human diseases. Mosquito control is a difficult task and the cost of preventing mosquito-borne diseases is much lower than that for curing the associated diseases. Thus, chemical control remains the most effective tool for mosquito. Due to the long-term intensive use of insecticides to control mosquito vectors, resistance to most chemical insecticides has been reported. This study aimed to investigate the relationship between insecticide resistance and target site mutation of L1014 kdr and G119 ace alleles in 5 species/species group of mosquitoes (Aedes vexans, Ae. albopictus, Anopheles spp., Culex pipiens complex, and Cx. tritaeniorhynchus) obtained from 6 collection sites. For Anopheles spp., the proportion of mosquitoes with mutated alleles in L1014 was 88.4%, homozygous resistant genotypes were observed in 46.7%, and heterozygous resistant genotypes were observed in 41.8%. For the Cx. pipiens complex and Cx. tritaeniorhynchus species, homozygous resistant genotypes were found in 25.9% and 9.8%, respectively. However, target site mutation of L1014 in the Ae. vexans nipponii and Ae. albopictus species was not observed. Anopheles spp., Cx. pipiens complex, and Cx. tritaeniorhynchus mosquitoes were resistant to deltamethrin and chlorpyriphos, whereas Ae. vexans nipponii and Ae. albopictus were clearly susceptible. We also found a correlation between the resistance phenotype and the presence of the L1014 kdr and G119 ace mutations only in the Anopheles spp. population. In this study, we suggest that insecticide resistance poses a growing threat and resistance management must be integrated into all mosquito control programs.
Citations Citations to this article as recorded by
The flaviviruses are small single-stranded RNA viruses that are typically transmitted by mosquitoes or tick vectors and are etiological agents of acute zoonotic infections. The viruses are found around the world and account for significant cases of human diseases. We investigated population of culicine mosquitoes in central region of Korean Peninsula, Incheon Metropolitan City and Hwaseong-si. Aedes vexans nipponii was the most frequently collected mosquitoes (56.5%), followed by Ochlerotatus dorsalis (23.6%), Anopheles spp. (10.9%), and Culex pipiens complex (5.9%). In rural regions of Hwaseong, Aedes vexans nipponii was the highest population (62.9%), followed by Ochlerotatus dorsalis (23.9%) and Anopheles spp. (12.0%). In another rural region of Incheon (habitat of migratory birds), Culex pipiens complex was the highest population (31.4%), followed by Ochlerotatus dorsalis (30.5%), and Aedes vexans vexans (27.5%). Culex pipiens complex was the predominant species in the urban region (84.7%). Culicine mosquitoes were identified at the species level, pooled up to 30 mosquitoes each, and tested for flaviviral RNA using the SYBR Green-based RT-PCR and confirmed by cDNA sequencing. Three of the assayed 2,683 pools (989 pools without Anopheles spp.) were positive for Culex flaviviruses, an insect-specific virus, from Culex pipiens pallens collected at the habitats for migratory birds in Incheon. The maximum likelihood estimation (the estimated number) for Culex pipiens pallens positive for Culex flavivirus was 25. Although viruses responsible for mosquito-borne diseases were not identified, we encourage intensified monitoring and long-term surveillance of both vector and viruses in the interest of global public health.
Citations Citations to this article as recorded by
Owing to global climate change, the global resurgence of vector-borne infectious diseases and their potential to inflict widespread casualties among human populations has emerged as a pivotal burden on public health systems. Tsutsugamushi disease (scrub typhus) in the Republic of Korea is steadily increasing and was designated as a legal communicable disease in 1994. The disease is a mite-borne acute febrile disease most commonly contracted from October to December. In this study, we tried to determine the prevalence of tsutsugamushi disease transmitted by chigger mites living on rodents and investigated their target vector diversity, abundance, and distribution to enable the mapping of hotspots for this disease in 2015. A total of 5 species belonging to 4 genera (109 mites): Leptotrombidium scutellare 60.6%, L. pallidum 28.4% Neotrombicula tamiyai 9.2%, Euschoengastia koreaensis/0.9%), and Neoschoengastia asakawa 0.9% were collected using chigger mite collecting traps mimicking human skin odor and sticky chigger traps from April to November 2015. Chigger mites causing tsutsugamushi disease in wild rodents were also collected in Hwaseong for the zoonotic surveillance of the vector. A total of 77 rodents belonging to 3 genera: Apodemus agrarius (93.5%), Crocidura lasiura (5.2%), and Micromys minutus (1.3%) were collected in April, October, and November 2015. The most common mite was L. pallidum (46.9%), followed by L. scutellare (18.6%), and L. orientale (18.0%). However, any of the chigger mite pools collected from rodent hosts was tested positive for Orientia tsutsugamushi, the pathogen of tsutsugamushi disease, in this survey.
Citations Citations to this article as recorded by
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 (Haemaphysalis longicornis, H. flava, and Ixodes nipponensis) were collected with collection traps. Of the identified ticks, H. longicornis was the most frequently collected ticks (except larval ticks) (94.26%, 8,653/9,180 ticks (nymphs and adults)), followed by H. flava (5.71%, 524/9,180) and Ix. nipponensis (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 (H. longicornis, H. flava, and Ix. nipponensis) were collected with flagging method. H. longicornis was the highest collected ticks (except larval ticks) (99.53%, 1,908/1,917 ticks (nymphs and adults)), followed by H. flava (1.15%, 22/1,917).
Citations Citations to this article as recorded by
Toxoplasma gondii is an apicomplexan parasite that can cause toxoplasmosis in a wide range of warm-blooded animals including humans. In this study, we analyzed seroprevalence of T. gondii among 467 school children living in the rural areas of Pyin Oo Lwin and Naung Cho, Myanmar. The overall seroprevalence of T. gondii among school children was 23.5%; 22.5% of children were positive for T. gondii IgG, 0.4% of children were positive for T. gondii IgM, and 0.6% of children were positive for both T. gondii IgG and IgM. Geographical factors did not significantly affect the seroprevalence frequency between Pyin Oo Lwin and Naung Cho, Myanmar. No significant difference was found between males (22.2%) and females (25.0%). The overall seroprevalence among school children differed by ages (10 years old [13.6%], 11-12 years old [19.8%], 13-14 years old [24.6%], and 15-16 years old [28.0%]), however, the result was not significant. Polymerase chain reaction analysis for T. gondii B1 gene for IgG-positive and IgM-positive blood samples were negative, indicating no direct evidence of active infection. These results collectively suggest that T. gondii infection among school children in Myanmar was relatively high. Integrated and improved strategies including reinforced education on toxoplasmosis should be implemented to prevent and control T. gondii infection among school children in Myanmar.
Citations Citations to this article as recorded by
Echinostoma cinetorchis is an oriental intestinal fluke causing significant pathological damage to the small intestine. The aim of this study was to determine a full-length cDNA sequence of E. cinetorchis endoribonuclease (RNase H; EcRNH) and to elucidate its molecular biological characters. EcRNH consisted of 308 amino acids and showed low similarity to endoribonucleases of other parasites (<40%). EcRNH had an active site centered on a putative DDEED motif instead of DEDD conserved in other species. A recombinant EcRNH produced as a soluble form in Escherichia coli showed enzymatic activity to cleave the 3'-O-P bond of RNA in a DNA-RNA duplex, producing 3'-hydroxyl and 5'-phosphate. These findings may contribute to develop antisense oligonucleotides which could damage echinostomes and other flukes.
|
|
