Characterisation of Plasmodium vivax lactate dehydrogenase dynamics in P. vivax infections.

Plasmodium vivax lactate dehydrogenase (PvLDH) is an essential enzyme in the glycolytic pathway of P. vivax. It is widely used as a diagnostic biomarker and a measure of total-body parasite biomass in vivax malaria. However, the dynamics of PvLDH remains poorly understood. Here, we developed mathematical models that capture parasite and matrix PvLDH dynamics in ex vivo culture and the human host. We estimated key biological parameters characterising in vivo PvLDH dynamics based on longitudinal data of parasitemia and PvLDH concentration collected from P. vivax-infected humans, with the estimates informed by the ex vivo data as prior knowledge in a Bayesian hierarchical framework. We found that the in vivo accumulation rate of intraerythrocytic PvLDH peaks at 10-20 h post-invasion (late ring stage) with a median estimate of intraerythrocytic PvLDH mass at the end of the life cycle to be 9.4 × 10-3ng. We also found that the median estimate of in vivo PvLDH half-life was approximately 21.9 h. Our findings provide a foundation with which to advance our quantitative understanding of P. vivax biology and will facilitate the improvement of PvLDH-based diagnostic tools.

Investigation of Sensitivity of Rapid Diagnosis Tests in Patients with Suspected Malaria

Objective: Malaria has been eradicated in Türkiye as of 2010, but there are imported cases. In this study, we aimed to compare the diagnostic value of two rapid tests; SD Bioline Malaria Ag Pf/Pan (SD-Pf/Pan) and SD Bioline Malaria Ag Pf/Pv (SD-Pf/Pv) with microscopy and real time-polymerase chain reaction (RT-PCR). Methods: Blood samples were taken from all participants. Thick drop smears were prepared. Thick drop smears were examined for malaria positive/negative distinction under the light microscopy. Then, two rapid diagnostic tests (SD-Pf/Pan and SD-Pf/Pv) were performed. After DNA extraction from blood samples, RT-PCR was typed. The data were evaluated with SPSS 21 program of statistics. Results: A total of 30 cases out of 66 suspected malaria cases were detected as positive with microscopy and RT-PCR. Twenty-seven patients were found positive with both SD-Pf/Pan and SD-Pf/Pv tests. Based on the microscopic results as a reference method, SD-Pf/Pan and SD-Pf/Pv rapid diagnostic tests had a 90% sensitivity, 100% specificity, 100% positive predictive value (PPV), and 92.86% negative predictive value (NPV). Based on the RT-PCR results as a reference method, for detection of P. falciparum, both tests had a 95.65% sensitivity, 100% specificity, 100% PPV, and 88.89% NPV. Moreover, while SD-Pf/Pv had a sensitivity, specificity, PPV, and NPV of 100% in detection of P. vivax; SD-Pf/Pan has a 77.78% sensitivity of, 61.90% specificity of, 46.67% PPV, and 86.67% NPV SD-Pf/Pan for detection of PAN. Conclusion: As a result, high sensitivity and specificity were detected in both kits in the diagnosis of malaria infections caused by P. falciparum and P. vivax. Rapid diagnostic tests can be used safely in diagnosis however the diagnosis should be supported by microscopy and RT-PCR methods when they are applicable.

A randomised controlled trial to compare the efficacy, safety, and tolerability of low dose, short course primaquine in adults with uncomplicated P. vivax malaria in two hospitals in India.

BACKGROUND: Plasmodium vivax remains a major challenge for malaria control and elimination due to its ability to cause relapsing illness. To prevent relapses the Indian National Center for Vector Borne Diseases Control (NCVBDC) recommends treatment with primaquine at a dose of 0.25 mg/kg/day provided over 14 days. Shorter treatment courses may improve adherence and treatment effectiveness. METHODS: This is a hospital-based, randomised, controlled, open-label trial in two centres in India. Patients above the age of 16 years, with uncomplicated vivax malaria, G6PD activity of ≥ 30% of the adjusted male median (AMM) and haemoglobin levels ≥ 8 g/dL will be recruited into the study and randomised in a 1:1 ratio to receive standard schizonticidal treatment plus 7-day primaquine at 0.50 mg/kg/day or standard care with schizonticidal treatment plus 14-day primaquine at 0.25 mg/kg/day. Patients will be followed up for 6 months. The primary endpoint is the incidence risk of any P. vivax parasitaemia at 6 months. Safety outcomes include the incidence risk of severe anaemia (haemoglobin < 8 g/dL), the risk of blood transfusion, a > 25% fall in haemoglobin and an acute drop in haemoglobin of > 5 g/dL during primaquine treatment. DISCUSSION: This study will evaluate the efficacy and safety of a 7-day primaquine regimen compared to the standard 14-day regimen in India. Results from this trial are likely to directly inform national treatment guidelines. TRIAL REGISTRATION: Trial is registered on CTRI portal, Registration No: CTRI/2022/12/048283.

Using serological diagnostics to characterize remaining high-incidence pockets of malaria in forest-fringe Cambodia.

BACKGROUND: Over the last decades, the number of malaria cases has drastically reduced in Cambodia. As the overall prevalence of malaria in Cambodia declines, residual malaria transmission becomes increasingly fragmented over smaller remote regions. The aim of this study was to get an insight into the burden and epidemiological parameters of Plasmodium infections on the forest-fringe of Cambodia. METHODS: 950 participants were recruited in the province of Mondulkiri in Cambodia and followed up from 2018 to 2020. Whole-blood samples were processed for Plasmodium spp. identification by PCR as well as for a serological immunoassay. A risk factor analysis was conducted for Plasmodium vivax PCR-detected infections throughout the study, and for P. vivax seropositivity at baseline. To evaluate the predictive effect of seropositivity at baseline on subsequent PCR-positivity, an analysis of P. vivax infection-free survival time stratified by serological status at baseline was performed. RESULTS: Living inside the forest significantly increased the odds of P. vivax PCR-positivity by a factor of 18.3 (95% C.I. 7.7-43.5). Being a male adult was also a significant predictor of PCR-positivity. Similar risk profiles were identified for P. vivax seropositivity. The survival analysis showed that serological status at baseline significantly correlated with subsequent infection. Serology is most informative outside of the forest, where 94.0% (95% C.I. 90.7-97.4%) of seronegative individuals survived infection-free, compared to 32.4% (95% C.I.: 22.6-46.6%) of seropositive individuals. CONCLUSION: This study justifies the need for serological diagnostic assays to target interventions in this region, particularly in demographic groups where a lot of risk heterogeneity persists, such as outside of the forest.

Methemoglobin levels in malaria: a systematic review and meta-analysis of its association with Plasmodium falciparum and Plasmodium vivax infections and disease severity.

Reports indicate that Plasmodium infections influence methemoglobin levels. However, findings have been inconclusive or have varied across different geographic and demographic contexts. This systematic review and meta-analysis aimed to consolidate existing data regarding the association between Plasmodium infections and alterations in methemoglobin levels related to the severity of the infection. A comprehensive literature search of several databases, including Ovid, ProQuest, Embase, Scopus, MEDLINE, and PubMed, was conducted to identify relevant studies that examined methemoglobin levels in patients with malaria. Qualitative synthesis and meta-analysis of the pooled standardized mean difference were conducted to synthesize the differences in methemoglobin levels between: (1) patients with malaria and those without malaria and (2) patients with severe malaria and those with uncomplicated malaria based on various themes including publication year, study design, study area, Plasmodium species, age group, symptomatic status, severity status, and method of malaria detection. Of the 1846 studies that were initially identified from the main databases and additional searches on Google Scholar, 10 studies met the eligibility criteria and were selected for this review. The systematic review distinctly highlighted an association between malaria and elevated methemoglobin levels, an observation consistent across diverse geographical regions and various Plasmodium species. Furthermore, the meta-analysis confirmed this by demonstrating increased methemoglobin levels in patients with malaria compared to those without malaria (P < 0.001, Hedges' g 2.32, 95% CI 1.36-3.29, I2 97.27, 8 studies). Moreover, the meta-analysis found elevated methemoglobin levels in patients with severe malaria compared to those with uncomplicated malaria (P < 0.001, Hedges' g 2.20, 95% CI 0.82-3.58, I2 96.20, 5 studies). This systematic review and meta-analysis revealed increased methemoglobin levels in patients with P. falciparum and P. vivax infections, with a notable association between elevated methemoglobin levels and severe malaria. Future research should focus on elucidating the specific mechanisms by which changes in methemoglobin levels are related to infections by P. falciparum and P. vivax, particularly in terms of severity, and how these alterations could potentially impact patient management and treatment outcomes.

Benefits of Lot Testing to Improve the Quality of Malaria Rapid Diagnostic Tests in India.

Since 2010, malaria rapid diagnostic tests (RDTs) are widely used to detect malaria. The Indian Council of Medical Research-National Institute of Malaria Research performed lot testing (LT) according to WHO procedures since 2016. Lot testing is performed to evaluate the lot-to-lot variation in performance of malaria RDTs. Four sets of positive quality control (QC) panels for P. falciparum (Pf) and P. vivax (Pv) and 10 negative panels tested RDTs. RDTs were reported as pass, failed, or deferred on the basis of WHO criteria. In the past 5 years, 275 lots containing 15,488 RDT kits for malaria diagnosis were subjected to LT. The monovalent RDTs (n = 1,216), based on either Pf histidine rich protein 2 (HRP2) or Pan-Plasmodium lactate dehydrogenase (Pan-pLDH) antigens, showed 90.4% sensitivity and 100% specificity, whereas RDTs based on HRP2 + Pan-pLDH or HRP2 + pLDH (n = 13,924) had sensitivity 95.6% and specificity 99.5%, respectively. RDTs based on PfHRP2 + Pv-pLDH + Pan-pLDH (n = 348) had 100% sensitivity and specificity. In a comparison between HRP2 + pLDH or HRP2 + Pan-pLDH to HRP2 + pLDH + Pan-pLDH RDTs, it was found that the sensitivity of PfHRP2 with Pan-pLDH RDTs (n = 2,382) was only 83%. Of the 275 lots analyzed, 15 lots of PfHRP2 with Pan-pLDH were deferred. The QC panel for Pf revealed a faint Pan band in the tested lots, which is a cause for concern. The results of deferred lots were reported to concerned government agencies. Quality-compromised RDTs may lead to an incorrect diagnosis. It is critical to have a QC system in place for effective malaria management.

A visualized hybrid PCR-LAMP assay for the detection of human Plasmodium species.

Combining the advantages of PCR and LAMP, we described a new technique, namely PCR-LAMP, for malaria diagnosis. The whole process of DNA amplification can be completed in 35 min. This hybrid amplification technique markedly improved the sensitivity of detection compared to the classic single PCR or LAMP assay alone. PCR-LAMP assay had a detection limit of 1 copy/µL for P. knowlesi and P. ovale, 0.1 copy/µL for P. vivax, P. falciparum and P. malariae, respectively. To facilitate the endpoint detection, xylenol orange was added. Positive samples were indicated in orange while negative reactions were violet. The inclusion of xylenol orange into the LAMP reaction mix significantly reduces the post-amplification workload. Without relying on the use of specific instruments, the color changes of the amplicons could be visualized directly through the naked eye. In conclusion, PCR-LAMP poses the potential to be developed as a new malaria molecular diagnosis tool.

Tafenoquine following G6PD screening versus primaquine for the treatment of vivax malaria in Brazil: A cost-effectiveness analysis using a transmission model.

BACKGROUND: Malaria transmission modelling has demonstrated the potential impact of semiquantitative glucose-6-phosphate dehydrogenase (G6PD) testing and treatment with single-dose tafenoquine for Plasmodium vivax radical cure but has not investigated the associated costs. This study evaluated the cost-effectiveness of P. vivax treatment with tafenoquine after G6PD testing using a transmission model. METHODS AND FINDINGS: We explored the cost-effectiveness of using tafenoquine after G6PD screening as compared to usual practice (7-day low-dose primaquine (0.5 mg/kg/day) without G6PD screening) in Brazil using a 10-year time horizon with 5% discounting considering 4 scenarios: (1) tafenoquine for adults only assuming 66.7% primaquine treatment adherence; (2) tafenoquine for adults and children aged >2 years assuming 66.7% primaquine adherence; (3) tafenoquine for adults only assuming 90% primaquine adherence; and (4) tafenoquine for adults only assuming 30% primaquine adherence. The incremental cost-effectiveness ratios (ICERs) were estimated by dividing the incremental costs by the disability-adjusted life years (DALYs) averted. These were compared to a willingness to pay (WTP) threshold of US$7,800 for Brazil, and one-way and probabilistic sensitivity analyses were performed. All 4 scenarios were cost-effective in the base case analysis using this WTP threshold with ICERs ranging from US$154 to US$1,836. One-way sensitivity analyses showed that the results were most sensitive to severity and mortality due to vivax malaria, the lifetime and number of semiquantitative G6PD analysers needed, cost per malaria episode and per G6PD test strips, and life expectancy. All scenarios had a 100% likelihood of being cost-effective at the WTP threshold. The main limitations of this study are due to parameter uncertainty around our cost estimates for low transmission settings, the costs of G6PD screening, and the severity of vivax malaria. CONCLUSIONS: In our modelling study that incorporated impact on transmission, tafenoquine prescribed after a semiquantitative G6PD testing was highly likely to be cost-effective in Brazil. These results demonstrate the potential health and economic importance of ensuring safe and effective radical cure.

An imported malaria case with repeated episodes of neurological syndromes resulting from different Plasmodium species.

BACKGROUND: Imported cerebral malaria (CM) cases in non-endemic areas are often misdiagnosed, which delays treatment. Post-malaria neurological syndrome (PMNS) after recovery from severe malaria can also complicate diagnosis. CASE: We report an imported malaria case from West Africa with two sequential episodes with neurological syndromes within about a month. The first episode was diagnosed as CM with microscopy-positive Plasmodium falciparum infection. The second episode, occurring a month after the recovery from the first CM episode, was consistent with PMNS, since malaria parasites were not detected by microscopy in peripheral blood smears. However, this diagnosis was complicated by the detection of Plasmodium vivax in peripheral blood by PCR, suggesting a potential cause of the second episode by P. vivax. CONCLUSION: This study suggests that PMNS often occurs after severe falciparum malaria. Concurrent P. vivax infection with pathogenic biomass being predominantly extravascular further complicates accurate diagnosis.

Clinical Profile and Treatment Outcomes of Patients with Malaria Complicated by Acute Kidney Injury.

As Odisha is an endemic region for malaria with many acute kidney injury (AKI) cases, this study evaluated the clinical profile and treatment outcomes of patients with malaria complicated by AKI. This prospective observational study was conducted between December 2015 and September 2017. Detailed histories and clinical examinations were recorded. On admission, tests for routine hematology, plasma glucose, liver function, renal function, serum electrolytes, thick smears, thin smears, and malarial parasites were performed. Of the 958 AKI malarial patients admitted, 202 (82.6 % males) were included in the study, with a mean age of 38.37 years. In total, 86.14%, 3.46%, and 10.39% of patients had Plasmodium falciparum, Plasmodium vivax, and mixed malaria, respectively. Headache and decreased urination (83.66% each) were the most common symptoms after fever (100%). Anuria and oliguria were reported in 5.95% and 67.82% of patients, respectively, whereas 26.23% reported a urine output of >400 mL/24 h. All patients had raised serum creatinine and urea levels, and >60% had anemia, proteinuria, and/or hyponatremia. Multiple organ dysfunction syndrome was observed in 62.87% of patients. Acute tubular necrosis was seen in 60% of renal biopsy specimens (n = 15). Of the 75.75% of patients requiring dialysis, 82.12% and 17.88% of patients required hemodialysis and peritoneal dialysis, respectively, during which 11 patients died. AKI, a serious complication of P. falciparum or P. vivax malaria, is a life-threatening condition. Fever, anemia, oligo/anuria, hepatic involvement, cerebral malaria, high serum creatinine and urea, and disseminated intravascular coagulation were the main predictors of mortality in our study.

Myositis-specific autoantibodies in a non-traveler, patient from a non-endemic country, with Plasmodium vivax malaria.

INTRODUCTION: Autoantibodies (AAb) are a hallmark of immune-mediated inflammatory diseases. Malaria is a parasitic disease caused by Plasmodium protozoa. Individuals with malaria may present with a wide range of symptoms. It is frequently linked to the development of different AAb. CASE DESCRIPTION: A 35-year-old male presented with repeated episodes of fever, malaise, myalgia, dark urine, and yellowish sclera. Initial diagnostic workup revealed severe Coombs-positive anemia, increased C-reactive protein, and procalcitonin, pathological liver tests, high concentration of serum IgE, IgG, IgM, IgA, positive antinuclear antibodies (ANA), and positive antineutrophil cytoplasmatic antibodies (ANCA). In addition, myositis-specific antibodies directed to polymiositis-scleroderma 75 protein (PmScl75), threonyl-tRNA synthetase (PL-7), alanyl-tRNA synthetase (PL-12), Mi-2 antigen (Mi-2), Ku DNA helicase complex (Ku), signal recognition particle (SRP), and antiaminoacyl tRNA synthetase (EJ) were detected. The patient was suspected of having systemic lupus erythematosus and sent to the Clinic of Allergy and Immunology for further evaluation and treatment. A peripheral blood film examined by the hematologist during an episode of fever revealed intra-erythrocytic parasitic forms of Plasmodium vivax (P. vivax). After being diagnosed with P. vivax malaria, he was transferred to the Clinic for Infective and Tropical Diseases. The therapy consisted of artesunate/mefloquine and prednisone led to a complete clinical recovery and autoantibodies gradually disappeared. CONCLUSIONS: Malaria would not normally be considered during the initial diagnostic workup in a non-traveler and a patient from a non-endemic country. However, a thorough parasitic evaluation in patients presenting with a broad range of autoantibodies might be of particular importance.

Successful elimination of falciparum malaria following the introduction of community-based health workers in Eastern Myanmar: A retrospective analysis.

BACKGROUND: Myanmar has a large majority of all malaria in the Greater Mekong Subregion. In the past decade, substantial progress was made in malaria control. The residual burden of malaria is in remote areas where currently recommended malaria elimination approaches are generally not feasible. In such hard-to-reach communities in Mon state, East Myanmar, Medical Action Myanmar introduced community health workers (CHWs) to deliver early diagnosis and treatment for malaria. We conducted a retrospective analysis to assess the impact of this intervention. METHODS AND FINDINGS: This retrospective analysis involved data collected routinely from a CHW programme in Mon state conducted between 2011 and 2018. A network of 172 CHWs serving a population of 236,340 was deployed. These CHWs carried out 260,201 malaria rapid diagnostic tests (RDTs) to investigate patients with acute febrile illness. The median blood examination rate was 1.33%; interquartile range (IQR) (0.38 to 3.48%); 95% CI [1.28%, 1.36%] per month. The changes in malaria incidence and prevalence in patients presenting with fever were assessed using negative binomial regression mixed effects models fitted to the observed data. The incidence of Plasmodium falciparum malaria (including mixed infections) declined by 70%; 95% CI [65%, 75%]; p < 0.001 for each year of CHW operation. The incidence of P. vivax malaria declined by 56%; 95% CI [50%, 62%]; p < 0.001 per year. Malaria RDT positivity rates for P. falciparum and P. vivax declined by 69%; 95% CI [62%, 75%]; p < 0.001 and 53%; 95% CI [47%, 59%]; p < 0.001 per year, respectively. Between 2017 and 2018, only 1 imported P. falciparum case was detected in 54,961 RDTs. The main limitations of the study are use of retrospective data with possible unidentified confounders and uncharacterised population movement. CONCLUSIONS: The introduction of CHWs providing community-based malaria diagnosis and treatment and basic health care services in remote communities in Mon state was associated with a substantial reduction in malaria. Within 6 years, P. falciparum was eliminated and the incidence of P. vivax fell markedly.

Standardization of DNA extraction from paraffinized spleen samples: molecular diagnosis of human malaria.

BACKGROUND: Plasmodium vivax is the main species responsible for human malaria in Brazil, and one of its manifestations is splenic malaria, though there are still challenges in its diagnosis. The present study aimed to standardize Plasmodium sp. DNA extraction from histological slices of spleen and diagnosis using real-time qPCR. METHODS: This study performed a microtomy of a paraffin-embedded spleen as a positive control for P. vivax from a patient who had been previously diagnosed with the parasite. The sample was deparaffinized with xylol and ethanol, then DNA extraction was performed with two commercial kits. qPCR was carried out with the Taqman system for detection of Plasmodium sp. and was made species-specific using PvmtCOX1 gene. From 2015 to 2019, 200 spleen samples were obtained from trauma patients subjected to splenectomy in Manaus, Amazonas. All the samples were tested for cell-free human DNA (cfDNA). RESULTS: The deparaffinization and the Plasmodium vivax DNA extraction method was successfully standardized, and the control sample was positive for P. vivax. Of the 200 samples, all qPCRs were negative, but they were positive for human PCR. CONCLUSION: Paraffinization is practical and efficient for the preservation of samples, but the formation of bonds between proteins and DNA makes extraction difficult. Despite this, in this study, it was possible to standardize a method of DNA extraction for detecting P. vivax.

[Autochthonous Case of Malaria Prediagnosed as Leukemia]. / Lösemi Ön Tanili Yerli Sitma Olgusu.

Malaria is a parasitic disease transmitted by infected female Anopheles mosquitoes. There are five species of Plasmodium species that can infect humans. Of these species, especially P.falciparum and P.vivax pose the greatest threat to human health. In the 2014 report of the World Health Organization, it was reported that there were no locally acquired cases of malaria in 16 countries including Türkiye. Malaria cases originating from outside the country and imported due to migration, travel and working abroad are reported as import cases. In this report, a case of non-imported malaria followed with a preliminary diagnosis of leukemia was presented. A 14-year-old female patient who was admitted to a health institution with complaints of high fever, headache, chills, nausea-vomiting, and diarrhea that had been going on for two weeks, was pre-diagnosed as leukemia and was referred to Manisa Celal Bayar University Faculty of Medicine, Hafsa Sultan Hospital, Department of Pediatric Hematology and after pancytopenia was detected in the complete blood count. The anamnesis of the patient revealed that she had no history of international travel and that she had been prescribed medications such as paracetamol, amoxicillin, and metoclopramide for flu-like complaints while working in the Southeastern Anatolia, Aegean, and Mediterranean Regions of Türkiye. Bone marrow aspiration was performed for the etiological examination of pancytopenia. Giemsa-stained blood smears, rapid diagnostics, and real-time quantative polymerase chain reaction (qRt-PCR) analyses were performed in the medical parasitology laboratory and malaria was suspected in both bone marrow and peripheral blood smears. P.vivax erythrocytic forms and gametocytes were present in abundance in smear preparations stained with Giemsa, and rapid diagnosis kit was positive for P.vivax. The strain was genotyped as P.vivax by qRt-PCR analysis. For the treatment of the patient, airalam (artemether + lumefantrine) tablets were provided with 2 x 4 daily posology for three days after the diagnosis, and primaquine was provided after one week of the diagnosis as 1 x 2 tablets (1 x 15 mg) for 14 days, and the patient was discharged without complications following the treatment regimen. The fight against malaria continues uninterruptedly since the establishment of the Republic of Türkiye. Tropical diseases, especially malaria, is of great importance for Türkiye due to numerous reasons such as its location in the subtropical region where Anopheles mosquitoes are capable of malaria transmission, it is situated at the crossroads on the migration routes between continents where human traffic is busy, there are many people who go abroad for work and most importantly rising temperatures due to climate change. For this reason, this case report is important to emphasize the importance of malaria for the country and to increase the awareness of clinicians and laboratories about malaria and the possibility of autochthonous malaria transmission in Türkiye.

Schoolchildren with asymptomatic malaria are potential hotspot for malaria reservoir in Ethiopia: implications for malaria control and elimination efforts.

BACKGROUND: Schoolchildren with asymptomatic malaria infections often go undiagnosed and untreated, serving as reservoirs for infection that hamper malaria control and elimination efforts. In this context, little is known about the magnitude of asymptomatic malaria infections in apparently healthy schoolchildren in Ethiopia. This study was aimed at determining the prevalence of asymptomatic malaria infection and its associated factors in apparently healthy schoolchildren in Ethiopia. METHODS: From September 2021 to January 2022, a school-based cross-sectional study was conducted on 994 apparently healthy schoolchildren (aged 6-15 years) selected from 21 primary schools in the Gomma district, of Jimma zone, southwestern Oromia, Ethiopia. A multi-stage sampling technique was used to select schools and participants. After allocating the total sample proportionally to each school and then to each grade, participants were selected using the lottery method from a list of student records (rosters). Finger-pricked blood samples were collected for microscopy blood film preparation and malaria rapid diagnostic test (RDT) (SD Bioline Malaria Ag Pf/Pv). Moreover, dry blood spots (DBSs) were prepared onto filter papers for quantitative real time polymerase chain reaction (qPCR) analysis. RESULTS: As determined by RDT and microscopy, the prevalence of asymptomatic malaria was 2.20% and 1.51%, respectively. Using qPCR, the overall prevalence was 5.03% (50/994). Of this, Plasmodium falciparum, Plasmodium vivax and mixed infections accounted for 90%, 6% and 4%, respectively. Submicroscopic asymptomatic malaria infection was also accounted for 70% (35/50) of the overall prevalence. Household head age, nighttime outdoor activities of household heads, family history of malaria, absence of insecticide-treated nets (ITN), and presence of stagnant water around the houses are all significantly associated with asymptomatic malaria infections among schoolchildren. CONCLUSIONS: This study found that both RDT and microscopy underestimated the prevalence of asymptomatic malaria in schoolchildren. However, qPCR was able to detect even low levels of parasitaemia and revealed a higher prevalence of asymptomatic submicroscopic malaria infections. The findings imply that schoolchildren with asymptomatic malaria infection are potential hotspot for malaria reservoir that fuels ongoing transmission. Therefore, it is imperative to include schoolchildren and schools in malaria intervention package and equally important is the adoption of more advanced and sensitive diagnostic tools, which would be crucial for successful malaria control and elimination efforts. Targeted interventions for asymptomatic malaria-infected schoolchildren can provide invaluable support to the National Malaria Control Programme in controlling and eventually eliminating the disease.

Trends in clinical features and severity of Plasmodium vivax malaria among children at tertiary care center in North India.

BACKGROUND: Malaria is a significant cause of morbidity and mortality in adults and children. Plasmodium falciparum is the primary cause of severe malaria, but recently Plasmodium vivax is also recognized to cause severe malaria-associated morbidity and mortality. The study focuses on determining the mortality related to severity parameters in individuals under 12 years and their critical presentation in P.vivax malaria-infected children. METHODS: A prospective cross-sectional hospital-based study was conducted at Safdarjung Hospital, New Delhi, and ICMR-NIMR, New Delhi. All clinically suspected cases were admitted for screening. Exclusion criteria (rapid malaria antigen test, microscopy and medication history) were applied to all the admitted patients (n = 221) to obtain P.vivax patients only. Patients aged ≤ 12 years were included in the study. DNA was extracted from dried blood spots and amplified by nested PCR, followed by visualization on gel electrophoresis. RESULT: A total of 221 clinically suspected cases of malaria were screened for P.vivax. After implementing various exclusion criteria, 45/221 cases were enrolled for the study, among which 44.4% (20/45) of children had the symptoms of severe malaria in terms of cerebral malaria, thrombocytopenia, anemia, pancytopenia, acute respiratory distress syndrome and hemophagocytic lymphohistiocytosis. CONCLUSION: Plasmodium vivax mono-infection can cause severe manifestation and must be treated as P.falciparum without any delay because it may lead to increased morbidity and mortality. A changing trend in clinical symptoms has shown in P.vivax which was an earlier phenomenon of P.falciparum.

A fatal respiratory complication of malaria caused by Plasmodium vivax.

BACKGROUND: Malaria is endemic and represents an important public health issue in Brazil. Knowledge of risk factors for disease progression represents an important step in preventing and controlling malaria-related complications. Reports of severe forms of Plasmodium vivax malaria are now becoming a common place, but respiratory complications are described in less than 3% of global literature on severe vivax malaria. CASE PRESENTATION: A severe respiratory case of imported vivax malaria in a previously healthy 40-year-old woman has been reported. The patient died after the fifth day of treatment with chloroquine and primaquine due to acute respiratory distress syndrome. CONCLUSIONS: Respiratory symptoms started 48 h after the initiation of anti-malarial drugs, raising the hypothesis that the drugs may have been involved in the genesis of the complication. The concept that vivax malaria is a benign disease that can sometimes result in the development of serious complications must be disseminated. This report highlights, once more, the crucial importance of malaria early diagnosis, a true challenge in non-endemic areas, where health personnel are not familiar with the disease and do not consider its diagnosis promptly.

Concurrent Staphylococcus aureus bacteraemia in Plasmodium vivax malaria Infection: A report of two cases from western India.

Malaria and concurrent bacteraemia cases have been reported globally, mostly in association with Plasmodium falciparum malaria. In comparison, concurrent bacteraemia with Plasmodium vivax infected patients is reported rarely. However, considering unavailability of blood culture testing and widespread community and empirical antibiotic usage in low- and middle-income countries (LMICs), the frequency of bacteraemia and P. vivax co-infection may be much higher. We reported two cases of Staphylococcus aureus bacteraemia with P. vivax malaria infection. Both patients presented with high grade fever and chills with unremarkable systemic examination. Liver enzymes were raised along with inflammatory markers. Simultaneous diagnosis of methicillin sensitive S. aureus bacteraemia was done using automated blood culture, automated identification and sensitivity testing system. P. vivax malaria was confirmed with microscopy, antigen detection test and molecular test. Patients recovered uneventfully with antimalarial drugs and antibiotics.

Clinical performance validation of the STANDARD G6PD test: A multi-country pooled analysis.

INTRODUCTION: Screening for G6PD deficiency can inform disease management including malaria. Treatment with the antimalarial drugs primaquine and tafenoquine can be guided by point-of-care testing for G6PD deficiency. METHODS AND FINDINGS: Data from similar clinical studies evaluating the performance of the STANDARD G6PD Test (SD Biosensor, South Korea) conducted in Bangladesh, Brazil, Ethiopia, India, Thailand, the United Kingdom, and the United States were pooled. Test performance was assessed in a retrospective analysis on capillary and venous specimens. All study sites used spectrophotometry for reference G6PD testing, and either the HemoCue or complete blood count for reference hemoglobin measurement. The sensitivity of the STANDARD G6PD Test using the manufacturer thresholds for G6PD deficient and intermediate cases in capillary specimens from 4212 study participants was 100% (95% Confidence Interval (CI): 97.5%-100%) for G6PD deficient cases with <30% activity and 77% (95% CI 66.8%-85.4%) for females with intermediate activity between 30%-70%. Specificity was 98.1% (95% CI 97.6%-98.5%) and 92.8% (95% CI 91.6%-93.9%) for G6PD deficient individuals and intermediate females, respectively. Out of 20 G6PD intermediate females with false normal results, 12 had activity levels >60% on the reference assay. The negative predictive value for females with G6PD activity >60% was 99.6% (95% CI 99.1%-99.8%) on capillary specimens. Sensitivity among 396 P. vivax malaria cases was 100% (69.2%-100.0%) for both deficient and intermediate cases. Across the full dataset, 37% of those classified as G6PD deficient or intermediate resulted from true normal cases. Despite this, over 95% of cases would receive correct treatment with primaquine, over 87% of cases would receive correct treatment with tafenoquine, and no true G6PD deficient cases would be treated inappropriately based on the result of the STANDARD G6PD Test. CONCLUSIONS: The STANDARD G6PD Test enables safe access to drugs which are contraindicated for individuals with G6PD deficiency. Operational considerations will inform test uptake in specific settings.

Malaria misdiagnosis in the routine health system in Arba Minch area district in southwest Ethiopia: an implication for malaria control and elimination.

BACKGROUND: Plasmodium falciparum and Plasmodium vivax are coendemic in Ethiopia, with different proportion in different settings. Microscopy is the diagnostic tool in Ethiopian health centres. Accurate species-specific diagnosis is vital for appropriate treatment of cases to interrupt its transmission. Therefore, this study assessed the status of species-specific misdiagnosis by microscope compared with polymerase chain reaction (PCR). METHODS: A health facility based cross-sectional study was conducted from November 2019 to January 2020 in Kolla Shelle Health centre, Arba Minch Zuria district. The study population were suspected malaria cases, who visited the health centre for a diagnosis and treatment. Consecutive microscopy positive cases as well as a sample of microscopically negative cases were included for molecular analysis by polymerase chain reaction (PCR). RESULTS: 254 microscopically negative and 193 microscopically positive malaria suspects were included. Of the 193 malaria positive cases, 46.1% [95% confidence interval (CI) 38.9-53.4] (89/193) were P. falciparum infection, 52.3% (95% CI 45.0-59.5) (101/193) were P. vivax infection, and 1.6% (3/193) had mixed infection of P. falciparum and P. vivax. Of the microscopically positive cases of P. falciparum, 3.4% (3/89) were P. vivax and 11.2% (10/89) were mixed infections with P. falciparum and P. vivax and a single case was negative molecularly. Similarly, of the microscopically positive P. vivax cases, 5.9% (6/101) were P. falciparum and 1% (1/101) was mixed infection. Single case was negative by molecular technique. Of the 254 microscopically negative cases, 0.8% were tested positive for P. falciparum and 2% for P. vivax by PCR. Considering molecular technique as a reference, the sensitivity of microscopy for detecting P. falciparum was 89.2% and for P. vivax, it was 91.2%. The specificity of microscopy for detecting P. falciparum was 96.1% and for P. vivax, it was 97.7%. However, the sensitivity of microscopy in detecting mixed infection of P. falciparum and P. vivax was low (8.3%). CONCLUSION: There were cases left untreated or inappropriately treated due to the species misidentification. Therefore, to minimize this problem, the gaps in the microscopic-based malaria diagnosis should be identified. It is recommended to regularly monitor the competency of malaria microscopists in the study area to improve species identification and diagnosis accuracy.