Self-use of rapid tests for malaria diagnosis by tourists

Setting-up a cross-border action-research project to control malaria in remote areas of the Amazon: describing the birth and milestones of a complex international project (Malakit)

Background

In French Guiana, gold miners working illegally represents a major reservoir of malaria. This mobile population, mainly of Brazilian descent, enters the French Guianese forest from neighbouring countries, Suriname and Brazil. A complex and innovative intervention was piloted as a cooperation with the three involved countries involved to control malaria in this specific population. The principle was that health workers called “facilitators” provide the participants with a self-diagnosis and self-treatment kit along with adequate training and material to rapidly manage an episode of malaria symptoms on their own, when they find themselves isolated from health care services.

Methods

This paper describes the design, development, content of the intervention and players’ organization of this multi-country project, the opportunities and constraints encountered, and the lessons learnt at this stage.

Results

The choice not to implement the usual “Test and Treat” approach within the community is mainly driven by regulatory reasons. The content of medical messages tends to balance the tension between thoroughness, accuracy and efficacy. The wide range of tools developed through a participatory approach was intended to cope with the challenges of the literacy level of the target population. Despite the difficulties encountered due to language, regulation differences and distance between partners, cooperation was fruitful, due to the complementary of stakeholders, their involvement at all important stages and regular face-to-face meetings.

Discussion and conclusion

This experience shows the feasibility of an ambitious project of action-research in a border malaria context, involving several countries and with a mobile and undocumented population. It reveals some factors of success which may be transferable in analogous settings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03748-5.

Potential for community based surveillance of febrile diseases: Feasibility of self-administered rapid diagnostic tests in Iquitos, Peru and Phnom Penh, Cambodia

Rapid diagnostic tests (RDTs) have the potential to identify infectious diseases quickly, minimize disease transmission, and could complement and improve surveillance and control of infectious and vector-borne diseases during outbreaks. The U.S. Defense Threat Reduction Agency's Joint Science and Technology Office (DTRA-JSTO) program set out to develop novel point-of-need RDTs for infectious diseases and deploy them for home use with no training. The aim of this formative study was to address two questions: 1) could community members in Iquitos, Peru and Phnom Penh, Cambodia competently use RDTs of different levels of complexity at home with visually based instructions provided, and 2) if an RDT were provided at no cost, would it be used at home if family members displayed febrile symptoms? Test kits with written and video (Peru only) instructions were provided to community members (Peru [n = 202]; Cambodia [n = 50]) or community health workers (Cambodia [n = 45]), and trained observers evaluated the competency level for each of the several steps required to successfully operate one of two multiplex RDTs on themselves or other consenting participant (i.e., family member). In Iquitos, >80% of residents were able to perform 11/12 steps and 7/15 steps for the two- and five-pathogen test, respectively. Competency in Phnom Penh never reached 80% for any of the 12 or 15 steps for either test; the percentage of participants able to perform a step ranged from 26-76% and 23-72%, for the two- and five-pathogen tests, respectively. Commercially available NS1 dengue rapid tests were distributed, at no cost, to households with confirmed exposure to dengue or Zika virus; of 14 febrile cases reported, six used the provided RDT. Our findings support the need for further implementation research on the appropriate level of instructions or training needed for diverse devices in different settings, as well as how to best integrate RDTs into existing local public health and disease surveillance programs at a large scale.

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.

'Everybody in Nigeria is a doctor…': a qualitative study of stakeholder perspectives on lay diagnosis of malaria and pneumonia in Nigeria

BACKGROUND

Lay diagnosis is a widely used diagnostic approach for home management of common illnesses in Nigeria. This study aimed to explore the perspectives of caregivers and healthcare professionals on lay diagnosis of childhood malaria and pneumonia. Aligned to this, the study sought to explore the feasibility of training caregivers in the Integrated Management of Childhood Illness (IMCI) guidelines for improved recognition and treatment of these diseases.

METHODS

A qualitative study using individual face-to-face semi-structured interviews was conducted in Benin City, Nigeria. Participants included 13 caregivers with children under 5 years and 17 healthcare professionals (HPs). An inductive approach to thematic analysis was used to generate themes and analyses.

RESULTS

Caregivers relied on lay diagnosis but recognised its limitations. The perceived severity of malaria and pneumonia significantly influenced caregivers' preference for reliance on lay diagnosis practices, health-seeking behaviour and willingness to undertake training in IMCI guidelines for home management of diseases. Safety and potential unintended misuse of medications were recognised by caregivers and HPs as the main challenges.

CONCLUSIONS

The high level of acceptance among caregivers to receive IMCI training could help improve effective management of childhood malaria and pneumonia at the community level through early recognition and prompt treatment.

Malaria standby emergency treatment (SBET) for travellers visiting malaria endemic areas: a systematic review and meta-analysis

BACKGROUND

Malaria prevention methods for travellers to low or moderate malaria risk areas vary and remain controversial. Standby emergency treatment (SBET) for malaria is one possible strategy increasingly recommended since 1988 with little evidence on its effectiveness or how it is truly being used.

METHODS

A systematic review and meta-analysis were performed based on a structured search in Embase, Medline, PubMed, Cochrane and Web of Science on 7 September 2018. The primary outcome was the overall prevalence of SBET use in travellers, and secondary outcomes were the proportion carrying SBET, the response to fever [use of SBET, health facility attendance and use of malaria rapid diagnostic test (mRDT)], adverse events to SBET and the proportion using SBET incorrectly (incorrect dosage/duration). The pooled SBET use prevalence was analysed using a random effects model. A descriptive summary was done to present secondary outcomes. The study protocol was registered with PROSPERO CRD42018103703.

RESULTS

A total of 11 studies were eligible for inclusion among the 1027 titles identified by our search. The studies included 7/11 prospective cohort studies that recruited pre-travel clinic attendees in Europe and 4/11 cross-sectional studies, of which 3 recruited travellers at airports before their return home from Southeast Asia and Africa and 1 from an employee registry including long-term travellers. The overall pooled prevalence of SBET use among the 26 403 travellers was 2.5% (95% confidence interval, 1.1-4.3%; range, 0.4-10.8%). There was significant variation in the proportion of travellers carrying SBET medication (40-100%), the proportion of travellers with appropriate response to fever (23-100%), adverse events (0-33%) and incorrect dosage/duration of SBET (0-100%).

CONCLUSION

Adherence to the proposed recommendations for SBET use, notably the response to fever, was poor. If the use of SBET is to be pursued, modifications to the current SBET strategy should be considered, such as better selection of travellers at higher risk for malaria and the potential addition of mRDTs.

Self-diagnosis of seasonal influenza in a rural primary care setting in Japan: A cross sectional observational study

OBJECTIVE

To elucidate the accuracy and optimal cut-off point of self-diagnosis and clinical symptoms of seasonal influenza compared with rapid influenza diagnostic tests as the reference standard, we conducted a cross sectional observational study at a rural clinic in Japan.

METHODS

Data during three influenza seasons (December 2013 to April 2016) were retrospectively collected from the medical records and pre-examination sheets of 111 patients aged >11 years (mean age 48.1 years, men 53.2%) who were suspected of influenza infection and underwent rapid influenza diagnostic testing. Patients' characteristics (age, sex, and past medical history of influenza infection), clinical signs (axillary temperature, pulse rate, cough, joint and muscle pain, and history of fever [acute or sudden, gradual, and absence of fever]), duration from the onset of symptoms, severity of feeling sick compared with a common cold (severe, similar, and mild), self-reported likelihood of influenza (%), and results of rapid influenza diagnostic tests.

RESULTS

At the optimal cut-off point (30%) for estimation of self-diagnosis of seasonal influenza, the positive likelihood ratio (LR+) was 1.46 (95% confidence interval 1.07 to 2.00) and negative likelihood ratio (LR-) was 0.57 (0.35 to 0.93). At a 10% cut-off point, LR-was 0.33 (0.12 to 0.96). At an 80% cut-off point, LR+ was 2.75 (0.75 to 10.07). As for clinical signs, the combination of acute or sudden onset fever and cough had LR+ of 3.27 (1.68 to 6.35). Absence of cough showed LR-of 0.15 (0.04 to 0.61).

CONCLUSIONS

Self-diagnosis of influenza using the optimal cut-off point (30%) was not found useful for ruling in or ruling out an influenza diagnosis. However, it could be useful when patients self-report extremely high (80%) or low (10%) probability of having influenza. Clinically useful signs were the combination of history of fever and cough, and absence of cough.

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.

Summary of recommendations on malaria issues in special hosts

BACKGROUND

On behalf of the Public Health Agency of Canada, the Committee to Advise on Tropical Medicine and Travel (CATMAT) developed the Canadian Recommendations for the Prevention and Treatment of Malaria Among International Travellers for Canadian health care providers who are preparing patients for travel to malaria-endemic areas and treating travellers who have returned ill.

OBJECTIVE

To provide guidelines on malaria issues related to special hosts.

METHODS

CATMAT reviewed all major sources of information on malaria prevention, as well as recent research and national and international epidemiological data, to tailor guidelines to the Canadian context. The evidence-based medicine recommendations were developed with associated rating scales for the strength and quality of the evidence.

RECOMMENDATIONS

All people visiting malaria endemic regions should use effective personal protective measures (PPM; topical repellants, bed nets, behavioural choices) and the prescribed chemoprophylaxis. Chemoprophylaxis for pregnant and breastfeeding women and for children requires careful consideration in the context of the pregnancy trimester, the age or size of the infant/child as well as their glucose-6-phosphate dehydrogenase (G6PD) status. Recommendations for long-term travellers, expatriates and people visiting friends and relatives (VFRs) do not differ markedly from those for short-term travellers. Some underlying medical conditions may make individuals more vulnerable to malaria. In addition, some conditions or their treatment may preclude the use of one or more antimalarial medications.

Home testing past, present and future: lessons learned and implications for HIV home tests

The recent approval in the United States of the first rapid home test to diagnose HIV raises questions about its potential use and impact. We reviewed the existing literature on the unassisted use of home tests involving self-collection and testing of biological samples by untrained users-including existing HIV self-testing studies-to shed some light on what can be expected from the availability of the HIV home test. The studies reviewed showed that most participants could properly perform home tests, obtain accurate results, and interpret them-yielding high correlations with laboratory and health-professional performed tests. Users often had trouble performing blood-based tests. Participants generally understood the need to confirm positive test results. Materials accompanying HIV home tests should emphasize symptoms of acute infection and the need for additional testing when recent infection is suspected. Different home-test-based screening modalities, personalized HIV-counseling resources and HIV home test impact evaluation methods should be studied.

Potential biomarkers and their applications for rapid and reliable detection of malaria

Malaria has been responsible for the highest mortality in most malaria endemic countries. Even after decades of malaria control campaigns, it still persists as a disease of high mortality due to improper diagnosis and rapidly evolving drug resistant malarial parasites. For efficient and economical malaria management, WHO recommends that all malaria suspected patients should receive proper diagnosis before administering drugs. It is thus imperative to develop fast, economical, and accurate techniques for diagnosis of malaria. In this regard an in-depth knowledge on malaria biomarkers is important to identify an appropriate biorecognition element and utilize it prudently to develop a reliable detection technique for diagnosis of the disease. Among the various biomarkers, plasmodial lactate dehydrogenase and histidine-rich protein II (HRP II) have received increasing attention for developing rapid and reliable detection techniques for malaria. The widely used rapid detection tests (RDTs) for malaria succumb to many drawbacks which promotes exploration of more efficient economical detection techniques. This paper provides an overview on the current status of malaria biomarkers, along with their potential utilization for developing different malaria diagnostic techniques and advanced biosensors.

Self-diagnosis of malaria by travelers and expatriates: assessment of malaria rapid diagnostic tests available on the internet

Introduction

In the past malaria rapid diagnostic tests (RDTs) for self-diagnosis by travelers were considered suboptimal due to poor performance. Nowadays RDTs for self-diagnosis are marketed and available through the internet. The present study assessed RDT products marketed for self-diagnosis for diagnostic accuracy and quality of labeling, content and instructions for use (IFU).

Methods

Diagnostic accuracy of eight RDT products was assessed with a panel of stored whole blood samples comprising the four Plasmodium species (n = 90) as well as Plasmodium negative samples (n = 10). IFUs were assessed for quality of description of procedure and interpretation and for lay-out and readability level. Errors in packaging and content were recorded.

Results

Two products gave false-positive test lines in 70% and 80% of Plasmodium negative samples, precluding their use. Of the remaining products, 4/6 had good to excellent sensitivity for the diagnosis of Plasmodium falciparum (98.2%–100.0%) and Plasmodium vivax (93.3%–100.0%). Sensitivity for Plasmodium ovale and Plasmodium malariae diagnosis was poor (6.7%–80.0%). All but one product yielded false-positive test lines after reading beyond the recommended reading time. Problems with labeling (not specifying target antigens (n = 3), and content (desiccant with no humidity indicator (n = 6)) were observed. IFUs had major shortcomings in description of test procedure and interpretation, poor readability and lay-out and user-unfriendly typography. Strategic issues (e.g. the need for repeat testing and reasons for false-negative tests) were not addressed in any of the IFUs.

Conclusion

Diagnostic accuracy of RDTs for self-diagnosis was variable, with only 4/8 RDT products being reliable for the diagnosis of P. falciparum and P. vivax, and none for P. ovale and P. malariae. RDTs for self-diagnosis need improvements in IFUs (content and user-friendliness), labeling and content before they can be considered for self-diagnosis by the traveler.

Malaria prevention in travelers

A common approach to malaria prevention is to follow the "A, B, C, D" rule: Awareness of risk, Bite avoidance, Compliance with chemoprophylaxis, and prompt Diagnosis in case of fever. The risk of acquiring malaria depends on the length and intensity of exposure; the risk of developing severe disease is primarily determined by the health status of the traveler. These parameters need to be assessed before recommending chemoprophylaxis and/or stand-by emergency treatment. This review discusses the different strategies and drug options available for the prevention of malaria during and post travel.

Self-diagnosis of influenza during a pandemic: a cross-sectional survey

BACKGROUND

Self-diagnosis of influenza is an important component of pandemic control and management as it may support self-management practices and reduce visits to healthcare facilities, thus helping contain viral spread. However, little is known about the accuracy of self-diagnosis of influenza, particularly during pandemics.

METHODS

We used cross-sectional survey data to correlate self-diagnosis of influenza with serological evidence of 2009 pandemic influenza A(H1N1) infection (haemagglutination inhibition titres of ≥1:40) and to determine what symptoms were more likely to be present in accurate self-diagnosis. The sera and risk factor data were collected for the national A(H1N1) seroprevalence survey from November 2009 to March 2010, 3 months after the first pandemic wave in New Zealand (NZ).

RESULTS

The samples consisted of 318 children, 413 adults and 423 healthcare workers. The likelihood of being seropositive was no different in those who believed they had influenza from those who believed they did not have influenza in all groups. Among adults, 23.3% (95% CI 11.9% to 34.7%) of those who reported having had influenza were seropositive for H1N1, but among those reporting no influenza, 21.3% (95% CI 13% to 29.7%) were also seropositive. Those meeting NZ surveillance or Ministry of Health influenza case definitions were more likely to believe they had the flu (surveillance data adult sample OR 27.1, 95% CI 13.6 to 53.6), but these symptom profiles were not associated with a higher likelihood of H1N1 seropositivity (surveillance data adult sample OR 0.93, 95% CI 0.5 to 1.7).

CONCLUSIONS

Self-diagnosis does not accurately predict influenza seropositivity. The symptoms promoted by many public health campaigns are linked with self-diagnosis of influenza but not with seropositivity. These findings raise challenges for public health initiatives that depend on accurate self-diagnosis by members of the public and appropriate self-management action.

Performance of self-diagnosis and standby treatment of malaria in international oilfield service employees in the field

Background

Falciparum malaria remains a major occupational illness that accounts for several deaths per year and numerous lost working days among the expatriate population, working or living in high-risk malarious areas. Compliance to preventive strategies is poor in travellers, especially business travellers, expatriates and long-term travellers.

Methods

In this cross-sectional, web-based study the adherence to and outcome of a preventive malaria programme on knowledge, attitudes and practices, including the practice of self-diagnosis and standby treatment (curative malaria kit, CMK) was evaluated in 2,350 non-immune expatriates, who had been working in highly malaria endemic areas.

Results

One-third (N = 648) of these expatriates visited a doctor for malaria symptoms and almost half (29 of 68) of all hospitalizations were due to malaria. The mandatory malaria training for non-immunes was completed by 92% of those who visited or worked in a high risk malaria country; 70% of the respondents at risk also received the CMK. The malaria awareness training and CMK significantly increased malaria knowledge [relative risk (RR) of 1.5, 95%CI 1.2–2.1], attitudes and practices, including compliance to chemoprophylaxis [RR = 2.2, 95%CI 1.6–3.2]. Hospitalization for malaria tended to be reduced by the programme [RR = 0.4, 95%CI 0.1–1.1], albeit not significantly. Respondents who did not receive instructions on the rapid diagnostic test were two times [RR = 2.3, 95%CI 1.6–3.3] more likely to have difficulties. Those who did receive instructions adhered poorly to the timing of repeating the test. Moreover, 6% (31 of 513) of those with a negative test result were diagnosed with malaria by a local doctor. 77% (N = 393) of the respondents with a negative test result did not take curative medication. 57% (252 of 441) of the respondents who took the curative medication that was included in the kit did not have a positive self-test or clinical malaria diagnosis made by a doctor.

Conclusion

This survey demonstrated that a comprehensive programme targeting malaria prevention in expatriates can be effectively implemented and that it significantly increased malaria awareness.

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.

Update on rapid diagnostic testing for malaria

To help mitigate the expanding global impact of malaria, with its associated increasing drug resistance, implementation of prompt and accurate diagnosis is needed. Malaria is diagnosed predominantly by using clinical criteria, with microscopy as the current gold standard for detecting parasitemia, even though it is clearly inadequate in many health care settings. Rapid diagnostic tests (RDTs) have been recognized as an ideal method for diagnosing infectious diseases, including malaria, in recent years. There have been a number of RDTs developed and evaluated widely for malaria diagnosis, but a number of issues related to these products have arisen. This review highlights RDTs, including challenges in assessing their performance, internationally available RDTs, their effectiveness in various health care settings, and the selection of RDTs for different health care systems.

Molecular diagnostic and surveillance tools for global malaria control

Malaria is the most devastating parasitic infection in the world, annually causing over 1 million deaths and extensive morbidity. The global burden of malaria has increased over the last several decades, as have rates of imported malaria into non-endemic regions. Rapid and accurate diagnostics are a crucial component of malaria control strategies, and epidemiological surveillance is required to monitor trends in malaria prevalence and antimalarial drug resistance. Conventional malaria diagnostic and surveillance tools can be cumbersome and slow with limitations in both sensitivity and specificity. New molecular techniques have been developed in an attempt to overcome these restrictions. These molecular techniques are discussed with regard to their technical advantages and disadvantages, with an emphasis on the practicality of implementation in malaria-endemic and non-endemic regions.

Bedside diagnosis of imported malaria using the Binax Now malaria antigen detection test

Malaria may be misdiagnosed in non-endemic countries when the necessary experience for rapid expert microscopy is lacking. Rapid diagnostic tests may improve the diagnosis and may play a role as a bedside diagnostic tool. In a multicentre study we recruited patients suspected of malaria over a period of 14 months. The Binax Now Malaria rapid test was used at the bedside and in the clinical microbiology laboratory. The training of clinical staff was monitored and their experience with the use of the test was recorded. 542 patients were included, 80 of whom had malaria diagnosed by microscopy. The rapid test used at the bedside had a sensitivity of 88% for the detection of P. falciparum compared to 95% when the test was performed in the microbiology laboratory. The risk of technical problems and invalid tests was highest when the test was used at the bedside. The rapid diagnostic test may be useful for the diagnosis of P. falciparum malaria when used by routine laboratory staff, but could lead to misdiagnoses when used at the bedside. Microscopy is still essential in order to identify the few missed diagnoses, to determine the degree of parasitaemia, and to ensure species diagnosis, including mixed infections.

Use of rapid diagnostic tests for diagnosis of malaria in the UK

BACKGROUND

Malaria is currently diagnosed almost exclusively by microscopy in clinical laboratories. The introduction of rapid diagnostic tests (RDTs) may be useful in achieving rapid detection of malaria parasites, especially in situations where malaria is not often seen or where staff are inexperienced.

AIM

To explore the use of RDT in UK laboratories.

METHODS

The current use of RDTs was surveyed in UK laboratories subscribing to the United Kingdom National External Quality Assessment Scheme blood parasitology and haematology schemes.

RESULTS

An overall survey response rate of 60.3% was seen. RDTs were found to be the preferred choice, either alone or in conjunction with microscopy in 31.2% of the samples examined during normal working hours and in 44.3% of the specimens examined on call.

CONCLUSIONS

During on-call hours, the use of RDTs was observed to increase and RDTs changed the diagnosis in 12% of laboratories. No established protocol for RDT use was, however, observed in the UK. A protocol that needs to be validated in the laboratory setting is suggested.

Malaria: Diagnosis and treatment of falciparum malaria in travelers during and after travel

Plasmodium falciparum is responsible for most of the mortality in travelers related to imported malaria. Problems that occur during travel include the inaccuracy of a microscopic diagnosis of malaria, both false positives and false negatives, when ill travelers seek care while abroad. A false positive diagnosis can result in unnecessary parenteral injections that carry a risk of transmission of blood-borne pathogens, receipt of potentially dangerous drugs such as halofantrine, or receipt of fake, counterfeit drugs. Increased morbidity and mortality are associated with delays in diagnosis and initiation of prompt treatment for falciparum malaria. Availability of expert microscopy to confirm the diagnosis of malaria is limited. The presence of splenomegaly and thrombocytopenia are strongly associated with malaria and would justify empiric treatment. The availability of atovaquone-proguanil, a safe and well tolerated oral drug, should prompt a reconsideration of current treatment recommendations that discourage empiric treatment on clinical suspicion alone.

New strategies for the prevention of malaria in travelers

Malaria prevention has benefited from many diverse disciplines of research, including epidemiologic monitoring, development of laboratory techniques, assessment of insect repellents, or pharmaceutical innovations. Strategies in all these sectors have been explored in recent years, resulting in improved options to prevent travelers' malaria. The addition of atovaquone-proguanil for malaria chemoprophylaxis and the recommendation of primaquine as primary prophylaxis have been significant advances. Tafenoquine seems promising. Standby treatment recommendations have been refined. Many areas still need better strategies. Problematic areas include chemoprophylaxis for long-term travelers, expatriates, and pregnant women; optimal criteria for terminal prophylaxis; and the prevention of malaria in populations that are least likely to seek pretravel evaluations, such as those visiting friends and relatives in their home countries (VFRs). Finally, research in travel and tropical medicine should continue to focus on additional strategies to confront the ever-widening challenge of drug-resistant malaria.

Malaria self-testing by travellers: opportunities and limitations

Accurate and timely treatment of imported malaria requires rapid and reliable diagnosis. The availability of a rapid and reliable diagnostic test could improve the quality of malaria diagnosis in febrile travelers after their return to non-endemic countries. Rapid and simple immuno-chromatographic tests have been marketed for several years. Dipstick tests for malaria diagnosis are still a potentially very useful additional tool. Trained laboratory personal have in general no problems in doing the tests. Also, the dipsticks are very valuable tools for use in epidemiological field studies. However, sensitivity and specificity of dipstick tests are still below that of trained microscopists. Exclusion of malaria should never be based on a negative dipstick test alone. Self-use of dipstick tests for malaria diagnosis by travelers should not be recommended routinely as there is enough evidence that performance and interpretation of results by the traveler is uncertain. Dipstick tests can only be recommended to travelers for specific situations (i.e. long term stay, far away from medical assistance, expedition-type travel) after appropriate instruction and training, including a successful performance of the test procedure.

Rapid diagnostic testing for malaria

Malaria rapid diagnostic devices (MRDD) have been developed with the hope that they would offer accurate, reliable, rapid, cheap and easily available alternatives to traditional methods of malaria diagnosis. The results from early malaria rapid diagnostic studies were quite promising, especially for detecting Plasmodium falciparum at densities of more than 100-500 parasites/microl. Despite the introduction of these devices over a decade ago, only a few target antigens have been introduced. Of greater concern, these devices have shown limitations in sensitivity, ability to differentiate species and robustness under field conditions in the tropics. Recent trials have revealed wide variability in sensitivity both within and between products. We review the recent trials assessing MRDD use for the diagnosis of P. falciparum and non-P. falciparum infections in endemic and non-endemic countries and describe the various aspects of these devices which need further improvement. High quality, accurate, rapid and affordable diagnostic tools are urgently needed now that new antimalarial regimens, characterized by higher cost and increased toxicity, have been introduced more widely in response to emerging multi-drug resistance.

Current strategies to avoid misdiagnosis of malaria

Malaria remains the most important parasitic disease, and tens of thousands of cases are imported into non-endemic countries annually. However, any single institution may see only a very few cases-this is probably the reason why laboratory and clinical misdiagnosis may not be uncommon. In the laboratory, unfamiliarity with microscopic diagnosis may be the main reason, considering the large number of laboratory staff who provide on-call services, often without expert help at hand, as well as the difficulty in detecting cases with low-level parasitemia. Staff should therefore be provided with continuing microscopic training to maintain proficiency. The complementary use of immunochromatographic rapid detection tests (RDTs) may be useful, especially during on-call hours, although, in order to ensure correct interpretation, their inherent limitations have to be well known. Diagnosis based on the polymerase chain reaction is still unsuitable for routine use, due to its long turnaround time, its cost, and its unavailability outside regular hours, although it may be helpful in selected cases. Once the alert clinician has considered the possibility of malaria, and suspicion continues to be high, malaria can be excluded by repeat smears or RDTs. However, the absence of clinical suspicion may not be infrequent, and may have more serious consequences. Depending on the local number of malaria cases seen, laboratory staff should have a low threshold for the decision to perform unsolicited malaria diagnostic tests on suspicious samples, especially if other laboratory tests are abnormal (e.g. thrombocytopenia, presence of atypical lymphocytes, or raised lactate dehydrogenase). The detection of intraleukocytic hemozoin during automated full blood counts is a promising new way to avoid misdiagnosis of clinically unsuspected malaria.

Sensitivity of P. vivax rapid antigen detection tests and possible implications for self-diagnostic use

In a prospective study amongst febrile travellers returning from malaria-endemic areas to Berlin, Germany, two rapid malarial antigen detection tests were compared for the diagnosis of vivax malaria with routine microscopy. With ICT Malaria P.f./P.v.((R)), 664 samples of 492 patients were examined. 17 patients had vivax malaria, out of which 11 infections were missed (35.3% sensitivity). With OptiMal((R)), 659 samples of 539 patients were examined. 22 patients had vivax malaria, and all infections were identified correctly (100% sensitivity). Specificity was 100% with both tests. The ICT Malaria P.f./P.v.((R)) is advertised for layman use during travel, and the literature was reviewed with respect to the question of suitability of these devices for self-testing. It is concluded that with the ICT Malaria P.f./P.v.((R)), the detection of non-falciparum (i.e. predominantly vivax) malaria is unreliable, and test interpretation for medically untrained individuals particularly in distress might be too complicated even after proper instruction.

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.

Evaluation of a dipstick test for the rapid diagnosis of imported malaria among patients presenting within the network TropNetEurop

Lack of experience on the part of involved laboratory personnel frequently complicates swift diagnosis of imported falciparum malaria in non-endemic areas. Diagnostic tools based on the dipstick principle for the detection of plasmodial histidine-rich protein 2 have been marketed for several years and have been extensively evaluated. Recently, a test kit capable of detecting antigen of Plasmodium falciparum and P. vivax has been introduced. In order to evaluate this newly available tool, specimens from 664 patients were screened during the course of a prospective multicentre study within the European Network on Imported Infectious Disease Surveillance (TropNetEurop). Among the screened specimens, samples from 82 patients (12.3%) were positive for falciparum malaria using expert microscopy. A further 17 samples were positive for vivax malaria. The evaluated test kit performed with a sensitivity of 87.8% and a specificity of 99% for detection of falciparum malaria. Respective values for vivax malaria were 76.5% and 100%. Dipstick tests have the potential of improving the speed and accuracy of the diagnosis of falciparum malaria, especially if non-specialized laboratories are involved. However, decreased values of sensitivity and specificity, in comparison with expert microscopy, still impose a clear limit on the usefulness of the currently available kits.

Use of dipstick tests for the rapid diagnosis of malaria in nonimmune travelers

BACKGROUND

Swift diagnosis of falciparum malaria in nonendemic areas is frequently complicated by lack of experience on the side of involved laboratory personnel. Diagnostic tools based on the dipstick principle for the detection of plasmodial histidine-rich protein 2 (HRP-2) (ICT Malaria P.f. (R)) and parasite-specific lactate-dehydrogenase (pLDH) (OptiMal(R)), respectively, have become available for the qualitative detection of falciparum malaria.

METHODS

In order to evaluate currently available assays, a series of studies was conducted: sensitivity and specificity were evaluated by investigation of specimens from 231 febrile returnees from endemic areas, cross reactivity in patients with rheumatoid factor (RF) was assessed among 92 patients from a rheumatology unit, and the quality of dipstick self-use by febrile travelers was tested in Kenya.

RESULTS

Whereas the test kit based on the detection of HRP-2 performed with a sensitivity of 92.5% and a specificity of 98.3%, the kit for the detection of pLDH showed a sensitivity of 88.5% and a specificity of 99.4%. Cross-reactions with sera positive for rheumatoid factor occurred in 6.6% with the ICT Malaria P.f.(R), and in 3.3% with the OptiMal(R) test. Only ICT Malaria P.f.(R) was tested for quality of self-use among travelers. This dipstick assay was performed successfully by 67 patients (68.4%), but 31 (31.6%) were unable to obtain a result.

CONCLUSION

Dipstick tests have the potential of enhancing speed and accuracy of the diagnosis of falciparum malaria, especially if nonspecialized laboratories are involved. However, microscopical testing remains mandatory in every single patient with the possible diagnosis of malaria. Self-use of dipstick tests for malaria diagnosis by travelers should only be recommended after appropriate instruction and training, including a successful performance of the test procedure.