Rapid diagnostic test-based management of malaria: an effectiveness study in Papua New Guinean infants with Plasmodium falciparum and Plasmodium vivax malaria

Vivax malaria: a possible stumbling block for malaria elimination in India

Plasmodium vivax is geographically the most widely dispersed human malaria parasite species. It has shown resilience and a great deal of adaptability. Genomic studies suggest that P. vivax originated from Asia or Africa and moved to the rest of the world. Although P. vivax is evolutionarily an older species than Plasmodium falciparum, its biology, transmission, pathology, and control still require better elucidation. P. vivax poses problems for malaria elimination because of the ability of a single primary infection to produce multiple relapses over months and years. P. vivax malaria elimination program needs early diagnosis, and prompt and complete radical treatment, which is challenging, to simultaneously exterminate the circulating parasites and dormant hypnozoites lodged in the hepatocytes of the host liver. As prompt surveillance and effective treatments are rolled out, preventing primaquine toxicity in the patients having glucose-6-phosphate dehydrogenase (G6PD) deficiency should be a priority for the vivax elimination program. This review sheds light on the burden of P. vivax, changing epidemiological patterns, the hurdles in elimination efforts, and the essential tools needed not just in India but globally. These tools encompass innovative treatments for eliminating dormant parasites, coping with evolving drug resistance, and the development of potential vaccines against the parasite.

Non-Malaria Causes of Fever among under-5 Children with Negative Results for Malaria Rapid Diagnostic Test in South-Western Nigeria

BACKGROUND

Although the global malaria burden is decreasing, there are still concerns about overdiagnosis of malaria and the danger of misdiagnosis of non-malaria causes of fever. Clinicians continue to face the challenge of differentiating between these causes despite the introduction of malaria rapid diagnostic tests (mRDTs).

AIM

To determine the prevalence and causes of non-malaria-caused fever in children in South-Western Nigeria.

METHODS

Secondary analysis of data obtained to evaluate the effect of restricting antimalarial treatment to positive mRDT children in rural and urban areas of southwest Nigeria. Clinical examinations, laboratory tests for malaria parasites (including thick blood film and mRDT) and bacterial identification were performed on children aged 3-59 months (n = 511). The non-malaria group comprised febrile children who had both negative mRDT and microscopy results, while the malaria group included those who were positive for either mRDT or microscopy. We compared the causes of fever among children with non-malaria fever and those with malaria.

RESULTS

The prevalence of non-malaria fever and bacteria-malaria co-infection was 37.2% and 2.0%, respectively. Non-malarial pathogens identified were viral (54.7%) and bacterial (32.1%) infections. The bacterial infections included bacteriaemia (2.7%), urinary tract infections (21.6%), skin infections (11.6%) and otitis media (2.6%). The leading bacterial isolates were Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pneumoniae.

CONCLUSION

The high prevalence and wide range of non-malarial infections reinforces the need for point-of-care tests to identify bacterial and viral infections to optimize the treatment of febrile illnesses in malaria-endemic areas.

Malaria diagnostic methods with the elimination goal in view

Malaria control measures have been in use for years but have not completely curbed the spread of infection. Ultimately, global elimination is the goal. A major playmaker in the various approaches to reaching the goal is the issue of proper diagnosis. Various diagnostic techniques were adopted in different regions and geographical locations over the decades, and these have invariably produced diverse outcomes. In this review, we looked at the various approaches used in malaria diagnostics with a focus on methods favorably used during pre-elimination and elimination phases as well as in endemic regions. Microscopy, rapid diagnostic testing (RDT), loop-mediated isothermal amplification (LAMP), and polymerase chain reaction (PCR) are common methods applied depending on prevailing factors, each with its strengths and limitations. As the drive toward the elimination goal intensifies, the search for ideal, simple, fast, and reliable point-of-care diagnostic tools is needed more than ever before to be used in conjunction with a functional surveillance system supported by the ideal vaccine.

Plasmodium vivax - How hidden reservoirs hinder global malaria elimination

Plasmodium vivax is the most geographically widespread human malaria parasite. Global malaria efforts have been less successful at reducing the burden of P. vivax compared to P. falciparum, owing to the unique biology and related treatment complexity of P. vivax. As a result, P. vivax is now the dominant malaria parasite throughout the Asia-Pacific and South America causing up to 14 million clinical cases every year and is considered a major obstacle to malaria elimination. Key features circumventing existing malaria control tools are the transmissibility of asymptomatic, low-density circulating infections and reservoirs of persistent dormant liver stages (hypnozoites) that are undetectable but reactivate to cause relapsing infections and sustain transmission. In this review we summarise the new knowledge shaping our understanding of the global epidemiology of P. vivax infections, highlighting the challenges for elimination and the tools that will be required achieve this.

Implications of asymptomatic infection for the natural history of selected parasitic tropical diseases

Progress has been made in the control or elimination of tropical diseases, with a significant reduction of incidence. However, there is a risk of re-emergence if the factors fueling transmission are not dealt with. Although it is essential to understand these underlying factors for each disease, asymptomatic carriers are a common element that may promote resurgence; their impact in terms of proportion in the population and role in transmission needs to be determined. In this paper, we review the current evidence on whether or not to treat asymptomatic carriers given the relevance of their role in the transmission of a specific disease, the efficacy and toxicity of existing drugs, the Public Health interest, and the benefit at an individual level, for example, in Chagas disease, to prevent irreversible organ damage. In the absence of other control tools such as vaccines, there is a need for safer drugs with good risk/benefit profiles in order to change the paradigm so that it addresses the complete infectious process beyond manifest disease to include treatment of non-symptomatic infected persons.

Plasmodium falciparum Histidine-Rich Protein 2 Gene Variation in a Malaria-Endemic Area of Papua New Guinea

Histidine-rich protein 2 of Plasmodium falciparum (PfHRP2) forms the basis of many current malaria rapid diagnostic tests (RDTs). It is concerning that there are parasites that lack part or all of the pfhrp2 gene, and thus do not express the PfHRP2 protein; such parasites are not identifiable by PfHRP2-detecting RDTs. Very limited information is available regarding pfhrp2 genetic variation in Papua New Guinea (PNG). In the present study, this gene variation was evaluated using 169 samples previously collected from the Wosera area in East Sepik Province of PNG. Molecular diagnosis of these samples showed that 81% were infected, and P. falciparum was present in 91% of those infected samples. One hundred and twenty samples were amplified for pfhrp2 exon-2, from which 12 randomly selected amplicons were sequenced, yielding 18 sequences, all of which were unique. Baker repeat type 2 × type 7 numbers ranged from 0 to 108. Epitope mapping analysis revealed that three major epitopes, DAHHAHHA, AHHAADAHHA, and AHHAADAHH, were present in high prevalence and frequencies. These major epitopes have been shown to be recognized by the monoclonal antibodies 3A4 and PTL-3 (DAHHAHHA), C1-13 (AHHAADAHHA), and S2-5 and C2-3 (AHHAADAHH). This study provides further information on the high genetic variation of pfhrp2 and its unclear relationship with prediction of RDT detection sensitivity, and identifies major epitopes in this gene from PNG. These results could be relevant and useful to understand the genetic diversity of this gene and the performance of current and future RDTs in this malarious region of the world.

The impact of the scale-up of malaria rapid diagnostic tests on the routine clinical diagnosis procedures for febrile illness: a series of repeated cross-sectional studies in Papua New Guinea

BACKGROUND

This paper examines the impact of the scale-up of malaria rapid diagnostic tests (RDT) on routine clinical diagnosis procedures for febrile illness in primary healthcare settings in Papua New Guinea.

METHODS

Repeat, cross-sectional surveys in randomly selected primary healthcare services were conducted. Surveys included passive observation of consecutive febrile case management cases and were completed immediately prior to RDT scale-up (2011) and at 12- (2012) and 60-months (2016) post scale-up. The frequency with which specified diagnostic questions and procedures were observed to occur, with corresponding 95% CIs, was calculated for febrile patients prescribed anti-malarials pre- and post-RDT scale-up and between febrile patients who tested either negative or positive for malaria infection by RDT (post scale-up only).

RESULTS

A total of 1809 observations from 120 health facilities were completed across the three survey periods of which 915 (51%) were prescribed an anti-malarial. The mean number of diagnostic questions and procedures asked or performed, leading to anti-malarial prescription, remained consistent pre- and post-RDT scale-up (range 7.4-7.7). However, alterations in diagnostic content were evident with the RDT replacing body temperature as the primary diagnostic procedure performed (observed in 5.3 and 84.4% of cases, respectively, in 2011 vs. 77.9 and 58.2% of cases in 2016). Verbal questioning, especially experience of fever, cough and duration of symptoms, remained the most common feature of a diagnostic examination leading to anti-malarial prescription irrespective of RDT use (observed in 96.1, 86.8 and 84.8% of cases, respectively, in 2011 vs. 97.5, 76.6 and 85.7% of cases in 2016). Diagnostic content did not vary substantially by RDT result.

CONCLUSIONS

Rapid diagnostic tests scale-up has led to a reduction in body temperature measurement. Investigations are very limited when malaria infection is ruled out as a cause of febrile illness by RDT.

Insecticide-treated nets and malaria prevalence, Papua New Guinea, 2008-2014

Objective

To investigate changes in malaria prevalence in Papua New Guinea after the distribution of long-lasting Insecticide-treated nets, starting in 2004, and the introduction of artemisinin-based combination therapy in 2011.

Methods

Two malaria surveys were conducted in 2010–2011 and 2013–2014. They included 77 and 92 randomly selected villages, respectively. In each village, all members of 30 randomly selected households gave blood samples and were assessed for malaria infection by light microscopy. In addition, data were obtained from a malaria survey performed in 2008–2009.

Results

The prevalence of malaria below 1600 m in altitude decreased from 11.1% (95% confidence interval, CI: 8.5–14.3) in 2008–2009 to 5.1% (95% CI 3.6–7.4) in 2010–2011 and 0.9% (95% CI 0.6–1.5) in 2013–2014. Prevalence decreased with altitude. Plasmodium falciparum was more common than P. vivax overall, but not everywhere, and initially the prevalence of P. vivax infection decreased more slowly than P. falciparum infection. Malaria infections were clustered in households. In contrast to findings in 2008–2009, no significant association between net use and prevalence was found in the later two surveys. The prevalence of both fever and splenomegaly also decreased but their association with malaria infection became stronger.

Conclusion

Large-scale insecticide-treated net distribution was associated with an unprecedented decline in malaria prevalence throughout Papua New Guinea, including epidemic-prone highland areas. The decline was accompanied by broader health benefits, such as decreased morbidity. Better clinical management of nonmalarial fever and research into residual malaria transmission are required.

Development of new malaria diagnostics: matching performance and need

Despite advances in diagnostic technology, significant gaps remain in access to malaria diagnosis. Accurate diagnosis and misdiagnosis leads to unnecessary waste of resources, poor disease management, and contributes to a cycle of poverty in low-resourced communities. Despite much effort and investment, few new technologies have reached the field in the last 30 years aside from lateral flow assays. This suggests that much diagnostic development effort has been misdirected, and/or that there are fundamental blocks to introduction of new technologies. Malaria diagnosis is a difficult market; resources are broadly donor-dependent, health systems in endemic countries are frequently weak, and the epidemiology of malaria and priorities of malaria programmes and donors are evolving. Success in diagnostic development will require a good understanding of programme gaps, and the sustainability of markets to address them. Targeting assay development to such clearly defined market requirements will improve the outcomes of product development funding. Six market segments are identified: (1) case management in low-resourced countries, (2) parasite screening for low density infections in elimination programmes, (3) surveillance for evidence of continued transmission, (4) clinical research and therapeutic efficacy monitoring, (5) cross-checking for microscopy quality control, and (6) returned traveller markets distinguished primarily by resource availability. While each of these markets is potentially compelling from a public health standpoint, size and scale are highly variable and continue to evolve. Consequently, return on investment in research and development may be limited, highlighting the need for potentially significant donor involvement or the introduction of novel business models to overcome prohibitive economics. Given the rather specific applications, a well-defined set of stakeholders will need to be on board for the successful introduction and scaling of any new technology to these markets.

Health Worker Compliance with a 'Test And Treat' Malaria Case Management Protocol in Papua New Guinea

The Papua New Guinea (PNG) Department of Health introduced a ‘test and treat’ malaria case management protocol in 2011. This study assesses health worker compliance with the test and treat protocol on a wide range of measures, examines self-reported barriers to health worker compliance as well as health worker attitudes towards the test and treat protocol. Data were collected by cross-sectional survey conducted in randomly selected primary health care facilities in 2012 and repeated in 2014. The combined survey data included passive observation of current or recently febrile patients (N = 771) and interviewer administered questionnaires completed with health workers (N = 265). Across the two surveys, 77.6% of patients were tested for malaria infection by rapid diagnostic test (RDT) or microscopy, 65.6% of confirmed malaria cases were prescribed the correct antimalarials and 15.3% of febrile patients who tested negative for malaria infection were incorrectly prescribed an antimalarial. Overall compliance with a strictly defined test and treat protocol was 62.8%. A reluctance to test current/recently febrile patients for malaria infection by RDT or microscopy in the absence of acute malaria symptoms, reserving recommended antimalarials for confirmed malaria cases only and choosing to clinically diagnose a malaria infection, despite a negative RDT result were the most frequently reported barriers to protocol compliance. Attitudinal support for the test and treat protocol, as assessed by a nine-item measure, improved across time. In conclusion, health worker compliance with the full test and treat malaria protocol requires improvement in PNG and additional health worker support will likely be required to achieve this. The broader evidence base would suggest any such support should be delivered over a longer period of time, be multi-dimensional and multi-modal.

New Malaria Tests: Square Pegs for Round Holes?

To eradicate malaria new technologies are needed, not least in the detection of parasites. However, malaria program implementation is complex, and solutions that appear obvious fit less well on close inspection. Understanding the gaps in current programs is essential to selecting approaches likely to transition successfully to the field.

Accuracy of an HRP-2/panLDH rapid diagnostic test to detect peripheral and placental Plasmodium falciparum infection in Papua New Guinean women with anaemia or suspected malaria

Background

The diagnosis of malaria during pregnancy is complicated by placental sequestration, asymptomatic infection, and low-density peripheral parasitaemia. Where intermittent preventive treatment (IPT) with sulfadoxine-pyrimethamine is threatened by drug resistance, or is inappropriate due to low transmission, intermittent screening and treatment (ISTp) with rapid diagnostic tests for malaria (RDT) could be a valuable alternative. Therefore, the accuracy of RDTs to detect peripheral and placental infection was assessed in a declining transmission setting in Papua New Guinea (PNG).

Methods

The performance of a combination RDT detecting histidine-rich protein-2 (HRP-2) and Plasmodium lactate dehydrogenase (pLDH), and light microscopy (LM), to diagnose peripheral Plasmodium falciparum and Plasmodium vivax infections during pregnancy, were assessed using quantitative real-time PCR (qPCR) as the reference standard. Participants in a malaria prevention trial in PNG with a haemoglobin ≤90 g/L, or symptoms suggestive of malaria, were tested. Ability of RDT and LM to detect active placental infection on histology was evaluated in some participants.

Results

Among 876 women, 1162 RDTs were undertaken (anaemia: 854 [73.5 %], suspected malaria: 308 [26.5 %]). qPCR detected peripheral infection during 190 RDT episodes (165 P. falciparum, 19 P. vivax, 6 mixed infections). Overall, RDT detected peripheral P. falciparum infection with 45.6 % sensitivity (95 % CI 38.0–53.4), a specificity of 96.4 % (95.0–97.4), a positive predictive value of 68.4 % (59.1–76.8), and a negative predictive value of 91.1 % (89.2–92.8). RDT performance to detect P. falciparum was inferior to LM, more so amongst anaemic women (18.6 vs 45.3 % sensitivity, Liddell’s exact test, P < 0.001) compared to symptomatic women (72.9 vs 82.4 % sensitivity, P = 0.077). RDT and LM missed 88.0 % (22/25) and 76.0 % (19/25) of P. vivax infections, respectively. In a subset of women tested at delivery and who had placental histology (n = 158) active placental infection was present in 19.6 %: all three peripheral blood infection detection methods (RDT, LM, qPCR) missed >50 % of these infections.

Conclusions

In PNG, HRP-2/pLDH RDTs may be useful to diagnose peripheral P. falciparum infections in symptomatic pregnant women. However, they are not sufficiently sensitive for use in intermittent screening amongst asymptomatic (anaemic) women. These findings have implications for the management of malaria in pregnancy. The adverse impact of infections undetected by RDT or LM on pregnancy outcomes needs further evaluation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-015-0927-5) contains supplementary material, which is available to authorized users.

Anti-malarial prescription practices among children admitted to six public hospitals in Uganda from 2011 to 2013

Background

In 2011, Uganda’s Ministry of Health switched policy from presumptive treatment of malaria to recommending parasitological diagnosis prior to treatment, resulting in an expansion of diagnostic services at all levels of public health facilities including hospitals. Despite this change, anti-malarial drugs are often prescribed even when test results are negative. Presented is data on anti-malarial prescription practices among hospitalized children who underwent diagnostic testing after adoption of new treatment guidelines.

Methods

Anti-malarial prescription practices were collected as part of an inpatient malaria surveillance program generating high quality data among children admitted for any reason at government hospitals in six districts. A standardized medical record form was used to collect detailed patient information including presenting symptoms and signs, laboratory test results, admission and final diagnoses, treatments administered, and final outcome upon discharge.

Results

Between July 2011 and December 2013, 58,095 children were admitted to the six hospitals (hospital range 3294–20,426).A total of 56,282 (96.9 %) patients were tested for malaria, of which 26,072 (46.3 %) tested positive (hospital range 5.9–57.3 %). Among those testing positive, only 84 (0.3 %) were first tested after admission and 295 of 30,389 (1.0 %) patients who tested negative at admission later tested positive. Of 30,210 children with only negative test results, 11,977 (39.6 %) were prescribed an anti-malarial (hospital range 14.5–53.6 %). The proportion of children with a negative test result who were prescribed an anti-malarial fluctuated over time and did not show a significant trend at any site with the exception of one hospital where a steady decline was observed. Among those with only negative test results, children 6–12 months of age (aOR 3.78; p < 0.001) and those greater than 12 months of age (aOR 4.89; p < 0.001) were more likely to be prescribed an anti-malarial compared to children less than 6 months of age. Children with findings suggestive of severe malaria were also more likely to be prescribed an anti-malarial after a negative test result (aOR 1.98; p < 0.001).

Conclusions

Despite high testing rates for malaria at all sites, prescription of anti-malarials to patients with negative test results remained high, with the exception of one site where a steady decline occurred.

Managing the Sick Child in the Era of Declining Malaria Transmission: Development of ALMANACH, an Electronic Algorithm for Appropriate Use of Antimicrobials

OBJECTIVE

To review the available knowledge on epidemiology and diagnoses of acute infections in children aged 2 to 59 months in primary care setting and develop an electronic algorithm for the Integrated Management of Childhood Illness to reach optimal clinical outcome and rational use of medicines.

METHODS

A structured literature review in Medline, Embase and the Cochrane Database of Systematic Review (CDRS) looked for available estimations of diseases prevalence in outpatients aged 2-59 months, and for available evidence on i) accuracy of clinical predictors, and ii) performance of point-of-care tests for targeted diseases. A new algorithm for the management of childhood illness (ALMANACH) was designed based on evidence retrieved and results of a study on etiologies of fever in Tanzanian children outpatients.

FINDINGS

The major changes in ALMANACH compared to IMCI (2008 version) are the following: i) assessment of 10 danger signs, ii) classification of non-severe children into febrile and non-febrile illness, the latter receiving no antibiotics, iii) classification of pneumonia based on a respiratory rate threshold of 50 assessed twice for febrile children 12-59 months; iv) malaria rapid diagnostic test performed for all febrile children. In the absence of identified source of fever at the end of the assessment, v) urine dipstick performed for febrile children <2 years to consider urinary tract infection, vi) classification of 'possible typhoid' for febrile children >2 years with abdominal tenderness; and lastly vii) classification of 'likely viral infection' in case of negative results.

CONCLUSION

This smartphone-run algorithm based on new evidence and two point-of-care tests should improve the quality of care of <5 year children and lead to more rational use of antimicrobials.

Quality of inpatient pediatric case management for four leading causes of child mortality at six government-run Ugandan hospitals

BACKGROUND

A better understanding of case management practices is required to improve inpatient pediatric care in resource-limited settings. Here we utilize data from a unique health facility-based surveillance system at six Ugandan hospitals to evaluate the quality of pediatric case management and the factors associated with appropriate care.

METHODS

All children up to the age of 14 years admitted to six district or regional hospitals over 15 months were included in the study. Four case management categories were defined for analysis: suspected malaria, selected illnesses requiring antibiotics, suspected anemia, and diarrhea. The quality of case management for each category was determined by comparing recorded treatments with evidence-based best practices as defined in national guidelines. Associations between variables of interest and the receipt of appropriate case management were estimated using multivariable logistic regression.

RESULTS

A total of 30,351 admissions were screened for inclusion in the analysis. Ninety-two percent of children met criteria for suspected malaria and 81% received appropriate case management. Thirty-two percent of children had selected illnesses requiring antibiotics and 89% received appropriate antibiotics. Thirty percent of children met criteria for suspected anemia and 38% received appropriate case management. Twelve percent of children had diarrhea and 18% received appropriate case management. Multivariable logistic regression revealed large differences in the quality of care between health facilities. There was also a strong association between a positive malaria diagnostic test result and the odds of receiving appropriate case management for comorbid non-malarial illnesses - children with a positive malaria test were more likely to receive appropriate care for anemia and less likely for illnesses requiring antibiotics and diarrhea.

CONCLUSIONS

Appropriate management of suspected anemia and diarrhea occurred infrequently. Pediatric quality improvement initiatives should target deficiencies in care unique to each health facility, and interventions should focus on the simultaneous management of multiple diagnoses.

Rapid diagnostic tests for diagnosing uncomplicated non-falciparum or Plasmodium vivax malaria in endemic countries

BACKGROUND

In settings where both Plasmodium vivax and Plasmodium falciparum infection cause malaria, rapid diagnostic tests (RDTs) need to distinguish which species is causing the patients' symptoms, as different treatments are required. Older RDTs incorporated two test lines to distinguish malaria due to P. falciparum, from malaria due to any other Plasmodium species (non-falciparum). These RDTs can be classified according to which antibodies they use: Type 2 RDTs use HRP-2 (for P. falciparum) and aldolase (all species); Type 3 RDTs use HRP-2 (for P. falciparum) and pLDH (all species); Type 4 use pLDH (fromP. falciparum) and pLDH (all species).More recently, RDTs have been developed to distinguish P. vivax parasitaemia by utilizing a pLDH antibody specific to P. vivax.

OBJECTIVES

To assess the diagnostic accuracy of RDTs for detecting non-falciparum or P. vivax parasitaemia in people living in malaria-endemic areas who present to ambulatory healthcare facilities with symptoms suggestive of malaria, and to identify which types and brands of commercial test best detect non-falciparum and P. vivax malaria.

SEARCH METHODS

We undertook a comprehensive search of the following databases up to 31 December 2013: Cochrane Infectious Diseases Group Specialized Register; MEDLINE; EMBASE; MEDION; Science Citation Index; Web of Knowledge; African Index Medicus; LILACS; and IndMED.

SELECTION CRITERIA

Studies comparing RDTs with a reference standard (microscopy or polymerase chain reaction) in blood samples from a random or consecutive series of patients attending ambulatory health facilities with symptoms suggestive of malaria in non-falciparum endemic areas.

DATA COLLECTION AND ANALYSIS

For each study, two review authors independently extracted a standard set of data using a tailored data extraction form. We grouped comparisons by type of RDT (defined by the combinations of antibodies used), and combined in meta-analysis where appropriate. Average sensitivities and specificities are presented alongside 95% confidence intervals (95% CI).

MAIN RESULTS

We included 47 studies enrolling 22,862 participants. Patient characteristics, sampling methods and reference standard methods were poorly reported in most studies. RDTs detecting 'non-falciparum' parasitaemiaEleven studies evaluated Type 2 tests compared with microscopy, 25 evaluated Type 3 tests, and 11 evaluated Type 4 tests. In meta-analyses, average sensitivities and specificities were 78% (95% CI 73% to 82%) and 99% (95% CI 97% to 99%) for Type 2 tests, 78% (95% CI 69% to 84%) and 99% (95% CI 98% to 99%) for Type 3 tests, and 89% (95% CI 79% to 95%) and 98% (95% CI 97% to 99%) for Type 4 tests, respectively. Type 4 tests were more sensitive than both Type 2 (P = 0.01) and Type 3 tests (P = 0.03).Five studies compared Type 3 tests with PCR; in meta-analysis, the average sensitivity and specificity were 81% (95% CI 72% to 88%) and 99% (95% CI 97% to 99%) respectively. RDTs detecting P.vivax parasitaemiaEight studies compared pLDH tests to microscopy; the average sensitivity and specificity were 95% (95% CI 86% to 99%) and 99% (95% CI 99% to 100%), respectively.

AUTHORS' CONCLUSIONS

RDTs designed to detect P. vivax specifically, whether alone or as part of a mixed infection, appear to be more accurate than older tests designed to distinguish P. falciparum malaria from non-falciparum malaria. Compared to microscopy, these tests fail to detect around 5% ofP. vivax cases. This Cochrane Review, in combination with other published information about in vitro test performance and stability in the field, can assist policy-makers to choose between the available RDTs.

Plasmodium falciparum parasites lacking histidine-rich protein 2 and 3: a review and recommendations for accurate reporting

Malaria rapid diagnostic tests (RDTs) play a critical role in malaria case management, surveillance and case investigations. Test performance is largely determined by design and quality characteristics, such as detection sensitivity, specificity, and thermal stability. However, parasite characteristics such as variable or absent expression of antigens targeted by RDTs can also affect RDT performance. Plasmodium falciparum parasites lacking the PfHRP2 protein, the most common target antigen for detection of P. falciparum, have been reported in some regions. Therefore, accurately mapping the presence and prevalence of P. falciparum parasites lacking pfhrp2 would be an important step so that RDTs targeting alternative antigens, or microscopy, can be preferentially selected for use in such regions. Herein the available evidence and molecular basis for identifying malaria parasites lacking PfHRP2 is reviewed, and a set of recommended procedures to apply for future investigations for parasites lacking PfHRP2, is proposed.

Rapid diagnostic tests for malaria and health workers' adherence to test results at health facilities in Zambia

Background

In Zambia, there has been a large scaling up of interventions to control malaria in recent years including the deployment of rapid diagnostic tests (RDTs) to improve malaria surveillance data as well as guide malaria treatment in health facilities. The practical challenge is the impact of RDT results on subsequent management of patients. This study explored the role of RDTs in malaria diagnosis and the health workers’ adherence to test results.

Methods

An observational prospective study was carried out at health centres in four districts, namely Chibombo, Chingola, Chipata, and Choma. Children under the age of five years with history of fever were recruited and the clinicians’ use of RDT results was observed to establish whether prescriptions were issued prior to the availability of parasitological results or after, and whether RDT results influenced their prescriptions.

Results

Of the 2, 393 recruited children, 2, 264 had both RDT and microscopic results. Two in three (68.6%) children were treated with anti-malarials despite negative RDT results and almost half (46.2%) of these were prescribed Coartem^®. Only 465 (19.4%) of the 2,393 children were prescribed drugs before receiving laboratory results. A total of 76.5% children were prescribed drugs after laboratory results. Children with RDT positive results were 2.66 (95% CI (2.00, 3.55)) times more likely to be prescribed anti-malarial drugs. Children who presented with fever at admission (although history of fever or presence of fever at admission was an entry criterion) were 42% less likely to be prescribed an anti-malarial drug compared to children who had no fever (AOR = 0.58; 95% CI (0.52, 0.65)). It was noted that proportions of children who were RDT- and microscopy-positive significantly declined over the years from 2005 to 2008.

Conclusions

RDTs may contribute to treatment of febrile illness by confirming malaria cases from non-malaria cases in children under the age of five. However, the adherence of the health workers to prescribing anti-malarials to only RDT-positive cases at health facility level will still require to be explored further as their role is crucial in more precise reporting of malaria cases in this era towards malaria elimination as the target.

Use of antibiotics within the IMCI guidelines in outpatient settings in Papua New Guinean children: an observational and effectiveness study

Introduction

There is a need to investigate the effectiveness and appropriateness of antibiotics prescription within the Integrated Management of Childhood Illness (IMCI) strategy in the context of routine outpatient clinics.

Methods

Making use of a passive case detection system established for a malaria prevention trial in outpatient clinics in Papua New Guinea, the appropriateness and effectiveness of the use of antibiotics within the IMCI was assessed in 1605 young children. Main outcomes were prescription of antibiotics and re-attendances within 14 days for mild pneumonia, mild diarrhoea and uncomplicated malaria whether they were managed with or without antibiotics (proxy of effectiveness). Appropriateness was assessed for both mild and severe cases, while effectiveness was assessed only for mild diseases.

Results

A total of 6975 illness episodes out of 8944 fulfilled inclusion criteria (no previous attendance <14 days+full medical records). Clinical incidence rates (episodes/child/year; 95% CI) were 0.85 (0.81–0.90) for pneumonia, 0.62 (0.58–0.66) for malaria and 0.72 (0.65–0.93) for diarrhoea. Fifty three percent of 6975 sick children were treated with antibiotics, 11% were not treated with antibiotics when they should have been and in 29% antibiotics were prescribed when they should not have been. Re-attendance rates within 14 days following clinical diagnosis of mild pneumonia were 9% (126/1401) when managed with antibiotics compared to 8% (56/701) when managed without (adjusted Hazard Ratio (aHR) = 1.00 (0.57–1.76), p = 0.98). Rates for mild diarrhoea were 8% (73/874) and 9% (79/866) respectively (aHR = 0.8 (0.42–1.57), p = 0.53).

Conclusion

Non-adherence to IMCI recommendations for prescription of antibiotics is common in routine settings in Papua New Guinea. Although recommended, the use of antibiotics in young children with mild pneumonia as defined by IMCI criteria did not impact on their outcome. Better tools and new strategies for the identification of bacterial infections that require antibiotics are urgently needed.

Beyond malaria--causes of fever in outpatient Tanzanian children

BACKGROUND

As the incidence of malaria diminishes, a better understanding of nonmalarial fever is important for effective management of illness in children. In this study, we explored the spectrum of causes of fever in African children.

METHODS

We recruited children younger than 10 years of age with a temperature of 38°C or higher at two outpatient clinics--one rural and one urban--in Tanzania. Medical histories were obtained and clinical examinations conducted by means of systematic procedures. Blood and nasopharyngeal specimens were collected to perform rapid diagnostic tests, serologic tests, culture, and molecular tests for potential pathogens causing acute fever. Final diagnoses were determined with the use of algorithms and a set of prespecified criteria.

RESULTS

Analyses of data derived from clinical presentation and from 25,743 laboratory investigations yielded 1232 diagnoses. Of 1005 children (22.6% of whom had multiple diagnoses), 62.2% had an acute respiratory infection; 5.0% of these infections were radiologically confirmed pneumonia. A systemic bacterial, viral, or parasitic infection other than malaria or typhoid fever was found in 13.3% of children, nasopharyngeal viral infection (without respiratory symptoms or signs) in 11.9%, malaria in 10.5%, gastroenteritis in 10.3%, urinary tract infection in 5.9%, typhoid fever in 3.7%, skin or mucosal infection in 1.5%, and meningitis in 0.2%. The cause of fever was undetermined in 3.2% of the children. A total of 70.5% of the children had viral disease, 22.0% had bacterial disease, and 10.9% had parasitic disease.

CONCLUSIONS

These results provide a description of the numerous causes of fever in African children in two representative settings. Evidence of a viral process was found more commonly than evidence of a bacterial or parasitic process. (Funded by the Swiss National Science Foundation and others.).

Malaria case management in Papua New Guinea following the introduction of a revised treatment protocol

Background

This paper reports on the availability of diagnostic tools and recommended anti-malarials in the 12-month period immediately following the implementation of a new national malaria treatment protocol (NMTP) in Papua New Guinea (PNG). Health worker adherence to the new NMTP is also examined and comparisons made with previously reported pre-implementation findings.

Methods

A countrywide cross-sectional survey in randomly selected primary health care facilities (n = 88). Data were collected via passive observation of the clinical case management of fever or suspected malaria patients and via an interviewer administered questionnaire completed with the officer in charge of each participating health care facility.

Results

Malaria rapid diagnostic tests (RDTs) and the new first-line anti-malarial medication, artemether-lumefantrine (AL), were available in 53.4% and 51.1% of surveyed heath facilities, respectively. However, they were more widely available in the larger health centres as compared to the smaller aid-posts (90.2% vs. 21.3% and 87.8% vs. 19.2%, respectively). Overall, 68.3% of observed fever cases (n = 445) were tested for malaria by RDT and 39% prescribed an anti-malarial, inclusive of 98.2% of RDT positive patients and 19.8% of RDT negative cases. The availability and use of malaria RDTs was greater in the current survey as compared to pre-implementation of the new NMTP (8.9% vs. 53.4% & 16.2% vs. 68.3%, respectively) as was the availability of AL (0% vs. 51.1%). The percentage of fever patients prescribed anti-malarials decreased substantially post implementation of the new NMTP (96.4% vs. 39.0%).

Conclusions

PNG has achieved high coverage of malaria RDTs and AL at the health centre level, but these resources have yet to reach the majority of aid-posts. Malaria case management practice has substantially changed in the 12-month period immediately following the new NMTP, although full protocol adherence was rarely observed.

The mechanistic, diagnostic and prognostic utility of biomarkers in severe malaria

Malaria remains an important global cause of severe illness and mortality. This literature review summarizes available data on how biomarkers might be applied to diagnose, prognosticate and provide mechanistic insights in patients with severe malaria. Of the large number of candidate biomarkers, only PfHRP2 has consistently demonstrated clinical utility and, when incorporated into rapid antigen detection tests, has shown diagnostic sensitivity above 95%, which is at least as good as light microscopy. As a quantitative test, PfHRP2 also shows some promise in differentiating severe malarial from non-malarial disease in areas where asymptomatic carriage of malaria parasites is common, and possibly as a tool to estimate sequestered parasite burden and subsequent mortality. Biomarkers such as pLDH and panmalarial antigen have lower sensitivity for non-falciparum malaria in rapid antigen detection tests. There is an urgent need to discover and validate better biomarkers for incorporation into rapid antigen detection tests in countries where Plasmodium vivax is a common cause of severe disease. A large number of host-derived acute-phase reactants, markers of endothelial dysfunction and immune mediators have been proposed as biomarkers. Although they have provided mechanistic insights into the immunopathology of severe malaria, their roles as clinical tools remain uncertain.

Zoonotic malaria: Plasmodium knowlesi, an emerging pathogen

PURPOSE OF REVIEW

The emergence of Plasmodium knowlesi, a parasite of Southeast Asian macaques, into the human population is ongoing and widespread across Southeast Asia. Humans entering P. knowlesi transmission areas are at risk. Patients present with uncomplicated, complicated and fatal disease, therefore prompt accurate diagnosis and treatment are essential. This review focuses on recent descriptions of asymptomatic and symptomatic infections in children, pathophysiology in adults, treatment and diagnosis, and highlights the importance of monitoring transmission and host-switch events.

RECENT FINDINGS

New reports on P. knowlesi infections identify regional differences in aetiology and vector species. Parasitaemia is associated with disease severity and specific diagnostic tools are required. Treatment failures have not been reported. The severe form of P. knowlesi malaria can be compared with severe falciparum malaria to inform the pathophysiology of both infections.

SUMMARY

P. knowlesi presents new challenges to malaria-control efforts in Southeast Asia. Sensitive and specific diagnostic tools are required for communities and travellers at risk. Currently P. knowlesi transmission appears to occur away from human settlements. However, ongoing host-switch events from macaques to humans cannot be excluded. Changes in P. knowlesi transmission across the region should be monitored to preempt outbreaks of this virulent pathogen.

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

Background

Rapid diagnostic tests for malaria (RDTs) allow accurate diagnosis and prompt treatment. Validation of their usefulness in travellers with fever was needed. The safety of a strategy to diagnose falciparum malaria based on RDT followed by immediate or delayed microscopy reading at first attendance was evaluated in one referral hospital in Switzerland.

Methods

A retrospective study was conducted in the outpatient clinic and emergency ward of University Hospital, covering a period of eight years (1999–2007). The study was conducted in the outpatient clinic and emergency ward of University Hospital. All adults suspected of malaria with a diagnostic test performed were included. RDT and microscopy as immediate tests were performed during working hours, and RDT as immediate test and delayed microscopy reading out of laboratory working hours. The main outcome measure was occurrence of specific complications in RDT negative and RDT positive adults.

Results

2,139 patients were recruited. 1987 had both initial RDT and blood smear (BS) result negative. Among those, 2/1987 (0.1%) developed uncomplicated malaria with both RDT and BS positive on day 1 and day 6 respectively. Among the 152 patients initially malaria positive, 137 had both RDT and BS positive, four only BS positive and five only RDT positive (PCR confirmed) (six had only one test performed). None of the four initially RDT negative/BS positive and none of the five initially BS negative/RDT positive developed severe malaria while 6/137 of both RDT and BS positive did so. The use of RDT allowed a reduction of a median of 2.1 hours to get a first malaria test result.

Conclusions

A malaria diagnostic strategy based on RDTs and a delayed BS is safe in non-immune populations, and shortens the time to first malaria test result.

Rapid antigen detection tests for malaria diagnosis in severely ill Papua New Guinean children: a comparative study using Bayesian latent class models

Background

Although rapid diagnostic tests (RDTs) have practical advantages over light microscopy (LM) and good sensitivity in severe falciparum malaria in Africa, their utility where severe non-falciparum malaria occurs is unknown. LM, RDTs and polymerase chain reaction (PCR)-based methods have limitations, and thus conventional comparative malaria diagnostic studies employ imperfect gold standards. We assessed whether, using Bayesian latent class models (LCMs) which do not require a reference method, RDTs could safely direct initial anti-infective therapy in severe ill children from an area of hyperendemic transmission of both Plasmodium falciparum and P. vivax.

Methods and Findings

We studied 797 Papua New Guinean children hospitalized with well-characterized severe illness for whom LM, RDT and nested PCR (nPCR) results were available. For any severe malaria, the estimated prevalence was 47.5% with RDTs exhibiting similar sensitivity and negative predictive value (NPV) to nPCR (≥96.0%). LM was the least sensitive test (87.4%) and had the lowest NPV (89.7%), but had the highest specificity (99.1%) and positive predictive value (98.9%). For severe falciparum malaria (prevalence 42.9%), the findings were similar. For non-falciparum severe malaria (prevalence 6.9%), no test had the WHO-recommended sensitivity and specificity of >95% and >90%, respectively. RDTs were the least sensitive (69.6%) and had the lowest NPV (96.7%).

Conclusions

RDTs appear a valuable point-of-care test that is at least equivalent to LM in diagnosing severe falciparum malaria in this epidemiologic situation. None of the tests had the required sensitivity/specificity for severe non-falciparum malaria but the number of false-negative RDTs in this group was small.

Lack of associations of α(+)-thalassemia with the risk of Plasmodium falciparum and Plasmodium vivax infection and disease in a cohort of children aged 3-21 months from Papua New Guinea

Despite consistent evidence of a protective effect of α(+)-thalassemia against severe Plasmodium falciparum disease, the mechanisms underlying this protection remain unknown. An increase in risk of Plasmodium vivax malaria in early childhood resulting in a cross-species protection against severe P. falciparum malaria has been proposed as a possible mechanism in Melanesian children. The association of α(+)-thalassemia genotypes with a risk of P. falciparum and P. vivax infection and uncomplicated illness was reassessed in a cohort of 1,112 Papua New Guinean children, followed from 3 to 21 months of age. Three hundred and eighty-nine (35.0%) children were homozygous for α(+)-thalassemia (-α/-α), 506 (45.5%) heterozygous (αα/-α) and 217 (19.5%) homozygous for the wild-type allele. No significant differences in the incidence of P. falciparum (Pf) or P. vivax (Pv) malaria were observed between α(+)-thalassemia homozygote (Pf: incidence rate ratio (IRR)=1.13, CI(95) (0.82, 1.56), P=0.45, Pv: IRR=1.15, CI(95) (0.88, 1.50), P=0.31), heterozygote (Pf: IRR=0.98, CI(95) (0.71, 1.34), P=0.93, Pv: IRR=1.14, CI(95) (0.88, 1.48), P=0.33) and wild-type children. The prevalence of infection with either species did not differ between α(+)-thalassemia genotypes, although densities of P. vivax (but not of P. falciparum) infections were significantly higher in α(+)-thalassemia homozygote and heterozygote children. An excessive risk of moderate-to-severe anemia (Hb<8 g/dl) was observed in α(+)-thalassemia homozygote children (IRR=1.54, CI(95) (1.12, 2.11), P=0.008). This study therefore failed to confirm an increased risk of P. vivax or P. falciparum malaria in very young, α(+)-thalassemic children without significant levels of acquired immunity. This confirms the lack of protection by α(+)-thalassemia against uncomplicated P. falciparum and challenges the hypothesis of immunological cross-protection between P. falciparum and P. vivax as a mechanism underlying α(+)-thalassemia protection against severe P. falciparum disease in Melanesian children.

Finding parasites and finding challenges: improved diagnostic access and trends in reported malaria and anti-malarial drug use in Livingstone district, Zambia

Background

Understanding the impact of malaria rapid diagnostic test (RDT) use on management of acute febrile disease at a community level, and on the consumption of anti-malarial medicines, is critical to the planning and success of scale-up to universal parasite-based diagnosis by health systems in malaria-endemic countries.

Methods

A retrospective study of district-wide community-level RDT introduction was conducted in Livingstone District, Zambia, to assess the impact of this programmed on malaria reporting, incidence of mortality and on district anti-malarial consumption.

Results

Reported malaria declined from 12,186 cases in the quarter prior to RDT introduction in 2007 to an average of 12.25 confirmed and 294 unconfirmed malaria cases per quarter over the year to September 2009. Reported malaria-like fever also declined, with only 4,381 RDTs being consumed per quarter over the same year. Reported malaria mortality declined to zero in the year to September 2009, and all-cause mortality declined. Consumption of artemisinin-based combination therapy (ACT) dropped dramatically, but remained above reported malaria, declining from 12,550 courses dispensed by the district office in the quarter prior to RDT implementation to an average of 822 per quarter over the last year. Quinine consumption in health centres also declined, with the district office ceasing to supply due to low usage, but requests for sulphadoxine-pyrimethamine (SP) rose to well above previous levels, suggesting substitution of ACT with this drug in RDT-negative cases.

Conclusions

RDT introduction led to a large decline in reported malaria cases and in ACT consumption in Livingstone district. Reported malaria mortality declined to zero, indicating safety of the new diagnostic regime, although adherence and/or use of RDTs was still incomplete. However, a deficiency is apparent in management of non-malarial fever, with inappropriate use of a low-cost single dose drug, SP, replacing ACT. While large gains have been achieved, the full potential of RDTs will only be realized when strategies can be put in place to better manage RDT-negative cases.