Plasmodium Parasitaemia Research Articles

The shape of the iceberg: quantification of submicroscopic Plasmodium falciparum and Plasmodium vivax parasitaemia and gametocytaemia in five low endemic settings in Ethiopia

BackgroundThe widespread presence of low-density asymptomatic infections with concurrent gametocytes may be a stumbling block for malaria elimination. This study investigated the asymptomatic reservoir of Plasmodium falciparum and Plasmodium vivax infections in schoolchildren from five settings in northwest Ethiopia.MethodsTwo cross-sectional surveys were conducted in June and November 2015, enrolling 551 students from five schools and 294 students from three schools, respectively. Finger prick whole blood and plasma samples were collected. The prevalence and density of P. falciparum and P. vivax parasitaemia and gametocytaemia were determined by 18S rRNA quantitative PCR (qPCR) and pfs25 and pvs25 reverse transcriptase qPCR. Antibodies against blood stage antigens apical membrane antigen-1 (AMA-1) and merozoite surface protein-1 (MSP-119) were measured for both species.ResultsWhilst only 6 infections were detected by microscopy in 881 slides (0.7%), 107 of 845 blood samples (12.7%) were parasite positive by (DNA-based) qPCR. qPCR parasite prevalence between sites and surveys ranged from 3.8 to 19.0% for P. falciparum and 0.0 to 9.0% for P. vivax. The median density of P. falciparum infections (n = 85) was 24.4 parasites/µL (IQR 18.0–34.0) and the median density of P. vivax infections (n = 28) was 16.4 parasites/µL (IQR 8.8–55.1). Gametocyte densities by (mRNA-based) qRT-PCR were strongly associated with total parasite densities for both P. falciparum (correlation coefficient = 0.83, p = 0.010) and P. vivax (correlation coefficient = 0.58, p = 0.010). Antibody titers against P. falciparum AMA-1 and MSP-119 were higher in individuals who were P. falciparum parasite positive in both surveys (p < 0.001 for both comparisons).DiscussionThis study adds to the available evidence on the wide-scale presence of submicroscopic parasitaemia by quantifying submicroscopic parasite densities and concurrent gametocyte densities. There was considerable heterogeneity in the occurrence of P. falciparum and P. vivax infections and serological markers of parasite exposure between the examined low endemic settings in Ethiopia.

Submicroscopic and Asymptomatic Plasmodium Parasitaemia Associated with Significant Risk of Anaemia in Papua, Indonesia.

Submicroscopic Plasmodium infections are an important parasite reservoir, but their clinical relevance is poorly defined. A cross-sectional household survey was conducted in southern Papua, Indonesia, using cluster random sampling. Data were recorded using a standardized questionnaire. Blood samples were collected for haemoglobin measurement. Plasmodium parasitaemia was determined by blood film microscopy and PCR. Between April and July 2013, 800 households and 2,830 individuals were surveyed. Peripheral parasitaemia was detected in 37.7% (968/2,567) of individuals, 36.8% (357) of whom were identified by blood film examination. Overall the prevalence of P. falciparum parasitaemia was 15.4% (396/2567) and that of P. vivax 18.3% (471/2567). In parasitaemic individuals, submicroscopic infection was significantly more likely in adults (adjusted odds ratio (AOR): 3.82 [95%CI: 2.49–5.86], p<0.001) compared to children, females (AOR = 1.41 [1.07–1.86], p = 0.013), individuals not sleeping under a bednet (AOR = 1.4 [1.0–1.8], p = 0.035), and being afebrile (AOR = 3.2 [1.49–6.93], p = 0.003). The risk of anaemia (according to WHO guidelines) was 32.8% and significantly increased in those with asymptomatic parasitaemia (AOR 2.9 [95% 2.1–4.0], p = 0.007), and submicroscopic P. falciparum infections (AOR 2.5 [95% 1.7–3.6], p = 0.002). Asymptomatic and submicroscopic infections in this area co-endemic for P. falciparum and P. vivax constitute two thirds of detectable parasitaemia and are associated with a high risk of anaemia. Novel public health strategies are needed to detect and eliminate these parasite reservoirs, for the benefit both of the patient and the community.

Characteristics and Outcomes of Pediatric Patients With Ebola Virus Disease Admitted to Treatment Units in Liberia and Sierra Leone: A Retrospective Cohort Study.

The clinical and virologic characteristics of Ebola virus disease (EVD) in children have not been thoroughly documented. Consecutive children aged <18 years with real-time polymerase chain reaction (RT-PCR)-confirmed EVD were enrolled retrospectively in 5 Ebola treatment units in Liberia and Sierra Leone in 2014/2015. Data collection and medical management were based on standardized International Medical Corps protocols. We performed descriptive statistics, multivariate logistic regression, and Kaplan-Meier survival analyses. Of 122 children enrolled, the median age was 7 years and one-third were aged <5 years. The female-to-male ratio was 1.3. The most common clinical features at triage and during hospitalization were fever, weakness, anorexia, and diarrhea, although 21% of patients were initially afebrile and 6 patients remained afebrile. Bleeding was rare at presentation (5%) and manifested subsequently in fewer than 50%. The overall case fatality rate was 57%. Factors associated with death in bivariate analyses were age <5 years, bleeding at any time during hospitalization, and high viral load. After adjustment with logistic regression modeling, the odds of death were 14.8-fold higher if patients were aged <5 years, 5-fold higher if the patient had any evidence of bleeding, and 5.2-fold higher if EVD RT-PCR cycle threshold value was ≤20. Plasmodium parasitemia had no impact on EVD outcomes. Age <5 years, bleeding, and high viral loads were poor prognostic indicators of children with EVD. Research to understand mechanisms of these risk factors and the impact of dehydration and electrolyte imbalance will improve health outcomes.

Timing of in utero malaria exposure influences fetal CD4 T cell regulatory versus effector differentiation.

BackgroundIn malaria-endemic areas, the first exposure to malaria antigens often occurs in utero when the fetal immune system is poised towards the development of tolerance. Children exposed to placental malaria have an increased risk of clinical malaria in the first few years of life compared to unexposed children. Recent work has suggested the potential of pregnancy-associated malaria to induce immune tolerance in children living in malaria-endemic areas. A study was completed to evaluate the effect of malaria exposure during pregnancy on fetal immune tolerance and effector responses.MethodsUsing cord blood samples from a cohort of mother-infant pairs followed from early in pregnancy until delivery, flow cytometry analysis was completed to assess the relationship between pregnancy-associated malaria and fetal cord blood CD4 and dendritic cell phenotypes.ResultsCord blood FoxP3+ Treg counts were higher in infants born to mothers with Plasmodium parasitaemia early in pregnancy (12–20 weeks of gestation; p = 0.048), but there was no association between Treg counts and the presence of parasites in the placenta at the time of delivery (by loop-mediated isothermal amplification (LAMP); p = 0.810). In contrast, higher frequencies of activated CD4 T cells (CD25+FoxP3−CD127+) were observed in the cord blood of neonates with active placental Plasmodium infection at the time of delivery (p = 0.035). This population exhibited evidence of effector memory differentiation, suggesting priming of effector T cells in utero. Lastly, myeloid dendritic cells were higher in the cord blood of infants with histopathologic evidence of placental malaria (p < 0.0001).ConclusionTogether, these data indicate that in utero exposure to malaria drives expansion of both regulatory and effector T cells in the fetus, and that the timing of this exposure has a pivotal role in determining the polarization of the fetal immune response.

Spatial mapping and prediction of Plasmodium falciparum infection risk among school-aged children in Côte d'Ivoire.

BackgroundIn Côte d’Ivoire, malaria remains a major public health issue, and thus a priority to be tackled. The aim of this study was to identify spatially explicit indicators of Plasmodium falciparum infection among school-aged children and to undertake a model-based spatial prediction of P. falciparum infection risk using environmental predictors.MethodsA cross-sectional survey was conducted, including parasitological examinations and interviews with more than 5,000 children from 93 schools across Côte d’Ivoire. A finger-prick blood sample was obtained from each child to determine Plasmodium species-specific infection and parasitaemia using Giemsa-stained thick and thin blood films. Household socioeconomic status was assessed through asset ownership and household characteristics. Children were interviewed for preventive measures against malaria. Environmental data were gathered from satellite images and digitized maps. A Bayesian geostatistical stochastic search variable selection procedure was employed to identify factors related to P. falciparum infection risk. Bayesian geostatistical logistic regression models were used to map the spatial distribution of P. falciparum infection and to predict the infection prevalence at non-sampled locations via Bayesian kriging.ResultsComplete data sets were available from 5,322 children aged 5–16 years across Côte d’Ivoire. P. falciparum was the predominant species (94.5 %). The Bayesian geostatistical variable selection procedure identified land cover and socioeconomic status as important predictors for infection risk with P. falciparum. Model-based prediction identified high P. falciparum infection risk in the north, central-east, south-east, west and south-west of Côte d’Ivoire. Low-risk areas were found in the south-eastern area close to Abidjan and the south-central and west-central part of the country.ConclusionsThe P. falciparum infection risk and related uncertainty estimates for school-aged children in Côte d’Ivoire represent the most up-to-date malaria risk maps. These tools can be used for spatial targeting of malaria control interventions.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1775-z) contains supplementary material, which is available to authorized users.

A Novel Model of Asymptomatic Plasmodium Parasitemia That Recapitulates Elements of the Human Immune Response to Chronic Infection.

In humans, immunity to Plasmodium sp. generally takes the form of protection from symptomatic malaria (i.e., 'clinical immunity') rather than infection ('sterilizing immunity'). In contrast, mice infected with Plasmodium develop sterilizing immunity, hindering progress in understanding the mechanistic basis of clinical immunity. Here we present a novel model in which mice persistently infected with P. chabaudi exhibit limited clinical symptoms despite sustaining patent parasite burdens for many months. Characterization of immune responses in persistently infected mice revealed development of CD4+ T cell exhaustion, increased production of IL-10, and expansion of B cells with an atypical surface phenotype. Additionally, persistently infected mice displayed a dramatic increase in circulating nonclassical monocytes, a phenomenon that we also observed in humans with both chronic Plasmodium exposure and asymptomatic infection. Following pharmacological clearance of infection, previously persistently infected mice could not control a secondary challenge, indicating that persistent infection disrupts the sterilizing immunity that typically develops in mouse models of acute infection. This study establishes an animal model of asymptomatic, persistent Plasmodium infection that recapitulates several central aspects of the immune response in chronically exposed humans. As such, it provides a novel tool for dissection of immune responses that may prevent development of sterilizing immunity and limit pathology during infection.

Minimising invasiveness in diagnostics: developing a rapid urine-based monoclonal antibody dipstick test for malaria.

To generate monoclonal antibodies (MAbs) for developing a rapid malaria diagnostic urine-based assay (RUBDA), using Plasmodium-infected human urinary antigens. Plasmodium-infected human urinary (PAgHU) and cultured parasite (CPfAg) antigens were used to generate mouse MAbs. The reactivity and accuracy of the MAbs produced were then evaluated using microplate ELISA, SDS-PAGE, Western blotting assay, microscopy and immunochromatographic tests. Ninety-six MAb clones were generated, of which 68.8% reacted to both PAgHU and CPfAg, 31.3% reacted to PAgHU only, and none reacted to CPfAg only. One promising MAb (UCP4W7) reacted in WBA, to both PAgHU and CPfAg, but not to Plasmodium-negative human urine and blood, Schistosoma haematobium and S. mansoni antigens nor measles and poliomyelitis vaccines. MAb UCP4W7 seems promising for diagnosing Plasmodium infection. Urine is a reliable biomarker source for developing non-invasive malaria diagnostic tests. SDS-PAGE and MAb-based WBA appear explorable in assays for detecting different levels of Plasmodium parasitaemia.

Improved light microscopy counting method for accurately counting Plasmodium parasitemia and reticulocytemia.

Even with the advances in molecular or automated methods for detection of red blood cells of interest (such as reticulocytes or parasitized cells), light microscopy continues to be the gold standard especially in laboratories with limited resources. The conventional method for determination of parasitemia and reticulocytemia uses a Miller reticle, a grid with squares of different sizes. However, this method is prone to errors if not used correctly and counts become inaccurate and highly time-consuming at low frequencies of target cells. In this report, we outline the correct guidelines to follow when using a reticle for counting, and present a new counting protocol that is a modified version of the conventional method for increased accuracy in the counting of low parasitemias and reticulocytemias. Am. J. Hematol. 91:852-855, 2016. © 2016 Wiley Periodicals, Inc.

Persistent Plasmodium falciparum and Plasmodium vivax infections in a western Cambodian population: implications for prevention, treatment and elimination strategies.

BackgroundSubclinical Plasmodium parasitaemia is an important reservoir for the transmission and persistence of malaria, particularly in low transmission areas.MethodsUsing ultrasensitive quantitative PCR (uPCR) for the detection of parasitaemia, the entire population of three Cambodian villages in Pailin province were followed for 1 year at three-monthly intervals. A cohort of adult participants found initially to have asymptomatic malaria parasitaemia was followed monthly over the same period.ResultsThe initial cross sectional survey in June 2013 (M0) of 1447 asymptomatic residents found that 32 (2.2 %) had Plasmodium falciparum, 48 (3.3 %) had P. vivax, 4 (0.3 %) had mixed infections and in 142/1447 (9.8 %) malaria was detected but there was insufficient DNA to identify the species (Plasmodium. species). Polymorphisms in the ‘K13-propeller’ associated with reduced susceptibility to artemisinin derivatives (C580Y) were found in 17/32 (51 %) P. falciparum strains. Monthly follow-up without treatment of 24 adult participants with asymptomatic mono or mixed P. falciparum infections found that 3/24 (13 %) remained parasitaemic for 2–4 months, whereas the remaining 21/24 (87 %) participants had cleared their parasitaemia after 1 month. In contrast, 12/34 (35 %) adult participants with P. vivax mono-infection at M0 had malaria parasites (P. vivax or P. sp.) during four or more of the following 11 monthly surveys.ConclusionsThis longitudinal survey in a low transmission setting shows limited duration of P. falciparum carriage, but prolonged carriage of P. vivax infections. Radical treatment of P. vivax infections by 8-aminoquinoline regimens may be required to eliminate all malaria from Cambodia.Trial registration ClinicalTrials.gov NCT01872702Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1224-7) contains supplementary material, which is available to authorized users.

Reactive case-detection of malaria in Pailin Province, Western Cambodia: lessons from a year-long evaluation in a pre-elimination setting.

BackgroundAs momentum towards malaria elimination grows, strategies are being developed for scale-up in elimination settings. One prominent strategy, reactive case detection (RACD), involves screening and treating individuals living in close proximity to passively detected, or “index” cases. This study aims to use RACD to quantify Plasmodium parasitaemia in households of index cases, and identify risk factors for infection; these data could inform reactive screening approaches and identify target risk groups.MethodsThis study was conducted in the Western Cambodian province of Pailin between May 2013 and March 2014 among 440 households. Index participants/index cases (n = 270) and surrounding households (n = 110) were screened for Plasmodium infection with rapid diagnostic tests (RDT), microscopy and real-time polymerase chain reaction (PCR). Participants were interviewed to identify risk factors. A comparison group of 60 randomly-selected households was also screened, to compare infection levels of RACD and non-RACD households. In order to identify potential risk factors that would inform screening approaches and identify risk groups, multivariate logistic regression models were applied.ResultsNine infections were identified in households of index cases (RACD approach) through RDT screening of 1898 individuals (seven Plasmodium vivax, two Plasmodium falciparum); seven were afebrile. Seventeen infections were identified through PCR screening of 1596 individuals (15 P. vivax, and 22 % P. falciparum/P. vivax mixed infections). In the control group, 25 P. falciparum infections were identified through PCR screening of 237 individuals, and no P. vivax was found. Plasmodium falciparum infection was associated with fever (p = 0.013), being a member of a control household (p ≤ 0.001), having a history of malaria infection (p = 0.041), and sleeping without a mosquito net (p = 0.011). Significant predictors of P. vivax infection, as diagnosed by PCR, were fever (p = 0.058, borderline significant) and history of malaria infection (p ≤ 0.001).ConclusionThis study found that RACD identified very few secondary infections when targeting index and neighbouring households for screening. The results suggest RACD is not appropriate, where exposure to malaria occurs away from the community, and there is a high level of treatment-seeking from the private sector. Piloting RACD in a range of transmission settings would help to identify the ideal environment for feasible and effective reactive screening methods.

Epidemiology of malaria in the Taabo health and demographic surveillance system, south-central Côte d'Ivoire.

Background A deep understanding of the local epidemiology of malaria is essential for the design and implementation of setting-specific control and elimination efforts. In Côte d’Ivoire, new initiatives are underway to reduce the burden of malaria, which requires high-quality longitudinal data. The epidemiology of malaria was studied in the Taabo health and demographic surveillance system (HDSS) in south-central Côte d’Ivoire and implications for control are discussed.MethodsTwo cross-sectional surveys were carried out in the rainy season of June/July in 2010 and 2011. Inhabitants of approximately 7 % of randomly selected households in the Taabo HDSS were invited to participate. People were clinically examined, ear temperature was measured and spleen size determined. Finger-prick blood samples were collected and subjected to a rapid diagnostic test (RDT). Additionally, thick and thin blood films were prepared on microscope slides and diagnosed under a microscope for Plasmodium infection and parasitaemia. Haemoglobin (Hb) level was determined using a HemoCue device.ResultsA total of 1187 and 1264 people in 2010 and 2011, respectively, had complete data records. The prevalence of Plasmodium infection was 46.0 % in 2010 and 56.6 % in 2011, owing to a statistically significant difference (p < 0.05). Males showed a higher Plasmodium infection prevalence than females (49.6 and 62.8 % versus 42.6 and 51.2 %; respectively, in 2010 and 2011; both p < 0.05). The highest malaria prevalence was observed among infants and young children (aged ≤9 years). The risk of Plasmodium infection was significantly higher in villages compared to small hamlets and urban settings (p < 0.05). Fever, Hb level and splenomegaly were associated with parasitaemia.ConclusionMalaria is highly endemic in the Taabo HDSS in south-central Côte d’Ivoire with considerable spatial heterogeneity of Plasmodium infection. There is a pressing need to scale-up control interventions against malaria.

Prevention of Transfusion-Transmitted Malaria By Treatment of Whole Blood with the Mirasol® PRT System

Background: Across sub-Saharan Africa, blood supplies are threatened by numerous pathogens. In some locations, Plasmodium parasitemia prevalence in donor blood is nearly 50%. Donor testing for malaria in these areas is not effective and the risk of transfusion-transmitted malaria (TTM) is high. The Mirasol® PRT System for Whole Blood (WB) is a medical device intended for extracorporeal pathogen reduction of WB. The current clinical study evaluated the ability of Mirasol-treated WB to reduce the incidence of TTM.Study Design/Methods: This was a prospective, randomized, double-blind, controlled, single-center study in Ghana, which is hyperendemic for malaria. The study had 90% power to demonstrate a 90% reduction in TTM. Hospitalized patients requiring WB transfusions were randomly allocated to receive ≤ 2 transfusions of standard (untreated) or Mirasol-treated WB. The primary endpoint was the incidence of TTM as measured by quantitative polymerase chain reaction and Plasmodium alleleic sequence homology between transfused and patient WB during 28 days of follow-up. Patient safety was assessed by monitoring treatment-emergent adverse events (TEAEs) and transfusion reactions.Clinical outcomes related to hemoglobin increments, hemostatic parameters, and clinical chemistries were monitored for 28 days post-transfusion.Results: Overall, 226 subjects (113 Mirasol, 113 Untreated) were enrolled; 223 subjects were included in the safety analysis. Sixty-five (65) subjects were non-parasitemic at pre-transfusion (28 Mirasol, 37 Untreated) and received at least 1 parasitemic WB transfusion. Of 16 cases of suspected TTM (3 Mirasol, 13 Untreated) with 2 consecutive days of parasitemia, 9 were confirmed by alleleic homology (1 Mirasol, 8 Untreated). Incidence of TTM was significantly reduced in patients receiving treated products. Hemoglobin (mean [standard deviation]) was similar between groups at baseline (6.71 g/dL; p = 1.0), and Day 1 following 1 transfusion (8.53 [2.0] vs 8.49 [1.5] g/dL; p = 0.93) or 2 transfusions (7.09 [1.5] vs 7.38 [1.6] g/dL; p = 0.33). Ninety-two subjects (48 Mirasol, 44 Untreated) reported 145 TEAEs (75 Mirasol, 70 Untreated). Transfusion reactions were observed in 8.1% and 13.4% of subjects receiving Mirasol-treated and untreated WB, respectively.TableIncidence of TTMMirasol n (%); 95% CIUntreated n (%); 95% CIP-Value2 Consecutive days of ParasitemiaN = 653 (10.7); 2.3, 28.2 n = 2813 (35.1); 20.2, 52.2n = 37< 0.052 Consecutive days of Parasitemia and >2 Allele match by PCRN = 651 (3.6); 0.1, 18.3n = 288 (21.6); 9.8, 38.2n = 37< 0.05ITT PopulationN = 2231 (0.9); 0.0, 4.9n = 1118 (7.1); 3.1, 13.6n = 112< 0.05Abbreviation: CI = confidence interval, ITT = intent-to-treat, PCR = polymerase chain reaction.Conclusions: The primary endpoint of the study was met. Mirasol treatment of WB clinically and statistically reduced TTM infections in the study population. This was the first human clinical study demonstrating that a PRT system can reduce transmission of a bloodborne pathogen. No safety issues were related to the device or device-treated WB. Transfusion reactions did not differ between patients receiving Mirasol-treated or untreated WB. Hemoglobin increments and transfusion outcome parameters in transfused patients did not differ between the treatment groups. DisclosuresAllain:Terumo BCT: Consultancy. Owusu-Ofori:Terumo BCT: Other: Clinical Study Sub-Investigator. Marschner:Terumo BCT: Employment. Goodrich:Terumo BCT: Employment. Owusu-Ofori:Terumo BCT: Other: Clinical Study Investigator.

Prevalence and clinical correlates of Schistosoma mansoni co-infection among malaria infected patients, Northwest Ethiopia.

BackgroundIn Ethiopia, where malaria and schistosomiasis are co-endemic, co-infections are expected to be high. However, data about the prevalence of malaria-schistosomiasis co-infection and their clinical correlation is lacking. Therefore, the aim of this study was to assess prevalence of Schistosoma mansoni co-infection and associated clinical correlates in malaria patients.MethodsA cross-sectional study was conducted in 2013 at Chwahit Health Center, in northwest Ethiopia. Blood film positive malaria patients (N = 205) were recruited for the study. Clinical, parasitological, hematological, and biochemical parameters were assessed from every study participant. Stool samples were also collected and processed with Kato-Katz technique to diagnose and classify intensity of Schistosoma mansoni.ResultsThe prevalence of Schistosoma mansoni and malaria co-infection was 19.5 %. The age group of 16–20 years old was significantly associated with co-infection. Co-infected patients with a moderate-heavy egg burden of Schistosoma mansoni had significantly high mean Plasmodium parasitemia. On the other hand, age group of 6–10 years old and moderate-heavy Schistosoma mansoni co-infection were significantly associated with severe malaria.ConclusionsPrevalence of malaria and Schistosoma mansoni co-infection in the study area was considerably high. Severity of malaria and parasitemia of Plasmodium were associated with certain age groups and intensity of concurrent Schistosoma mansoni. Further study is needed to explore the underlying mechanisms of interaction between malaria and Schistosoma mansoni.

Unravelling the patterns of host immune responses in Plasmodium vivax malaria and dengue co-infection.

BackgroundConcurrent malaria and dengue infection is frequently diagnosed in endemic countries, but its immunopathology remains largely unknown. In the present study, a large panel of cytokines/chemokines and clinical laboratory markers were measured in patients with Plasmodium vivax and dengue co-infection as well as in individuals with malaria or dengue mono-infections in order to identify biosignatures of each clinical condition.MethodsIndividuals from the Brazilian Amazon were recruited between 2009 and 2013 and classified in three groups: vivax malaria (n = 52), dengue (n = 30) and vivax malaria and dengue co-infection (n = 30). P. vivax malaria was diagnosed by thick blood smear and confirmed by PCR; dengue cases were detected by IgM ELISA or NS1 protein. The plasma levels of cytokines and chemokines were determined by multiplex assay.ResultsIndividuals with malaria and dengue co-infection displayed lower levels of platelets and haemoglobin than those with malaria or dengue mono-infections (p = 0.0047 and p = 0.0001, respectively). The group of individuals co-infected exhibited the highest median concentrations of IFN-γ, IL-6, CCL4 than the mono-infected groups. Network analyses of plasma cytokines/chemokines revealed that malaria and dengue co-infection exhibits a distinct immune profile with critical roles for TNF, IL-6 and IFN-γ. Further, parasitaemia levels displayed positive significant interactions with IL-6, CCL4 and IL-10 in the group of patients co-infected with malaria and dengue. No differences were observed in distribution of dengue virus serotypes and Plasmodium parasitaemia levels between the groups.ConclusionsThe findings described here identify unique patterns of circulating immunological markers in cases of malaria and dengue co-infection and provide insights on the immunopathology of this co-morbid condition.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-015-0835-8) contains supplementary material, which is available to authorized users.

Disparities of Plasmodium falciparum infection, malaria-related morbidity and access to malaria prevention and treatment among school-aged children: a national cross-sectional survey in Côte d'Ivoire.

BackgroundThere is limited knowledge on the malaria burden of school-aged children in Côte d’Ivoire. The aim of this study was to assess Plasmodium falciparum infection, malaria-related morbidity, use of preventive measures and treatment against malaria, and physical access to health structures among school-aged children across Côte d’Ivoire.MethodsA national, cross-sectional study was designed, consisting of clinical and parasitological examinations and interviews with schoolchildren. More than 5,000 children from 93 schools in Côte d’Ivoire were interviewed to determine household socioeconomic status, self-reported morbidity and means of malaria prevention and treatment. Finger-prick blood samples were collected and Plasmodium infection and parasitaemia determined using Giemsa-stained blood films and a rapid diagnostic test (RDT). Haemoglobin levels and body temperature were measured. Children were classified into wealth quintiles using household assets and principal components analysis (PCA). The concentration index was employed to determine significant trends of health variables according to wealth quintiles. Logistic and binomial negative regression analyses were done to investigate for associations between P. falciparum prevalence and parasitaemia and any health-related variable.ResultsThe prevalence of P. falciparum was 73.9% according to combined microscopy and RDT results with a geometric mean of parasitaemia among infected children of 499 parasites/μl of blood. Infection with P. falciparum was significantly associated with sex, socioeconomic status and study setting, while parasitaemia was associated with age. The rate of bed net use was low compared to the rate of bed net ownership. Preventive measures (bed net ownership, insecticide spray and the reported use of malaria treatment) were more frequently mentioned by children from wealthier households who were at lower risk of P. falciparum infection. Self-reported morbidity (headache) and clinical morbidity (anaemia) were more often reported by children from less wealthy households.ConclusionSeven out of ten school-aged children in Côte d’Ivoire are infected with P. falciparum and malaria-related morbidity is considerable. Furthermore, this study points out that bed net usage is quite low and there are important inequalities in preventive measures and treatment. These results can guide equity-oriented malaria control strategies in Côte d’Ivoire.Electronic supplementary materialThe online version of this article (doi:10.1186/1475-2875-14-7) contains supplementary material, which is available to authorized users.

Diagnosis of Malaria among Blood Donors in Port Harcourt, Nigeria: Microscopy or Rapid Diagnostic Tests?

The two most common techniques available for diagnosis of malaria in Nigeria are microscopy and rapid diagnostic tests (RDTs). However, in diagnosing asymptomatic Plasmodium parasitaemia among donors, the preferred technique should not only be timely but must not compromise diagnosis. It should be more sensitive with minimal chances of false negative results. This study was carried out to compare microscopy and RDTs as effective tools for diagnosis of Plasmodium parasitaemia among blood donors in Port Harcourt. There were 200 donors involved in the study among which 135 (67.5%) tested positive and 65 (32.5%) tested negative on microscopy whereas 30 (15.0%) tested positive and 170 (85.0%) tested negative to RDT with a statistically significant difference between both techniques. Data were analysed using the statistical package epi-info version 7.02. We therefore recommend that microscopy using giemsa-stained blood films remain the method of choice for diagnosis of Plasmodium parasitaemia among blood donors to prevent the spread of transfusion malaria.

Prevalence of &amp;lt;i&amp;gt;Plasmodium&amp;lt;/i&amp;gt; Parasitaemia among Blood Donors in Port Harcourt, Nigeria

Globally, efforts are being intensified to control and possibly eliminate malaria. Transfusion transmitted Malaria unfortunately still occurs commonly in malaria endemic countries such as Nigeria and may continue to hamper efforts at control of malaria because blood donors are not routinely screened for malaria before donation. This study was carried out to determine the prevalence of Plasmodium Parasitaemia among blood donors who presented in our institution between 2012 and 2014, using light microscopy. Among the 200 donors studied, 135 (67.5%) were infected. Males (97.5%) were statistically more than females (2.5%) but infection rate was higher among the female population (100% as against 66.7% in males), with this difference being statistically significant. All donors were infected with Plasmodium falciparum with the majority of the donors having mild to moderate degrees of Parasitaemia. Women (52.5%) and children (17.5%) formed the bulk of recipients for which blood was donated. The high prevalence of Plasmodium Parasitaemia among blood donors in Port Harcourt highlights the need for more efforts to be targeted at preventing transmission of malaria via blood transfusion as this will ultimately contribute to reduction in the incidence of malaria and indeed its control/elimination in Nigeria.

Prevalence of placenta Plasmodium parasitemia and pregnancy outcome in asymptomatic patients at delivery in a university teaching hospital in Nigeria.

Malaria is an important public health issue in pregnancy association with poor fetal and maternal outcome, especially in malaria endemic area like Nigeria. The objective was to determine the prevalence of placental malaria in asymptomatic women in labor and to compare the fetal and maternal outcome between affected and unaffected women. A prospective cross-sectional study of 210 women who delivered at a tertiary health facility in Nigeria. Participants' peripheral venous blood, cord blood, and placental blood samples were examined microscopically for the presence of malaria parasite. Data collected were analyzed using SPSS version 16. Prevalence of placental malaria was 65.2%. Nulliparity was significantly associated with placental malaria (χ² = 21.32, P = 0.0000039, odds ratio [OR] =5.6). Poor compliance to intermittent preventive therapy was significantly associated with placental malaria (χ² = 16.67, P = 0.00004). The mean gestational age at delivery was 38.57 ± 1.7 weeks and 12.85% of women had preterm delivery. Sixty-seven (31.9%) women had anemia and malaria parasitemia was significantly associated with anemia (χ² = 8.34, P = 0.0039, OR = 2.6). Fourteen (6.67%) babies had low birth weight, but placental malaria was not significantly associated with low birth weight (χ² = 0.03, P = 0.87). There is a high prevalence of placental malaria in the study population. Nulliparity, poor drug compliance, and maternal anemia were associated with placental malaria.

Enterobiasis and strongyloidiasis and associated co-infections and morbidity markers in infants, preschool- and school-aged children from rural coastal Tanzania: a cross-sectional study.

BackgroundThere is a paucity of data pertaining to the epidemiology and public health impact of Enterobius vermicularis and Strongyloides stercoralis infections. We aimed to determine the extent of enterobiasis, strongyloidiasis, and other helminth infections and their association with asymptomatic Plasmodium parasitaemia, anaemia, nutritional status, and blood cell counts in infants, preschool-aged (PSAC), and school-aged children (SAC) from rural coastal Tanzania.MethodsA total of 1,033 children were included in a cross-sectional study implemented in the Bagamoyo district in 2011/2012. Faecal samples were examined for intestinal helminth infections using a broad set of quality controlled methods. Finger-prick blood samples were subjected to filariasis and Plasmodium parasitaemia testing and full blood cell count examination. Weight, length/height, and/or mid-upper arm circumference were measured and the nutritional status determined in accordance with age.ResultsE. vermicularis infections were found in 4.2% of infants, 16.7%, of PSAC, and 26.3% of SAC. S. stercoralis infections were detected in 5.8%, 7.5%, and 7.1% of infants, PSAC, and SAC, respectively. Multivariable regression analyses revealed higher odds of enterobiasis in children of all age-groups with a reported anthelminthic treatment history over the past six months (odds ratio (OR): 2.15; 95% confidence interval (CI): 1.22 - 3.79) and in SAC with a higher temperature (OR: 2.21; CI: 1.13 - 4.33). Strongyloidiasis was associated with eosinophilia (OR: 2.04; CI: 1.20-3.48) and with Trichuris trichiura infections (OR: 4.13; CI: 1.04-16.52) in children of all age-groups, and with asymptomatic Plasmodium parasitaemia (OR: 13.03; CI: 1.34 - 127.23) in infants. None of the investigated helminthiases impacted significantly on the nutritional status and anaemia, but moderate asymptomatic Plasmodium parasitaemia was a strong predictor for anaemia in children aged older than two years (OR: 2.69; 95% CI: 1.23 – 5.86).ConclusionsE. vermicularis and S. stercoralis infections were moderately prevalent in children from rural coastal Tanzania. Our data can contribute to inform yet missing global burden of disease and prevalence estimates for strongyloidiasis and enterobiasis. The association between S stercoralis and asymptomatic Plasmodium parasitaemia found here warrants further comprehensive investigations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0644-7) contains supplementary material, which is available to authorized users.

Role of IL6, IL12B and VDR gene polymorphisms in Plasmodium vivax malaria severity, parasitemia and gametocytemia levels in an Amazonian Brazilian population

ObjectiveTo investigate the influence of IL6, IL12B and VDR single nucleotide polymorphisms (SNPs) in uncomplicated Plasmodium vivax infection symptoms intensity, parasitemia and gametocytemia levels in a Brazilian Amazonian population. MethodsA total of 167 malaria patients infected by P. vivax have parasitemia and gametocytemia levels estimated before treatment. Fourteen clinical symptoms were evaluated and included in a principal component analysis to derive a clinical symptom index. Patients were genotyped for IL6-174C>G, IL12B 735T>C, 458A>G, 159A>C, and VDR FokI, TaqI, BsmI SNPs by Taqman 5’ nuclease assays. A General Linear Model analysis of covariance with age, gender, exposure period and infection history and genetic ancestry was performed to investigate the association of genotypes with parasitemia and gametocytemia levels and with a clinical symptom index. ResultsHigher parasitemia levels were observed in IL6-174C carriers (p=0.02) whereas IL12B CGT haplotype carriers presented lower parasitemia levels (p=0.008). VDR TaqIC/BsmIA haplotype carriers showed higher gametocyte levels than non-carriers (p=0.013). Based on the clinical index values the IL6-174C>G polymorphism was associated with malaria severity. The IL6-174C carriers presented a more severe clinical index when compared to GG homozygotes (p=0.001). ConclusionThe present study suggests that IL6, IL12 and VDR influence severity, parasitemia and gametocytemia clearance in P. vivax infections, and highlights their potential role in malaria immune response in an Amazonian population.