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Plasmodium vivax

Safety and feasibility of apheresis to harvest and concentrate parasites from subjects with induced blood stage Plasmodium vivax infection

January 20, 2021 - 08:23 -- Open Access
Author(s): 
Anand Odedra, Kari Mudie, Fiona Amante, et al.
Reference: 
Malaria Journal 2021 20:43, 14 January 2021

In the absence of a method to culture Plasmodium vivax, the only way to source parasites is ex vivo. This hampers many aspects of P. vivax research. This study aimed to assess the safety of apheresis, a method for selective removal of specific components of blood as a means of extracting and concentrating P. vivax parasites.

NOT Open Access | Restricted genetic heterogeneity of the Plasmodium vivax transmission-blocking vaccine (TBV) candidate Pvs48/45 in a low transmission setting: Implications for the Plasmodium vivax malaria vaccine development

January 16, 2021 - 09:16 -- NOT Open Access
Author(s): 
Asali S, Raz A, Turki H, Mafakher L, Razmjou E, Solaymani-Mohammadi S
Reference: 
Infect Genet Evol. 2021 Jan 6:104710

Plasmodium vivax is the most widespread malaria species parasitizing humans outside Africa, with approximately 100 million cases reported per year. Most human cases of P. vivax are asymptomatic with low parasitemia, making active case detection-based elimination programme challenging and less effective. Despite the widespread distribution of P. vivax, no effective vaccines are currently available. Transmission blocking vaccines have recently emerged as potential vaccine candidates to reduce transmission rates to below the essential levels required for the maintenance of the parasite life cycle.

NOT Open Access | Long-lasting infectivity of Plasmodium vivax present in malarial patient blood to Anopheles aquasalis

January 16, 2021 - 08:54 -- NOT Open Access
Author(s): 
Pereira-Silva JW, Martins-Campos KM, Sabrina Dos Reis Martins E, de Souza Menezes A, Guimarães Lacerda MV, Costa Pessoa FA, Ríos-Velásquez CM
Reference: 
Exp Parasitol. 2021 Jan 6:108064

Experimental studies for understanding the relationship between Plasmodium vivax and its vector hosts are difficult, because of to the lack of a long-term, in vitro continuous culture system unavailability of infected blood samples, seasonality of the disease, and the concentration of most cases in remote areas. This study evaluates the duration of the infectivity of P. vivax to Anopheles aquasalis after collecting blood from malaria-infected patients. Blood was collected from patients and stored at 4 ºC and 37 ºC. Every day, for 4 days, the blood was fed to An. aquasalis adult females, and a Giemsa-stained thick blood smear was mounted to account for sexual (gametocytes) and asexual (trophozoites and schizonts) stages and calculate parasitemia.

Severe orthostatic hypotension in otherwise uncomplicated Plasmodium vivax infection

January 13, 2021 - 08:33 -- Open Access
Author(s): 
Chaisith Sivakorn, Polrat Wilairatana, Srivicha Krudsood, Marcus J. Schultz, Tachpon Techarang, Khanittha Kheawsawaung and Arjen M. Dondorp
Reference: 
Malaria Journal 2021 20:28, 7 January 2021

Impaired autonomic control of postural homeostasis resulting in orthostatic hypotension has been described in falciparum malaria. However, severe orthostatic intolerance in Plasmodium vivax has been rarely reported.

Should we care about Plasmodium vivax and HIV co-infection? A systematic review and a cases series from the Brazilian Amazon

January 9, 2021 - 12:17 -- Open Access
Author(s): 
Paola López Del-Tejo, Nadia Cubas-Vega, Fernando Val, et al.
Reference: 
Malaria Journal 2021 20:13, 6 January 2021

Malaria and HIV are two important public health issues. However, evidence on HIV-Plasmodium vivax co-infection (HIV/PvCo) is scarce, with most of the available information related to Plasmodium falciparum on the African continent. It is unclear whether HIV can change the clinical course of vivax malaria and increase the risk of complications. In this study, a systematic review of HIV/PvCo studies was performed, and recent cases from the Brazilian Amazon were included.

Plasmodium vivax Cysteine-Rich Protective Antigen Polymorphism at Exon-1 Shows Recombination and Signatures of Balancing Selection

January 7, 2021 - 10:33 -- Open Access
Author(s): 
González-Cerón L, Cebrián-Carmona J, Mesa-Valle CM, García-Maroto F, Santillán-Valenzuela F, Garrido-Cardenas JA
Reference: 
Genes (Basel). 2020 Dec 28;12(1):E29

Plasmodium vivax Cysteine-Rich Protective Antigen (CyRPA) is a merozoite protein participating in the parasite invasion of human reticulocytes. During natural P. vivax infection, antibody responses against PvCyRPA have been detected. In children, low anti-CyRPA antibody titers correlated with clinical protection, which suggests this protein as a potential vaccine candidate. This work analyzed the genetic and amino acid diversity of pvcyrpa in Mexican and global parasites. Consensus coding sequences of pvcyrpa were obtained from seven isolates.

NOT Open Access | Phylogenetic analysis suggests single and multiple origins of dihydrofolate reductase mutations in Plasmodium vivax

January 7, 2021 - 10:30 -- NOT Open Access
Author(s): 
Shaukat A, Ali Q, Raud L, Wahab A, Khan TA, Rashid I, Rashid M, Hussain M, Saleem MA, Sargison ND, Chaudhry U
Reference: 
Acta Trop. 2021 Jan 3:105821

Pyrimethamine was first introduced for the treatment of malaria in Asia and Africa during the early 1980s, replacing chloroquine, and has become the first line of drugs in many countries. In recent years, development of pyrimethamine resistance in Plasmodium vivax has become a barrier to effective malaria control strategies. Here, we describe the use of meta-barcoded deep amplicon sequencing technology to assess the evolutionary origin of pyrimethamine resistance by analysing the flanking region of dihydrofolate reductase (dhfr) locus.

NOT Open Access | Antibody Dynamics for Plasmodium vivax Malaria: A Mathematical Model

January 6, 2021 - 12:54 -- NOT Open Access
Author(s): 
Mehra S, McCaw JM, Flegg MB, Taylor PG, Flegg JA
Reference: 
Bull Math Biol. 2021 Jan 2;83(1):6

Malaria is a mosquito-borne disease that, despite intensive control and mitigation initiatives, continues to pose an enormous public health burden. Plasmodium vivax is one of the principal causes of malaria in humans. Antibodies, which play a fundamental role in the host response to P. vivax, are acquired through exposure to the parasite. Here, we introduce a stochastic, within-host model of antibody responses to P. vivax for an individual in a general transmission setting.

An Ultra-Sensitive Technique: Using Pv-mtCOX1 qPCR to Detect Early Recurrences of Plasmodium vivax in Patients in the Brazilian Amazon

January 5, 2021 - 15:31 -- Open Access
Author(s): 
Barbosa LRA, da Silva EL, Melo GC, et al.
Reference: 
Pathogens. 2020 Dec 30;10(1):E19

Early recurrence of Plasmodium vivax is a challenge for malaria control in the field, particularly because this species is associated with lower parasitemia, which hinders diagnosis and monitoring through blood smear testing. Early recurrences, defined as the persistence of parasites in the peripheral blood despite adequate drug dosages, may arise from resistance to chloroquine. The objective of the study was to estimate early recurrence of P. vivax in the Brazilian Amazon by using a highly-sensitive detection method, in this case, PCR.

NOT Open Access | Liver-targeted polymeric prodrugs of 8-aminoquinolines for malaria radical cure

January 1, 2021 - 16:00 -- NOT Open Access
Author(s): 
Srinivasan S, Roy D, Stayton PS, et al.
Reference: 
J Control Release. 2020 Dec 27:S0168-3659(20)30770-7

Primaquine and tafenoquine are the two 8-aminoquinoline (8-AQ) antimalarial drugs approved for malarial radical cure - the elimination of liver stage hypnozoites after infection with Plasmodium vivax. A single oral dose of tafenoquine leads to high efficacy against intra-hepatocyte hypnozoiites after efficient first pass liver uptake and metabolism. Unfortunately, both drugs cause hemolytic anemia in G6PD-deficient humans. This toxicity prevents their mass administration without G6PD testing given the approximately 400 million G6PD deficient people across malarial endemic regions of the world.

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