Time to stimulate Plasmodium vivax research in India: A way forwards

India bears the largest Plasmodium (P.) vivax (Pv) malaria burden and contributes 48%of Pv cases globally[1]. The efforts of government and private bodies to control malaria have successfully reduced the number of Plasmodium falciparum (Pf) malaria cases in several countries, including India.

Assessment of in vitro sensitivity of Plasmodium vivax fresh isolates

Objective:To compare the applicability of the SYBK Grcen-Ⅰ assay with the standard schizont maturalion assay,for determination of sensitivity of Plasmodium vivax(P.vivax) to chloroquine and a new antifolale WR 99210.Methods:The study was conducted at Mae Tao Clinic for migrant workers,Tak Province during April 2009 to July 2010.A total of 64 blood samples(1 mL blood collected into sodium heparinized plastic tube) were collected from patients with monoinfection with P.vivax malaria prior to treatment with standard regimen of a 3-day chloroquine. In vitro sensitivity of P.vivax isolates was evaluated by schizont maturation inhibition and SYBR Green-Ⅰ assays.Results:A total of 30 out of 64 blood samples collected from patients with P.vivax malaria were successfully analyzed using both the microscopic schizont maturation inhibition and SYBR Green-I assays.The failure rates of the schizont maturation inhibition assay(50%) and the SYBR Green-I assay(54%) were similar(P=0.51).The median IC_(10)s,IC_(50)s and IC_(90)s of both chloroquine and WR99210 were not significantly different from the clinical isolates of P.vivax tested.Based on the cut-off of 100 nM,the prevalences of chloroquine resistance determined by schizont maturation inhibition and SYBR Green-I assays were 19 and 11 isolates,respectively.The strength of agreement between the two methods was very poor for both chloroquine and WR992I0.Conclusions:On the basis of this condition and its superior sensitivity,the microscopic method appears better than the SYUK Green-I Green assay for assessing in vitro sensitivity of fresh P.vivax isolates to antimalarial drugs.

Plasmodium vivax cerebral malaria complicated with venous sinus thrombosis in Colombia

Complicated malaria is usually due to Plasmodium falciparum.Nevertheless,Plasmodium vivax is infrequently related with life-threatening complications.Few cases have been reported of severe Plasmodium vivax infection,and most of them from Southeast Asia and India.We report the first case of cerebral malaria due to Plasmodium vivax in Latin America,complicated with sagittal sinus thrombosis and confirmed by a molecular method.

Vivax malaria:a rare cause of thalamic bleed

Most common cause of thalamic bleed is hypertension;other causes are arteriovenous malformation,aneurysm,bleeding thathesis,drugs,amyloid angiopathy,tumor etc.We present a case of Plasmodium vivax(P.vivax) malaria with unusual site of bleeding i.e.left thalamus of brain.To the best of our knowledge,this is the first reported case of thalamic bleed caused by vivax malaria in absence of severe thrombocytopenia/disseminated intravascular coagulation (DIC).

The genetic polymorphism of Plasmodium vivax genes in endemic regions of Thailand

Objective:To investigate the genetic polymorphism of Plasmodium vivax(P.vivax) PvCSP and PvMSP1 genes from field isolates at four endemic regions(North,East,West and South) of Thailand.Methods:The 152 P.vivax injected cases from dried blood spots were DMA extracted and confirmed by species-specific primer sets using multiplex PCR method.PvMSPI fragments F2 and F3:PvCSP were gcnotvped using RFLP-PCR method.Resuits:Totally amplified DNA which was multiple genotypes for PvMSP1 F2 and PvMSP1 F3 were 12.50%and 8.55%.respectively while PvCSP was 3.95%.The overall frequency of multiple genotypes was 25%.There were 12 allele tvpes of PvMSP1 F2 using AluI enzyme digestion and 8 size variations were found in P\MSP1 F3.The isolates from western region was highly genetic diverse when compare among all isolates.The predominant variant type of PvCSP gene was \ K2I0 type.Conclusions:The niulliple genotypes are common found in Thailand and it might hide the real genotype.PvCSP does not have extensive genetic diversity in this study.However.PvMSPI marker due to multiple genotypes is difficult In be analyzed.The multiple genotypes findings might stem from population migration and vector species findings.

Spectrum of complications associated with Plasmodium vivax infection in a tertiary hospital in South-Western India

Objective:To determine the range and incidence of complications associated with Plasmodium vivax[P.vivax) malaria.Methods:A retrospective analysis was performed of all patients of P.vivax malaria admitted in kasturba Medical College.Manipal between January and December,2010.Patients with mixed malarial infection were excluded by appropriate tests. Clinical presentation and laboratory parameters were studied.Results:Medical records of 213 individuals who satisfied the inclusion criteria were reviewed.Anaemia was seen in 65 (30.5%),leucopenia in 38(17.8%]and thrombocytopenia in 184(86.4%l patients.Aspartate and alanine aminotransferases were elevated in 86(40.4%).and 89(41.9%) patients respectively. Hypoalbuminemia was observed in 157(73.6%) cases.Elevated serum creatinine was noted in in 59(27.5%) patients.Creatine kinase was elevated in 30 nut of 59 patients(50.8%).Overall.107 (50.2%) patients fulfilled WHO criteria for sever=e malaria.None of the patients succumbed to the disease.Conclusion:P.vivax malaria is a potentially severe disease,and the term ’ benign" tertian malaria is a misnomer.Despite significant morbidity,with timely and appropriate treatment P.rirax malaria has an excellent outcome.

A study on the clinical profile of complicated Plasmodium vivax mono-infections

Objective:To identify cases of severe Plasmodium vivax(P.vivax) mono-infections among adults.Methods:In this retrospective study,30 adult patients admitted to medical wards of a tertiary hospital in a malaria endemic urban area from March 2010 to April 2010 were included. The diagnosis of P.vivax malaria was established by peripheral blood film(PBF) examination, and severe malaria was categorized as per World Health Organization guidelines.Results: Complications observed were thrombocytopenia in 28(93.3%),hepatic dysfunction and jaundice in 13(433%),renal dysfunction in 8(26.7%),severe anaemia in 3(10.0%),cerebral malaria in 2 (6.7%),and acute respiratory distress syndrome(ARDS) in 1(3.3%) of 30 patients.Conclusions:P. vivax malaria with severe complications is common in the investigated area,and an intensive and large-scale study of the disease is necessary.

在在东南的伊朗的 Baoulch 人口的疟疾变形体 vivax 病人之中的 Duffy 血型遗传型

Objective:To determine the distribution of Duffy blood group genotypes in Balouch population as a major ethnic group that living in a sub-tropical area in south East of Iran.Methods:In this study,the Duffy blood group FY phenolypes were determined using indireet anti-globulin technique and also genotype by PCR-RFLP in 160 vivax malaria patients and 160 control individuals.Results:The results showed that the most common Duffy geitolype was FYA/FYB(46.6%)followed by FYA/FYA(15.3%),FYA/FYO(14.4%),FYB/FYO(11.9%,),FYB/FYB(10%)and FYO/FYO(1.9%).In case individuals,frequency of FY A.FYB and FYO alleles were 0.471,0.431and 0.097,respectively compaired to 0.444,0.353 and 0.203,respectively in control(non-infected)group.Conclusions:This data provide evidence that individuals with the FYA/FYB genotype have higher susceptibility to malaria and there are significant associations between Duffy blood group variants and susceptibility or resistance to vivax malaria.

Multiple splenic infarcts in acute Plasmodium vivax malaria:A rare case report

In tropical countries like India,malaria has been one of the most common parasitic illnesses leading to frequent hospitalization and causing major economic burden among the masses. Although Plasmodium vivax infection is considered to be benign,in contrast to Plasmodium, falciparum infection which is notorious for its severe splenic complications can occur frequently. Splenomegaly tends not to receive special attention,as it is not usually accompanied by any symptoms and can be gradually resolved via standard antimalarial therapy.Splenic infarction, although rarely attributable to malaria in an endemic region with high parasitemia,can be a rare presentation of this disease entity.

Conserved regions of Plasmodium vivax potential vaccine candidate antigens in Sri Lanka:Conscious in silico analysis of prospective conformational epitope regions

Objective:To do mapping and modeling of conformational B cell epitope regions of highly conserved and protective regions of three merozoitecandidate vaccine proteins of Plasmodium vivax(P.vivax),ie.merozoite purface protein-1(PvMSP-1),apical membrane antigen-1 domainⅡ(PvAMA1-DⅡ)and regionⅡof the Duffy binding protein(PvDBPⅡ).and to analyze the immunogenie properties of these predicted epitopes.Methods:3-D structures of amino acid haplotypes from Sri Lanka(available in GeneBank)of PvMSP-1_(19)(n=27),PvAMA1-DⅡ(n=21)and PvDBPⅡ(n=33)were modeled.SEPPA,selected as the best online server was used for conformational epitope predictions,while prediction and moodeling of protein structuve and properties related to immunogenicity was carried out with Geno3D server.SCRATCH Protein Server,NetSurfP Server and standaloneroftware,Genious 5.4.4.Results:SEPPA revealed that regions of predicted conformational epitopes formed 4 clusters in PvMSP-I_(19),and 3 clusters each in PvAMA1-DⅡand PvDBPⅡ,all of which displayed a high degree of hydrophilicity,contained solveut exposed residues,displayed high probability of antigenicity and showed positive antigenic propensity values,that indicated high degree of immunogenicity.Conclusions:Findings of this study revealed and confirmed that different parts of the sequences of each of the conserved regions of the three selected potential vaccine candidate antigens of P.vivax are important with regard to conformational epitope prediction that warrants further laboratory experimental invertigations in in vivo animal models.

Sequential check and computer analysis of a cloned DNA fragment specific for Plasmodium vivax

A cloned DNA fragment specific for Plasmodium vivax was cleaved from theplasmid pVA1 and ligated into phage M13mp18.The nucleotides of the insert were se-quenced by the dideoxy-chain termination procedure.The fragment was composed of 261base pairs and 3 Hinf Ⅰ sites but no tandem repeat sequences.Computer retrieval andanalysis show that the nucleotide sequence of the cloned DNA fragment is unique,forthere has not been any significant homologue with that of other Plasmodium genes pub-lished as yet.

A case of hemophagocytic syndrome as a complication of <i>Plasmodium</i>vivax malaria

Hemophagocytic lymphohistiocytosis syndrome (HPS) is a potentially fatal hyperinflammatory response characterized by a generalized histiocytic proliferation with marked hemophagocytosis in bone marrow [1]. Hemophagocytic syndrome has been associated with genetic mutations, autoimmune diseases, hematological malignancies or infections [2,3]. According to the data from Centre for Disease Control and prevention (CDC) Plasmodium falciparum has been associated with HPS but not the Plasmodium vivax [4-7]. We report a case of hemophagocytic syndrome as a complication of Plasmodium vivax malaria which is a rare presentation according to the data. This patient presented with high grade fever with chills (P. vivax positive), fever however did not respond to anti-malarials. The patient continued to have high grade fever with altered sensorium and deranged liver function with pancytopenia. Since she fulfilled the criteria of (HPS), patient was put on injectable steroids and responded dramatically. Hemophagocytic syndrome is a potentially fatal syndrome and therefore high index suspicion and early treatment is the key to reduce the mortatlity.

Molecular Diagnosis of Subclinical African Trypanosoma vivax Infection and Association with Physiological Indices and Serum Metabolites in Extensively Managed Goats in the Tropics

Trypanosomosis remains a major challenge to livestock production in much of tropical Sub-Saharan Africa, while diagnosis and treatment still depend on inefficient parasitological techniques. Endemic infections depend on animal reservoirs with subclinical parasitemia. We report molecular diagnosis of subclinical Trypanosoma vivax (T. vivax) infection using polymerase chain reaction (PCR) for the first time in Nigerian goats and associate parasite presence with gross physiological traits and serum metabolites in extensively managed Nigerian goats. PCR was used to amplify a 400 bp DNA fragment of the parasite genome in 205 goats across three geographical zones of the country. Results showed a high subclinical infection rate (SCIR) of 71.7% in the total goats examined. Overall SCIRs of 71%, 75.9% and 55.6% were recorded in West African Dwarf, Red Sokoto and Sahel goats respectively, while geographical SCIRs were 71.2% (Southwest), 75% (Northwest) and 70% (Northeast). T. vivax presence had significant (P 0.05) effect on respiratory rate and is associated with higher creatinine levels in sera. Logistic regression analyses with Hosmer-Lemeshow goodness-of-fit showed that respiratory rate is the most important predictive trait for the presence of T. vivax infection (P 0.05). Goats appear to be a viable reservoir for T. vivax infection of other livestock. Molecular diagnosis of subclinical trypanosomosis using PCR could be useful for large scale epidemiological studies, early diagnosis of subclinical infection and treatment of the disease in extensively managed tropical goats.

Molecular Docking Investigation of New Inhibitors of <i>Falciparum vivax</i>

Despite the vigorous research and development, as of 2017, there is currently no widely available antimalarial vaccine. An effective, commercially available vaccine would be a huge game changer;however, it seems like there is still a long way to go until that target is reached. Therefore, the purpose of this study was to use molecular docking technique to identify new inhibitors for a novel antimalarial target with the overall aim of finding hit compounds which could be further optimized to become potential drug candidates. The docking protocol AutoDockVina was used alongside the molecular visualisation software UCSF Chimera to dock 100 naphthoquinones (labelled TM1-100) and 66 aryl diketones (labelled TM101-166) with the chosen target, Plasmodium vivax N-myristoyltransferase (PvNMT). Each docking session yielded the best 9 binding modes between the ligand and target. The hydrogen bond interactions of all binding modes were analysed, and the top six target molecules (TM) were short listed as the possible hit compounds (TM40, TM65, TM66, TM81, TM94 and TM165). These compounds displayed more than six hydrogen bonds under 3 angstroms over the 9 binding modes. Using Lipinski’s rule of 5, the potential hit compounds were further analysed to determine the drug-likeness and all were found to obey the parameters. Following the same method used to dock the ligands, twelve FDA approved antimalarial drugs were also docked with PvNMT for comparison purposes. Apart from proguanil, the other eleven antimalarial drugs displayed fewer hydrogen bonds under 3 angstroms over the 9 binding modes compared to all six of the potential hit compounds. This study discovered six compounds which displayed stronger interactions with the target protein compared to majority of the FDA approved drugs. The results of this investigation gave us new molecules that could be further investigated for the designing of novel drug-like compounds for the treatment of Malaria.

Higher-Dose Primaquine to Prevent Relapse of Plasmodium vivax Malaria

Background:In most of the Americas,the recommended treatment to prevent relapse of Plasmodium vivax malaria is primaquine at a total dose of 3.5 mg per kilogram of body weight,despite evidence of only moderate efficacy.Methods:In this trial conducted in Brazil,we evaluated three primaquine regimens to prevent relapse of P.vivax malaria in children at least 5 years of age and in adults with microscopy-confirmed P.vivax monoinfection.All the patients received directly observed chloroquine for 3 days(total dose,25 mg per kilogram).Group 1 received a total primaquine dose of 3.5 mg per kilogram(0.5 mg per kilogram per day)over 7 days with unobserved administration;group 2 received the same regimen as group 1 but with observed administration;and group 3 received a total primaquine dose of 7.0 mg per kilogram over 14 days(also 0.5 mg per kilogram per day)with observed administration.We monitored the patients for 168 days.

Insights into the elimination of vivax malaria in China

Background Malaria is caused by multiple parasitic species of the genus Plasmodium.Plasmodium vivax is the most geographically widespread and poses challenges in elimination due to its unique biological and epidemiological characteristics.The aim of study was to highlight the practices and experience targeting vivax malaria control and elimination in China.Main body P.vivax malaria was historically endemic in more than 70%of counties in China,with reported vivax malaria cases as high as 26 million a year.After around 70 years of effort,China was certified as malaria-free in June of 2021.The key insights into China’s vivax malaria control and elimination were offered,including radical cure strategies,comprehensive but adaptive strategies targeting species of Plasmodium and Anopheles,mass drug administration,and case-/focus-centred surveillance and response systems.Conclusion The complete global eradication of P.vivax and eventually malaria will be more difficult,and China’s practices and experience could be a valuable reference in this campaign.

上林县输入性间日疟和卵形疟与G6PD缺乏患者流行病学调查研究

目的统计分析上林县输入性间日疟和卵形疟与葡萄糖-6-磷酸脱氢酶(G6PD)缺乏患者流行病学特征,为疟疾防治提供科学依据。方法收集上林县人民医院2017年6月18日至2023年3月29日入院治疗输入性疟疾患者的数据进行整理分析。结果收治输入性疟疾患者共578例,其中恶性疟患者占40.48%(234/578),需要伯氨喹进行根治的间日疟、卵形疟及混合感染患者占37.54%(217/578);其中G6PD缺乏患者占10.90%(63/578),需根治的G6PD缺乏患者占9.68%(21/217)。结论上林县需要根治的输入性间日疟和卵形疟患者较多,特别是对G6PD缺乏又需根治的患者应加强管理,预防二代病例的出现。

Severe thrombocytopaenia in patients with vivax malaria compared to falciparum malaria:a systematic review and metaanalysis

Background:Plasmodium vivax is the most geographically widespread species among human malaria parasites.Immunopathological studies have shown that platelets are an important component of the host innate immune response against malaria infections.The objectives of this study were to quantify thrombocytopaenia in P.vivax malaria patients and to determine the associated risks of severe thrombocytopaenia in patients with vivax malaria compared to patients with P.falciparum malaria.Main body:A systematic review and meta-analysis of the available literature on thrombocytopaenia in P.vivax malaria patients was undertaken.Relevant studies in health-related electronic databases were identified and reviewed.The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed.Fifty-eight observational studies(n=29664)were included in the current review.Severe thrombocytopaenia(<50000/mm3)to very severe thrombocytopaenia(<20000/mm3)was observed in 10.1%of patients with P.vivax infection.A meta-analysis of 11 observational studies showed an equal risk of developing severe/very severe thrombocytopaenia between the patients with P.vivax malaria and those with P.falciparum malaria(OR:1.98,95%CI:0.92-4.25).This indicates that thrombocytopaenia is as equally a common manifestation in P.vivax and P.falciparum malaria patients.One study showed a higher risk of developing very severe thrombocytopaenia in children with severe P.vivax malaria than with severe P.falciparum malaria(OR:2.80,95%CI:1.48-5.29).However,a pooled analysis of two studies showed an equal risk among adult severe cases(OR:1.19,95%CI:0.51-2.77).This indicates that the risk of developing thrombocytopaenia in P.vivax malaria can vary with immune status in both children and adults.One study reported higher levels of urea and serum bilirubin in patients with P.vivax malaria and severe thrombocytopaenia compared with patients mild thrombocytopaenia or no thrombocytopaenia,(P<0.001 in all comparisons).A pooled analysis of two other studies showed a similar proportion of bleeding episodes with thrombocytopaenia in severe P.vivax patients and severe P.falciparum patients(P=0.09).This implied that both P.vivax and P.falciparum infections could present with bleeding episodes,if there had been a change in platelet counts in the infected patients.A pooled analysis of another two studies showed an equal risk of mortality with severe thrombocytopaenia in both P.vivax and P.falciparum malaria patients(OR:1.16,95%CI:0.30-4.60).However,due to the low number of studies with small sample sizes within the subset of studies that provided clinically relevant information,our confidence in the estimates is limited.Conclusion:The current review has provided some evidence of the clinical relevance of severe thrombocytopaenia in P.vivax malaria.To substantiate these findings,there is a need for well designed,large-scale,prospective studies among patients infected with P.vivax.These should include patients from different countries and epidemiological settings with various age and gender groups represented.

Polymorphisms of potential drug resistant molecular markers in Plasmodium vivax from China-Myanmar border during 2008-2017

Background:Plasmodium vivax remains the predominant species at the China–Myanmar border,imposing a major challenge to the recent gains in regional malaria elimination.To closely supervise the emerging of drug resistance in this area,we surveyed the variations in genes potentially correlated with drug resistance in P.vivax parasite and the possible drug selection with time.Methods:A total of 235 P.vivax samples were collected from patients sufering uncomplicated malaria at Yingjiang,Tengchong,and Longling counties,and Nabang port in China,Yunnan province,and Laiza sub-township in Myanmar,from 2008 to 2017.Five potential drug resistance genes were amplifed utilizing nested-PCR and analyzed,including pvdhfr,pvdhps,pvmdr1,pvcrt-o,and pvk12.The Pearson’s Chi-squared test or Fisher’s exact test were applied to determine the statistical frequency diferences of mutations between categorical data.Results:The pvdhfr F57I/L,S58R,T61M and S117T/N presented in 40.6%,56.7%,40.1%,and 56.0% of the sequenced P.vivax isolates,and these mutations signifcantly decreased with years.The haplotype formed by these quadruple mutations predominated in Yingjiang,Tengchong,Longling and Nabang.While a mutation H99S/R(56.6%)dominated in Laiza and increased with time.In pvdhps,the A383G prevailed in 69.2% of the samples,which remained the most prevalent haplotype.However,a signifcant decrease of its occurrence was also noticed over the time.The S382A/C and A553G existed in 8.4% and 30.8% of the isolates,respectively.In pvmdr1,the mutation Y976F occurred at a low frequency in 5/232(2.2%),while T958M was fxed and F1076L was approaching fxed(72.4%).The K10 insertion was detected at an occurrence of 33.2% in pvcrt-o,whereas there was no signifcant diference among the sites or over the time.No mutation was identifed in pvk12.Conclusions:Mutations related with resistance to antifolate drugs are prevalent in this area,while their frequencies decrease signifcantly with time,suggestive of increased susceptibility of P.vivax parasite to antifolate drugs.Resistance to chloroquine(CQ)is possibly emerging.However,since the molecular mechanisms underneath CQ resistance is yet to be better understood,close supervision of clinical drug efciency and continuous function investigation is urgently needed to alarm drug resistance.

Prevalence of antifolate drug resistance markers in Plasmodium vivax in China

The dihydrofolate reductase(dhfr)and dihydropteroate synthetase(dhps)genes of Plasmodium vivax,as antifolate resistance-associated genes were used for drug resistance surveillance.A total of 375 P.vivax isolates collected from different geographical locations in China in 2009–2019 were used to sequence Pvdhfr and Pvdhps.The majority of the isolates harbored a mutant type allele for Pvdhfr(94.5%)and Pvdhps(68.2%).The most predominant point mutations were S117T/N(77.7%)in Pvdhfr and A383G(66.8%)in Pvdhps.Amino acid changes were identified at nine residues in Pvdhfr.A quadruple-mutant haplotype at 57,58,61,and 117 was the most frequent(57.4%)among 16 distinct Pvdhfr haplotypes.Mutations in Pvdhps were detected at six codons,and the double-mutant A383G/A553G was the most prevalent(39.3%).Pvdhfr exhibited a higher mutation prevalence and greater diversity than Pvdhps in China.Most isolates from Yunnan carried multiple mutant haplotypes,while the majority of samples from temperate regions and Hainan Island harbored the wild type or single mutant type.This study indicated that the antifolate resistance levels of P.vivax parasites were different across China and molecular markers could be used to rapidly monitor drug resistance.Results provided evidence for updating national drug policy and treatment guidelines.