Protective effect of amiodarone in malaria

According to previous observations, amiodarone triggers suicidal erythrocyte death or eryptosis, which is characterized by cell shrinkage and exposure of phosphatidylserine at the erythrocyte surface. Eryptosis may in turn accelerate the clearance of Plasmodium-infected erythrocytes. The present study tested whether amiodarone augments phosphatidylserine exposure of Plasmodium-infected erythrocytes, interferes with the development of parasitemia and thus influences the course of malaria. The in vitro infection of human erythrocytes with Plasmodium falciparum (strain BinH) increased annexin V-binding, an effect significantly augmented by amiodarone (10 μM). Amiodarone further significantly decreased intraerythrocytic DNA/RNA content (≥5 μM) and in vitro parasitemia (≥1 μM). Following infection of mice with Plasmodiumberghei ANKA by intraperitoneal injection of parasitized murine erythrocytes (1 × 10⁶) amiodarone (intraperitoneal 50 mg/kg b.w.) significantly decreased the parasitemia and increased the survival of P. berghei-infected mice (from 0% to 70% 26 days after infection). Moreover, treatment with amiodarone significantly increased the percentage of PS-exposing infected erythrocytes. In conclusion, amiodarone inhibits intraerythrocytic growth of P. falciparum, enhances suicidal death of infected erythrocytes, decreases parasitemia following P. berghei infection and supports host survival during malaria.     

Malaria prevalence in north–eastern Nigeria: A cross–sectional study

ObjectiveTo assess the prevalence of malaria parasitemia in north–east Nigeria and to evaluate the measures for the prevention of malaria.MethodsA village in north–eastern Nigeria was selected for the cross sectional study at the height of the rainy season in October 2011. A total of 550 inhabitants of a hamlet were recruited for this study. After obtaining the consent individuals received a structured interview and were tested for malaria parasites in their blood films. Recruits testing positive for malaria were given a course of artemesinin–based combination therapy (ACT).ResultsA total of 497 inhabitants representing approximately 90 percent of the population participated: a quarter of the study group carried malaria parasitesexclusively Plasmodium falciparum (P. falciparum)–representing a P. falciparum parasite rate (PfPR) of 24.5%. Besides, 53/138 in the age group of 2 to < 10 years old children tested positive for P. falciparum representing a PfPR_2–10 value of 38.4%. Malaria control measures were used in just under a third (157/497) of this cohort. Despite these measures 28/157 (17.8%) still tested positive for P. falciparum.ConclusionsThe malaria burden is overestimated for this region in north–east Nigeria. The findings support an intermediate pattern of malaria endemicity. The 30% bed nets coverage for malaria control is well below the WHO estimates for 2011.     

Relation between vitamin B12 and folate status, and hemoglobin concentration and parasitemia during acute malaria infections in Colombia

Anemia is a common complication of human malaria. Since micronutrient deficiencies are highly prevalent in malaria-endemic areas and appear to contribute to anemia etiology, we conducted a cross-sectional study in Tumaco, Colombia, to examine the associations between plasma vitamin B12 or erythrocyte folate concentrations and hemoglobin (Hb) among 96 adults with predominantly Plasmodium falciparum malaria. Prevalence of folate and vitamin B12 deficiencies was 26.0 and 26.6%, respectively. There was an inverse, linear relation between folate and Hb concentrations. Adjusted difference in Hb between lowest and highest folate quartiles was 1 g/dL (p = 0.04; p, test for trend = 0.01). Vitamin B12 was not associated with Hb concentrations and did not modify the associations between folate and Hb. Incidentally, body mass index (BMI) was inversely associated with parasitemia and risk of clinical malaria. Future longitudinal studies are warranted to determine the potential pathophysiological role of folate in malaria-related anemia.     

Relative Undernourishment and Food Insecurity Associations with Plasmodium falciparum Among Batwa Pygmies in Uganda: Evidence from a Cross-Sectional Survey

Although malnutrition and malaria co-occur among individuals and populations globally, effects of nutritional status on risk for parasitemia and clinical illness remain poorly understood. We investigated associations between Plasmodium falciparum infection, nutrition, and food security in a cross-sectional survey of 365 Batwa pygmies in Kanungu District, Uganda in January of 2013. We identified 4.1% parasite prevalence among individuals over 5 years old. Severe food insecurity was associated with increased risk for positive rapid immunochromatographic test outcome (adjusted relative risk [ARR] = 13.09; 95% confidence interval [95% CI] = 2.23–76.79). High age/sex-adjusted mid-upper arm circumference was associated with decreased risk for positive test among individuals who were not severely food-insecure (ARR = 0.37; 95% CI = 0.19–0.69). Within Batwa pygmy communities, where malnutrition and food insecurity are common, individuals who are particularly undernourished or severely food-insecure may have elevated risk for P. falciparum parasitemia. This finding may motivate integrated control of malaria and malnutrition in low-transmission settings.     

Evidence for genetic linkage between a polymorphism in the GNAS gene and malaria in South Indian population

The complex imprinted GNAS locus which encodes G-alpha subunit (Gαs) is involved in a number of G-protein coupled signaling pathways in eukaryotic cells. Erythrocyte invasion by Plasmodium falciparum parasites is significantly regulated by protein of GNAS gene. This study was designed to evaluate the association between single nucleotide polymorphisms (SNPs) present in GNAS locus and susceptibility to malaria. In this case control study, individuals affected by P. falciparum malaria (n = 230), Plasmodium vivax malaria (n = 230) and normal controls (n = 230) were tested for the association of eighteen (18) known SNPs to evaluate their role in the onset of the disease. There was no significant difference in genotype frequencies of all the SNPs tested between P. falciparum and P. vivax affected individuals. However, when Bonferroni correction for multiple comparisons were performed as a control, our results demonstrated alleles and genotypes of rs7121: C > T (NC_000020.10:g.57478807C > T), a silent polymorphism situated in the exon 5, were significantly (p < 0.05) associated with susceptibility to malaria in the South Indians participants. Our results demonstrate that population specific polymorphisms that exist in GNAS gene may alter the risk of occurrence of malaria.     

Falciparum malaria parasitemia index for predicting severe malaria

Introduction: While hyperparasitemia is considered an important indicator for the development of severe malaria, there is currently no consensus on the quantitative definition of hyperparasitemia. This study was conducted to establish a cutoff point for peripheral parasitemia among patients with Plasmodium falciparum malaria, to define severe malaria. Methods: The clinical presentations of 200 uncomplicated P. falciparum malaria, and 189 severe P. falciparum malaria, patients, admitted to the Hospital for Tropical Diseases, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand, were analyzed. Results: A peripheral parasitemia of 0.5% was found to be the optimal cutoff point for defining severe malaria, demonstrating highest sensitivity (85.1%), specificity (62.0%), and accuracy (73.2%). Conclusion: Symptoms of severe falciparum malaria depend on many factors. For the definition of hyperparasitemia in areas of low or seasonal transmission, peripheral parasitemia of 0.5% might be considered a cutoff point for discrimination between severity levels. This value might be useful for the clinical management of malaria, particularly in hypo‐endemic areas, unstable transmission areas, and other areas with similar transmission patterns.     

Effect of transmission intensity and age on subclass antibody responses to Plasmodium falciparum pre-erythrocytic and blood-stage antigens

Cytophilic immunoglobulin (IgG) subclass responses (IgG1 and IgG3) to Plasmodium falciparum antigens have been associated with protection from malaria, yet the relative importance of transmission intensity and age in generation of subclass responses to pre-erythrocytic and blood-stage antigens have not been clearly defined. We analyzed IgG subclass responses to the pre-erythrocytic antigens CSP, LSA-1, and TRAP and the blood-stage antigens AMA-1, EBA-175, and MSP-1 in asymptomatic residents age 2 years or older in stable (n = 116) and unstable (n = 96) transmission areas in Western Kenya. In the area of stable malaria transmission, a high prevalence of cytophilic (IgG1 and IgG3) antibodies to each antigen was seen in all age groups. Prevalence and levels of cytophilic antibodies to pre-erythrocytic and blood-stage P. falciparum antigens increased with age in the unstable transmission area, yet IgG1 and IgG3 responses to most antigens for all ages in the unstable transmission area were less prevalent and lower in magnitude than even the youngest age group from the stable transmission area. The dominance of cytophilic responses over non-cytophilic (IgG2 and IgG4) was more pronounced in the stable transmission area, and the ratio of IgG3 over IgG1 generally increased with age. In the unstable transmission area, the ratio of cytophilic to non-cytophilic antibodies did not increase with age, and tended to be IgG3-biased for pre-erythrocytic antigens yet IgG1-biased for blood-stage antigens. The differences between areas could not be attributed to active parasitemia status, as there were minimal differences in antibody responses between those positive and negative for Plasmodium infection by microscopy in the stable transmission area. Individuals in areas of unstable transmission have low cytophilic to non-cytophilic IgG subclass ratios and low IgG3:IgG1 ratios to P. falciparum antigens. These imbalances could contribute to the persistent risk of clinical malaria in these areas and serve as population-level, age-specific biomarkers of transmission.     

An epidemiological study on clinical profile of malaria in Rampachodavaram and Maredumilli the tribal belt of east Godavari,Andhra Pradesh,India

ObjectiveTo observe the distribution of malaria infection in the tribal area of East Godavari District of Andhra Pradesh, India.MethodsThe data for the present study was collected from 6 342 and 765 patients who were admitted at tribal hospital and hill forest camps respectively during the study period. The data was collected from the malaria suspected patients admitted in paediatric and adult critical care wards of a tertiary hospital and in interior hill and forest camps in and around the Rampachodavaram. The detailed medical case sheet proforma were prepared and data has been analyz. It was found that RDT's can be helpful to screen Plasmodium falciparum (P. falciparum) inendemic areas and remote tribal belt.ResultsA total number of 6 342 and 765 patients were admitted at tribal hospital and hill forest camps respectively during the study period. Among 6 342 of individuals tested, 4 387 individuals were reported for malaria positive. Out of the 4 387 slides examined, 59.0% were positive P. falciparum infection, 19.4% slides showed positive Plasmodium vivax infection and 21.5% had mixed infection. The total P. falciparum burden was estimated as 80.5%. In hill forest camps, out of 765 admitted patients, 650 patients who had clinical history showed suggestive of malaria were examined for malaria parasites.ConclusionsThe maximum numbers of malaria infection (4 387) were reported from the tribal based hospital. Malaria is responsible for major health concern in this region, particularly in rainy season. P. falciparum was the major parasite type causing malaria, and most of the complications were due to Plasmodium vivax. Compared to rest of the hills and forest areas, where most of the tribal people reside has the heavy load of malaria mainly P. falciparum. One important finding from the present study was the sex-difference observed in the admission rate. The rate of malaria infection was significantly high for male (53.5%), followed by female (46.5%) and children (33%).     

Multiple splenic infarcts in acute Plasmodium vivax malaria: A rare case report

In tropical countries like India, malaria has been one of the most common parasitic illnesses leading to frequent hospitalization and causing major economic burden among the masses. Although Plasmodium vivax infection is considered to be benign, in contrast to Plasmodium falciparum infection which is notorious for its severe splenic complications can occur frequently. Splenomegaly tends not to receive special attention, as it is not usually accompanied by any symptoms and can be gradually resolved via standard antimalarial therapy. Splenic infarction, although rarely attributable to malaria in an endemic region with high parasitemia, can be a rare presentation of this disease entity.     

Stronger host response per parasitized erythrocyte in Plasmodium vivax or ovale than in Plasmodium falciparum malaria

Objective and methods Fever tends to start at a lower level of parasitemia in Plasmodium vivax or ovale than in P. falciparum malaria, but hyperparasitemia and complications are more likely to occur in P. falciparum malaria. Therefore, we compared the relationship between parasitemia and host response parameters before therapy in 97 patients with P. faciparum malaria (18 with complications), and 28 with P. vivax or ovale malaria. Results In both types of malaria, parasitemia correlated with blood levels of tumour necrosis factor alpha (TNF‐alpha), lactate dehydrogenase (LDH), Thrombin–antithrombin III (TAT) and elastase, and these parameters were higher in P. falciparum malaria than in P. vivax or ovale malaria. In contrast, the ratios of TNF‐alpha, TAT, elastase, and LDH per parasitized erythrocyte were higher in P. vivax or ovale malaria than in uncomplicated P. falciparum malaria. They were lowest in complicated disease. Multivariate regression analysis confirmed that parasitemia did not affect these differences. Conclusion The host response may reach full strength at lower parasitemia in Plasmodium vivax or ovale, than in P. falciparum malaria. With hyperparasitemia in P. falciparum malaria, the host response seems to be unable to control parasite multiplication.     

Efficacy of Chloroquine for the Treatment of Uncomplicated Plasmodium falciparum Malaria in Honduras

Chloroquine (CQ) is officially used for the primary treatment of Plasmodium falciparum malaria in Honduras. In this study, the therapeutic efficacy of CQ for the treatment of uncomplicated P. falciparum malaria in the municipality of Puerto Lempira, Gracias a Dios, Honduras was evaluated using the Pan American Health Organization—World Health Organization protocol with a follow-up of 28 days. Sixty-eight patients from 6 months to 60 years of age microscopically diagnosed with uncomplicated P. falciparum malaria were included in the final analysis. All patients who were treated with CQ (25 mg/kg over 3 days) cleared parasitemia by day 3 and acquired no new P. falciparum infection within 28 days of follow-up. All the parasite samples sequenced for CQ resistance mutations (pfcrt) showed only the CQ-sensitive genotype (CVMNK). This finding shows that CQ remains highly efficacious for the treatment of uncomplicated P. falciparum malaria in Gracias a Dios, Honduras.     

A prospective analysis of the Ab response to Plasmodium falciparum before and after a malaria season by protein microarray

Abs are central to malaria immunity, which is only acquired after years of exposure to Plasmodium falciparum (Pf). Despite the enormous worldwide burden of malaria, the targets of protective Abs and the basis of their inefficient acquisition are unknown. Addressing these knowledge gaps could accelerate malaria vaccine development. To this end, we developed a protein microarray containing ∼23% of the Pf 5,400-protein proteome and used this array to probe plasma from 220 individuals between the ages of 2–10 years and 18–25 years in Mali before and after the 6-month malaria season. Episodes of malaria were detected by passive surveillance over the 8-month study period. Ab reactivity to Pf proteins rose dramatically in children during the malaria season; however, most of this response appeared to be short-lived based on cross-sectional analysis before the malaria season, which revealed only modest incremental increases in Ab reactivity with age. Ab reactivities to 49 Pf proteins measured before the malaria season were significantly higher in 8–10-year-old children who were infected with Pf during the malaria season but did not experience malaria (n = 12) vs. those who experienced malaria (n = 29). This analysis also provided insight into patterns of Ab reactivity against Pf proteins based on the life cycle stage at which proteins are expressed, subcellular location, and other proteomic features. This approach, if validated in larger studies and in other epidemiological settings, could prove to be a useful strategy for better understanding fundamental properties of the human immune response to Pf and for identifying previously undescribed vaccine targets.     

Plasmodium falciparum infection during suppressive prophylaxis with mefloquine does not induce an antibody response to merozoite surface protein-1(42)

A sensitive biomarker of malaria infection would obviate the need for placebo control arms in clinical trials of malaria prophylactic drugs. Antibodies to the 42-kDa fragment of merozoite surface protein-1 (MSP1₄₂) have been identified as a potential marker of malaria exposure in individuals receiving prophylaxis with mefloquine. We conducted an open-label trial to determine the sensitivity of seroconversion to MSP1₄₂, defined as a fourfold rise in enzyme-linked immunosorbant assay (ELISA) titer, among 23 malaria naïve volunteers receiving mefloquine prophylaxis and 6 controls after Plasmodium falciparum sporozoite challenge. All members of the control cohort but none of the mefloquine cohort developed patent parasitemia. Four of six controls but zero of the mefloquine cohort seroconverted to MSP1₄₂. We conclude that malaria infection during suppressive prophylaxis does not induce antibody response to the blood-stage antigen MSP1₄₂ in a malaria-naïve study population.     

Subtle changes in Plasmodium falciparum infection complexity following enhanced intervention in Malawi

With support from the Global Fund, the United States President's Malaria Initiative (PMI) and other cooperating partners, Malawi is implementing a comprehensive malaria control programme involving indoor residual spraying in targeted districts, universal coverage with insecticide-treated bed nets, use of rapid diagnostic tests to confirm the clinical diagnosis of malaria and use of the highly effective artemisinin-based combination therapy, artemether-lumefantrine (AL), as the first-line treatment for malaria. We genotyped 24 genome-wide single nucleotide polymorphisms (SNPs) in Plasmodium falciparum infections (n = 316) sampled from a single location in Malawi before (2006 and 2007) and after enhanced intervention (2008 and 2012). The SNP data generated were used to examine temporal changes in the proportion of multiple-genotype infections (MIs), mean number of heterozygous SNPs within MIs, parasite genetic diversity (expected heterozygosity and genotypic richness), multilocus linkage disequilibrium and effective population size (N_e). While the proportion of MIs, expected heterozygosity, genotypic richness, multilocus linkage disequilibrium and N_e were unchanged over time, the mean number (±standard deviation) of heterozygous SNPs within MIs decreased significantly (p = 0.01) from 9(±1) in 2006 to 7(±1) in 2012. These findings indicate that the genetic diversity of P. falciparum malaria parasites in this area remains high, suggesting that only subtle gains, if any, have been made in reducing malaria transmission. Continued surveillance is required to evaluate the impact of malaria control interventions in this area and the rest of Malawi, and to better target control interventions.     

Transplacentally transferred functional antibodies against Plasmodium falciparum decrease with age

Transplacental transfer of antibodies from clinically malaria immune pregnant women to their fetuses is thought to provide passive protection against malaria during infancy. However, the presences and duration of functional antibodies against Plasmodium falciparum (Pf) in newborns has not been described. We used growth inhibition assays (GIA) to measure total anti-malaria functional antibodies present at birth and over the following year. Samples were drawn from cord blood (n = 86) and in infants at six and 12 months of life (n = 86 and 65 respectively). Three laboratory Pf strains (D10, W2mef, 3D7) and a field isolate (Msambweni 2006) were used in the assays. Median (ranges) GIA levels for cord plasma differed between laboratory parasite strains: D10, 0% (0–81); W2mef, 6% (0–80); 3D7, 18% (0–88); Msambweni 2006, 6% (0–43) (P < 0.001, Wilcoxon signed-rank test). GIA levels against all Pf strains were found to decline in infants from birth to six months (P < 0.01, Wilcoxon, signed-rank test). Functional antibodies as measured by GIA are transferred to the fetus and wane in the infants over time. Infant protection from clinical malaria disease may in part be mediated by these functional anti-malaria antibodies.     

Hemoglobin Concentration and Parasitemia on Hospital Admission Predict Risk of Multiple Organ Dysfunction Syndrome among Adults with Malaria

Risk factors for progression from acute malaria to multiple organ dysfunction syndrome (MODS) are poorly understood. The MODS is commonly diagnosed with the sequential organ failure assessment (SOFA) scale, but this scale has been understudied in patients with severe malaria. We conducted a cohort study among 426 adult males admitted to hospital with malaria in Bogotá, Colombia. We estimated SOFA scores and relative risks (RRs) for MODS during hospitalization according to patients'' characteristics on admission. Risk of MODS was 7.3% over a median 6.0 days in hospital. Baseline hemoglobin was strongly, inversely associated with MODS (adjusted RR for hemoglobin ≤ 8.5 g/dL versus hemoglobin > 11 g/dL = 9.5, 95% confidence interval [CI]: 3.6, 25.3). Plasmodium falciparum malaria and parasitemia were positively associated with MODS. There was a strong interaction between baseline parasitemia and hemoglobin on MODS risk. In conclusion, the use of parasitemia and hemoglobin on admission to identify high-risk patients deserves consideration.     

Case Report: Severe Congenital Malaria Acquired in utero

Vertical transmission of Plasmodium falciparum is under-recognized and usually associated with asymptomatic low-level parasitemia at birth. We report symptomatic congenital malaria presenting as a neonatal sepsis syndrome. The presence at birth of a high asexual parasitemia, gametocytemia, and splenomegaly indicated in utero rather than intrapartum transmission. The neonate was successfully treated with intravenous artesunate followed by oral dihydroartemisinin-piperaquine, without apparent adverse effects.     

Social determinants of malaria and health care seeking patterns among rice farming and pastoral communities in Kilosa District in central Tanzania

This study was carried out to understand the role social determinants and health seeking behavior among rice farming and pastoral communities in Kilosa District in central Tanzania. The study involved four villages; two with rice farming communities while the other two with pastoral communities. In each village, heads of households or their spouses were interviewed to seek information on livelihoods activities, knowledge and practices on malaria and its preventions. A total of 471 individuals (males = 38.9%; females = 61.1%) were interviewed. Only 23.5% of the respondents had adequate knowledge on malaria. Fifty-six percent of the respondents could not associate any livelihood activity with malaria transmission. Majority (79%) of the respondents believed that most of fevers were due to malaria; this was higher among the pastoral (81.7%) than rice farming communities (76.1%) (p = 0.038). Cases of fever were significantly higher in households with non-educated (31.2%) than educated respondents (21.5%). Women experienced significantly more episodes of fever than men (p < 0.001). Of the total of 2606 individuals living in the households, 26.9% were reported to have had fever in the previous three months. Fever was reported more frequently among pastoral than rice farming communities (p < 0.01). Of those who had fever, 36.6% were clinically diagnosed with malaria and 22.9% were confirmed to be infected with malaria. A combination of fever + convulsions or joint pains + headache was most frequently perceived to be malaria. Treatment seeking frequency differed by the size of the household and between rice farming and pastoral communities (p = 0.05). In conclusion, education, sex, availability of health care facility and livelihood practices were the major social determinants that influence malaria acquisition and care seeking pattern in central Tanzania. Appropriate public health promotion should be designed to address the links of livelihoods and malaria transmission among rural farming communities in an ecohealth approach.     

Development of a Polymerase Chain Reaction (PCR) method based on amplification of mitochondrial DNA to detect Plasmodium falciparum and Plasmodium vivax

In this study we standardized a new technical approach in which the target mitochondrial DNA sequence (mtDNA) is amplified using a simple but sensitive PCR method as a tool to detect Plasmodium falciparum and Plasmodium vivax. Specific primers were designed to hybridize with cytochrome c oxidase genes of P. falciparum (cox III) and P. vivax (cox I). Amplification products were obtained for all positive samples, presenting homology only for species-specific mtDNA. Sensitivity and specificity were 100%. The applicability of the method was tested in a cross-sectional study, in which 88 blood samples from individuals naturally exposed to malaria in the Brazilian Amazon region were analyzed. Based on the results, the sensitivity and specificity were 100% and 88.3%, respectively. This simple and sensitive PCR method can be useful in specific situations and in different settings of malaria management, in endemic as well as non-endemic areas (travelers), and in clinical or epidemiological studies, with applications in malaria control programs.