Diagnosis Of Plasmodium Falciparum Malaria Research Articles

Accuracy of diagnosis among clinical malaria patients: comparing microscopy, RDT and a highly sensitive quantitative PCR looking at the implications for submicroscopic infections

BackgroundThe World Health Organization recommends parasitological confirmation of all suspected malaria cases by microscopy or rapid diagnostic tests (RDTs) before treatment. These conventional tools are widely used for point-of-care diagnosis in spite of their poor sensitivity at low parasite density. Previous studies in Ghana have compared microscopy and RDT using standard 18S rRNA PCR as reference with varying outcomes. However, how these conventional tools compare with ultrasensitive varATS qPCR has not been studied. This study, therefore, sought to investigate the clinical performance of microscopy and RDT assuming highly sensitive varATS qPCR as gold standard.Methods1040 suspected malaria patients were recruited from two primary health care centers in the Ashanti Region of Ghana and tested for malaria by microscopy, RDT, and varATS qPCR. The sensitivity, specificity, and predictive values were assessed using varATS qPCR as gold standard.ResultsParasite prevalence was 17.5%, 24.5%, and 42.1% by microscopy, RDT, and varATS qPCR respectively. Using varATS qPCR as the standard, RDT was more sensitive (55.7% vs 39.3%), equally specific (98.2% vs 98.3%), and reported higher positive (95.7% vs 94.5%) and negative predictive values (75.3% vs 69.0%) than microscopy. Consequently, RDT recorded better diagnostic agreement (kappa = 0.571) with varATS qPCR than microscopy (kappa = 0.409) for clinical detection of malaria.ConclusionsRDT outperformed microscopy for the diagnosis of Plasmodium falciparum malaria in the study. However, both tests missed over 40% of infections that were detected by varATS qPCR. Novel tools are needed to ensure prompt diagnosis of all clinical malaria cases.

Rapid diagnosis of Plasmodium falciparum malaria using a point-of-care loop-mediated isothermal amplification device.

LAMP diagnosis of malaria is simple and cost-effective with acceptable sensitivity and specificity as compared to standard diagnostic modules such as microscopy, RDTs and nested PCR, and thus its deployment for onsite screening of malaria in resource-limited regions is under consideration. However, the requirement of an electricity-operated dry bath and bulky read-out unit is still a major concern. In an effort to simplify this limitation, we have developed a portable LAMP device and fluorescence readout unit which can be used in the rapid point-of-care diagnosis of malaria. We have developed a point-of-care diagnostic LAMP device that is easy to operate by a mobile application, and the results can be quantified with a fluorescent readout unit. The diagnostic performance of the device was evaluated in 90 P. falciparum-infected clinical isolates stored at 4°C for 6-7 years and 10 freshly collected isolates from healthy volunteers. The LOD and quantitative ability of LAMP in estimating parasitemia levels were revealed with laboratory-grown P. falciparum strain (3D7). The LAMP assay performed in our device was exclusive for P. falciparum detection with sensitivity and specificity determined to be 98.89% and 100%, respectively, in clinical isolates. The LOD was documented to be 1 parasite/µl at the cut-off ADC value of 20. Parasite density estimated from ADC values showed concordance with microscopically determined parasite density of the cultured P. falciparum 3D7 strain. The LAMP assay performed in our device provides a possible portable platform for its deployment in the point-of-care diagnosis of malaria. Further validation of the quantitative ability of the assay with freshly collected or properly stored clinical samples of known parasitemia is necessary for field applicability.

Comparison of clinical, microscopic, and rapid diagnostic test methods in the diagnosis of Plasmodium falciparum malaria in four districts in the Eastern Region, Ghana

Comparison of clinical, microscopic, and rapid diagnostic test methods in the diagnosis of Plasmodium falciparum malaria in four districts in the Eastern Region, Ghana

Prevalence of Pfhrp2/3 gene deletions among false negative rapid antigen test results in central India.

Febrile patients from three districts of Chhattisgarh, India were screened for malaria during 2016-2017 by microscopy and RDT. All microscopy P. falciparum positive samples were validated by PCR. Microscopy positive and RDT negative samples were analyzed for the presence of Exon 2, across Exon 1-2, upstream and downstream of both the Pfhrp2 and Pfhrp3 genes fragment by PCR. Out of 203 screened samples, 85 were detected positive for P. falciparum malaria based on microscopy and PCR. Among these 85 P. falciparum positive samples, 4 samples were observed Pf-HRP2 RDT negative. Although, it signified that the RDTs used were reliable with sensitivity of 95.3% (81/85). 3/4 PfHRP2-RDT negative samples of the P. falciparum isolates exhibited complete deletion of Pfhrp2 and Pfhrp3 genes and one sample was found RDT false negative due to high parasite density. Pfhrp2 and Pfhrp3 deletions that result in false negative RDTs were uncommon in our setting. The continued monitoring of RDTS which results in false negative tests due to Pfhrp2/3 gene deletion is the need of the hour for an effective malaria elimination strategy.

Diarrhea in Children with Plasmodium falciparum Malaria: A Case-Control Study on the Prevalence and Response to Antimalarial Treatment.

The role of Plasmodium in the etiology of acute diarrhea in developing countries remains controversial, and gastrointestinal (GI) symptoms are inconsistently reported in malaria. In this observational case-control study, we investigated the prevalence and risk factors for GI symptoms in hospitalized malarious children aged 1 month to 5 years in northern Uganda. Children with a diagnosis of Plasmodium falciparum malaria were enrolled as cases, and feverish children in whom malaria was excluded were enrolled as controls. Among 451 malarious children, 46.1% had GI symptoms at admission. Compared with controls, the frequency of diarrhea (24.8% versus 11.2%, P < 0.001) and vomiting (35.5% versus 17.5%, P < 0.001) was significantly higher in children with malaria, who had a higher chance of showing either vomiting (odds ratio [OR]: 3.22; 95% CI: 2.14-4.91) or diarrhea (OR: 3.14; 95% CI: 1.99-5.07) at hospital admission. A subgroup analysis performed in children with severe malaria, severe anemia, or high-grade fever confirmed these results. Diarrhea was more frequent in infants and children younger than 3 years than in older children. The analysis of 71 malarious children with diarrhea who received intravenous artesunate showed that the symptom resolved within the first 24 hours since the beginning of the treatment in 85.9% of cases. The 3-fold higher prevalence of diarrhea and vomiting in malarious children compared with febrile controls may provide rationale for incorporating malaria testing in the symptom-guided diagnostic approach of the young child with diarrhea and vomiting in malaria-endemic settings.

Evaluation of Loop Mediated Isothermal Amplification (LAMP) for Diagnosis of Plasmodium falciparum in Wad Medani City, Gezira State, Sudan

Plasmodium falciparum considered as the most serious form of species causes malaria compared with other species. Diagnosis of falciparum malaria in Sudan remain a major problem, the laboratory diagnosis depends solely on microscopy and RDTs. Loop mediated isothermal amplification (LAMP) assay is a molecular technique done in isothermal temperature using simple, inexpensive instruments for detection of falciparum malaria. The aim of the study is to evaluate the diagnostic performance of loop mediated isothermal amplification (LAMP) assay for detection of P. falciparum and compare with microscopic detection. A cross sectional hospital based study conducted on 220 blood samples collected from participants suspected to have falciparum malaria attending Wad Medani Teaching Hospitals and 26 healthy participants during the period November 2018 to January 2019. Thick blood films were done and used for P. falciparum detection. The extracted DNA by TE buffer was amplified by LAMP assay targeting 18S rRNA gene. Data were analyzed using Medical calculator (MedCalc) programs (V. 16). The results showed that the sensitivity, specificity, positive predictive value, negative predictive values were 99.1%, 84.6%, 53.2%, 99.8% respectively. Validation of LAMP diagnostic performance revealed that area under the curve is 0.919, while Weighted Kappa is 0.866. The study concluded that the LAMP assay had the identical diagnostic performance compared with microscopy in diagnosis of Plasmodium falciparum malaria. This gives a relative effortlessness application of LAMP assay in Sudan after availing the required logistics.

False-negative malaria rapid diagnostic test results and their impact on community-based malaria surveys in sub-Saharan Africa

Surveillance and diagnosis of Plasmodium falciparum malaria relies predominantly on rapid diagnostic tests (RDT). However, false-negative (FN) RDT results are known to occur for a variety of reasons, including operator...

Anesthetic Implications of Malarial Infection in a Child

Malaria is a life-threatening mosquito-borne parasitic disease, with a wide clinical spectrum and multisystem involvement. It is associated with high rates of mortality and morbidity worldwide, particularly in Africa and Southeast Asia. Cases are now being reported in developed countries resulting from global and international travel. Given the varied presentation and multisystem involvement, patients with malaria may present for surgery, thereby necessitating anesthetic care. We present a 4-year-old child from Burkina Faso, Africa, with a known diagnosis of Plasmodium falciparum malaria, who presented for anesthetic care for a magnetic resonance imaging of the lumbar spine, requiring general anesthesia. The etiology and presentation of malaria are discussed and its end-organ involvement is reviewed with emphasis on the anesthetic implications of the disease. J Med Cases. 2019;10(3):84-88 doi: https://doi.org/10.14740/jmc3267

A comparison of thick-film microscopy, rapid diagnostic test, and polymerase chain reaction for accurate diagnosis of Plasmodium falciparum malaria

BackgroundAccurate diagnosis of malaria is important for effective disease management and control. In Cameroon, presumptive clinical diagnosis, thick-film microscopy (TFM), and rapid diagnostic tests (RDT) are commonly used to diagnose cases of Plasmodium falciparum malaria. However, these methods lack sensitivity to detect low parasitaemia. Polymerase chain reaction (PCR), on the other hand, enhances the detection of sub-microscopic parasitaemia making it a much-needed tool for epidemiological surveys, mass screening, and the assessment of interventions for malaria elimination. Therefore, this study sought to determine the frequency of cases missed by traditional methods that are detected by PCR.MethodsBlood samples, collected from 551 febrile Cameroonian patients between February 2014 and February 2015, were tested for P. falciparum by microscopy, RDT and PCR. The hospital records of participants were reviewed to obtain data on the clinical diagnosis made by the health care worker.ResultsThe prevalence of malaria by microscopy, RDT and PCR was 31%, 45%, and 54%, respectively. However, of the 92% of participants diagnosed as having clinical cases of malaria by the health care worker, 38% were malaria-negative by PCR. PCR detected 23% and 12% more malaria infections than microscopy and RDT, respectively. A total of 128 (23%) individuals had sub-microscopic infections in the study population. The sensitivity of microscopy, RDT, and clinical diagnosis was 57%, 78% and 100%; the specificity was 99%, 94%, and 17%; the positive predictive values were 99%, 94%, and 59%; the negative predictive values were 66%, 78%, and 100%, respectively. Thus, 41% of the participants clinically diagnosed as having malaria had fever caused by other pathogens.ConclusionsMalaria diagnostic methods, such as TFM and RDT missed 12–23% of malaria cases detected by PCR. Therefore, traditional diagnostic approaches (TFM, RDT and clinical diagnosis) are not adequate when accurate epidemiological data are needed for monitoring malaria control and elimination interventions.

Overview of artemisinin effectiveness during outset years of its implementation in the western Brazilian Amazon.

BACKGROUND The elimination of malaria depends on the blocking of transmission and of an effective treatment. In Brazil, artemisinin therapy was introduced in 1991, and here we present a performance overview during implementation outset years.METHODS It is a retrospective cohort (1991 to 2002) of patients treated in a tertiary centre of Manaus, with positive microscopic diagnosis of Plasmodium falciparum malaria, under treatment with using injectable or rectal artemisinin derivatives, and followed over 35-days to evaluate parasite clearance, death and recurrence.FINDINGS This cohort outcome resulted 97.6% (1554/1593) of patients who completed the 35-day follow-up, 0.6% (10/1593) of death and 1.8% (29/1593) of follow-up loss. All patients that died and those that presented parasitaemia recurrence had pure P. falciparum infections and received monotherapy. Considering patients who completed 35-day treatment, 98.2% (1527/1554) presented asexual parasitaemia clearance until D4 and 1.8% (27/1554) between D5-D10. It is important to highlight that had no correlation between the five treatment schemes and the sexual parasite clearance. Finally, it is noteworthy that we were able to observe also gametocytes carriage during all follow-up (D0-D35).MAIN CONCLUSIONS Artemisinin derivatives remained effective in the treatment of falciparum malaria during first 12-years of use in north area of Brazil.

A diagnostic performance evaluation of rapid diagnostic tests and microscopy for malaria diagnosis using nested polymerase chain reaction as reference standard in a tertiary hospital in Jos, Nigeria.

Rapid diagnostic tests are frequently used in healthcare settings across Nigeria for diagnosis of Plasmodium falciparum malaria, which is the commonest form of malaria in the country. In this study, the performance of a rapid diagnostic test (RDT) was compared with expert microscopy using the polymerase chain reaction (PCR) as the reference standard in a tertiary hospital in Jos, Nigeria. This study was a prospective, cross-sectional, hospital-based study. A total of 200 participants of all ages presenting to Jos University Teaching Hospital with a history of fever or an axillary temperature of >37.5°C were recruited. Blood specimens were collected and malaria testing was done using RDT, microscopy and PCR. The prevalence of malaria in this study was 17%, 15% and 13% by PCR, microscopy and RDT, respectively. Compared with microscopy, RDT had lower sensitivity of 75% (95% CI: 56.60-88.54) vs 88.24% (95% CI: 72.55-96.70), lower specificity of 98.80% (95% CI: 95.72-99.85) vs 100.0% (95% CI: 97.80-100.0), lower positive predictive value 92.31 (95% CI: 74.89-97.97) vs 100 (95% CI: 98.0-100.0), and lower negative predictive value 95.35 (95% CI: 91.83-97.39) versus 97.65 (95% CI: 94.30-99.05). The diagnostic performance of expert microscopy was better than RDT in the diagnosis of Plasmodium falciparum malaria. Quality assurance procedures such as using expert microscopy to cross-check a proportion of RDT negative results in patients with clinical features of malaria is desirable.

Streamlined, PCR-based testing for pfhrp2- and pfhrp3-negative Plasmodium falciparum

BackgroundRapid diagnostic tests (RDTs) that detect histidine-rich protein 2 (PfHRP2) are used throughout Africa for the diagnosis of Plasmodium falciparum malaria. However, recent reports indicate that parasites lacking the pfhrp2 and/or histidine-rich protein 3 (pfhrp3) genes, which produce antigens detected by these RDTs, are common in select regions of South America, Asia, and Africa. Proving the absence of a gene is challenging, and multiple PCR assays targeting these genes have been described. A detailed characterization and comparison of published assays is needed to facilitate robust and streamlined testing approaches.ResultsAmong six pfhrp2 and pfhrp3 PCR assays tested, the lower limit of detection ranged from 0.01 pg/µL to 0.1 ng/µL of P. falciparum 3D7 strain DNA, or approximately 0.4–4000 parasite genomes/µL. By lowering the elongation temperature to 60 °C, a tenfold improvement in the limit of detection and/or darker bands for all exon 1 targets and for the first-round reaction of a single exon 2 target was achieved. Additionally, assays targeting exon 1 of either gene yielded spurious amplification of the paralogous gene. Using these data, an optimized testing algorithm for the detection of pfhrp2- and pfhrp3-negative P. falciparum is proposed.ConclusionsSurveillance of pfhrp2- and pfhrp3-negative P. falciparum requires careful laboratory workflows. PCR-based testing methods coupled with microscopy and/or antigen testing serve as useful tools to support policy development. Standardized approaches to the detection of pfhrp2- and pfhrp3-negative P. falciparum should inform efforts to define the impact of these parasites.

The sensitivity and specificity of a urine based Rapid Diagnostic Test for the diagnosis of plasmodium falciparum in a malaria endemic area in Odisha, India

Background: Rapid and accurate diagnosis is crucial in the treatment of malaria. Rapid Diagnostic Tests (RDTs) using blood have been recommended by the WHO as an acceptable method for the diagnosis of malaria. RDTs provide results quickly, is simple to use and easy to interpret. However, its use requires collection of blood by skin puncture. Hence the aim of the pilot study is to explore the sensitivity and specificity of RDTs using urine (collected non-invasively) for diagnosis of Plasmodium falciparum malaria and to assess the relation between parasite density in blood with HRP-2 Ag detection in urine. Material and Method: All fever cases admitted to Ispat General Hospital (IGH) Rourkela, India, during June 2012-March 2013 with a clinical diagnosis of malaria were examined for the presence of asexual forms of P. falciparum in peripheral blood smears. All smear positive febrile patients who met the eligibility criteria were enrolled. Smear negative fever cases were enrolled as control cases. RDTs were performed using both urine and blood samples by using commercially available blood specific kits. Results: Sixty blood smear positive cases and 51 febrile blood smear negative cases were enrolled. Sensitivity and specificity of RDT urine were 86.67% (95%CI:75.83–93.09) and 94.12% (95%CI:84.08–97.98) respectively whereas those of RDT blood were 91.67% (95% CI: 81.93–96.39) and 98.04% (95% CI 89.7–99.65). The sensitivity of both RDT urine as well as RDT blood were found to be dependent on the level of parasitemia. Conclusion: Results of this study are promising. Larger studies are needed to assess whether RDTs using urine could serve as a practical, reliable method for the detection of P. falciparum in a non-invasive manner where invasive blood taking is less feasible.

A simple, sensitive and reduced cost paper-based device with low quantity of chemicals for the early diagnosis of Plasmodium falciparum malaria using an enzyme-based colorimetric assay

In this study, we report the development of a paper-based platform with low amount of reagents for the detection of the histidine-rich protein 2 by an enzyme-based colorimetric assay aiming for the early diagnosis of Plasmodium falciparum malaria. A CO2 laser cutter was used for the fabrication of the device in a simple layout suitable to perform the lateral flow assay, which consisted in a region for sample addition, a detection zone and an absorbent pad, all of which were linked by microfluidic channels. Investigations related to the performance of the sandwich immunoassay in the nitrocellulose membrane shown that the blocking and washing steps are essential to promote efficient antigen-antibody recognition and to generate reliable results, avoiding misinterpretations. Several parameters were also evaluated and the experimental conditions were optimized: concentration and incubation time with the capture antibody (50μgmL−1 and 5min, respectively); BSA solution at 1.5% (w/v) containing 0.1% (v/v) Tween 20 for blocking the nitrocellulose and 10min as the incubation time; 10mmolL−1 Tris-HCl buffer solution at pH 7.4 containing 0.15molL−1 NaCl and 0.1% (v/v) Tween 20 for washing the device before adding the ready to use TMB substrate at the detection zone. The system demonstrated a good sensitivity and detectability reaching a visual and calculated limit of detection of 5.0ngmL−1 (65 parasites μL−1) and 4.5ngmL−1 (59 parasites μL−1) respectively, a clinically relevant concentration that should be sufficient to identify the disease in the appearance of the first symptoms and with the advantage of not needing to use nanostructures or other strategy for signal amplification beyond the enzyme.

Histidine-rich protein 2 (pfhrp2) and pfhrp3 gene deletions in Plasmodium falciparum isolates from select sites in Brazil and Bolivia

More than 80% of available malaria rapid diagnostic tests (RDTs) are based on the detection of histidine-rich protein-2 (PfHRP2) for diagnosis of Plasmodium falciparum malaria. Recent studies have shown the genes that code for this protein and its paralog, histidine-rich protein-3 (PfHRP3), are absent in parasites from the Peruvian Amazon Basin. Lack of PfHRP2 protein through deletion of the pfhrp2 gene leads to false-negative RDT results for P. falciparum. We have evaluated the extent of pfhrp2 and pfhrp3 gene deletions in a convenience sample of 198 isolates from six sites in three states across the Brazilian Amazon Basin (Acre, Rondonia and Para) and 25 isolates from two sites in Bolivia collected at different times between 2010 and 2012. Pfhrp2 and pfhrp3 gene and their flanking genes on chromosomes 7 and 13, respectively, were amplified from 198 blood specimens collected in Brazil. In Brazil, the isolates collected in Acre state, located in the western part of the Brazilian Amazon, had the highest percentage of deletions for pfhrp2 25 (31.2%) of 79, while among those collected in Rondonia, the prevalence of pfhrp2 gene deletion was only 3.3% (2 out of 60 patients). In isolates from Para state, all parasites were pfhrp2-positive. In contrast, we detected high proportions of isolates from all 3 states that were pfhrp3-negative ranging from 18.3% (11 out of 60 samples) to 50.9% (30 out of 59 samples). In Bolivia, only one of 25 samples (4%) tested had deleted pfhrp2 gene, while 68% (17 out of 25 samples) were pfhrp3-negative. Among the isolates tested, P. falciparum pfhrp2 gene deletions were present mainly in those from Acre State in the Brazilian Amazon. These results indicate it is important to reconsider the use of PfHRP2-based RDTs in the western region of the Brazilian Amazon and to implement appropriate surveillance systems to monitor pfhrp2 gene deletions in this and other parts of the Amazon region.

Two Cases of Plasmodium falciparum Malaria in the Netherlands without Recent Travel to a Malaria-Endemic Country

Recently, two patients of African origin were given a diagnosis of Plasmodium falciparum malaria without recent travel to a malaria-endemic country. This observation highlights the importance for clinicians to consider tropical malaria in patients with fever. Possible transmission routes of P. falciparum to these patients will be discussed. From a public health perspective, international collaboration is crucial when potential cases of European autochthonous P. falciparum malaria in Europe re considered.

Irregular Migration as a Potential Source of Malaria Reintroduction in Sri Lanka and Use of Malaria Rapid Diagnostic Tests at Point-of-Entry Screening

Background. We describe an irregular migrant who returned to Sri Lanka after a failed people smuggling operation from West Africa. Results. On-arrival screening by Anti-Malaria Campaign (AMC) officers using a rapid diagnostic test (RDT) (CareStart Malaria HRP2/PLDH) indicated a negative result. On day 3 after arrival, he presented with fever and chills but was managed as dengue (which is hyperendemic in Sri Lanka). Only on day 7, diagnosis of Plasmodium falciparum malaria was made by microcopy and CareStart RDT. The initially negative RDT was ascribed to a low parasite density. Irregular migration may be an unrecognized source of malaria reintroduction. Despite some limitations in detection, RDTs form an important point-of-entry assessment. As a consequence of this case, the AMC is now focused on repeat testing and close monitoring of all irregular migrants from malaria-endemic zones. Conclusion. The present case study highlights the effective collaboration and coordination between inter-governmental agencies such as IOM and the Ministry of Health towards the goals of malaria elimination in Sri Lanka.

Are rapid diagnostic tests more accurate in diagnosis of plasmodium falciparum malaria compared to microscopy at rural health centres?

BackgroundPrompt, accurate diagnosis and treatment with artemisinin combination therapy remains vital to current malaria control. Blood film microscopy the current standard test for diagnosis of malaria has several limitations that necessitate field evaluation of alternative diagnostic methods especially in low income countries of sub-Saharan Africa where malaria is endemic.MethodsThe accuracy of axillary temperature, health centre (HC) microscopy, expert microscopy and a HRP2-based rapid diagnostic test (Paracheck) was compared in predicting malaria infection using polymerase chain reaction (PCR) as the gold standard. Three hundred patients with a clinical suspicion of malaria based on fever and or history of fever from a low and high transmission setting in Uganda were consecutively enrolled and provided blood samples for all tests. Accuracy of each test was calculated overall with 95% confidence interval and then adjusted for age-groups and level of transmission intensity using a stratified analysis. The endpoints were: sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). This study is registered with Clinicaltrials.gov, NCT00565071.ResultsOf the 300 patients, 88(29.3%) had fever, 56(18.7%) were positive by HC microscopy, 47(15.7%) by expert microscopy, 110(36.7%) by Paracheck and 89(29.7%) by PCR. The overall sensitivity >90% was only shown by Paracheck 91.0% [95%CI: 83.1-96.0]. The sensitivity of expert microscopy was 46%, similar to HC microscopy. The superior sensitivity of Paracheck compared to microscopy was maintained when data was stratified for transmission intensity and age. The overall specificity rates were: Paracheck 86.3% [95%CI: 80.9-90.6], HC microscopy 93.4% [95%CI: 89.1-96.3] and expert microscopy 97.2% [95%CI: 93.9-98.9]. The NPV >90% was shown by Paracheck 95.8% [95%CI: 91.9-98.2]. The overall PPV was <88% for all methods.ConclusionThe HRP2-based RDT has shown superior sensitivity compared to microscopy in diagnosis of malaria and may be more suitable for screening of malaria infection.

Comparison of different methods for delayed post-mortem diagnosis of falciparum malaria

BackgroundBetween 10,000 and 12,000 cases of imported malaria are notified in the European Union each year. Despite an excellent health care system, fatalities do occur. In case of advanced autolysis, the post-mortem diagnostic is impaired. Quicker diagnosis could be achieved by using rapid diagnostic malaria tests.MethodsIn order to evaluate different methods for the post-mortem diagnosis of Plasmodium falciparum malaria in non-immunes, a study was performed on the basis of forensic autopsies of corpses examined at variable intervals after death in five cases of fatal malaria (with an interval of four hours to five days), and in 20 cases of deaths unrelated to malaria. Detection of parasite DNA by PCR and an immunochromatographic test (ICT) based upon the detection of P. falciparum histidine-rich protein 2 (PfHRP2) were compared with the results of microscopic examination of smears from cadaveric blood, histopathological findings, and autopsy results.ResultsIn all cases of fatal malaria, post-mortem findings were unsuspicious for the final diagnosis, and autoptic investigations, including histopathology, were only performed because of additional information by police officers and neighbours. Macroscopic findings during autopsy were unspecific. Histopathology confirmed sequestration of erythrocytes and pigment in macrophages in most organs in four patients (not evaluable in one patient due to autolysis). Microscopy of cadaveric blood smears revealed remnants of intraerythrocytic parasites, and was compromised or impossible due to autolysis in two cases. PCR and ICT performed with cadaveric blood were positive in all malaria patients and negative in all controls.ConclusionIn non-immune fatalities with unclear anamnesis, ICT can be recommended as a sensitive and specific tool for post-mortem malaria diagnosis, which is easier and faster than microscopy, and also applicable when microscopic examination is impossible due to autolysis. PCR is more expensive and time-consuming, but may be used as confirmatory test. In highly endemic areas where asymptomatic parasitaemia is common, confirmation of the diagnosis of malaria as the cause of death has to rely on histopathological findings.

Comparison of clinical, microscopic and rapid diagnostic test methods in the diagnosis of Plasmodium falciparum malaria in Enugu, Nigeria

To compare the use of clinical, microscopic and immunochromato-graphic methods in the diagnosis of Plasmodium falciparum malaria. Children with history of fever were consecutively recruited. Information on personal characteristics, and clinical features were obtained with the parental consent before enrolment. Malaria parasite density was done with quantitative microscopy, as well as specie identification in both local and reference laboratories. Rapid diagnostic test (RDT) kits were also used for parasite detection. Eighty three children had clinical diagnosis of malaria, while the remaining 6 had other diagnoses. On microscopy 89 and 26 patients had parasitaemia by the local and reference laboratories respectively. With the RDT, 15 patients had parasitaemia with corresponding minimum densities of 1200 and 716 parasites per ul from the local and reference laboratories. The sensitivity and specificity of the RDT to the reference laboratory were 42.31% and 93.65% respectively, while concordance was 57.69% for RDT, 30.49% for clinical diagnosis (all symptoms), 43.75% for clinical diagnosis (fever alone), and 29.21% for local laboratory. There was a significant deficiency in malaria diagnosis using any of the methods alone. For reliable diagnosis of malaria a combination of the methods of diagnosis is recommended. Degradation of the RDTs might have contributed to its low sensitivity. Training and better quality assurance should be established for the medical and laboratory workers in order to improve malaria diagnosis.