-
Cold Spring Harbor Perspectives in... Mar 2017Understanding transmission biology at an individual level is a key component of intervention strategies that target the spread of malaria parasites from human to... (Review)
Review
Understanding transmission biology at an individual level is a key component of intervention strategies that target the spread of malaria parasites from human to mosquito. Gametocytes are specialized sexual stages of the malaria parasite life cycle developed during evolution to achieve crucial steps in transmission. As sexual differentiation and transmission are tightly linked, a deeper understanding of molecular and cellular events defining this relationship is essential to combat malaria. Recent advances in the field are gradually revealing mechanisms underlying sexual commitment, gametocyte sequestration, and dynamics of transmissible stages; however, key questions on fundamental gametocyte biology still remain. Moreover, species-specific variation between and transmission dynamics pose another significant challenge for worldwide malaria elimination efforts. Here, we review the biology of transmission stages, highlighting numerous factors influencing development and dynamics of gametocytes within the host and determinants of human infectiousness.
Topics: Animals; Culicidae; Humans; Life Cycle Stages; Malaria; Plasmodium falciparum; Plasmodium vivax
PubMed: 27836912
DOI: 10.1101/cshperspect.a025452 -
Journal of Vector Borne Diseases 2018Malaria, caused by the protozoan parasites of the genus Plasmodium, is a major health problem in many countries of the world. Five parasite species namely, Plasmodium... (Review)
Review
Malaria, caused by the protozoan parasites of the genus Plasmodium, is a major health problem in many countries of the world. Five parasite species namely, Plasmodium falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi, cause malaria in humans. Of these, P. falciparum and P. vivax are the most prevalent and account for the majority of the global malaria cases. In most areas of Africa, P. vivax infection is essentially absent because of the inherited lack of Duffy antigen receptor for chemokines on the surface of red blood cells that is involved in the parasite invasion of erythrocytes. Therefore, in Africa, most malaria infections are by P. falciparum and the highest burden of P. vivax infection is in Southeast Asia and South America. Plasmodium falciparum is the most virulent and as such, it is responsible for the majority of malarial mortality, particularly in Africa. Although, P. vivax infection has long been considered to be benign, recent studies have reported life-threatening consequences, including acute respiratory distress syndrome, cerebral malaria, multi-organ failure, dyserythropoiesis and anaemia. Despite exhibiting low parasite biomass in infected people due to parasite's specificity to infect only reticulocytes, P. vivax infection triggers higher inflammatory responses and exacerbated clinical symptoms than P. falciparum, such as fever and chills. Another characteristic feature of P. vivax infection, compared to P. falciparum infection, is persistence of the parasite as dormant liver-stage hypnozoites, causing recurrent episodes of malaria. This review article summarizes the published information on P. vivax epidemiology, drug resistance and pathophysiology.
Topics: Antimalarials; Asia, Southeastern; Drug Resistance; Female; Humans; Inflammation; Liver; Malaria, Vivax; Male; Plasmodium vivax; Pregnancy; Pregnancy Complications, Parasitic; Recurrence; South America
PubMed: 29916441
DOI: 10.4103/0972-9062.234620 -
Parasitology International Oct 2021An estimated 229 million cases of malaria occurred worldwide in 2019. Both, Plasmodium falciparum and P. vivax are responsible for most of the malaria disease burden in... (Review)
Review
An estimated 229 million cases of malaria occurred worldwide in 2019. Both, Plasmodium falciparum and P. vivax are responsible for most of the malaria disease burden in the world. Despite difficulties in obtaining an accurate number, the global estimates of cases in 2019 are approximately 229 million of which 2.8% are due to P. vivax, and the total number of malaria deaths are approximately 409 million. Regional elimination or global eradication of malaria will be a difficult task, particularly for P. vivax due to the particular biological features related to the hypnozoite, leading to relapse. Countries that have shown successful episodes of a decrease in P. falciparum malaria, are left with remaining P. vivax malaria cases. This is caused by the mechanism that the parasite has evolved to remain dormant in the liver forming hypnozoites. Furthermore, while clinical trials of vaccines against P. falciparum are making fast progress, a very different picture is seen with P. vivax, where only few candidates are currently active in clinical trials. We discuss the challenge that represent the hypnozoite for P. vivax vaccine development, the potential of Controlled Human Malaria Challenges (CHMI) and the leading vaccine candidates assessed in clinical trials.
Topics: Animals; Humans; Malaria Vaccines; Malaria, Vivax; Plasmodium vivax
PubMed: 34166786
DOI: 10.1016/j.parint.2021.102411 -
Cold Spring Harbor Perspectives in... Sep 2017is the second most prevalent cause of malaria worldwide and the leading cause of malaria outside of Africa. Although infections are seldom fatal clinical disease can be... (Review)
Review
is the second most prevalent cause of malaria worldwide and the leading cause of malaria outside of Africa. Although infections are seldom fatal clinical disease can be debilitating and imposes significant health and economic impacts on affected populations. Estimates of transmission and prevalence intensity can be problematic because many episodes of vivax originate from hypnozoite stages in the liver that have remained dormant from previous infections by an unknown mechanism. Lack of treatment options to clear hypnozoites and the ability to infect mosquitoes before disease symptoms present represent major challenges for control and eradication of vivax malaria. Compounding these challenges is the unique biology of and limited progress in development of experimental research tools, thereby hindering development of new drugs and vaccines. Renewed emphasis on vivax malaria research is beginning to make progress in overcoming some of these challenges.
Topics: Animals; Asymptomatic Infections; Humans; Malaria, Vivax; Plasmodium vivax
PubMed: 28490540
DOI: 10.1101/cshperspect.a025585 -
Experimental Biology and Medicine... Oct 2023Malaria is the leading human parasitosis and is transmitted through the bite of anopheline mosquitoes infected with parasites of the genus spp. Among the seven species... (Review)
Review
Malaria is the leading human parasitosis and is transmitted through the bite of anopheline mosquitoes infected with parasites of the genus spp. Among the seven species that cause malaria in humans, is the most prevalent species in Latin America. In recent years, there have been an increasing number of reports of clinical complications caused by infections, which were previously neglected and underestimated. biology remains with large gaps. The emergence of next-generation sequencing technology has ensured a breakthrough in species knowledge. Coupled with this, the deposition of the Sal-1 reference genome allowed an increase in transcriptomics projects by accessing messenger RNA. Thus, the regulation of differential gene expression according to the parasite life stage was verified, and several expressed genes were linked to different biological functions. Today, with the progress associated with RNA sequencing technologies, it is possible to detect nuances and obtain robust results. Discoveries provided by transcriptomic studies allow us to understand topics such as RNA expression and regulation and proteins and metabolic pathways involved during different stages of the parasite life cycle. The information obtained enables a better comprehension of immune system evasion mechanisms; invasion and adhesion strategies used by the parasite; as well as new vaccine targets, potential molecular markers, and others therapeutic targets. In this review, we provide new insights into biology by summarizing recent findings in transcriptomic studies.
Topics: Animals; Humans; Plasmodium vivax; Malaria, Vivax; Malaria; Parasites; Gene Expression Profiling
PubMed: 37786955
DOI: 10.1177/15353702231198070 -
Malaria Journal Aug 2014A study searching for Plasmodium vivax and Plasmodium falciparum DNA among blood donors from the non-endemic area in Brazil reported a rate of 7.41%. This number is at...
A study searching for Plasmodium vivax and Plasmodium falciparum DNA among blood donors from the non-endemic area in Brazil reported a rate of 7.41%. This number is at least three times higher than what has been observed in blood donors from the Amazon, an endemic area concentrating >99% of all malaria cases in Brazil. Moreover, the majority of the donors were supposedly infected by P. falciparum, a rare finding both in men and anophelines from the Atlantic forest. These findings shall be taken with caution since they disagree with several publications in the literature and possibly overestimate the actual risk of malaria transmission by blood transfusion in São Paulo city.
Topics: Asymptomatic Infections; Humans; Malaria, Falciparum; Malaria, Vivax; Plasmodium falciparum; Plasmodium vivax; Transfusion Reaction
PubMed: 25168246
DOI: 10.1186/1475-2875-13-336 -
Malaria Journal Nov 2022This review article aims to investigate the genotypic profiles of Plasmodium falciparum and Plasmodium vivax isolates collected across a wide geographic region and their... (Review)
Review
This review article aims to investigate the genotypic profiles of Plasmodium falciparum and Plasmodium vivax isolates collected across a wide geographic region and their association with resistance to anti-malarial drugs used in Indonesia. A systematic review was conducted between 1991 and date. Search engines, such as PubMed, Science Direct, and Google Scholar, were used for articles published in English and Indonesian to search the literature. Of the 471 initially identified studies, 61 were selected for 4316 P. falciparum and 1950 P. vivax individual infections. The studies included 23 molecular studies and 38 therapeutic efficacy studies. K76T was the most common pfcrt mutation. K76N (2.1%) was associated with the haplotype CVMNN. By following dihydroartemisinin-piperaquine (DHA-PPQ) therapy, the mutant pfmdr1 alleles 86Y and 1034C were selected. Low prevalence of haplotype N86Y/Y184/D1246Y pfmdr1 reduces susceptibility to AS-AQ. SNP mutation pvmdr1 Y976F reached 96.1% in Papua and East Nusa Tenggara. Polymorphism analysis in the pfdhfr gene revealed 94/111 (84.7%) double mutants S108N/C59R or S108T/A16V in Central Java. The predominant pfdhfr haplotypes (based on alleles 16, 51, 59,108, 164) found in Indonesia were ANCNI, ANCSI, ANRNI, and ANRNL. Some isolates carried A437G (35.3%) or A437G/K540E SNPs (26.5%) in pfdhps. Two novel pfdhps mutant alleles, I588F/G and K540T, were associated with six pfdhps haplotypes. The highest prevalence of pvdhfr quadruple mutation (F57L/S58R/T61M/S117T) (61.8%) was detected in Papua. In pvdhps, the only polymorphism before and after 2008 was 383G mutation with 19% prevalence. There were no mutations in the pfk13 gene reported with validated and candidate or associated k13 mutation. An increased copy number of pfpm2, associated with piperaquine resistance, was found only in cases of reinfection. Meanwhile, mutation of pvk12 and pvpm4 I165V is unlikely associated with ART and PPQ drug resistance. DHA-PPQ is still effective in treating uncomplicated falciparum and vivax malaria. Serious consideration should be given to interrupt local malaria transmission and dynamic patterns of resistance to anti-malarial drugs to modify chemotherapeutic policy treatment strategies. The presence of several changes in pfk13 in the parasite population is of concern and highlights the importance of further evaluation of parasitic ART susceptibility in Indonesia.
Topics: Plasmodium vivax; Plasmodium falciparum; Indonesia; Antimalarials; Artemisinins; Polymorphism, Single Nucleotide; Drug Resistance
PubMed: 36443817
DOI: 10.1186/s12936-022-04385-2 -
The American Journal of Tropical... Dec 2016Plasmodium vivax is the most widespread human malaria, putting 2.5 billion people at risk of infection. Its unique biological and epidemiological characteristics pose... (Review)
Review
Plasmodium vivax is the most widespread human malaria, putting 2.5 billion people at risk of infection. Its unique biological and epidemiological characteristics pose challenges to control strategies that have been principally targeted against Plasmodium falciparum Unlike P. falciparum, P. vivax infections have typically low blood-stage parasitemia with gametocytes emerging before illness manifests, and dormant liver stages causing relapses. These traits affect both its geographic distribution and transmission patterns. Asymptomatic infections, high-risk groups, and resulting case burdens are described in this review. Despite relatively low prevalence measurements and parasitemia levels, along with high proportions of asymptomatic cases, this parasite is not benign. Plasmodium vivax can be associated with severe and even fatal illness. Spreading resistance to chloroquine against the acute attack, and the operational inadequacy of primaquine against the multiple attacks of relapse, exacerbates the risk of poor outcomes among the tens of millions suffering from infection each year. Without strategies accounting for these P. vivax-specific characteristics, progress toward elimination of endemic malaria transmission will be substantially impeded.
Topics: Global Health; Humans; Malaria, Vivax; Plasmodium vivax
PubMed: 27402513
DOI: 10.4269/ajtmh.16-0141 -
Malaria Journal May 2022Malaria is a vector-borne disease caused by protozoan parasites of the genus Plasmodium. Plasmodium vivax is the most prevalent human-infecting species in the Americas.... (Review)
Review
Malaria is a vector-borne disease caused by protozoan parasites of the genus Plasmodium. Plasmodium vivax is the most prevalent human-infecting species in the Americas. However, the origins of this parasite in this continent are still debated. Similarly, it is now accepted that the existence of Plasmodium simium is explained by a P. vivax transfer from humans to monkey in America. However, many uncertainties still exist concerning the origin of the transfer and whether several transfers occurred. In this review, the most recent studies that addressed these questions using genetic and genomic approaches are presented.
Topics: Biological Evolution; Genome; Humans; Malaria; Plasmodium; Plasmodium vivax
PubMed: 35505431
DOI: 10.1186/s12936-022-04132-7 -
Frontiers in Cellular and Infection... 2021The development of genetic manipulation of in the 1980s was key to study malaria biology. Genetically modified parasites have been used to study several aspects of the... (Review)
Review
The development of genetic manipulation of in the 1980s was key to study malaria biology. Genetically modified parasites have been used to study several aspects of the disease, such as red blood cell invasion, drug resistance mechanisms, gametocyte development and mosquito transmission. However, biological and genetic differences between and the other human malaria parasites make a poor model to study different species. The lack of robust systems of long-term culture of and the other human malaria parasites lagged the genetic manipulation of these species. Here we review the efforts to generate genetically modified non- human malaria parasites, and . Using models - infection of non-human primates such as rhesus macaques and saimiri monkeys - researchers were able to generate transgenic lines of , and . The development of long-term culture of in the 2000's, using rhesus and human red blood cells, created a platform to genetically manipulate non- malaria parasites. Recently, the use of CRISPR/Cas9 technology to genome edit provides another tool to non-falciparum malaria research, extending the possibilities and allowing researchers to study different aspects of the biology of these parasites and understand the differences between these species and .
Topics: Animals; Humans; Macaca mulatta; Malaria; Malaria, Vivax; Parasites; Plasmodium knowlesi; Plasmodium vivax
PubMed: 34527600
DOI: 10.3389/fcimb.2021.680460