Practical diagnostic algorithms for Chagas disease: a focus on low resource settings

INTRODUCTION

Chagas disease, caused by parasite Trypanosoma cruzi, is the most important neglected tropical disease in the Americas. Two drugs are available for treatment, but access to them is challenging, in part due to complex diagnostic algorithms. These are stage-dependent, involve multiple tests, and are ill-adapted to the reality of vast areas where the disease is endemic. Molecular and serologic tools are used to detect acute and chronic infections, with the performance of the latter showing geographic differences. Breakthroughs in the development of new diagnostic tools include the validation of a loop-mediated isothermal amplification assay for acute infections (T. cruzi-LAMP), and the regional validation of several rapid diagnostic tests (RDTs) for chronic infection, which simplify testing in resource-limited settings. The literature search was carried out in the MEDLINE database until 1 August 2023.

AREAS COVERED

This review outlines existing algorithms, and proposes new ones focused on point-of-care testing.

EXPERT OPINION

Integrating point-of-care testing into existing diagnostic algorithms in certain endemic areas will increase access to timely diagnosis and treatment. However, additional research is needed to validate the use of these techniques across a wider geography, and to better understand the cost-effectiveness of their large-scale implementation.

Prevalence, type of infections and comparative analysis of detection techniques of intestinal parasites in the province of Belgarn, Saudi Arabia

Background

The study was conducted to observe the prevalence and type of infection caused by intestinal parasites and to compare the techniques that are available for the detection.

Method

A total of 112 stool samples were obtained from study participants, and the laboratory examinations were performed at Special Infectious Agents Unit, King Abdulaziz University, Jeddah. One hundred and twelve participants were included in this study.

Result

The color of positive specimens was mainly brown (86.4%). Stool consistency in infected cases was soft in (64%) samples. There was no statistically significant difference with the physical characteristics of the stool (P > 0.05). In total, 59 of the 112 participants were infected with intestinal parasites, representing 52.7%. Different intestinal protozoa parasites were identified in which Blastocystis hominis (86.4%) was highest. None of the intestinal helminths were detected. Out of the 59 infected cases, single infections were found in (62.7%) samples. The intestinal protozoan parasites in single infections were B. hominis (78.4%), Giardia lamblia (8.1%), and (2.7%) from each Entamoeba histolytica, Cryptosporidium parvum, Entamoeba coli, Endolimax nana, and Chilomastix mesnili. Microscopy, RDTs, and real-time PCR were used for detection and identification of G. lamblia, E. histolytica, and C. parvum.

Conclusion

The study reported a high rate of intestinal parasitic infections, mainly with B. hominis. There were no statistical differences in parasite detection between the three techniques in detection of the thirteen cases infected with the pathogenic protozoa.

Evaluation of SARS-CoV-2 diagnostics and risk factors associated with SARS-CoV-2 infection in Zambia

OBJECTIVES

To conduct a diagnostic validation study of SARS-CoV-2 diagnostic kits.

METHODS

We compared SARS-CoV-2 diagnostic test results from 3 RT-PCR assays used by the Zambian government between November 2020 and February 2021 (Panther Fusion assay, Da An Gene's 2019-nCoV RNA kit and Maccura's PCR Kit) with the Altona RealStar RT-PCR kit which served as the gold standard. We also evaluated results from rapid antigen testing and whether comorbidities were linked with increased odds of infection.

RESULTS

We recruited 244 participants, 61% (149/244) were positive by at least 1 PCR assay. Da An Gene, Maccura, and Panther Fusion assays had sensitivities of 0.0% (95% confidence interval [CI] 0%-41%), 27.1% (95% CI 15%-42%), and 76% (95% CI 65%-85%), respectively, but specificity was low (<85% for all 3 assays). HIV and TB were not associated with SARS-CoV-2, whereas female sex (OR 0.5 [0.3-0.9], p = 0.026) and chronic pulmonary disease (0.1 [0.0-0.8], p = 0.031) were associated with lower odds of SARS-CoV-2 infection. Of 44 samples, 84% sequenced were Beta variant.

CONCLUSIONS

The RT-PCR assays evaluated did not meet WHO recommended minimum sensitivity of 80%. Local diagnostic validation studies should be embedded within preparedness plans for future outbreaks to improve the public health response.

SARS-CoV-2/COVID-19 laboratory biosafety practices and current molecular diagnostic tools

The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)/coronavirus disease 2019 (COVID-19) pandemic has crippled several countries across the globe posing a serious global public health challenge. Despite the massive rollout of vaccines, molecular diagnosis remains the most important method for timely isolation, diagnosis, and control of COVID-19. Several molecular diagnostic tools have been developed since the beginning of the pandemic with some even gaining emergency use authorization from the United States (US) Food and Drug Administration for in vitro diagnosis of SARS-CoV-2. Herein, we discuss the working principles of some commonly used molecular diagnostic tools for SARS-CoV-2 including nucleic acid amplification tests, isothermal amplification tests, and rapid diagnostic tests. To ensure successful detection while minimizing the risk of cross-infection and misdiagnosis when using these diagnostic tools, laboratories should adhere to proper biosafety practices. Hence, we also present the common biosafety practices that may ensure the successful detection of SARS-CoV-2 from specimens while protecting laboratory workers and non-suspecting individuals from being infected. From this review article, it is clear that the SARS-CoV-2 pandemic has led to an increase in molecular diagnostic tools and the formation of new biosafety protocols that may be important for future and ongoing outbreaks.

Epidemiological Analysis of COVID-19 Cases in Native Amazonian Communities from Peru

Despite early control measures, SARS-CoV-2 reached all regions of Peru during the first wave of the pandemic, including native communities of the Peruvian Amazon. Here, we aimed to describe the epidemiological situation of COVID-19 in the Amazonas region of Peru using an open database of 11,124 COVID-19 cases reported from 19 March to 29 July 2020, including 3278 cases from native communities. A high-incidence area in northern Amazonas (Condorcanqui) reported a cumulative incidence of 63.84/1000 inhabitants with a much lower death rate (0.95%) than the national average. Our results showed at least eight significant factors for mortality, and the Native Amazonian ethnicity as a protective factor. Molecular confirmatory tests are necessary to better explain the high incidence of antibody response reported in these communities.

How to (ab)use a COVID-19 antigen rapid test with soft drinks?

With reasonably good specificity and sensitivity, the speed and convenience of COVID-19 antigen tests have led to self-testing in schools, offices, and universities in the European Union (EU). Although self-testing can be beneficial and increase the accessibility to testing, there are potential ways to confound a positive COVID-19 lateral flow test. We observed that all soft drinks, energy drinks, alcoholic beverages (vodka, whiskey, and brandy), commercially bottled mineral water, and carbonated mineral water caused the appearance of a red test line. However, when equal volumes of the buffer and the respective beverages are mixed, there are no false-positive test lines. Deceitful methods may easily lead to misuse of COVID-19 antigen rapid tests and lead to false-positive results; however, this does not prove that these tests are unreliable when performed correctly.

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

Background &objectives: The diagnosis of Plasmodium falciparum malaria is widely dependent on the P. falciparum histidine rich protein 2 (PfHRP2) antigens based rapid diagnostic tests. There are few possible factors like Pfhrp2 polymorphism, Pfhrp2 deletion and density of malaria parasite which can affect the sensitivity of the Pf-HRP2-based RDT. The primary objective of the investigation was to check whether the Pfhrp2 gene deletion is the primary cause of RDT false negative cases.

METHODS

Febrile patients from three districts of Chhattisgarh, India were screened for malaria during 2016-2017 by microscopy and RDT. All microscopy P. falciparum positive samples were validated by PCR. Microscopy positive and RDT negative samples were analyzed for the presence of Exon 2, across Exon 1-2, upstream and downstream of both the Pfhrp2 and Pfhrp3 genes fragment by PCR.

RESULTS

Out of 203 screened samples, 85 were detected positive for P. falciparum malaria based on microscopy and PCR. Among these 85 P. falciparum positive samples, 4 samples were observed Pf-HRP2 RDT negative. Although, it signified that the RDTs used were reliable with sensitivity of 95.3% (81/85). 3/4 PfHRP2-RDT negative samples of the P. falciparum isolates exhibited complete deletion of Pfhrp2 and Pfhrp3 genes and one sample was found RDT false negative due to high parasite density.

INTERPRETATION & CONCLUSION

Pfhrp2 and Pfhrp3 deletions that result in false negative RDTs were uncommon in our setting. The continued monitoring of RDTS which results in false negative tests due to Pfhrp2/3 gene deletion is the need of the hour for an effective malaria elimination strategy.

First evidence of the deletion in the pfhrp2 and pfhrp3 genes in Plasmodium falciparum from Equatorial Guinea

Background

The World Health Organization (WHO) recommends rapid diagnostic tests (RDTs) as a good alternative malaria-diagnosis method in remote parts of sub-Saharan Africa. The majority of commercial RDTs currently available detect the Plasmodium falciparum protein histidine-rich protein 2 (PfHRP2). There have also been recent reports of pfhrp2 gene deletions being found in parasites collected from several African countries. The WHO has concluded that lacking the pfhrp2 gene must be monitored in Africa. The purpose of the study was to analyse why the samples that were positive by PCR were negative by RDTs and, therefore, to determine whether there have been deletions in the pfhrp2 and/or pfhrp3 genes.

Methods

Malaria NM-PCR was carried out on all the samples collected in the field. A group of 128 samples was positive by PCR but negative by RDT; these samples were classified as RDT false-negatives. PCR was carried out for exon2 of pfhrp2 and pfhrp3 genes to detect the presence or absence of these two genes. Frequencies with 95% confidence intervals (CIs) were used for prevalence estimates. Associations were assessed by the Chi square test or Fisher´s exact test. The level of significance was set at p ≤ 0.05. Statistical analyses were performed using the software package SPSSv.15.0.

Results

After PCR, 81 samples were identified (4.7%, 95% CI 3.8–5.8) which had deletion in both genes, pfhrp2 and pfhrp3. Overall, however, 11 samples (0.6%, 95% CI 0.36–1.14) had deletion only in pfhrp2 but not in pfhrp3, and 15 (0.9%, 95% CI 0.6–1.5) presented with deletion only in pfhrp3 but not in pfhrp2. Considering the pfhrp2 gene separately, within the total of 1724 samples, 92 (5.3%, 95% CI 4.37–6.5) had evidence of deletion.

Conclusion

The present study provides the first evidence of deletion in the pfhrp2 and pfhrp3 genes in P. falciparum isolates from Equatorial Guinea. However, larger studies across different regions within the country and across different seasonal profiles are needed to determine the full extent of pfhrp2 and pfhrp3 deletion. It is strongly recommended to implement an active surveillance programme in order to detect any increases in pfhrp2 and pfhrp3 deletion frequencies.

Molecular surveillance of pfhrp2 and pfhrp3 genes deletion in Plasmodium falciparum isolates and the implications for rapid diagnostic tests in Nigeria

Prompt diagnosis and appropriate treatment of malaria remain the hallmark for reducing malaria-related mortality in high transmission areas. Plasmodium falciparum histidine-rich protein2 (PfHRP2) based rapid diagnostic tests (RDT) play a vital role in prompt and accurate malaria diagnosis. However, pfhrp2 gene deletion threatens the RDT test sensitivity. This study reports the presence of pfhrp2 and pfhrp3 genes deletion among parasite isolates in Nigeria. Febrile children were screened using histidine-rich protein (HRP2) specific RDT (SD-Bioline RDT) and microscopy for P. falciparum infections. All RDT negative samples were re-evaluated by polymerase chain reaction (PCR). The presence of parasite in RDT false negative cases and randomly selected RDT positive cases were validated using PCRs targeting glutamate-rich protein (glurp) and merozoite surface proteins (msp-1 and msp-2). Thereafter, exon 2 of pfhrp2 and pfhrp3 were amplified, and Sanger sequenced. A total of 511 febrile children were enrolled out of which 309 (61%) were positive by RDT. The presence of pfhrp2 and pfhrp3 genes were analyzed in 66 PCR positive samples comprising of 31 RDT false negative and 35 RDT true positive randomly selected samples. The pfhrp2 and pfhrp3 genes failed to amplify in 17% (11/66) and 6% (4/66) samples, respectively. Seven of the eleven samples had only pfhrp2 deletion while four had both pfhrp2 and pfhrp3 deletions. The absence of the pfhrp2 gene may be responsible for the seven RDT false negative cases observed. Three RDT positive cases lacked pfhrp2 whereas pfhrp3 was absent in only four RDT false negative cases. The pfhrp2 and pfhrp3 amino acid repeat sequences were highly diverse. The P. falciparum isolates lacking pfhrp2 and pfhrp3 genes may be circulating and contributing to RDT false negativity in Nigeria. More studies in larger population and seasonally defined cases will be needed to determine the extent of pfhrp2/3 genes deletion in different geographical areas of Nigeria.

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

Surveillance and diagnosis of Plasmodium falciparum malaria relies predominantly on rapid diagnostic tests (RDT). However, false-negative (FN) RDT results are known to occur for a variety of reasons, including operator error, poor storage conditions, pfhrp2/3 gene deletions, poor performance of specific RDT brands and lots, and low-parasite density infections. We used RDT and microscopy results from 85 000 children enrolled in Demographic Health Surveys and Malaria Indicator Surveys from 2009 to 2015 across 19 countries to explore the distribution of and risk factors for FN-RDTs in sub-Saharan Africa, where malaria’s impact is greatest. We sought to (1) identify spatial and demographic patterns of FN-RDT results, defined as a negative RDT but positive gold standard microscopy test, and (2) estimate the percentage of infections missed within community-based malaria surveys due to FN-RDT results. Across all studies, 19.9% (95% CI 19.0% to 20.9%) of microscopy-positive subjects were negative by RDT. The distribution of FN-RDT results was spatially heterogeneous. The variance in FN-RDT results was best explained by the prevalence of malaria, with an increase in FN-RDT results observed at lower transmission intensities, among younger subjects, and in urban areas. The observed proportion of FN-RDT results was not predicted by differences in RDT brand or lot performance alone. These findings characterise how the probability of detection by RDTs varies in different transmission settings and emphasise the need for careful interpretation of prevalence estimates based on surveys employing RDTs alone. Further studies are needed to characterise the cost-effectiveness of improved malaria diagnostics (eg, PCR or highly sensitive RDTs) in community-based surveys, especially in regions of low transmission intensity or high urbanicity.

Genetic diversity of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) and its effect on the performance of PfHRP2-based rapid diagnostic tests

OBJECTIVE

Rapid diagnostic tests (RDTs) play a crucial role in the management and control of malaria infection. The histidine-rich protein 2 (PfHRP-2) based RDTs are the most commonly used RDTs for malaria diagnosis in Sudan. Deletion of pfhrp2 in Plasmodium falciparum genome affect the accuracy of PfHRP-2 based RDT kits. This study aimed to identify molecular variation of pfhrp2 among suspected malaria patients from different clinics in Omdurman, Sudan.

RESULTS

A noticeable variation between the RDT (Alltest Biotech, China) and nPCR results was observed, for RDT 78% (46/59) were P. falciparum positive, 6.8% (4/59) were co-infected with both P. falciparum and Plasmodium vivax, 15.3% (9/59) were negative by the RDT. However, when the nPCR was applied only 44.1% (26/59) and 55.9% (33/59) was P. falciparum positive and negative respectively. The pfhrp2 was further amplified form all nPCR positive samples. Only 17 DNA samples were positive from the 26 positive P. falciparum, interestingly, variation in band sizes was observed and further confirmed by DNA sequencing, and sequencing analysis revealed a high-level of genetic diversity of the pfhrp2 gene in the parasite population from the study area. However, despite extreme sequence variation, diversity of PfHRP2 does not appear to affect RDT performance.

Major Threat to Malaria Control Programs by Plasmodium falciparum Lacking Histidine-Rich Protein 2, Eritrea

False-negative results for Plasmodium falciparum histidine-rich protein (HRP) 2–based rapid diagnostic tests (RDTs) are increasing in Eritrea. We investigated HRP gene 2/3 (pfhrp2/pfhrp3) status in 50 infected patients at 2 hospitals. We showed that 80.8% (21/26) of patients at Ghindae Hospital and 41.7% (10/24) at Massawa Hospital were infected with pfhrp2-negative parasites and 92.3% (24/26) of patients at Ghindae Hospital and 70.8% (17/24) at Massawa Hospital were infected with pfhrp3-negative parasites. Parasite densities between pfhrp2-positive and pfhrp2-negative patients were comparable. All pfhrp2-negative samples had no detectable HRP2/3 antigen and showed negative results for HRP2-based RDTs. pfhrp2-negative parasites were genetically less diverse and formed 2 clusters with no close relationships to parasites from Peru. These parasites probably emerged independently by selection in Eritrea. High prevalence of pfhrp2-negative parasites caused a high rate of false-negative results for RDTs. Determining prevalence of pfhrp2-negative parasites is urgently needed in neighboring countries to assist case management policies.

Household costs and time to treatment for children with severe febrile illness in rural Burkina Faso: the role of rectal artesunate

Background

Community health workers (CHWs) were trained to identify children with malaria who could not take oral medication, treat them with rectal artesunate (RA) and refer them to the closest healthcare facility to complete management. However, many children with such symptoms did not seek CHWs’ care. The hypothesis was that the cost of referral to a health facility was a deterrent. The goal of this study was to compare the out-of-pocket costs and time to seek treatment for children who sought CHW care (and received RA) versus those who did not.

Methods

Children with symptoms of severe malaria receiving RA at CHWs and children with comparable disease symptoms who did not go to a CHW were identified and their parents were interviewed. Household out-of-pocket costs per illness episode and speed of treatment were evaluated and compared between RA-treated children vs. non-RA treated children and by central nervous symptoms (CNS: repeated convulsions, altered consciousness or coma).

Results

Among children with CNS symptoms, costs of RA-treated children were similar to those of non-RA treated children ($5.83 vs. $4.65; p = 0.52), despite higher transport costs ($2.74 vs. $0.91; p < 0.0001). However, among children without CNS symptoms, costs of RA-treated children were higher than the costs of non-RA treated children with similar symptoms ($5.62 vs. $2.59; p = 0.0001), and the main driver of the cost difference was transport. After illness onset, CNS children reached CHWs for RA an average of 9.0 h vs. 16.1 h for non-RA treated children reaching first treatment [difference 7.1 h (95% CI − 1.8 to 16.1), p = 0.11]. For non-CNS patients the average time to CHW-delivered RA treatment was 12.2 h vs. 20.1 h for those reaching first treatment [difference 7.9 h (95% CI 0.2–15.6), p = 0.04]. More non-RA treated children developed CNS symptoms before arrival at the health centre but the difference was not statistically significant (6% vs. 4%; p = 0.58).

Conclusions

Community health worker-delivered RA does not affect the total out-of-pocket costs when used in children with CNS symptoms, but is associated with higher total out-of-pocket costs when used in children with less severe symptoms. RA-treated children sought treatment more quickly.

Electronic supplementary material

The online version of this article (10.1186/s12936-018-2526-8) contains supplementary material, which is available to authorized users.

Comparison of three diagnostic methods (microscopy, RDT, and PCR) for the detection of malaria parasites in representative samples from Equatorial Guinea

Background

Malaria in Equatorial Guinea remains a major public health problem. The country is a holo-endemic area with a year-round transmission pattern. In 2016, the prevalence of malaria was 12.09% and malaria caused 15% of deaths among children under 5 years. In the Continental Region, 95.2% of malaria infections were Plasmodium falciparum, 9.5% Plasmodium vivax, and eight cases mixed infection in 2011. The main strategy for malaria control is quick and accurate diagnosis followed by effective treatment. Early and accurate diagnosis of malaria is essential for both effective disease management and malaria surveillance. The quality of malaria diagnosis is important in all settings, as misdiagnosis can result in significant morbidity and mortality. Microscopy and RDTs are the primary choices for diagnosing malaria in the field. However, false-negative results may delay treatment and increase the number of persons capable of infecting mosquitoes in the community. The present study analysed the performance of microscopy and RDTs, the two main techniques used in Equatorial Guinea for the diagnosis of malaria, compared to semi-nested multiplex PCR (SnM-PCR).

Results

A total of 1724 samples tested by microscopy, RDT, and SnM-PCR were analysed. Among the negative samples detected by microscopy, 335 (19.4%) were false negatives. On the other hand, the negative samples detected by RDT, 128 (13.3%) were false negatives based on PCR. This finding is important, especially since it is a group of patients who did not receive antimalarial treatment.

Conclusions

Owing to the high number of false negatives in microscopy, it is necessary to reinforce training in microscopy, the “Gold Standard” in endemic areas. A network of reference centres could potentially support ongoing diagnostic and control efforts made by malaria control programmes in the long term, as the National Centre of Tropical Medicine currently supports the National Programme against Malaria of Equatorial Guinea to perform all of the molecular studies necessary for disease control. Taking into account the results obtained with the RDTs, an exhaustive study of the deletion of the hrp2 gene must be done in EG to help choose the correct RDT for this area.

PfHRP2-PfHRP3 diversity among Kenyan isolates and comparative evaluation of PfHRP2/pLDH malaria RDT with microscopy and nested PCR methodologies

Rapid diagnostic tests (RDT) are valuable tools that support prudent and timely use of antimalarial drugs, particularly if reliable microscopy is not available. However, the performance and reliability of these tests vary between and within geographical regions. The present study evaluated the performance of routine malaria RDT in Kenyan febrile patients in Busia County, Kenya. A cross sectional study design was employed to recruit febrile patients attending health facilities between August and November 2016. A total of 192 febrile patients who were slide positive and negative were evaluated for their infection status by nested PCR and RDTs (PfHRP2/pLDH). In addition, P. falciparum diversity of the histidine-rich proteins 2 and 3, that influences the RDT test results were determined. All individuals were P. falciparum positive. Among the investigated 192 febrile patients, 76 (40%) were positive by microscopy, 101 (53%) by RDTs and 80 (42%) were PCR positive. The performance of the CareStart™ HRP2/pLDH (pf) RDTs was better than microscopy (Sensitivity 94%; Specificity 75%) and Nucleic acid testing (sensitivity 95%, specificity 77%) with high negative predictive values, indicating the suitability of the RDT in routine practice. Specific pfhrp2/pfhrp3 deletions shown to associate with RDT false negativity was not observed. However, high genetic diversity among pfhrp2 gene was observed. Eleven new PfHRP2 and nine PfHRP3 repeats were observed. False positivity by microscopy and under reporting of infections may thus be a barrier in malaria control and elimination programs. The HRP2/pLDH(Pf) based RDT yet demonstrate to be an effective tool for malaria surveillance program.

Evaluation of the Clinical Proficiency of RDTs, Microscopy and Nested PCR in the Diagnosis of Symptomatic Malaria in Ilorin, North-Central, Nigeria

BACKGROUND:

Accurate laboratory diagnosis of suspected malaria is the hallmark to the control of the disease.

AIM:

The clinical proficiency of commercial Rapid Diagnostic test kits (RDTs) using nested PCR as quality control was evaluated among patients attending two public healthcare providing institutions in Ilorin, Kwara state, North-Central, Nigeria.

METHOD:

A cross-sectional evaluation of finger prick blood samples of volunteer patients were accessed for malaria parasites with pLDH, HRP2, Pf, Pf/PAN and nested PCR molecular assays. The data derived were analysed using standard formulae for diagnostic accuracy, and the obtained predictive values were subjected to a comparison with one-way analysis of variance (ANOVA).

RESULT:

Three hundred and sixty-eight (368) patients comprising 203 (55%) females and 165 (45%) males participated in this study. Routine microscopy revealed that 54 (32.7%) males and 80 (39.4%) was infected with Plasmodium falciparum. SD Bioline (pLDH) 47.4%; Carestart Malaria (HRP2) 49.8% recorded low sensitivities. Micropoint (pfPAN) 82.8% and Micropoint (Mal. Pf) 64.4% recorded a high sensitivity. SD Bioline (pLDH) 67.4%; Carestart Malaria (HRP2) 85.9%; Micropoint (PfPAN) 62.2% and Micropoint (Mal. Pf) 86.7% had high specificities. The positive predictive value (PPV) ranged from 67.7% to 85.94%, while the negative predictive values (NPV) of 64.4% for SD Bioline (pLDH); 86.7% for Carestart Malaria (HRP2); 89.3% for Micropoint (pfPAN) and 58.5% for Micropoint (Mal. Pf). Agarose gel analysis of P. falciparumssrRNA gene (206 bp) for 28 specimens containing 10% concordant and discordant samples showed that all 12 negative specimens for RDTs and routine microscopy were truly negative for nPCR. However, the remaining 16 specimens were positive for nPCR and showed discrepancies with routine microscopy and RDTs. Cohen’s interrater diagnostic measure analysis revealed that the weighted kappa for the RDTs was moderate 0.417 (p=0.027), 95%CI (0.756, 0.078) and good for nPCR 0.720 (p < 0.001), 95%CI (0.963, 0.477). The area under the curve (AUC) specify that nPCR has been more effective than the RDTs (nPCRAUC = 0.875; p < 0.001 and RDTsAUC = 0.708; p = 0.063).

CONCLUSION:

A thorough large-scale quality control is advocated on all commercial RDTs being used in most sub-Saharan African countries. This is to avoid double jeopardy consequent upon misdiagnosis on unidentified positive cases serving as pool reservoir for the insect vector and cyclical infection and re-infection of the populace.

Quantifying and Valuing Community Health Worker Time in Improving Access to Malaria Diagnosis and Treatment

Background. Community health workers (CHWs) are members of a community who are chosen by their communities as first-line, volunteer health workers. The time they spend providing healthcare and the value of this time are often not evaluated. Our aim was to quantify the time CHWs spent on providing healthcare before and during the implementation of an integrated program of diagnosis and treatment of febrile illness in 3 African countries.

Methods. In Burkina Faso, Nigeria, and Uganda, CHWs were trained to assess and manage febrile patients in keeping with Integrated Management of Childhood Illness recommendations to use rapid diagnostic tests, artemisinin-based combination therapy, and rectal artesunate for malaria treatment. All CHWs provided healthcare only to young children usually <5 years of age, and hence daily time allocation of their time to child healthcare was documented for 1 day (in the high malaria season) before the intervention and at several time points following the implementation of the intervention. Time spent in providing child healthcare was valued in earnings of persons with similar experience.

Results. During the high malaria season of the intervention, CHWs spent nearly 50 minutes more in daily healthcare provision (average daily time, 30.2 minutes before the intervention vs 79.5 minutes during the intervention; test for difference in means P < .01). On average, the daily time spent providing healthcare during the intervention was 55.8 minutes (Burkina Faso), 77.4 minutes (Nigeria), and 72.2 minutes (Uganda). Using the country minimum monthly salary, CHWs’ time allocated to child healthcare for 1 year was valued at US Dollars (USD) $52 in Burkina Faso, USD $295 in Nigeria, and USD $141 in Uganda.

Conclusions. CHWs spend up to an hour and a half daily on child healthcare in their communities. These data are informative in designing reward systems to motivate CHWs to continue providing good-quality services.

Clinical Trials Registration. ISRCTN13858170.

Deployment and use of mobile phone technology for real-time reporting of fever cases and malaria treatment failure in areas of declining malaria transmission in Muheza district north-eastern Tanzania

Background

Early detection of febrile illnesses at community level is essential for improved malaria case management and control. Currently, mobile phone-based technology has been commonly used to collect and transfer health information and services in different settings. This study assessed the applicability of mobile phone-based technology in real-time reporting of fever cases and management of malaria by village health workers (VHWs) in north-eastern Tanzania.

Methods

The community mobile phone-based disease surveillance and treatment for malaria (ComDSTM) platform, combined with mobile phones and web applications, was developed and implemented in three villages and one dispensary in Muheza district from November 2013 to October 2014. A baseline census was conducted in May 2013. The data were uploaded on a web-based database and updated during follow-up home visits by VHWs. Active and passive case detection (ACD, PCD) of febrile cases were done by VHWs and cases found positive by malaria rapid diagnostic test (RDT) were given the first dose of artemether–lumefantrine (AL) at the dispensary. Each patient was visited at home by VHWs daily for the first 3 days to supervise intake of anti-malarial and on day 7 to monitor the recovery process. The data were captured and transmitted to the database using mobile phones.

Results

The baseline population in the three villages was 2934 in 678 households. A total of 1907 febrile cases were recorded by VHWs and 1828 (95.9%) were captured using mobile phones. At the dispensary, 1778 (93.2%) febrile cases were registered and of these, 84.2% were captured through PCD. Positivity rates were 48.2 and 45.8% by RDT and microscopy, respectively. Nine cases had treatment failure reported on day 7 post-treatment and adherence to treatment was 98%. One patient with severe febrile illness was referred to Muheza district hospital.

Conclusion

The study showed that mobile phone-based technology can be successfully used by VHWs in surveillance and timely reporting of fever episodes and monitoring of treatment failure in remote areas. Further optimization and scaling-up will be required to utilize the tools for improved malaria case management and drug resistance surveillance.

Prevalence of malaria, typhoid, toxoplasmosis and rubella among febrile children in Cameroon

Background

The current roll-out of rapid diagnostic tests (RDTs) in many endemic countries has resulted in the reporting of fewer cases of malaria-attributed illnesses. However, lack of knowledge of the prevalence of other febrile illnesses and affordable diagnostic tests means that febrile patients are not managed optimally. This study assessed the prevalence of commonly treatable or preventable febrile illnesses in children between 6 months and 15 years using rapid diagnostic tests at the point-of-care.

Methods

Febrile children were enrolled between February-April 2014 at a health facility after obtaining informed consent from parent. Eligible participants were aged 6 months-15 years with a history of fever in the last 24 h or axillary temperature ≥38 °C at consultation. All participants were tested using RDTs for malaria, typhoid, toxoplasmosis and rubella. Malaria parasites were further identified by microscopy and PCR. Clinical and household characteristics were recorded and association with pathogens determined.

Results

Of the 315 children enrolled, the mean age was 5.8 ± 3.8 years. Stomach pain (41.2 %) was the most reported symptom. Prior to attending the health facility, 70.8 % had taken antipyretics, 27.9 % antimalarials, 11.4 % antibiotics and 13.3 % antifungal drugs. Among 315 children with fever, based on RDTs, 56.8 % were infected with malaria, 4.4 % with typhoid, 3.2 % with acute toxoplasmosis, and 1.3 % with rubella (all positive for rubella were in the same family and not vaccinated). All non-malarial infections were co-infections and approximately 30 % of the fever cases went un-diagnosed. Malaria prevalence by microscopy and PCR was 43.4 and 70.2 % respectively. The sensitivity and specificity of RDTs for the diagnosis of malaria were 75.98 and 100 % respectively, with 0.73 measurement agreement between RDTs and microscopy while that of RDT and PCR were 81 and 100 % respectively with a K value of 0.72. The use of Insecticide Treated Bednets was 44 %. There was a significant association between ITN non-usage and malaria (p = 0. 029) as well as drinking water and presence of typhoid (p = 0.047). No association was observed between type of housing and malaria, or toxoplasmosis and raising cats.

Conclusion

Though malaria still remains the major cause of fever in children, using RDTs for other treatable febrile illnesses like typhoid and toxoplasmosis could facilitate the optimal management of febrile illnesses in children especially when these occur as co-infections with malaria

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1996-y) contains supplementary material, which is available to authorized users.

Low sensitivity of the ImmunocardSTAT® Crypto/Giardia Rapid Assay test for the detection of Giardia and Cryptosporidium in fecal samples from children living in Libreville, Central Africa

Giardiasis and cryptosporidiosis are now recognized as neglected tropical parasitic diseases. The risk of their dissemination  in developing countries, such as Gabon, is increasing, due to urban crowding and poor sanitation. Accurate, simple and rapid diagnosis tools are thus necessary for the estimation of their real burden. The aim of this study was to evaluate the performances of the ImmunocardSTAT^®Crypto/Giardia Rapid Assay test for the detection of Cryptosporidium (C.) spp. and Giardia (G.) duodenalis in children living in Libreville, Gabon. Stool samples of 173 healthy children were screened by routine microscopic using the merthiolate iodine formol concentration technique for Giardia, the modified Ziehl Neelsen (ZN) staining for Cryptosporidium and the ImmunocardSTAT^® Crypto/Giardia RDT for the detection of Giardia and Cryptosporidium parasite forms and antigens respectively. G. duodenalis was detected with microscopy and the ImmunocardSTAT^® Crypto/Giardia in 27 (15.6 %) and 22 (13.3 %) fecal samples respectively. C. spp. oocysts were found in 18 (10.4 %) ones, whereas only one sample was positive with the immunochromatographic assay. When microscopic examination was considered as the reference method, sensitivity and specificity of the ImmunocardSTAT^® Crypto/Giardia Rapid Assay were found to be 63.0 %, 96.6 and 5.5 %, 99.3 % for G. duodenalis and C. spp. respectively. The prevalence of G. duodenalis and C. spp. carriage is high in children from Libreville. A low sensitivity of the ImmunocardSTAT^® Crypto/Giardia for the detection of both parasites is observed. It is thus inappropriate as a diagnostic tool for detecting asymptomatic carriers.