Safety of falciparum malaria diagnostic strategy based on rapid diagnostic tests in returning travellers and migrants: a retrospective study

Usefulness of serial testing for the diagnosis of malaria in cases of fever upon return from travel

BACKGROUND

When malaria is suspected in case of fever after travel in endemic areas, the current recommendation is to repeat the malaria test at 24-hour intervals, with up to two additional tests, as long as the test result is negative. A retrospective analysis was conducted to investigate the appropriateness of this recommendation by determining the proportion of tests with negative result at first and subsequently with a positive one at second or third attempt.

METHODS

A retrospective study was conducted at the Centre for Primary Care and Public Health, Lausanne, covering a period of 15 years. All patients tested once for malaria were included. Testing included microscopy thick and thin films as well as malaria rapid diagnostic test used in combination. The main outcome measure was the proportion of patients with a first negative test result, subsequently positive on second or third test over the total patients with suspected malaria assessed. Demographic, travel, clinical, and laboratory variables were collected from patients' records to identify potential predictors of an initially negative and then positive test result.

RESULTS

Four thousand nine hundred seventy-two patients were included. Of those, 4557 (91.7%) had definitive negative test results, and 415 (8.3%) had a positive result on the first test [332/415 (80%) Plasmodium falciparum, 40/415 (9.6%) P. vivax, 21/415 (5.1%) P. ovale, 12/415 (2.9%) P. vivax/ovale, 9/415 (2.2%) P. malariae and 1/415 (0.2%) P. knowlesi], and 3/4972 (0.06%) had a positive result on the second test after a first negative result, 1/4972(0.02%) had a positive test result after 2 negative results, all with P. falciparum. One of the four patients that were positive after their initial negative test was pregnant. The very small number of patients with an initially negative test result and secondarily positive did not allow for risk factor analysis.

CONCLUSIONS

The current recommendation of serial malaria testing is not supported by the present study, a fortiori for those who do not present with a strong clinical or laboratory predictor of malaria.

Malaria Diagnosis in Non-Endemic Settings: The European Experience in the Last 22 Years

Accurate, prompt, and reliable tools for the diagnosis of malaria are crucial for tracking the successes or drawbacks of control and elimination efforts, and for future programs aimed at global malaria eradication. Although microscopy remains the gold standard method, the number of imported malaria cases and the risk of reappearance of autochthonous cases stimulated several laboratories located in European countries to evaluate methods and algorithms suited to non-endemic settings, where skilled microscopists are not always available. In this review, an overview of the field evaluation and a comparison of the methods used for the diagnosis of malaria by European laboratories is reported, showing that the development of numerous innovations is continuous. In particular, the combination of rapid diagnostic tests and molecular assays with microscopy represents a reliable system for the early diagnosis of malaria in non-endemic settings.

A diagnostic evaluation of single screen testing for malaria in the returning traveler: A large retrospective cohort study

BACKGROUND

Screening for malaria in the returning traveler has often required repeat testing; however, audit data suggest that patients have not been reattending. We sought to ascertain if this was safe by examining the diagnostic efficacy of a single screen consisting of a rapid diagnostic test (RDT) and a thin film.

METHODS

We conducted a retrospective cohort study of patients with suspected malaria who attended in the past 5 years from two large teaching hospitals. We assessed the diagnostic accuracy of a single screen, reporting measures of sensitivity and specificity. To establish a reference standard, we cross-linked data with the national malaria registry held at Public Health England and regional centers.

RESULTS

The cohort consisted of 1365 patients, of whom 33 opted out of the research and one did not have a complete initial screen. Of those 1331 screens there were 74 cases of Plasmodium falciparum (prevalence of 5.6%) and 104 of any malaria species (prevalence of 7.8%). Sensitivity for the detection of P. falciparum was 100.00% (95% confidence interval [CI] = 95.1 to 100), with a specificity of 99.4% (95% CI = 98.9 to 99.8). For the detection of any species of malaria the sensitivity was slightly lower due to the presence of one false negative; sensitivity was 99.0% (95% CI = 94.8 to 100) and specificity was 99.5% (95% CI = 98.9 to 99.8).

CONCLUSIONS

A single thin film and RDT is likely to be sufficient as a first screen for falciparum malaria in the returning traveler with important caveats. For those sent home from emergency departments, appropriate safety netting must be provided. Further prospective study is required to investigate this approach.

Self-diagnosis and self-treatment of Plasmodium spp. infection by travellers (1989-2019): A systematic review and meta-analysis

BACKGROUND

Standby emergency self-treatment (SBET) is often recommended as an anti-malaria strategy for travellers to low-risk endemic areas. This self-treatment enables competent malaria therapy, if medical assistance is unavailable. The World Health Organization (WHO) recommends performing reliable diagnostic tests before starting antimalarial treatment. For the self-diagnosis of malaria in travellers, rapid diagnostic tests (RDT) can be used to confirm the infection before SBET is used. The aim of this research is to assess the use of RDT and/or SBET in travellers.

METHODS

We searched the databases (PubMed, Scopus, Embase, CINAHL) using terms and synonyms for 'self-diagnosis' and 'self-treatment' combined with 'malaria' and 'travel'. Articles in English, French and German were included. Potential articles were screened and extracted by two authors (KU and PS). Only original articles and case reports documenting the self-use of RDT and/or SBET in travellers were included. Data were extracted using a standardised approach. We defined 'correct use' of RDT and SBET. Data on number and performance of RDT and SBET use, as well as malaria verification were collected in an Excel table. Five meta-analyses were performed using a random effects model and calculating pooled proportions. This systematic review was conducted according to the PRISMA guidelines and registered in PROSPERO (CRD42018108874).

RESULTS

The research resulted in 867 articles of possible relevance on RDT and 955 articles on SBET. After screening, a total of 4 articles on RDT use and 17 articles for SBET use in travellers were included in the systematic review. Most of the RDT were performed and interpreted properly by the travellers (pooled proportion 88%, 95% confidence interval (CI) from 64% to 97%), whereby the proportion of correct performance was increased after a pre-travel test run (97%). Major problems in the implementation such as pricking finger, placing blood drop, identifying lines and interpreting results could be discovered. We found data on 1025 SBET uses in studies of travellers to high-risk African countries. In these studies, the pooled proportion of SBET uses was 6% (95% CI from 2% to 13%). We found 545 SBET uses in studies of travellers to countries of mixed malaria risk. In these studies, the pooled proportion of SBET uses was 2% (95% CI from 1% to 7%). Furthermore, the evaluation showed a high proportion of correct SBET use (pooled proportion 69%, 95% CI from 35% to 90%). As a cause for incorrect use, errors in dosage (under- or overdose), disregard of minimal incubation period (< 7 days since first possible malaria exposure) and absence of fever were identified. Four cases of post-SBET severe adverse events were documented. In a third of travellers who used SBET, a Plasmodium spp. infection could be detected (pooled proportion 31%, 95% CI from 16% to 51%).

CONCLUSIONS

This systematic review and meta-analysis showed that the majority of travellers were able to use RDT and SBET correctly. Standardised pre-travel instructions and specific training are indicated to increase the proportions of correct RDT and SBET use. With improved and user-friendly technology, RDT may become an integral part of SBET malaria recommendations for travellers. Combined use of RDT and SBET could be an appropriate strategy for selected subgroups of travellers to low-risk, remote malaria areas. Future research should focus on combined RDT and SBET strategies.

Clinical relevance of low-density Plasmodium falciparum parasitemia in untreated febrile children: A cohort study

BACKGROUND

Low-density (LD) Plasmodium infections are missed by standard malaria rapid diagnostic tests (standard mRDT) when the blood antigen concentration is below the detection threshold. The clinical impact of these LD infections is unknown. This study investigates the clinical presentation and outcome of untreated febrile children with LD infections attending primary care facilities in a moderately endemic area of Tanzania.

METHODS/FINDINGS

This cohort study includes 2,801 febrile pediatric outpatients (median age 13.5 months [range 2-59], female:male ratio 0.8:1.0) recruited in Dar es Salaam, Tanzania between 01 December 2014 and 28 February 2016. Treatment decisions were guided by a clinical decision support algorithm run on a mobile app, which also collected clinical data. Only standard mRDT+ cases received antimalarials. Outcomes (clinical failure, secondary hospitalization, and death) were collected in follow-up visits or interviews on days 3, 7, and 28. After patient recruitment had ended, frozen blood from all 2,801 patients was tested for Plasmodium falciparum (Pf) by ultrasensitive-quantitative polymerase chain reaction (qPCR), standard mRDT, and "ultrasensitive" mRDT. As the latter did not improve sensitivity beyond standard mRDT, it is hereafter excluded. Clinical features and outcomes in LD patients (standard mRDT-/ultrasensitive-qPCR+, not given antimalarials) were compared with those with no detectable (ND) parasitemia (standard mRDT-/ultrasensitive-qPCR-) or high-density (HD) infections (standard mRDT+/ultrasensitive-qPCR+, antimalarial-treated). Pf positivity rate was 7.1% (n = 199/2,801) and 9.8% (n = 274/2,801) by standard mRDT and ultrasensitive qPCR, respectively. Thus, 28.0% (n = 76/274) of ultrasensitive qPCR+ cases were not detected by standard mRDT and labeled "LD". LD patients were, on average, 10.6 months younger than those with HD infections (95% CI 7.0-14.3 months, p < 0.001). Compared with ND, LD patients more frequently had the diagnosis of undifferentiated fever of presumed viral origin (risk ratio [RR] = 2.0, 95% CI 1.3-3.1, p = 0.003) and were more often suffering from severe malnutrition (RR = 3.2, 95% CI 1.1-7.5, p = 0.03). Despite not receiving antimalarials, outcomes for the LD group did not differ from ND regarding clinical failures (2.6% [n = 2/76] versus 4.0% [n = 101/2,527], RR = 0.7, 95% CI 0.2-3.5, p = 0.7) or secondary hospitalizations (2.6% [n = 2/76] versus 2.8% [n = 72/2,527], RR = 0.7,95% CI 0.2-3.2, p = 0.9), and no deaths were reported in any Pf-positive groups. HD patients experienced more secondary hospitalizations (10.1% [n = 20/198], RR = 0.3, 95% CI 0.1-1.0, p = 0.005) than LD patients. All the patients in this cohort were febrile children; thus, the association between parasitemia and fever cannot be investigated, nor can the conclusions be extrapolated to neonates and adults.

CONCLUSIONS

During a 28-day follow-up period, we did not find evidence of a difference in negative outcomes between febrile children with untreated LD Pf parasitemia and those without Pf parasitemia. These findings suggest LD parasitemia may either be a self-resolving fever or an incidental finding in children with other infections, including those of viral origin. These findings do not support a clinical benefit nor additional risk (e.g. because of missed bacterial infections) to using ultrasensitive malaria diagnostics at a primary care level.

Rapid diagnostic tests failing to detect infections by Plasmodium falciparum encoding pfhrp2 and pfhrp3 genes in a non-endemic setting

Background

Rapid diagnostic tests (RDTs) detecting the histidine-rich protein 2 (PfHRP2) have a central position for the management of Plasmodium falciparum infections. Yet, variable detection of certain targeted motifs, low parasitaemia, but also deletion of pfhrp2 gene or its homologue pfhrp3, may result in false-negative RDT leading to misdiagnosis and delayed treatment. This study aimed at investigating the prevalence, and understanding the possible causes, of P. falciparum RDT-negative infections at Montpellier Academic Hospital, France.

Methods

The prevalence of falsely-negative RDT results reported before and after the introduction of a loop-mediated isothermal amplification (LAMP) assay, as part as the malaria screening strategy in January 2017, was analysed. Negative P. falciparum RDT infections were screened for pfhrp2 or pfhrp3 deletion; and exons 2 were sequenced to show a putative genetic diversity impairing PfHRP2 detection.

Results

The overall prevalence of P. falciparum negative RDTs from January 2006 to December 2018 was low (3/446). Whereas no cases were reported from 2006 to 2016 (0/373), period during which the malaria diagnostic screen was based on microscopy and RDT, prevalence increased up to 4.1% (3/73) between 2017 and 2018, when molecular detection was implemented for primary screening. Neither pfhrp2/3 deletion nor major variation in the frequency of repetitive epitopes could explain these false-negative RDT results.

Conclusion

This paper demonstrates the presence of pfhrp2 and pfhrp3 genes in three P. falciparum RDT-negative infections and reviews the possible reasons for non-detection of HRP2/3 antigens in a non-endemic setting. It highlights the emergence of falsely negative rapid diagnostic tests in a non-endemic setting and draws attention on the risk of missing malaria cases with low parasitaemia infections using the RDT plus microscopy-based strategy currently recommended by French authorities. The relevance of a novel diagnostic scheme based upon a LAMP assay is discussed.

Diagnostic Performance of Conventional and Ultrasensitive Rapid Diagnostic Tests for Malaria in Febrile Outpatients in Tanzania

BACKGROUND

A novel ultrasensitive malaria rapid diagnostic test (us-RDT) has been developed for improved active Plasmodium falciparum infection detection. The usefulness of this us-RDT in clinical diagnosis and fever management has not been evaluated.

METHODS

Diagnostic performance of us-RDT was compared retrospectively to that of conventional RDT (co-RDT) in 3000 children and 515 adults presenting with fever to Tanzanian outpatient clinics. The parasite density was measured by an ultrasensitive qPCR (us-qPCR), and the HRP2 concentration was measured by an enzyme-linked immunosorbent assay.

RESULTS

us-RDT identified few additional P. falciparum-positive patients as compared to co-RDT (276 vs 265 parasite-positive patients detected), with only a marginally greater sensitivity (75% vs 73%), using us-qPCR as the gold standard (357 parasite-positive patients detected). The specificity of both RDTs was >99%. Five of 11 additional patients testing positive by us-RDT had negative results by us-qPCR. The HRP2 concentration was above the limit of detection for co-RDT (>3653 pg of HRP2 per mL of blood) in almost all infections (99% [236 of 239]) with a parasite density >100 parasites per µL of blood. At parasite densities <100 parasites/µL, the HRP2 concentration was above the limits of detection of us-RDT (>793 pg/mL) and co-RDT in 29 (25%) and 24 (20%) of 118 patients, respectively.

CONCLUSION

There is neither an advantage nor a risk of using us-RDT, rather than co-RDT, for clinical malaria diagnosis. In febrile patients, only a small proportion of infections are characterized by a parasite density or an HRP2 concentration in the range where use of us-RDT would confer a meaningful advantage over co-RDT.

Photo-based External Quality Assessment of Malaria rapid diagnostic tests in a non-endemic setting

Introduction

In non-endemic settings, expertise in malaria microscopy is limited and rapid diagnostic tests (RDTs) are an adjunct to malaria diagnosis.

Aim

We performed an External Quality Assessment (EQA) on reading and interpretation of malaria RDTs in a non-endemic setting.

Methods

Participants were medical laboratories in Belgium and the Grand Duchy of Luxembourg using malaria RDTs; they received (i) 10 high-resolution photographs presenting test line combinations of RDTs with interpretations listed in a multiple choice format and (ii) a questionnaire about their practices of malaria diagnosis.

Results

Among 135 subscribing laboratories, 134 (99.3%) used 139 RDT products (11 different products from 8 brands). After exclusion of the results of one laboratory, analysis was done for 133 laboratories using 137 RDT products. Scores of 10/10, 9/10 and 8/10 were achieved for 58.4%, 13.1% and 8.0% of 137 RDT products respectively. For three-band P. falciparum–pan-Plasmodium RDTs (113 (82.5%) products, 6 brands), most frequent errors were (1) disregarding faint test lines (18.6%), (2) reporting invalid instead of P. falciparum (16.8%) and (3) reporting “Plasmodium spp., no further differentiation possible” without mentioning the presence or absence of P. falciparum (11.5%). For four-band RDTs (21 (15.3%) products, 1 brand), errors were (4) disregarding faint P. vivax test lines (47.6%) and (5) reporting “Plasmodium spp., no further differentiation possible” without mentioning the presence of P. falciparum and P. vivax (28.6%). Instructions for use (IFU) of only 4 out of 10 RDT products mentioned to interpret faint-intensity test lines as positive (conducive to errors 1 and 4) and IFU of 2 products displayed incorrect information (conducive to errors 2 and 5). Outside of office hours, 36.1% of participants relied on RDTs as the initial diagnostic test; 13.9% did not perform microscopic confirmation.

Conclusion

Reading and interpretation of malaria RDTs was satisfactory, but errors were embedded in the instructions for use of the products. Relying on RDTs alone for malaria diagnosis (about one third of participants) is not a recommended practice.

Self-diagnosis of malaria by travellers: a cohort study on the use of malaria rapid diagnostic tests provided by a Swiss travel clinic

Background

The WHO recommends that all suspect malaria cases be tested before receiving treatment. Rapid diagnostic tests (RDT) for malaria can be performed reliably by community health workers with no formal medical background and thus, RDTs could also be provided to travellers for self-diagnosis during visits to endemic regions.

Methods

RDTs were proposed during pre-travel consultations to pre-defined categories of travellers. A training run on their own blood was performed and, if carried out correctly, the traveller was given a written procedure on how to perform the test and act on its result. The travellers were then proposed to buy a malaria RDT kit and were interviewed upon their return.

Results

From February 2012 to February 2017, 744 travellers were proposed RDTs and 692 performed the training run (one could not complete it due to a hand tremor). Among the 691 subjects included, 69% travelled to moderate- or low-risk areas of malaria, 18% to high-risk areas and 13% to mixed-risk areas. The two most frequent categories of travellers to whom RDTs were proposed were long-term travellers (69%) and those travelling to remote areas (57%). 543 travellers (79%) were interviewed upon return. During their trip, 17% (91/543) had a medical problem with fever and 12% (65/543) without fever. Among 91 febrile patients, 57% (52/91) performed an RDT, 22% (20/91) consulted immediately without using the test, and 21% (19/91) did neither. Four RDTs (4/52; 8%) were positive: 2 in low-risk and 2 in high-risk areas (0.7% attack rate of self-documented malaria). Two travellers could not perform the test correctly and attended a facility or took standby emergency treatment. Four travellers with negative results repeated the test after 24 h; all were still negative. Carrying RDTs made travellers feel more secure, especially when travelling with children.

Conclusions

1/6 travellers experienced fever and 4/5 of those reacted appropriately: more than half used RDTs and a quarter consulted immediately. Four travellers (including 2 from low-risk areas) diagnosed themselves with malaria and self-treated successfully. This strategy allows prompt treatment for malaria in high-risk groups and may avoid over-diagnosis (and subsequent inappropriate treatment) of malaria on-site.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-017-2079-2) contains supplementary material, which is available to authorized users.

Toward a Framework for Benefit-Risk Assessment in Diagnostic Imaging: Identifying Scenario-specific Criteria

RATIONALE AND OBJECTIVES

Diagnostic imaging has many effects and there is no common definition of value in diagnostic radiology. As benefit-risk trade-offs are rarely made explicit, it is not clear which framework is used in clinical guideline development. We describe initial steps toward the creation of a benefit-risk framework for diagnostic radiology.

MATERIALS AND METHODS

We performed a literature search and an online survey of physicians to identify and collect benefit-risk criteria (BRC) relevant to diagnostic imaging tests. We operationalized a process for selection of BRC with the use of four clinical use case scenarios that vary by diagnostic alternatives and clinical indication. Respondent BRC selections were compared across clinical scenarios and between radiologists and nonradiologists.

RESULTS

Thirty-six BRC were identified and organized into three domains: (1) those that account for differences attributable only to the test or device (n = 17); (2) those that account for clinical management and provider experiences (n = 12); and (3) those that capture patient experience (n = 7). Forty-eight survey participants selected 22 criteria from the initial list in the survey (9-11 per case). Engaging ordering physicians increased the number of criteria selected in each of the four clinical scenarios presented. We developed a process for standardizing selection of BRC in guideline development.

CONCLUSION

These results suggest that a process relying on elements of comparative effectiveness and the use of standardized BRC may ensure consistent examination of differences among alternatives by way of making explicit implicit trade-offs that otherwise enter the decision-making space and detract from consistency and transparency. These findings also highlight the need for multidisciplinary teams that include input from ordering physicians.

Malaria in the Traveler: How to Manage Before Departure and Evaluate Upon Return

Malaria is the clinical syndrome when a patient experiences symptoms in response to infection with one of several strains of the Plasmodium parasite. This article is intended for health care providers to become familiar with some of the basics of care of patients who are travelling to or returning from an area with ongoing malaria transmission. The specific focus is on patients from nonendemic areas who plan on travel for a finite period to an area where malaria is endemic.

Severe malaria in immigrant haematological patient

Severe malaria is a life-threatening condition caused by Plasmodium falciparum. Rupture of red blood cells when merozoites release to the bloodstream is responsible for the clinical manifestations, febrile fever reaching 39 °C, and other unspecific symptoms. P. falciparum is considered as the worst form of malaria. Moreover, this species has cytoadherence to red blood cells. This can lead to an organic dysfunction. People coming from hyper endemic areas have developed a partial immunity, but immunodepressed people are a group with a greater risk. Due to the high mortality rate associated to this disease, early diagnosis and a prompt treatment implementation are essential. However, the missed or delayed diagnosis is one of the major reasons of reaching a severe malaria disease. This case reflects the complexity of the diagnosis in an immigrant and immunodepressed patient with a haematological neoplasm with a severe infection by P. falciparum due to the unspecified symptoms and the overlapping of the same.

Ability of physicians to diagnose influenza and usefulness of a rapid influenza antigen test in febrile returning travelers: A randomized controlled trial

BACKGROUND

Fever is a frequent cause of medical consultation among returning travelers. The objectives of this study were to assess whether physicians were able to identify patients with influenza and whether the use of an influenza rapid diagnostic test (iRDT) modified the clinical management of such patients.

METHODS

Randomized controlled trial conducted at 2 different Swiss hospitals between December 2008 and November 2012. Inclusion criteria were 1) age ≥ 18 years, 2) documented fever of ≥ 38 °C or anamnestic fever + cough or sore throat within the last 4 days, 3) illness occurring within 14 days after returning from a trip abroad, 4) no definitive alternative diagnosis. Physicians were asked to estimate the likelihood of influenza on clinical grounds, and a single nasopharyngeal swab was taken. Thereafter patients were randomized into 2 groups: i) patients with iRDT (BD Directigen A + B) performed on the nasopharyngeal swab, ii) patients receiving usual care. A quantitative PCR to detect influenza was done on all nasopharyngeal swabs after the recruitment period. Clinical management was evaluated on the basis of cost of medical care, number of X-rays requested and prescription of anti-infective drugs.

RESULTS

100 eligible patients were referred to the investigators. 93 patients had a naso-pharyngeal swab for a PCR and 28 (30%) swabs were positive for influenza. The median probability of influenza estimated by the physician was 70% for the PCR positive cases and 30% for the PCR negative cases (p < 0.001). The sensitivity of the iRDT was only 20%, and specificity 100%. Mean medical cost for the patients managed with iRDT and without iRDT were USD 581 (95%CI 454-707) and USD 661 (95%CI 522-800) respectively. 14/60 (23%) of the patients managed with iRDT were prescribed antibiotics versus 13/33 (39%) in the control group (p = 0.15). No patient received antiviral treatment.

CONCLUSION

Influenza was a frequent cause of fever among these febrile returning travelers. Based on their clinical assessment, physicians had a higher level of suspicion for influenza in PCR positive cases. The iRDT used in this study showed a disappointingly low sensitivity and can therefore not be recommended for the management of these patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00821626.

Imported malaria among people who travel to visit friends and relatives: is current UK policy effective or does it need a strategic change?

Background

The proportion of all imported malaria reported in travellers visiting friends and relatives (VFRs) in the UK has increased over the past decade and the proportion of Plasmodium falciparum malaria affecting this group has remained above 80% during that period. The epidemiological data suggest that the strategies employed in the UK to prevent imported malaria have been ineffective for VFRs. This paper attempts to identify possible reasons for the failure of the malaria prevention strategy among VFRs and suggest potential alternatives.

Methods

A review of the current UK malaria prevention guidelines was undertaken and their approach was compared to the few data that are available on malaria perceptions and practices among VFRs.

Results

The current UK malaria prevention guidelines focus on educating travellers and health professionals using messages based on the personal threat of malaria and promoting the benefits of avoiding disease through the use of chemoprophylaxis. While malaria morbidity disproportionately affects VFRs, the mortality rates from malaria in VFRs is eight times, and severe disease eight times lower than in tourist and business travellers. Recent research into VFR malaria perceptions and practices has highlighted the complex socio-ecological context within which VFRs make their decisions about malaria. These data suggest that alternative strategies that move beyond a knowledge-deficit approach are required to address the burden of malaria in VFRs.

Discussion

Potential alternative strategies include the use of standby emergency-treatment (SBET) for the management of fevers with an anti-malarial provided pre-travel, the provision of rapid diagnostic testing and treatment regimen based in general-practitioner surgeries, and urgent and walk-in care centres and local accident and emergency (A&E) departments to provide immediate diagnosis and accessible ambulatory treatment for malaria patients. This latter approach would potentially address some of the practical barriers to reducing the burden of malaria in VFRs by moving the process nearer to the community.

Performance and clinical usefulness of the Optimal-IT® test in the treatment of confirmed malaria cases in rural areas in Côte d'Ivoire

Background

In Africa, malaria care is mostly based on clinical presumption and the general application of antimalarial treatment to all febrile episodes over several years. Treatment limited to confirmed cases might curb the practice of equating fever with malaria, antimalarial drug abuse and the extension of Plasmodium resistance, provided that powerful and reliable rapid diagnostic tests are used. This study aimed at determining the performances of the Optimal-IT® test in the strategy for the exclusive treatment of uncomplicated malaria in rural areas.

Materials and Methods

A prospective study conducted in the forest region of San Pedro, Côte d'Ivoire, included patients exhibiting clinical signs of uncomplicated malaria who gave their consent and benefited from thick blood film (TBF), blood smear (BS) and Optimal-IT® (pLDH-based) test. Rapid diagnostic test (RDT) results were taken into consideration to decide on malaria treatment and then compared with TBF/BS results (reference) to assess the performances and clinical usefulness of the RDT.

Results

The mean age of the 384 patients included (209 men, 175 women) was 28 years and the mean temperature was 38.1°C. TBF/BS and Optimal-IT® were concordant in 92% of patients but discordant in 10 false negative (3%) and 19 false-positive patients (5%). The average parasite density of P. falciparum was 25,600 trophozoites/μl. The performances calculated were: sensitivity=95%, specificity=91%, positive predictive value=90%, negative predictive value=95%, positive likelihood ratio=10, negative likelihood ratio=0.06 and diagnostic odds ratio=166, indicating that Optimal-IT® is a powerful and credible diagnostic tool. The 193 RDT-positive patients treated were healed, despite three recurrence cases at day (D) D17, D25 and D27, respectively. RDT-negative patients received various treatments (antibiotics, paracetamol), but two patients among them presented with a bout of malaria on D7. None of the previously untreated patients returned with severe malaria.

Conclusions

The Optimal-IT® test, which is already used in the field, showed good performances to effectively detect patients with and without malaria. It is therefore adapted to the malaria treatment strategy limited to confirmed cases.

Feasibility and clinical outcomes when using practice guidelines for evaluation of fever in returning travelers and migrants: a validation study

BACKGROUND

Practice guidelines for examining febrile patients presenting upon returning from the tropics were developed to assist primary care physicians in decision making. Because of the low level of evidence available in this field, there was a need to validate them and assess their feasibility in the context they have been designed for.

OBJECTIVES

The objectives of the study were to (1) evaluate physicians' adherence to recommendations; (2) investigate reasons for non-adherence; and (3) ensure good clinical outcome of patients, the ultimate goal being to improve the quality of the guidelines, in particular to tailor them for the needs of the target audience and population.

METHODS

Physicians consulting the guidelines on the Internet (www.fevertravel.ch) were invited to participate in the study. Navigation through the decision chart was automatically recorded, including diagnostic tests performed, initial and final diagnoses, and clinical outcomes. The reasons for non-adherence were investigated and qualitative feedback was collected.

RESULTS

A total of 539 physician/patient pairs were included in this study. Full adherence to guidelines was observed in 29% of the cases. Figure-specific adherence rate was 54.8%. The main reasons for non-adherence were as follows: no repetition of malaria tests (111/352) and no presumptive antibiotic treatment for febrile diarrhea (64/153) or abdominal pain without leukocytosis (46/101). Overall, 20% of diversions from guidelines were considered reasonable because there was an alternative presumptive diagnosis or the symptoms were mild, which means that the corrected adherence rate per case was 40.6% and corrected adherence per figure was 61.7%. No death was recorded and all complications could be attributed to the underlying illness rather than to adherence to guidelines.

CONCLUSIONS

These guidelines proved to be feasible, useful, and leading to good clinical outcomes. Almost one third of physicians strictly adhered to the guidelines. Other physicians used the guidelines not to forget specific diagnoses but finally diverged from the proposed attitudes. These diversions should be scrutinized for further refinement of the guidelines to better fit to physician and patient needs.

[Malaria]

Malaria is the most important infectious disease imported by travelers and migrants from tropical and subtropical areas. It is imported quite frequently. It is a life-threatening disease. Symptoms are nonspecific and cannot easily be distinguished from a wide range of other febrile conditions. Therefore, travel history must be taken in all patients with fever of unknown origin and malaria diagnostics must be performed immediately on suspicion of malaria. Uncomplicated falciparum malaria should be treated in the hospital with either atovaquone-proguanil or with an artemisinin-based combination preparation. If there is evidence of severe malaria, the patient must be moved to an intensive care unit. The antiparasitic agent of choice is then artesunate.

Performance of rapid diagnostic tests for imported malaria in clinical practice: results of a national multicenter study

We compared the performance of four rapid diagnostic tests (RDTs) for imported malaria, and particularly Plasmodium falciparum infection, using thick and thin blood smears as the gold standard. All the tests are designed to detect at least one protein specific to P. falciparum (Plasmodium histidine-rich protein 2 (PfHRP2) or Plasmodium LDH (PfLDH)) and one pan-Plasmodium protein (aldolase or Plasmodium LDH (pLDH)). 1,311 consecutive patients presenting to 9 French hospitals with suspected malaria were included in this prospective study between April 2006 and September 2008. Blood smears revealed malaria parasites in 374 cases (29%). For the diagnosis of P. falciparum infection, the three tests detecting PfHRP2 showed high and similar sensitivity (96%), positive predictive value (PPV) (90%) and negative predictive value (NPV) (98%). The PfLDH test showed lower sensitivity (83%) and NPV (80%), despite good PPV (98%). For the diagnosis of non-falciparum species, the PPV and NPV of tests targeting pLDH or aldolase were 94-99% and 52-64%, respectively. PfHRP2-based RDTs are thus an acceptable alternative to routine microscopy for diagnosing P. falciparum malaria. However, as malaria may be misdiagnosed with RDTs, all negative results must be confirmed by the reference diagnostic method when clinical, biological or other factors are highly suggestive of malaria.