A conserved epitope in VAR2CSA is targeted by a cross-reactive antibody originating from Duffy binding protein.

During infection in pregnancy, VAR2CSA is expressed on the surface of infected erythrocytes (IEs) and mediates their sequestration in the placenta. As a result, antibodies to VAR2CSA are largely restricted to women who were infected during pregnancy. However, we discovered that VAR2CSA antibodies can also be elicited by Duffy binding protein (PvDBP).

Antibodies to Cryptic Epitopes in Distant Homologues Underpin a Mechanism of Heterologous Immunity between PvDBP and VAR2CSA.

Many pathogens evolve extensive genetic variation in virulence proteins as a strategy to evade host immunity. This poses a significant challenge for the host to develop broadly neutralizing antibodies. In , we show that a mechanism to circumvent this challenge is to elicit antibodies to cryptic epitopes that are not under immune pressure.

Cross-Species Immune Recognition Between Plasmodium vivax Duffy Binding Protein Antibodies and the Plasmodium falciparum Surface Antigen VAR2CSA.

Background: In pregnancy, Plasmodium falciparum parasites express the surface antigen VAR2CSA, which mediates adherence of red blood cells to chondroitin sulfate A (CSA) in the placenta. VAR2CSA antibodies are generally acquired during infection in pregnancy and are associated with protection from placental malaria. We observed previously that men and children in Colombia also had antibodies to VAR2CSA, but the origin of these antibodies was unknown.

Negative immunomodulation by parasitic infections in the human response to vaccines.

Parasitic infections are an important cause of global morbidity and mortality and are highly prevalent in "underdeveloped" countries. The presence of parasitic infections is associated with modulation of the immune system and changes in the response to bacterial and viral vaccines. The objective of this review was to compile, summarize and analyze information about immunomodulation by parasitic infections and its effects on the immune response to vaccines.

A sensitive species-specific reverse transcription real-time PCR method for detection of and .

As the global burden of malaria decreases and countries strive towards disease elimination, there is a greater demand for sensitive diagnostics to target the submicroscopic reservoir of infection. We describe here a sensitive species-specific RT-qPCR method to differentiate between and infections at the submicroscopic level. With amplification of the 18S rRNA genes from total nucleic acids (both DNA and RNA), we discern and with a limit of detection of 10 parasites/mL and 18 copies/μL, respectively.

Clinical Outcomes of Submicroscopic Infections and Correlates of Protection of VAR2CSA Antibodies in a Longitudinal Study of Pregnant Women in Colombia.

Malaria in pregnancy can cause serious adverse outcomes for the mother and the fetus. However, little is known about the effects of submicroscopic infections (SMIs) in pregnancy, particularly in areas where and cocirculate. A cohort of 187 pregnant women living in Puerto Libertador in northwest Colombia was followed longitudinally from recruitment to delivery.

Asymptomatic plasmodial infection in pregnant women: A global scenario.

Though asymptomatic plasmodial infection (API) is well known phenomenon and play an important role in different populations and malaria transmission settings, it has received less attention in malaria intervention strategies. This review was aimed to estimate the prevalence of API in pregnant women across the world. The bibliography records relevant to the study were searched on PubMed and Lilacs, till August 15, 2016, without restriction of language.

Efficacy of Different Primaquine Regimens to Control Gametocytemia in Colombia.

Treatment against malaria includes blood schizonticides to clear asexual parasites responsible for disease. The addition of gametocytocidal drugs can eliminate infectious sexual stages with potential for transmission and the World Health Organization recommends a single dose (SD) of primaquine (PQ) to this end. The efficacy of PQ at 0.

Microscopic detection of hemozoin in peripheral leukocytes fails to indicate plasmodial placental infection in pregnant women.

Introduction: Malaria in pregnancy very often includes gestational (parasites in maternal peripheral blood) and placental (parasites in placental blood) infection, but the later condition can only be detected after delivery. High frequency of placental plasmodial infection has been confirmed in many countries and is associated with negative birth outcomes. With the hypothesis that placental infection is accompanied by hemozoin circulation in maternal peripheral blood, an exploratory study was conducted to evaluate the association between peripheral leukocytes with hemozoin and placental infection by Plasmodium vivax or Plasmodium falciparum in parturient women.

Asymptomatic plasmodial infection in Colombian pregnant women.

Information about asymptomatic plasmodial infection is scarce in the world, and the current antimalarial program goals (control, elimination, and eradication) demand this evidence to be well documented in different populations and malaria transmission settings. This study aimed to measure the prevalence of API in Colombian pregnant women at delivery. A retrospective prevalence survey was used.

A high resolution case study of a patient with recurrent Plasmodium vivax infections shows that relapses were caused by meiotic siblings.

Plasmodium vivax infects a hundred million people annually and endangers 40% of the world's population. Unlike Plasmodium falciparum, P. vivax parasites can persist as a dormant stage in the liver, known as the hypnozoite, and these dormant forms can cause malaria relapses months or years after the initial mosquito bite.

Status of allele frequency and diversity of Plasmodium falciparum msp1, msp2 and glurp before implementation of an artemisinin-based combined therapy in Northwestern Colombia.

Introduction: The status of msp1, msp2 and glurp allele frequency and the diversity of Plasmodium falciparum in Northwestern Colombia before the implementation of an artemisinin-combined therapy have been explored only by a few authors and in a relatively small number of samples from this highly endemic region.

Objective: To evaluate the frequency of msp1, msp2, and glurp alleles and the diversity of P. falciparum in two Colombian regions before the use of an artemisinin-combined therapy.

Functional antibodies against VAR2CSA in nonpregnant populations from colombia exposed to Plasmodium falciparum and Plasmodium vivax.

In pregnancy, parity-dependent immunity is observed in response to placental infection with Plasmodium falciparum. Antibodies recognize the surface antigen, VAR2CSA, expressed on infected red blood cells and inhibit cytoadherence to the placental tissue. In most settings of malaria endemicity, antibodies against VAR2CSA are predominantly observed in multigravid women and infrequently in men, children, and nulligravid women.

Submicroscopic infection of placenta by Plasmodium produces Th1/Th2 cytokine imbalance, inflammation and hypoxia in women from north-west Colombia.

Background: A large-scale study was set up in order to study the epidemiology, clinical aspects, and immunopathology of gestational and placental malaria in north-west Colombia. In this region, recent reports using a qPCR technique, confirmed frequencies of infection, by Plasmodium falciparum or Plasmodium vivax, up to 45%. Given the high rates of infection observed both in mother and placenta, a first exploratory study was proposed in order to characterize the effect on the inflammation status, tissue damage and hypoxia in Plasmodium spp.

Prevalence of gestational, placental and congenital malaria in north-west Colombia.

Background: The frequency of pregnancy-associated malaria is increasingly being documented in American countries. In Colombia, with higher frequency of Plasmodium vivax over Plasmodium falciparum infection, recent reports confirmed gestational malaria as a serious public health problem. Thick smear examination is the gold standard to diagnose malaria in endemic settings, but in recent years, molecular diagnostic methods have contributed to elucidate the dimension of the problem of gestational malaria.

Molecular detection of malaria at delivery reveals a high frequency of submicroscopic infections and associated placental damage in pregnant women from northwest Colombia.

Plasmodium infection in pregnancy causes substantial maternal and infant morbidity and mortality. In Colombia, both P. falciparum and P.

Placental malaria in Colombia: histopathologic findings in Plasmodium vivax and P. falciparum infections.

Studies on gestational malaria and placental malaria have been scarce in malaria-endemic areas of the Western Hemisphere. To describe the histopathology of placental malaria in Colombia, a longitudinal descriptive study was conducted. In this study, 179 placentas were studied by histologic analysis (112 with gestational malaria and 67 negative for malaria).

Genotype comparison of Plasmodium vivax and Plasmodium falciparum clones from pregnant and non-pregnant populations in North-west Colombia.

Background: Placental malaria is the predominant pathology secondary to malaria in pregnancy, causing substantial maternal and infant morbidity and mortality in tropical areas. While it is clear that placental parasites are phenotypically different from those in the peripheral circulation, it is not known whether unique genotypes are associated specifically with placental infection or perhaps more generally with pregnancy. In this study, genetic analysis was performed on Plasmodium vivax and Plasmodium falciparum parasites isolated from peripheral and placental blood in pregnant women living in North-west Colombia, and compared with parasites causing acute malaria in non-pregnant populations.

Efficacy of different primaquine-based antimalarial regimens against Plasmodium falciparum gametocytemia.

This study compared the efficacy against Plasmodium falciparum gametocytes of four regimens: amodiaquine-sulfadoxine/pyrimethamine (AQ-SP) and mefloquine-artesunate (MQ-AS), with and without primaquine (PQ) administered with the second dose of the schizonticide (AQ-SP; AQ-SP-PQ; MQ-AS; MQ-AS-PQ). Efficacy was determined by thick smear on days 1, 4 and 8 after the beginning of treatment. A total of 82 patients (19-23/group) were recruited.

Real-time PCR detection of Plasmodium directly from whole blood and filter paper samples.

Background: Real-time PCR is a sensitive and specific method for the analysis of Plasmodium DNA. However, prior purification of genomic DNA from blood is necessary since PCR inhibitors and quenching of fluorophores from blood prevent efficient amplification and detection of PCR products.

Methods: Reagents designed to specifically overcome PCR inhibition and quenching of fluorescence were evaluated for real-time PCR amplification of Plasmodium DNA directly from blood.

[Effect of submicroscopic or polyclonal Plasmodium falciparum infection on mother and gestation product: systematic review].

Background: Malaria in pregnancy causes substantial maternal and infant morbidity-mortality, even at submicroscopic parasite levels. In addition, the presence of polyclonal infections secondary to high parasite genetic diversity is a common finding.

Objectives: To determine the frequency of submicroscopic and/or polyclonal plasmodial infection during pregnancy and to establish their impact on clinical presentation, immunity acquisition, and consequences on mother and gestation product.

[In vitro susceptibility of Colombian Plasmodium falciparum isolates to different antimalarial drugs].

Introduction: The in vitro assays for susceptibility of Plasmodium falciparum to antimalarial drugs are important tools for monitoring drug resistance, however few such studies have been undertaken in Colombia.

Objective: P. falciparum isolates were obtained from several municipalities in western Colombia (Urabá, Bajo Cauca, Pacific Coast) and characterized for their in vivo susceptibility to chloroquine (CQ), amodiaquine (AQ), mefloquine (MQ), quinine (QN) and artesunate (AS).

[Gametocytemia in falciparum malaria treated with amodiaquine or artesunate].

Introduction: Antimalarial treatment effects on Plasmodium falciparum gametocytemia has been the focus of few studies in the Americas.

Objective: Relationships are described that occur between falciparum gametocytemia and the treatment with amodiaquine-sulfadoxine-pyrimethamine, artesunate-sulfadoxine-pyrimethamine or amodiaquine-artesunate.

Materials And Methods: The experimental design consisted of a randomized selection of patients not balanced or blinded.

Prevention of sporogony of Plasmodium vivax in Anopheles albimanus by steroids of Solanum nudum Dunal (Solanaceae).

The sporontocidal activity of three steroids (SN-1, SN-2 and SN-4) from Solanum nudum Dunal (Solanaceae) was determined against naturally circulating isolates of Plasmodium vivax in Anopheles albimanus. Laboratory-reared Anopheles albimanus mosquitoes were infected with P. vivax from gametocytemic blood of volunteers resident in Buenaventura, Valle del Cauca (Colombian Pacific Coast) by using an artificial membrane feeder.