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Thailand

Genetic polymorphism of the extracellular region in surface associated interspersed 1.1 gene of Plasmodium falciparum field isolates from Thailand

August 18, 2021 - 16:27 -- Open Access
Author(s): 
Natpasit Chaianantakul, Tippawan Sungkapong, Jirapinya Changpad, Keawalin Thongma, Sasiwimon Sim-ut and Morakot Kaewthamasorn
Reference: 
Malaria Journal 2021 20:343, 16 August 2021

A novel variable surface antigens (VSAs), Surface-associated interspersed proteins (SUFRINs), is a protein that is modified on the surface of infected red blood cell (iRBC). Modified proteins on the iRBC surface cause severe malaria, which can lead to death throughout the life cycle of a malaria parasite. Previous study suggested that SURFIN1.1 is an immunogenic membrane-associated protein which was encoded by using the surf1.1 gene expressed during the trophozoite and schizont stages. This study aimed to identify the regions of SURFIN1.1 and investigate the genetic diversity of the extracellular region of the surf1.1 gene.

NOT Open Access | Molecular Detection of Mutations in the Propeller Domain of Kelch 13 and pfmdr1 Copy Number Variation in Plasmodium falciparum Isolates from Thailand Collected from 2002 to 2007

July 21, 2021 - 17:03 -- NOT Open Access
Author(s): 
Chaisatit C, Sai-Ngam P, Thaloengsok S, Sriwichai S, Jongsakul K, Fukuda M, Spring M, Wojnarski M, Waters N, Lertsethtakarn P, Vesely BA
Reference: 
Am J Trop Med Hyg. 2021 Jul 16:tpmd210303

We determined the prevalence of Kelch 13 mutations and pfmdr1 copy number in samples collected from the Thailand-Myanmar border, the Thailand-Cambodia border, and southern Thailand from 2002 to 2007.

Plasmodium falciparum phenotypic and genotypic resistance profile during the emergence of Piperaquine resistance in Northeastern Thailand

June 30, 2021 - 09:39 -- Open Access
Author(s): 
Boonyalai N, Thamnurak C, Gaywee J, et al.
Reference: 
Sci Rep. 2021 Jun 28;11(1):13419

Malaria remains a public health problem in Thailand, especially along its borders where highly mobile populations can contribute to persistent transmission. This study aimed to determine resistant genotypes and phenotypes of 112 Plasmodium falciparum isolates from patients along the Thai-Cambodia border during 2013-2015. The majority of parasites harbored a pfmdr1-Y184F mutation. A single pfmdr1 copy number had CVIET haplotype of amino acids 72-76 of pfcrt and no pfcytb mutations. All isolates had a single pfk13 point mutation (R539T, R539I, or C580Y), and increased % survival in the ring-stage survival assay (except for R539I).

Progress and challenges of integrated drug efficacy surveillance for uncomplicated malaria in Thailand

June 16, 2021 - 12:34 -- Open Access
Author(s): 
Prayuth Sudathip, Aungkana Saejeng, Jui A. Shah, et al.
Reference: 
Malaria Journal 2021 20:261, 9 June 2021

Integrated drug efficacy surveillance (iDES) was formally introduced nationally across Thailand in fiscal year 2018 (FY2018), building on a history of drug efficacy monitoring and interventions. According to the National Malaria Elimination Strategy for Thailand 2017–2026, diagnosis is microscopically confirmed, treatment is prescribed, and patients are followed up four times to ensure cure.

NOT Open Access | Forced Egg Laying Method to Establish F1 Progeny from Field Populations and Laboratory Strains of Anopheles Mosquitoes (Diptera: Culicidae) in Thailand

June 15, 2021 - 14:30 -- NOT Open Access
Author(s): 
Panthawong A, Sukkanon C, Ngoen-Klan R, Hii J, Chareonviriyaphap T
Reference: 
J Med Entomol. 2021 Jun 9:tjab105

Successful monitoring of physiological resistance of malaria vectors requires about 150 female mosquitoes for a single set of tests. In some situations, the sampling effort is insufficient due to the low number of field-caught mosquitoes. To address this challenge, we demonstrate the feasibility of using the forced oviposition method for producing F1 from field-caught Anopheles mosquitoes.

NOT Open Access | Trophic Behavior and Species Diversity of the Anopheles barbirostris Complex (Diptera: Culicidae) in Thailand

May 5, 2021 - 10:25 -- NOT Open Access
Author(s): 
Udom C, Thanispong K, Manguin S, Chareonviriyaphap T, Fungfuang W
Reference: 
J Med Entomol. 2021 May 4:tjab067

Species of the Anopheles barbirostris complex (Myzorhynchus Series of the subgenus Anopheles) are potential vectors of malaria and filariasis parasites. Owing to the lack of reliable identification methods, the biting activity and host preference of the species within this complex have not been previous described. In this study, the trophic behavior and host preferences of the species in the complex were determined in Thailand, and a map of their geographical distributions constructed.

Implementation and success factors from Thailand’s 1-3-7 surveillance strategy for malaria elimination

April 28, 2021 - 15:52 -- Open Access
Author(s): 
Cheewanan Lertpiriyasuwat, Prayuth Sudathip, Preecha Prempree, et al.
Reference: 
Malaria Journal 2021 20:201, 27 April 2021

Thailand’s National Malaria Elimination Strategy 2017–2026 introduced the 1-3-7 strategy as a robust surveillance and response approach for elimination that would prioritize timely, evidence-based action. Under this strategy, cases are reported within 1 day, cases are investigated within 3 days, and foci are investigated and responded to within 7 days, building on Thailand’s long history of conducting case investigation since the 1980s. However, the hallmark of the 1-3-7 strategy is timeliness, with strict deadlines for reporting and response to accelerate elimination.

Glucose-6-phosphate dehydrogenase mutations in malaria endemic area of Thailand by multiplexed high‐resolution melting curve analysis

April 21, 2021 - 15:07 -- Open Access
Author(s): 
Usa Boonyuen, Duantida Songdej, Mallika Imwong, et al.
Reference: 
Malaria Journal 2021 20:194, 20 April 2021

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, the most common enzymopathy in humans, is prevalent in tropical and subtropical areas where malaria is endemic. Anti-malarial drugs, such as primaquine and tafenoquine, can cause haemolysis in G6PD-deficient individuals. Hence, G6PD testing is recommended before radical treatment against vivax malaria. Phenotypic assays have been widely used for screening G6PD deficiency, but in heterozygous females, the random lyonization causes difficulty in interpreting the results. Over 200 G6PD variants have been identified, which form genotypes associated with differences in the degree of G6PD deficiency and vulnerability to haemolysis. This study aimed to assess the frequency of G6PD mutations using a newly developed molecular genotyping test.

A foci cohort analysis to monitor successful and persistent foci under Thailand’s Malaria Elimination Strategy

March 3, 2021 - 15:43 -- Open Access
Author(s): 
Prayuth Sudathip, Suravadee Kitchakarn, Jui A. Shah, Donal Bisanzio, Felicity Young, Deyer Gopinath, Niparueradee Pinyajeerapat, David Sintasath and Cheewanan Lertpiriyasuwat
Reference: 
Malaria Journal 2021 20:118, 27 February 2021

Thailand’s success in reducing malaria burden is built on the efficient “1-3-7” strategy applied to the surveillance system. The strategy is based on rapid case notification within 1 day, case investigation within 3 days, and targeted foci response to reduce the spread of Plasmodium spp. within 7 days. Autochthonous transmission is still occurring in the country, threatening the goal of reaching malaria-free status by 2024. This study aimed to assess the effectiveness of the 1-3-7 strategy and identify factors associated with presence of active foci.

Immunoglobulin G responses to variant forms of Plasmodium vivax merozoite surface protein 9 upon natural infection in Thailand

February 8, 2021 - 10:16 -- Open Access
Author(s): 
Songsaigath S, Makiuchi T, Putaporntip C, Pattanawong U, Kuamsab N, Tachibana H, Jongwutiwes S
Reference: 
Sci Rep. 2021 Feb 5;11(1):3201

Merozoite surface protein 9 (MSP9) constitutes a ligand complex involved in erythrocyte invasion by malarial merozoites and is a promising vaccine target. Plasmodium vivax MSP9 (PvMSP9) is immunogenic upon natural malaria exposure. To address whether sequence diversity in PvMSP9 among field isolates could affect natural antibody responses, the recombinant proteins representing two variants each for the N- and the C-terminal domains of PvMSP-9 were used as antigens to assess antibody reactivity among 246 P. vivax-infected patients' sera from Tak and Ubon Ratchathani Provinces in Thailand.

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