MyMedR

Proguanil-resistance in Malayan strains of Plasmodium vivax

Wilson T, Munro DS, Richard DR

Br Med J, 1952;1:564-568.

Matched MeSH terms: Plasmodium; Plasmodium vivax

Morphological variation in Plasmodium vivax (Grassi & Feletti, 1890)

Field JW

Parasitology, 1942;34:82-87.

DOI: 10.1017/S0031182000016000

Two vivax-like parasites, believed to be true P. vivax but in abnormal form, are described. The deviation from normal appearances was probably due, it is suggested, to growth in an abnormal environment.

Matched MeSH terms: Plasmodium vivax

Fulltext Plasmodium vivax malaria serological exposure markers: Assessing the degree and implications of cross-reactivity with P. knowlesi

Longley RJ, Grigg MJ, Schoffer K, Obadia T, Hyslop S, Piera KA, et al.

Cell Rep Med, 2022 06 21;3(6):100662.

PMID: 35732155 DOI: 10.1016/j.xcrm.2022.100662

Serological markers are a promising tool for surveillance and targeted interventions for Plasmodium vivax malaria. P. vivax is closely related to the zoonotic parasite P. knowlesi, which also infects humans. P. vivax and P. knowlesi are co-endemic across much of South East Asia, making it important to design serological markers that minimize cross-reactivity in this region. To determine the degree of IgG cross-reactivity against a panel of P. vivax serological markers, we assayed samples from human patients with P. knowlesi malaria. IgG antibody reactivity is high against P. vivax proteins with high sequence identity with their P. knowlesi ortholog. IgG reactivity peaks at 7 days post-P. knowlesi infection and is short-lived, with minimal responses 1 year post-infection. We designed a panel of eight P. vivax proteins with low levels of cross-reactivity with P. knowlesi. This panel can accurately classify recent P. vivax infections while reducing misclassification of recent P. knowlesi infections.

Matched MeSH terms: Plasmodium vivax; Plasmodium knowlesi*

Plasmodium knowlesi circumsporozoite protein: genetic characterisation and predicted antigenicity of the central repeat region

Tan JH, Cheong FW, Lau YL, Fong MY

Trop Biomed, 2023 Mar 01;40(1):37-44.

PMID: 37356002 DOI: 10.47665/tb.40.1.004

Circumsporozoite protein (CSP) central repeat region is one of the main target regions of the RTS,S/AS01 vaccine for falciparum infection as it consists of immunodominant B cell epitopes. However, there is a lack of study for P. knowlesi CSP central repeat region. This study aims to characterise the CSP repeat motifs of P. knowlesi isolates in Peninsular Malaysia. CSP repeat motifs of 64 P. knowlesi isolates were identified using Rapid Automatic Detection and Alignment of Repeats (RADAR). Antigenicity of the repeat motifs and linear B cell epitopes were predicted using VaxiJen 2.0, BepiPred-2.0 and BCPred, respectively. A total of 35 dominant repeat motifs were identified. The repeat motif "AGQPQAQGDGANAGQPQAQGDGAN" has the highest repeat frequency (n=15) and antigenicity index of 1.7986. All the repeat regions were predicted as B cell epitopes. In silico approaches revealed that all repeat motifs were antigenic and consisted of B cell epitopes which could be designed as knowlesi malaria vaccine.

Matched MeSH terms: Plasmodium falciparum; Plasmodium knowlesi*

Triazole hybrid compounds: A new frontier in malaria treatment

Ravindar L, Hasbullah SA, Rakesh KP, Hassan NI

Eur J Med Chem, 2023 Nov 05;259:115694.

PMID: 37556947 DOI: 10.1016/j.ejmech.2023.115694

Reviewing the advancements in malaria treatment, the emergence of triazole hybrid compounds stands out as a groundbreaking development. Combining the advantages of triazole and other moieties, these hybrid compounds offer a new frontier in the battle against malaria. Their potential as effective antimalarial agents has captured the attention of researchers and holds promise for overcoming the challenges posed by drug-resistant malaria strains. We focused on their broad spectrum of antimalarial activity of diverse hybridized 1,2,3-triazoles and 1,2,4-triazoles, structure-activity relationship (SAR), drug-likeness, bioavailability and pharmacokinetic properties reported since 2018 targeting multiple stages of the Plasmodium life cycle. This versatility makes them highly effective against both drug-sensitive and drug-resistant strains of P. falciparum, making them invaluable tools in regions where resistance is prevalent. The synergistic effects of combining the triazole moiety with other pharmacophores have resulted in even greater antimalarial potency. This approach has the potential to circumvent existing resistance mechanisms and provide a more sustainable solution to malaria treatment. While triazole hybrid compounds show great promise, further research and clinical trials are warranted to fully evaluate their safety, efficacy and long-term effects. As research progresses, these compounds can potentially revolutionize the field and contribute to global efforts to eradicate malaria, ultimately saving countless lives worldwide.

Matched MeSH terms: Plasmodium*; Plasmodium falciparum

Fulltext The threat of increased transmission of non-knowlesi zoonotic malaria in humans: a systematic review

Chaturvedi R, Biswas S, Bisht K, Sharma A

Parasitology, 2023 Nov;150(13):1167-1177.

PMID: 37929579 DOI: 10.1017/S003118202300077X

Of the 5 human malarial parasites, Plasmodium falciparum and Plasmodium vivax are the most prevalent species globally, while Plasmodium malariae, Plasmodium ovale curtisi and Plasmodium ovale wallikeri are less prevalent and typically occur as mixed-infections. Plasmodium knowlesi, previously considered a non-human primate (NHP) infecting species, is now a cause of human malaria in Malaysia. The other NHP Plasmodium species, Plasmodium cynomolgi, Plasmodium brasilianum, Plasmodium inui, Plasmodium simium, Plasmodium coatneyi and Plasmodium fieldi cause malaria in primates, which are mainly reported in southeast Asia and South America. The non-knowlesi NHP Plasmodium species also emerged and were found to cross-transmit from their natural hosts (NHP) – to human hosts in natural settings. Here we have reviewed and collated data from the literature on the NHPs-to-human-transmitting non-knowlesi Plasmodium species. It was observed that the natural transmission of these NHP parasites to humans had been reported from 2010 onwards. This study shows that: (1) the majority of the non-knowlesi NHP Plasmodium mixed species infecting human cases were from Yala province of Thailand; (2) mono/mixed P. cynomolgi infections with other human-infecting Plasmodium species were prevalent in Malaysia and Thailand and (3) P. brasilianum and P. simium were found in Central and South America.

Matched MeSH terms: Plasmodium vivax; Plasmodium knowlesi*

THE SUCEPTIBILITY OF MALAYAN ANOPHELINES TO PLASMODIUM CYNOMOLGI BASTIANELLII

WARREN M, EYLES DE, WHARTON RH, KONG OY

Indian J Malariol, 1963 Mar;17:85-105.

PMID: 14274297

Matched MeSH terms: Plasmodium*; Plasmodium cynomolgi*

A malaria parasite of the Malayan squirrel

Field JW, Edeson JFB

Bull Inst Med Res Kuala Lumpur, 1949.

Matched MeSH terms: Plasmodium

Detection of asymptomatic malaria in Asian countries: a meta-analysis of diagnostic accuracy

Naing C, Htet NH, Aye SN, Aung HH, Tanner M, Whittaker MA

Malar J, 2022 Feb 16;21(1):50.

PMID: 35172833 DOI: 10.1186/s12936-022-04082-0

BACKGROUND: Achieving malaria elimination requires the targeting of the human reservoir of infection, including those patients with asymptomatic infection. The objective was to synthesise evidence on the accuracy of the rapid-onsite diagnostic tests (RDTs) and microscopy for the detection of asymptomatic malaria as part of the surveillance activities in Asian countries.

METHODS: This was a meta-analysis of diagnostic test accuracy. Relevant studies that evaluated the diagnostic performance of RDTs and microscopy for detection of asymptomatic malaria were searched in health-related electronic databases. The methodological quality of the studies included was assessed using the QUADAS-2 tool.

RESULTS: Ten studies assessing RDT and/or microscopy were identified. The diagnostic accuracies in all these studies were verified by PCR. Overall, the pooled sensitivities of RDT, as well as microscopy for detection of any malaria parasites in asymptomatic participants, were low, while their pooled specificities were almost ideal. For the detection of Plasmodium falciparum, pooled sensitivity by RDT (59%, 95%CI:16-91%) or microscopy (55%, 95%CI: 25-82%) were almost comparable. For detection of Plasmodium vivax, pooled sensitivity of RDT (51%, 95% CI:7-94%) had also the comparable accuracy of microscopy (54%, 95%CI,11-92%). Of note are the wide range of sensitivity and specificity.

CONCLUSION: The findings of this meta-analysis suggest that RDTs and microscopy have limited sensitivity and are inappropriate for the detection of asymptomatic Plasmodium infections. Other methods including a combination of PCR-based strategies, Loop-Mediated Isothermal Amplification (LAMP) technique must be considered to target these infections, in order to achieve malaria elimination. However, more data is needed for the wide acceptance and feasibility of these approaches. Studies to explore the role of asymptomatic and sub-patent infections in the transmission of malaria are of critical importance and are recommended.

Matched MeSH terms: Plasmodium*; Plasmodium falciparum; Plasmodium vivax

Fulltext The presence of Plasmodium malariae and Plasmodium knowlesi in near malaria elimination setting in western Indonesia

Nainggolan IRA, Syafutri RD, Sinambela MN, Devina C, Handayani, Hasibuan BS, et al.

Malar J, 2022 Nov 05;21(1):316.

PMID: 36333701 DOI: 10.1186/s12936-022-04335-y

BACKGROUND: Indonesia is progressing towards malaria elimination. To achieve this goal, intervention measures must be addressed to cover all Plasmodium species. Comprehensive control measures and surveillance programmes must be intensified. This study aims to determine the prevalence of microscopic and submicroscopic malaria in Langkat district, North Sumatera Province, Indonesia.

METHODS: A cross-sectional survey was conducted in six villages in Langkat district, North Sumatera Province in June 2019. Data were recorded using a standardized questionnaire. Finger pricked blood samples were obtained for malaria examination using rapid diagnostic test, thick and thin blood smears, and polymerase chain reaction.

RESULTS: A total of 342 individuals were included in the study. Of them, one (0.3%) had a microscopic Plasmodium malariae infection, no positive RDT examination, and three (0.9%) were positive for P. malariae (n = 1) and Plasmodium knowlesi (n = 2). The distribution of bed net ownership was owned by 40% of the study participants. The participants had a house within a radius of 100-500 m from the forest (86.3%) and had the housing material of cement floor (56.1%), a tin roof (82.2%), wooden wall (35.7%), bamboo wall (28.1%), and brick wall (21.6%).

CONCLUSION: Malaria incidence has substantially decreased in Langkat, North Sumatera, Indonesia. However, submicroscopic infection remains in the population and may contribute to further transmission. Surveillance should include the detection of microscopic undetected parasites, to enable the achievement of malaria elimination.

Matched MeSH terms: Plasmodium falciparum; Plasmodium malariae; Plasmodium knowlesi*

Retinal Changes in Uncomplicated and Severe Plasmodium knowlesi Malaria

Govindasamy G, Barber BE, Ghani SA, William T, Grigg MJ, Borooah S, et al.

J Infect Dis, 2016 May 1;213(9):1476-82.

PMID: 26671886 DOI: 10.1093/infdis/jiv746

Plasmodium knowlesicauses severe malaria, but its pathogenesis is poorly understood. Retinal changes provide insights into falciparum malaria pathogenesis but have not been studied in knowlesi malaria.

Matched MeSH terms: Plasmodium

Fulltext Antimalarial ceramicines Q-T from Chisocheton ceramicus

Nugroho AE, Wong CP, Hirasawa Y, Kaneda T, Tougan T, Horii T, et al.

J Nat Med, 2023 Jun;77(3):596-603.

PMID: 37162697 DOI: 10.1007/s11418-023-01706-w

Ceramicines are a series of limonoids that were isolated from the bark of Malaysian Chisocheton ceramicus (Meliaceae) and were known to show various biological activity. Four new limonoids, ceramicines Q-T (1-4) were isolated from the barks of C. ceramicus, and their structures were determined on the basis of the 1D and 2D NMR analyses in combination with calculated 13C chemical shift data. Ceramicines Q-T (1-4) were established to be new limonoids with a cyclopentanone[α]phenanthren ring system with a β-furyl ring at C-17, and without a tetrahydrofuran ring like ceramicine B, which is characteristic of known ceramicines. Ceramicine R (2) exhibited potent antimalarial activity against Plasmodium falciparum 3D7 strain with IC50 value of 2.8 µM.

Matched MeSH terms: Plasmodium falciparum

Fulltext Accelerated diversification of nonhuman primate malarias in Southeast Asia: adaptive radiation or geographic speciation?

Muehlenbein MP, Pacheco MA, Taylor JE, Prall SP, Ambu L, Nathan S, et al.

Mol Biol Evol, 2015 Feb;32(2):422-39.

PMID: 25389206 DOI: 10.1093/molbev/msu310

Although parasitic organisms are found worldwide, the relative importance of host specificity and geographic isolation for parasite speciation has been explored in only a few systems. Here, we study Plasmodium parasites known to infect Asian nonhuman primates, a monophyletic group that includes the lineage leading to the human parasite Plasmodium vivax and several species used as laboratory models in malaria research. We analyze the available data together with new samples from three sympatric primate species from Borneo: The Bornean orangutan and the long-tailed and the pig-tailed macaques. We find several species of malaria parasites, including three putatively new species in this biodiversity hotspot. Among those newly discovered lineages, we report two sympatric parasites in orangutans. We find no differences in the sets of malaria species infecting each macaque species indicating that these species show no host specificity. Finally, phylogenetic analysis of these data suggests that the malaria parasites infecting Southeast Asian macaques and their relatives are speciating three to four times more rapidly than those with other mammalian hosts such as lemurs and African apes. We estimate that these events took place in approximately a 3-4-Ma period. Based on the genetic and phenotypic diversity of the macaque malarias, we hypothesize that the diversification of this group of parasites has been facilitated by the diversity, geographic distributions, and demographic histories of their primate hosts.

Matched MeSH terms: Plasmodium/classification; Plasmodium/genetics*; Plasmodium/parasitology; Plasmodium/pathogenicity*; Plasmodium vivax/classification; Plasmodium vivax/genetics; Plasmodium vivax/pathogenicity

Diffusion-in-gel enzyme-linked immunosorbent assay, ELISA and IFA test in the detection of malarial antibodies

Kumar GS, Mak JW, Lam PL, Tan MA, Lim PK

Southeast Asian J. Trop. Med. Public Health, 1987 Dec;18(4):502-6.

PMID: 3129797

Malarial antibodies in 80 patients were measured using the diffusion-in-gel enzyme linked immunosorbent assay (DIG-ELISA), enzyme-linked immunosorbent assay (ELISA) and the indirect fluorescent antibody (IFA) test. Good correlations were obtained between all three tests in terms of sensitivity and reliability. DIG-ELISA has the advantage of being a rapid diagnostic tool for the detection of malarial antibodies.

Matched MeSH terms: Plasmodium/immunology*; Plasmodium falciparum/immunology; Plasmodium malariae/immunology; Plasmodium vivax/immunology

Fulltext A study of monkey malaria, and its experimental transmission to man

Knowles R, Gupta BMD

Ind Med Gaz, 1932 Jun;67(6):301-320.

PMID: 29010910

This is the first report of new Plasmodium species (later known as P. knowlesi, after its discoverer) in a long-tailed macaque (Macaca fascicularis) imported to India from Singapore.

Matched MeSH terms: Plasmodium knowlesi*

The exoerythrocytic schizonts of Plasmodium fieldi

Coombs GL, Fredericks HJ, Cheong WH, Sandosham AA, Sta Maria FL

Med J Malaya, 1968 Mar;22(3):225-7.

PMID: 4234360

Matched MeSH terms: Plasmodium/growth & development*

An allied Plasmodium to Plasmodium booliati from the Taiwan flying squirrel

Sandosham AA, Yap LF

Med J Malaya, 1968 Mar;22(3):225.

PMID: 4234359

Matched MeSH terms: Plasmodium/classification*

Separation of P. Berghei antigens by disc electrophoresis

Desowitz R

Med J Malaya, 1966 Jun;20(4):324.

PMID: 4224343

Matched MeSH terms: Plasmodium/immunology*

A malaria parasite, plasmodium (Vinckeia) booliati sp.nov., from a Malayan giant flying squirrel

Sandosham AA, Yap LF, Omar I

Med J Malaya, 1965 Sep;20(1):3-7.

PMID: 4221411

Matched MeSH terms: Plasmodium*

Cross-resistance between "Daraprim" and proguanil

Wilson T, Edeson JFB

Br Med J, 1953;1:731.

A letter from Drs. G. I. Robertson, D. G. Davey, and Sir Hamilton Fairley (December 6, 1952, p. 1255) reported that a proguanil-resistant strain of Plasmodium falciparum from Malaya had proved to be resistant also to pyrimethamine (" daraprim "). Proguanil-resistance in Malayan strains of P. falciparum has been recognized since 19491; and if a true cross-resistance exists, this might-as implied by Dr. J. S. K. Boyd (February 7, p. 337)-go far to explain the pyrimethamine failures described in our paper (January 31, p. 253). Proguanil has been so widely used throughout Malaya for the past six years that there can be few strains of parasite which have not yet come into contact with it; thus there is little chance of deciding now how the "parent" strains (without previous contact with proguanil) might have responded to pyrimethamine. We have not, however, been able to confirm that there is any consistent cross-resistance between these two drugs in naturally acquired falciparum malaria since pyrimethamine was first used in Malaya in 1951. Pyrimethamine failures have been successfully treated with normal doses of proguanil, and proguanilresistant infections have responded readily to pyrimethamine. In some of these cases an interval of several days was allowed to elapse between treatments, so the possibility of a combined action of the two drugs should have 'been small. We consider that these apparently conflicting results can best be explained by assuming that some present-day strains of P. falciparum in Malaya possess a " natural" resistance to pyrimethamine, whether or not any particular strain is also demonstrably resistant to proguanil. With this species of parasite, a true cross-resistance has still to be proved. REFERENCE 1 British Medical Journal, 1950. 1, 147.

Matched MeSH terms: Plasmodium; Plasmodium falciparum

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