Assessment of routine malaria diagnosis in the Venezuelan Amazon

The quality of routine malaria diagnosis is a crucial topic of malaria control. The aim of this assessment was to monitor and evaluate the quality of routine malaria diagnosis in Amazonas (Venezuela) and to improve the quality control system. The traditional non-blinded quality control system was found to be overburdened with diagnostic samples. A modified sampling system with fewer samples to be tested was proposed. Expert microscopists blindly double-checked 1000 slides and 550 rapid diagnostic tests (RDT) (OptiMAL-IT®) from health posts (HP). For Plasmodium vivax, HP microscopy and OptiMAL-IT® showed sensitivies of 86% and 63%, respectively. For P. falciparum, HP microscopy and OptiMAL-IT® showed sensitivities of 68% and 89%, respectively. Both methods lost accuracy when fewer parasites occurred in the sample. HP microscopists from different municipalities displayed significant differences in diagnostic quality. Overall, quality of routine malaria diagnosis in the Venezuelan Amazon is good but not optimal. The change from the traditional non-blinded quality control system to blinded cross-checking of a minimal selection of samples is - comparatively - a low cost intervention with possibly high impact on the quality of routine malaria diagnosis. The introduction of RDTs should be discussed carefully in order not to displace an existing network of HP microscopists.     

Cost-effectiveness of malaria diagnostic methods in sub-Saharan Africa in an era of combination therapy

OBJECTIVE: To evaluate the relative cost-effectiveness in different sub-Saharan African settings of presumptive treatment, field-standard microscopy and rapid diagnostic tests (RDTs) to diagnose malaria. METHODS: We used a decision tree model and probabilistic sensitivity analysis applied to outpatients presenting at rural health facilities with suspected malaria. Costs and effects encompassed those for both patients positive on RDT (assuming artemisinin-based combination therapy) and febrile patients negative on RDT (assuming antibiotic treatment). Interventions were defined as cost-effective if they were less costly and more effective or had an incremental cost per disability-adjusted life year averted of less than US$ 150. Data were drawn from published and unpublished sources, supplemented with expert opinion. FINDINGS: RDTs were cost-effective compared with presumptive treatment up to high prevalences of Plasmodium falciparum parasitaemia. Decision-makers can be at least 50% confident of this result below 81% malaria prevalence, and 95% confident below 62% prevalence, a level seldom exceeded in practice. RDTs were more than 50% likely to be cost-saving below 58% prevalence. Relative to microscopy, RDTs were more than 85% likely to be cost-effective across all prevalence levels, reflecting their expected better accuracy under real-life conditions. Results were robust to extensive sensitivity analysis. The cost-effectiveness of RDTs mainly reflected improved treatment and health outcomes for non-malarial febrile illness, plus savings in antimalarial drug costs. Results were dependent on the assumption that prescribers used test results to guide treatment decisions. CONCLUSION: RDTs have the potential to be cost-effective in most parts of sub-Saharan Africa. Appropriate management of malaria and non-malarial febrile illnesses is required to reap the full benefits of these tests.     

Evaluation of a new Plasmodium lactate dehydrogenase assay (OptiMAL-IT) for the detection of malaria

The new OptiMAL-IT(R) rapid diagnostic test for malaria was evaluated in 271 patients in Thailand with uncomplicated malaria between June and July 2002. The sensitivity and specificity for the diagnosis of Plasmodium falciparum parasites were 88% and 92%, respectively. For species other than P. falciparum, the sensitivity was 65% and specificity was 99%. The performance of the new test decreased markedly at low levels of parasitaemia.     

Use of rapid diagnostic tests for malaria in an emergency situation after the flood disaster in Mozambique

OBJECTIVES: To determine how diagnosis of malaria may be improved by combining the use of rapid diagnostic tests (RDTs) for Plasmodium falciparum malaria with clinical diagnosis by the presence or history of fever compared with clinical diagnosis alone in emergency situations with flood-affected displaced populations in Mozambique. STUDY DESIGN: A cross-sectional study conducted at the emergency outpatient clinic in a village in the Chòkwè district of Gaza Province, 3 weeks after Cyclone Eline hit Mozambique in February 2000. METHODS: A hundred and thirty children aged less than 15 years with clinical malaria were selected for examination by RDT and fluorescent microscopy using acridine orange as a reference test. The diagnosis of clinical malaria was made by a history of fever in the last three days or axillary temperature above 37.0 degrees C at the time of attending the emergency outpatient clinic. Two positive predictive values were calculated; RDTs combined with clinical diagnosis and clinical diagnosis alone. RESULTS: Positive predictive values of RDTs combined with clinical diagnosis by the presence of fever or history of fever were 87.6% (92/105) (95% confidence interval (CI) 80.8-92.8) compared with 74.6% (97/130) (95% CI 66.2-81.8) for clinical diagnosis alone. Five patients were diagnosed false negative. CONCLUSION: RDTs combined with clinical diagnosis has sufficient positive predictive value to be used in emergency situations, while RDTs could result in increasing failure to treat when they are used for decisions of treatment compared with clinical diagnosis alone.     

Comparison of placental blood microscopy and the ICT HRP2 rapid diagnostic test to detect placental malaria

Monitoring interventions to prevent malaria in pregnancy requires sensitive detection of placental infection. Rapid diagnostic tests (RDTs) are good candidates, but little information is available on their sensitivity on placental blood. We have evaluated the agreement (kappa coefficient) between microscopy and a Plasmodium falciparum histidine-rich protein 2 (HRP2)-based immuno-chromatographic test (ICT) on placental blood from 1151 women at delivery. Prevalences of placental infection by microscopy and RDT were 5.1% and 5.0%, respectively, showing 82.9% agreement (p<0.0001). Discordances were found at low parasitemias (<500 parasites/μL) or negative microscopy. The results suggest that the HRP2-RDTs from ICT diagnostics is a good alternative to microscopy for diagnosing placental malaria at delivery.     

Rapid diagnostic tests for malaria ---Haiti, 2010

Plasmodium falciparum malaria is endemic to Haiti and remains a major concern for residents, including displaced persons, and emergency responders in the aftermath of the January 12, 2010 earthquake. Microscopy has been the only test approved in the national policy for the diagnosis and management of malaria in Haiti; however, the use of microscopy often has been limited by lack of equipment or trained personnel. In contrast, malaria rapid diagnostic tests (RDTs) require less equipment or training to use. To assist in the timely diagnosis and treatment of malaria in Haiti, the Ministry of Public Health and Population (MSPP), in collaboration with CDC, conducted a field assessment that guided the decision to approve the use of RDTs. This data-driven policy change greatly expands the opportunities for accurate malaria diagnosis across the country, allows for improved clinical management of febrile patients, and will improve the quality of malaria surveillance in Haiti.     

Economic Evaluation of a Cluster Randomized Trial of Interventions to Improve Health Workers’ Practice in Diagnosing and Treating Uncomplicated Malaria in Cameroon

BackgroundMalaria rapid diagnostic tests (RDTs) are a valid alternative to malaria testing with microscopy and are recommended for the testing of febrile patients before prescribing an antimalarial. There is a need for interventions to support the uptake of RDTs by health workers.ObjectiveTo evaluate the cost-effectiveness of introducing RDTs with basic or enhanced training in health facilities in which microscopy was available, compared with current practice.MethodsA three-arm cluster randomized trial was conducted in 46 facilities in central and northwest Cameroon. Basic training had a practical session on RDTs and lectures on malaria treatment guidelines. Enhanced training included small-group activities designed to change health workers’ practice and reduce the consumption of antimalarials among test-negative patients. The primary outcome was the proportion of febrile patients correctly treated: febrile patients should be tested for malaria, artemisinin combination therapy should be prescribed for confirmed cases, and no antimalarial should be prescribed for patients who are test-negative. Individual patient data were obtained from facility records and an exit survey. Costs were estimated from a societal perspective using project reports and patient exit data. The analysis used bivariate multilevel modeling and adjusted for imbalance in baseline covariates.ResultsIncremental cost per febrile patient correctly treated was $8.40 for the basic arm and $3.71 for the enhanced arm. On scale-up, it was estimated that RDTs with enhanced training would save $0.75 per additional febrile patient correctly treated.ConclusionsIntroducing RDTs with enhanced training was more cost-effective than RDTs with basic training when each was compared with current practice.     

Point-of-care testing for malaria outbreak management

A rapid antigen assay for malaria was performed on blood samples collected during a simultaneous outbreak of falciparum malaria and vivax malaria on a remote island in the Indonesian archipelago. During the outbreak, a total of 89 patients (4.3% of the population) were diagnosed with malaria within a week. Microscopic examination revealed 78 malaria slide-positive cases, of whom 49 (62.8%) were identified as P. falciparum, 7 (9.0%) as P. vivax and 22 (28.2%) as mixed P. falciparum and P. vivax infections. The rapid malaria assay showed excellent correlation with expert-confirmed routine microscopy for P. falciparum and P. vivax monoinfections and mixed infections with a parasite density >50 parasites/microl. Several slide-negative blood samples collected from febrile patients with clinical malaria tested positive in the rapid test. The estimated sensitivity calculated for the rapid test (91.0%) was slightly higher than that of microscopy (87.6%). The result indicates that rapid antigen detection for malaria could be a useful alternative to microscopy to reduce the workload during emergency outbreak situations.     

Performance of an immunochromatography test for vivax malaria in the Amazon region,Brazil

The study was carried out to evaluate the diagnostic performance of the ICT malaria Pf/Pv test for vivax malaria diagnosis in Bel m, Amazon region, Brazil. The results of blood malaria parasites examination using an immunochromatography test were compared with thick blood film (TBF) examination. It was also evaluated the performance of this test storaged at three different temperatures (25 degree C, 30 degree C, and 37 degree C) for 24 hours before use. Overall sensitivity of ICT Pf/Pv was 61.8% with a specificity of 100%, positive and negative predictive value of 100% and 71.8%, respectively and accuracy of 80.6%. The test sensitivity was independent of the parasite density. This test needs to be further reviewed in order to have better performance for P. vivax malaria diagnosis.     

Introducing malaria rapid diagnostic tests at registered drug shops in Uganda: limitations of diagnostic testing in the reality of diagnosis

In Uganda, around two thirds of medicines are procured from the private sector, mostly from drug shops. The introduction of malaria rapid diagnostic tests (RDTs) at drug shops therefore has the potential to make a significant contribution to targeting antimalarial drugs to those with malaria parasites. We undertook formative research in a district in Uganda in preparation for a randomised trial of RDTs in drug shops. In May to July 2009, we interviewed 9 drug shop workers, 5 health workers and 4 district health officials and carried out 10 focus group discussions with a total of 75 community members to investigate the role of drug shops and the potential for implementation of RDTs at these health care outlets. Drug shops were seen to provide an important service to community members, the nature of which is determined by responsiveness to client demands. However, drug shops hold a liminal status: in the eyes of different actors, these outlets are at once a shop and clinic; legitimate and illegitimate; and trusted and distrusted. Malaria treatment was found to be synonymous with diagnosis. Diagnostic testing was deemed useful in theory, and community members were curious about the results, with the expectation that a test would decrease uncertainty and help secure an end to illness. However, whether testing would be sought as a routine step in treatment decisions in practice is uncertain, since the appeal of the tests waned in light of their costs and potential for results to conflict with presumed diagnosis. Interventions that increase awareness of multiple causes and management of malaria-like illness will be needed to support the new rationalisation for malaria treatment represented by parasitological diagnosis.     

Clinical and epidemiological profiles of severe malaria in children from Delhi, India

Plasmodium vivax is traditionally known to cause benign tertian malaria, although recent reports suggest that P. vivax can also cause severe life-threatening disease analogous to severe infection due to P. falciparum. There are limited published data on the clinical and epidemiological profiles of children suffering from 'severe malaria' in an urban setting of India. To assess the clinical and epidemiological profiles of children with severe malaria, a prospective study was carried out during June 2008-December 2008 in the Department of Pediatrics, Guru Teg Bahadur Hospital, a tertiary hospital located in East Delhi, India. Data on children aged < or = 12 years, diagnosed with severe malaria, were analyzed for their demographic, clinical and laboratory parameters. All patients were categorized and treated as per the guidelines of the World Health Organization. In total, 1,680 children were screened for malaria at the paediatric outpatient and casualty facilities of the hospital. Thirty-eight children tested positive for malaria on peripheral smear examination (2.26% slide positivity rate). Of these, 27 (71%) were admitted and categorized as severe malaria as per the definition of the WHO while another 11 (29%) received treatment on outpatient basis. Most (24/27; 88.8%) cases of severe malaria (n=27) were infected with P. vivax. Among the cases of severe malaria caused by Plasmodium vivax (n=24), 12 (50%) presented with altered sensorium (cerebral malaria), seven (29.1%) had severe anaemia (haemoglobin <5 g/dL), and 17 (70.8%) had thrombocytopaenia, of which two had spontaneous bleeding (epistaxis). Cases of severe vivax malaria are clinically indistinguishable from severe falciparum malaria. Our study demonstrated that majority (88.8%) of severe malaria cases in children from Delhi and adjoining districts of Uttar Pradesh were due to P. vivax-associated infection. P. vivax should, thus, be regarded as an important causative agent for severe malaria in children.     

Latest developments in the laboratory diagnosis of malaria

Malaria is the most important parasitic disease worldwide. With the advent of multidrug-resistant strains, it is highly important that the disease be diagnosed both early and accurately. For the diagnosis of malaria parasites, the thick blood film approach remains the gold standard. However, the use of that standard requires a microscope, stains, and a trained microscopist to interpret the films. The author describes the microscopical detection of the malaria parasite through the use of fluorochrome as well as the development of antigen detection tests to improve the laboratory diagnosis of malaria. Histidine-rich protein II (HRPII) is expressed by the asexual stages of Plasmodium falciparum. The detection of HRPII antigen appears to be a useful alternative diagnostic technique when microscopes are unavailable. However, a negative test result may indicate the presence of non-P falciparum malaria or that it is too early in the course of infection to detect parasites. One advantage of a parasite lactate dehydrogenase (pLDH) detection system is its ability to detect all 4 species of malaria and to diagnose both P. falciparum and P. vivax infections.     

The phylogeny of rodent malaria parasites: simultaneous analysis across three genomes.

Species of Plasmodium that naturally infect wild rodents but can also be maintained in laboratory mice have long been used as model systems in which to study the biology of malaria parasites. Several of these rodent parasites are now providing useful genomic comparisons to those species that cause malaria in humans. Here we examined the phylogenetic relationships of 19 strains of rodent malaria parasites including four species native to African thicket rats (Plasmodium berghei, Plasmodium chabaudi, Plasmodium vinckei, and Plasmodium yoelii) and one from a porcupine (Plasmodium atheruri) using DNA sequence data collected from seven genes from each of the three parasite genomes. These included the nuclear dihydrofolate reductase gene and a cysteine protease gene, mitochondrial cytochrome b and cytochrome oxidase I genes, and the elongation factor tufA, caseinolytic protease C, and "open reading frame 470" genes from the apicoplast genome, for a combined total of 5049 nucleotides. Using simultaneous analysis, a method of combining each of the gene partitions into a super-matrix, two equally parsimonious trees were recovered. Bayesian analysis of the dataset produced the same topology. The basic species groups were well supported, with the exception of the placement of P. atheruri within the P. vinckei clade. Named subspecies showed a wide array of genetic differentiation, but fell into monophyletic groups.     

Diagnosis of malaria in the field by fluorescence microscopy of QBC capillary tubes.

The diagnostic performance of commercial capillary tubes containing acridine orange dye (QBC) was compared with the standard diagnosis of malaria by microscopical examination of Giemsa-stained thick blood films (GTS) in remote field conditions. The comparison was conducted among 165 volunteers living in northeastern Irian Jaya, Indonesia, an area having hyperendemic malaria transmission. By GTS, 65 volunteers were positive for malaria, but only 49 were judged positive by QBC. Among the 100 blood films found negative by GTS, 5 were considered positive by QBC. Thus, relative to a GTS standard, the sensitivity and specificity of the QBC was 75% and 95%, respectively. The mean limit of detection for the QBC was approximately 60 parasites per microliter blood, whereas the limit of detection for GTS was 20 parasites per microliter blood. Also, a number of practical difficulties were encountered using the QBC at the field site. The QBC approach to diagnosis of malaria was less sensitive and more inconvenient than GTS under the conditions in remote Irian Jaya.     

2014-2018年湖北省疟疾诊断参比实验室检测结果

目的  分析2014-2018年湖北省疟疾诊断参比实验室样本检测结果,为巩固湖北省疟疾诊断水平提供科学依据。 方法  收集湖北省2014-2018年疟疾网报病例诊断结果和样本,由省级疟疾诊断参比实验室通过镜检和巢式PCR对每份样本进行检测,分析不同年份和不同地区网报阳性结果和虫种符合情况,分析省级镜检和巢式PCR结果。 结果  2014-2018年湖北省共网报疟疾病例674例,省级疟疾诊断参比实验室复核672例,确定疟疾病例633例。总体阳性符合率为94.20%,各年和各地、市(州)阳性符合率均高于80.00%,不同地、市(州)间的阳性符合率差异有统计学意义(χ² =42.49, P＜0.001)。总体虫种符合率为89.73%,不同年份和不同地、市(州)间虫种符合率差异均有统计学意义(均有P＜0.001)。省级疟疾诊断参比实验室镜检与巢式PCR结果一致率为88.89%,两种方法检测结果一致率在不同虫种间的差异有统计学意义(χ² =57.37, P＜0.001)。 结论  湖北省2014-2018年疟疾网报病例诊断质量总体较高,对非恶性疟原虫的虫种鉴别能力有待提高。     

Managing meningitis and severe malaria

Fever is often an indication of a serious illness in children. In areas endemic to malaria, hospital workers should check a febrile child for malaria parasites. Children with a fever associated with meningitis or malaria need immediate attention. To diagnose meningitis: microscopic examination of cerebrospinal fluid obtained by lumbar puncture is the only reliable method. If a febrile child also has a stiff neck, health workers should immediately administer antibiotic treatment without waiting for the results of the lumbar puncture. If available and in epidemic situations, oily chloramphenicol may be administered, since it is effective in a single dose. Treatment with other antibiotics should last for 10 days in children and 14-21 days for young infants. To diagnose malaria in endemic areas: laboratory technicians should examine thick and thin blood films of sick children with fever. Health workers must consider as medical emergencies children who have a slide positive for malaria parasites plus severe anemia, hypoglycemia, deep rapid breathing, any indication of kidney malfunction or failure, or altered consciousness. They should begin antimalarial treatment with quinine, the drug of choice for severe and complicated malaria. In cases of convulsions lasting longer than 5 minutes, health workers should administer anticonvulsants and take actions to prevent aspiration pneumonia. If the fever persists for 14 days or if the child does not emerge from unconsciousness and someone in the family has active tuberculosis, health workers should consider tuberculous meningitis. If a child with malaria has low hemoglobin levels (5 g/dl) and many malaria parasites in the blood and is in heart failure, a blood transfusion (15-20 ml/kg whole blood over 4 hours) and infusion of 1 mg/kg fursemide (to prevent cardiac failure) are needed. If the preceding case has pulmonary edema, a single dose of fursemide at the same dosage is needed to prevent overloading of the circulation. Health workers should closely monitor that intravenous fluids not exacerbate brain swelling.     

Epidemiologic investigations of a malaria outbreak in northern Delhi area.

Epidemiologic investigations revealed a 56.7 and 13.32% slide positivity rate in febrile and afebrile malaria cases, respectively. In both cases, Plasmodium falciparum was predominant. Anopheles culicifacies resistant to dichlorodiphenyltrichloroethane and benzene hexachloride (hexachlorocyclohexane) was found breeding profusely in pools and ponds created by excavation of earth around brick kiln in the region. Furthermore, children were not found to be producing significant levels of antibodies and a large percentage of patients harbored chloroquine-resistant parasites. Also, more than 1 P. falciparum strain was present in the population. We detected 2 strains, VI and VII, of which type VI was predominant.     

Field and laboratory comparative evaluation of ten rapid malaria diagnostic tests

The paper reports on a comparative evaluation of 10 rapid malaria tests available in South Africa in 1998: AccuCheck (AC, developmental), Cape Biotech (CB), ICT Malaria Pf (ICT1) and Pf/Pv (ICT2), Kat Medical (KAT), MakroMal (MM), OptiMAL (OP), ParaSight-F (PS), Quorum (Q), Determine-Malaria (DM). In a laboratory study, designed to test absolute detection limits, Plasmodium falciparum-infected blood was diluted with uninfected blood to known parasite concentrations ranging from 500 to 0.1 parasites per microlitre (P/microL). The 50% detection limits were: ICT1, 3.28; ICT2, 4.86; KAT, 6.36; MM, 9.37; CB, 11.42; DM, 12.40; Q, 16.98; PS, 20; AC, 31.15 and OP, 91.16 P/microL. A field study was carried out to test post-treatment specificity. Blood samples from malaria patients were tested with all products (except AC and DM) on the day of treatment and 3 and 7 days thereafter, against a gold standard of microscopy and polymerase chain reaction (PCR). OP and PS produced fewer false-positive results on day 7 (18 and 19%, respectively) than the other rapid tests (38-56%). However, microscopy, PCR, OP and PS disagreed largely as to which individuals remained positive. The tests were further compared with regard to general specificity, particularly cross-reactivity with rheumatoid factor, speed, simplicity, their ability to detect other species, storage requirements and general presentation.     

Molecular Epidemiology of Plasmodium falciparum Malaria Outbreak,Tumbes, Peru, 2010–2012

During 2010–2012, an outbreak of 210 cases of malaria occurred in Tumbes, in the northern coast of Peru, where no Plasmodium falciparum malaria case had been reported since 2006. To identify the source of the parasite causing this outbreak, we conducted a molecular epidemiology investigation. Microsatellite typing showed an identical genotype in all 54 available isolates. This genotype was also identical to that of parasites isolated in 2010 in the Loreto region of the Peruvian Amazon and closely related to clonet B, a parasite lineage previously reported in the Amazon during 1998–2000. These findings are consistent with travel history of index case-patients. DNA sequencing revealed mutations in the Pfdhfr, Pfdhps, Pfcrt, and Pfmdr1 loci, which are strongly associated with resistance to chloroquine and sulfadoxine/pyrimethamine, and deletion of the Pfhrp2 gene. These results highlight the need for timely molecular epidemiology investigations to trace the parasite source during malaria reintroduction events.