OBJECTIVE:To compare the symptomatology of Aboriginal and Torres Strait Islander and non-Indigenous patients presenting to an emergency department (ED) with suspected acute coronary syndrome (ACS) and to determine whether specific symptoms increased the odds of ACS diagnosis and whether traditional groupings of typical or atypical symptoms are relevant in these populations. METHODS:Prospectively collected symptom data from 1643 adult patients presenting at two Queensland emergency departments between 2011-2014 and 2016-2019 who were assessed for suspected ACS were analysed according to self-reported Indigenous status. ACS diagnosis was the primary outcome. RESULTS:In 1643 patients investigated for suspected ACS, chest pain (92.1%), diaphoresis (47.8%), and shortness of breath (52.2%) were the most reported symptoms. For the 194 patients diagnosed with ACS, chest pain was reported less frequently in Aboriginal and Torres Strait Islander patients compared with non-Indigenous patients (81.5% vs. 94.2%, p = 0.009). For Aboriginal and Torres Strait Islander patients, vomiting and indigestion were associated with increased odds of ACS; left-sided chest pain or sharp pain was associated with decreased odds. Aboriginal and Torres Strait Islander patients with ACS were more likely to present atypically than non-Indigenous patients, but typicality was not associated with ACS. CONCLUSION:Clinicians must have a high index of suspicion for ACS in Aboriginal and Torres Strait Islander people with chest pain who present with symptoms of gastrointestinal upset such as indigestion or vomiting. Typical or atypical groupings of ACS symptoms are of limited value or relevance in Australian populations, and these terms should be phased out. TRIAL REGISTRATION:ANZCRN12617000756325.

Background In critically ill patients with acute kidney injury (AKI), a fluid balance (FB) > 2 L at 72 h after AKI diagnosis is associated with adverse outcomes. Identification of patients at high-risk for such fluid accumulation may help prevent it. Methods We used Australian electronic medical record (EMR)-based clinical data to develop the “AKI-FB risk score”, validated it in a British cohort and used it to predict a positive FB >2 L at 72 h after AKI diagnosis. Results We developed the AKI-FB score in 32,030 patients with a median age of 63 years and a median APACHE 2 score of 16. We validated it in 4465 patients, with significant differences in admission diagnoses and interventions. The key score variables were admission after trauma, sepsis or septic shock, and, on the day of AKI diagnosis, highest creatinine, daily cumulative FB, mechanical ventilation, noradrenaline use, noradrenaline equivalent dose >0.07 μg/kg/min, lactate ≥2 mmol/L, transfusion, and nutritional support. A score threshold of 32 had a sensitivity of 75 % and a specificity of 72 % for predicting a > 2 L positive FB with an AUC-ROC of 0.805; 95 % CI 0.799 to 0.810. External validation demonstrated an AUC of 0.761 (95 % CI 0.746 to 0.775). Conclusion We developed and validated the “AKI-FB risk score” to predict patients who developed a positive FB >2 L within 72 h of AKI diagnosis. This prediction score was robust and facilitated the identification of high-risk AKI patients who could be the tarted for preventive measures and be included in future clinical trials of FB management.

Introduction: In critically ill patients undergoing continuous renal replacement therapy (CRRT), a positive fluid balance (FB) is associated with adverse outcomes. However, current FB management practices in CRRT patients are poorly understood. We aimed to study FB and its components in British and Australian CRRT patients to inform future trials. Methods: We obtained detailed electronic health record data on all fluid-related variables during CRRT and hourly FB for the first 7 days of treatment. Results: We studied 1,616 patients from three tertiary intensive care units (ICUs) in two countries. After the start of CRRT, the mean cumulative FB became negative at 31 h and remained negative over 7 days to a mean nadir of -4.1 L (95% confidence interval (CI) of -4.6 to -3.5). The net ultrafiltration (NUF) rate was the dominant fluid variable (-67.7 mL/h; standard deviation (SD): 75.7); however, residual urine output (-34.7 mL/h; SD: 54.5), crystalloid administration (48.1 mL/h; SD: 44.6), and nutritional input (36.4 mL/h; SD: 29.7) significantly contributed to FB. Patients with a positive FB after 72 h of CRRT were more severely ill, required high-dose vasopressors, and had high lactate concentrations (5.0 mmol/L; interquartile range: 2.3-10.5). A positive FB was independently associated with increased hospital mortality (odds ratio: 1.70; 95% CI; p = 0.004). Conclusion: In the study ICUs, most CRRT patients achieved a predominantly NUF-dependent negative FB. Patients with a positive FB at 72 h had greater illness severity and haemodynamic instability. Achieving equipoise for conducting trials that target a negative early FB in such patients may be difficult.

Background Radical cure of Plasmodium vivax infections is key to the control of vivax malaria. However, the standard doses of 8-aminoquinoline drugs used for radical cure can cause severe haemolysis in G6PD-deficient patients. The availability of near-patient G6PD tests could increase use of primaquine (PQ), however direct evidence of the impacts that G6PD testing has on downstream patient outcomes, such as haemolysis and recurrence is lacking. Methodology/Principle findings A linked-evidence model was created to investigate changes in the number of severe haemolysis events and P. vivax recurrences within 6 months of treatment when qualitative G6PD testing was used to guide PQ treatment (0.25mg/kg/day for 14 days and 0.5mg/kg/day for 7 days), compared to prescribing 14-day PQ with no G6PD testing. In the model patients identified as G6PD-deficient received 8-week PQ (0.75mg/kg/week). The model was used to simulate scenarios with 1%, 5% and 10% prevalence of G6PD-deficiency (G6PDd) in theoretical populations of 10,000 male and female P. vivax patients and initially assumed 100% adherence to the prescribed PQ regiment. Results illustrate that G6PD testing to guide the 14-day PQ regiment reduced severe haemolysis by 21-80% and increased recurrences by 3-6%, compared to applying the 14-day PQ regiment without G6PD testing. Results for the 7-day PQ regiment informed by G6PD testing were mixed, dependent on G6PDd prevalence and sex. When adherence to the PQ regiments was less than perfect the model predicted reductions in the number of recurrences at all prevalence levels, provided adherence to 7-day PQ was 5-10% higher than adherence to the 14-day regiment. Conclusions/Significance Introduction of G6PD testing to guide PQ treatment reduces severe haemolysis events for the 14-day regiment, and the 7-day regiment in higher G6PDd prevalence settings, compared to use of 14-day PQ without G6PD testing when all patients adhere to the prescribed PQ treatment. At a population level, there were increases in recurrences, but this could be resolved when the 7-day regiment was used and had superior adherence compared to the 14-day regiment.

OBJECTIVES:The accuracy of malaria rapid diagnostic tests is threatened by Plasmodium falciparum with pfhrp2/3 deletions. This study compares gene deletion prevalence determined by multiplex real time polymerase chain reaction (qPCR) and conventional polymerase chain reaction (cPCR) using existing samples with clonality previously determined by microsatellite genotyping. METHODS:Multiplex qPCR was used to estimate prevalence of pfhrp2/3 deletions in three sets of previously collected patient samples from Eritrea and Peru. The qPCR was validated by multiplex digital polymerase chain reaction. Sample classification was compared with cPCR, and receiver operating characteristic curve analysis was used to determine the optimal ΔCq threshold that aligned the results of the two assays. RESULTS:qPCR classified 75% (637 of 849) of samples as single, and 212 as mixed-pfhrp2/3 genotypes, with a positive association between clonality and proportion of mixed-pfhrp2/3 genotype samples. The sample classification agreement between cPCR and qPCR was 75.1% (95% confidence interval [CI] 68.6-80.7%) and 47.8% (95% CI 38.9-56.9%) for monoclonal and polyclonal infections. The qPCR prevalence estimates of pfhrp2/3 deletions showed almost perfect (κ = 0.804, 95% CI 0.714-0.895) and substantial agreement (κ = 0.717, 95% CI 0.562-0.872) with cPCR for Peru and 2016 Eritrean samples, respectively. For 2019 Eritrean samples, the prevalence of double pfhrp2/3 deletions was approximately two-fold higher using qPCR. The optimal threshold for matching the assay results was ΔCq = 3. CONCLUSIONS:Multiplex qPCR and cPCR produce comparable estimates of gene deletion prevalence when monoclonal infections dominate; however, qPCR provides higher estimates where multi-clonal infections are common.

Household food security in Vietnam remains tenuous. We surveyed 552 households to investigate household food insecurity (HFI) in rural districts in the Vietnamese Mekong Delta. HFI prevalence was 34.4% and 48.4% in the last month and last year, respectively. Khmer households were twice as likely to experience HFI compared to their Kinh counterparts. The primary factors associated with HFI were weak livelihood assets including lower natural, financial, and human assets (being landless, low incomes), physical and social assets (poor market access, social networks), lower kitchen utensil scores, belonging to a minority and experiencing financial, agricultural, and extreme weather shocks.

Healthy, diverse diets are vital for life. In low/middle-income countries, however, the focus is more on food quantity rather than diet quality. This study assessed household diet diversity (HDD) in the Vietnamese Mekong Delta and its associations with household food insecurity (HFI) and household food availability (HFA) controlling for socioeconomic factors. Primary food-preparers in 552 randomly selected households in two rural provinces were interviewed about socioeconomic factors, HDD, HFI, and HFA. More than 80% of households predominantly consumed energy-dense foods, whereas less than 20% consumed nutrient-dense foods. Lower HDD was associated with HFI, lower HFA, for the Khmer ethnic minority, and low livelihood capitals (landlessness, low expenditure, debt) and low utensil scores. The study highlighted the need to provide improved food and nutrition policies that increase availability and access to diverse and healthy foods as well as reduce poverty and increase incomes for at-risk rural and ethnic minority groups.

BACKGROUND:Acute respiratory infections (ARI) in Cúcuta -Colombia, have a comparatively high burden of disease associated with high public health costs. However, little is known about the epidemiology of these diseases in the city and its distribution within suburban areas. This study addresses this gap by estimating and mapping the risk of ARI in Cúcuta and identifying the most relevant risk factors. METHODS:A spatial epidemiological analysis was designed to investigate the association of sociodemographic and environmental risk factors with the rate of ambulatory consultations of ARI in urban sections of Cúcuta, 2018. The ARI rate was calculated using a method for spatial estimation of disease rates. A Bayesian spatial model was implemented using the Integrated Nested Laplace Approximation approach and the Besag-York-Mollié specification. The risk of ARI per urban section and the hotspots of higher risk were also estimated and mapped. RESULTS:A higher risk of IRA was found in central, south, north and west areas of Cúcuta after adjusting for sociodemographic and environmental factors, and taking into consideration the spatial distribution of the city's urban sections. An increase of one unit in the percentage of population younger than 15 years; the Index of Multidimensional Poverty and the rate of ARI in the migrant population was associated with a 1.08 (1.06-1.1); 1.04 (1.01-1.08) and 1.25 (1.22-1.27) increase of the ARI rate, respectively. Twenty-four urban sections were identified as hotspots of risk in central, south, north and west areas in Cucuta. CONCLUSION:Sociodemographic factors and their spatial patterns are determinants of acute respiratory infections in Cúcuta. Bayesian spatial hierarchical models can be used to estimate and map the risk of these infections in suburban areas of large cities in Colombia. The methods of this study can be used globally to identify suburban areas and or specific communities at risk to support the implementation of prevention strategies and decision-making in the public and private health sectors.

This study employed parallel growth curve modelling to examine the changes in both psychological distress and at-risk and problem gambling as a development process. We used a prospective longitudinal population-based study to provide further insights beyond treatment samples and cross-sectional studies. A secondary data analysis was conducted by extracting a sample of 3460 Victorian adults from the Victorian Gambling Study 2008–2011. Findings suggested that psychological distress was a consistent risk factor for at-risk and problem gambling, as measured by the problem gambling severity index (PGSI), after controlling for other risk factors such as sex, age, histories of at-risk and problem gambling, and the experience of trauma. A more rapid increase in psychological distress over time was related to a more rapid increase in the PGSI trajectory. It is concluded that this study supports a positive association in the development trends of problem gambling severity and psychological distress in individuals who engaged in gambling. The association persists after adjusting for histories of gambling problem risk and the experience of trauma in life. The implications of the study suggest addressing the comorbidity of problem gambling risk and psychological distress in treatment and prevention, and the development of dual-diagnosis treatment programs.

Objective: The overall objective of this scoping review is to assess the extent of the literature related to the fluid management of critically ill patients with acute kidney injury (AKI). Introduction: AKI is common in critically ill patients where fluid therapy is a mainstay of treatment. An association between fluid balance (FB) and adverse patient-centred outcomes in critically ill patients with AKI regardless of severity has been demonstrated. The evidence for the prospective intervention of FB and its impact on outcomes is unknown. Inclusion criteria: All studies investigating FB in patients with AKI admitted to an intensive care unit were included. Literature not related to FB in the critically ill patient with AKI population was excluded. Methods: We searched MEDLINE, EMBASE, and CINAHL from January 1st, 2012, onwards. We included primary research studies, experimental and observational, recruiting adult participants admitted to an intensive care unit who had an AKI. We extracted data on study and patient characteristics, as well as FB, renal-based outcomes, and patient-centred outcomes. Two reviewers independently screened citations for eligible studies and performed data extraction. Results: Of the 13,767 studies reviewed, 22 met the inclusion criteria. Two studies examined manipulation of fluid input, 18 studies assessed enhancing fluid removal, and two studies applied a restrictive fluid protocol. Sixteen studies examined patients receiving renal replacement therapy, five studies included non-renal replacement therapy patients, and one study included both. Current evidence is broad with varied approaches to managing fluid input and fluid removal. The studies did not demonstrate a consensus approach for any aspect of the fluid management of critically ill patients. There was a limited application of a restrictive fluid protocol with no conclusions possible. Conclusions: The current body of evidence for the management of FB in critically ill patients with AKI is limited in nature. The current quality of evidence is unable to guide current clinical practice. The key outcome of this review is to highlight areas for future research. (c) 2023 The Authors. Published by Elsevier B.V. on behalf of College of Intensive Care Medicine of Australia and New Zealand. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

Introduction Light microscopy remains a standard method for detection of malaria parasites in clinical cases but training to expert level requires considerable time. Moreover, excessive workflow causes fatigue and can impact performance. An automated microscopy tool could aid in clinics with limited access to highly skilled microscopists, where case numbers are excessive, or in multi-site studies where consistency is essential. The EasyScan GO is an automated scanning microscope combined with machine learning software designed to detect malaria parasites in field-prepared Giemsa-stained blood films. This study evaluates the ability of the EasyScan GO to detect, quantify and identify the species of parasite present in blood films compared with expert light microscopy. Methods Travelers returning to the UK and testing positive for malaria were screened for eligibility and enrolled. Blood samples from enrolled participants were used to make Giemsa-stained smears assessed by expert light microscopy and the EasyScan GO to determine parasite density and species. Blood samples were also assessed by PCR to confirm parasite density and species present and resolve discrepancy between manual microscopy and the EasyScan GO. Results When compared to light microscopy, the EasyScan GO exhibited a sensitivity of 88% (95% CI: 80-93%) and a specificity of 89% (95% CI: 87-91%). Of the 99 samples labelled positive by both, manual microscopy identified 87 as Plasmodium falciparum ( Pf ) and 12 as non- Pf . The EasyScan GO correctly reported Pf for 86 of the 87 Pf samples and non- Pf for 11 of 12 non- Pf samples. However, it failed to distinguish between non- Pf species, reporting all as P. vivax . The EasyScan GO calculated parasite densities were within +/-25% of light microscopy densities for 33% of samples between 200 and 2000 p/µL, falling short of WHO level 1 (expert) manual microscopy competency (50% of samples should be within +/-25% of the true parasitemia). Discussion This study shows that the EasyScan GO can be proficient in detecting malaria parasites in Giemsa-stained blood films relative to expert light microscopy and accurately distinguish between Pf and non- Pf species. Performance at low parasite densities, distinguishing between non- Pf species and accurate quantitation of parasitemia require further development and evaluation.

ABSTRACT Plasmodium vivax infections and relapses remain a major health problem for malaria-endemic countries, deployed military personnel, and travelers. Presumptive anti-relapse therapy and radical cure using the 8-aminoquinoline drugs primaquine and tafenoquine are necessary to prevent relapses. Although it has been demonstrated that the efficacy of primaquine is associated with Cytochrome P450 2D6 (CYP2D6) activity, there is insufficient data on the role of CYP2D6 in the anti-relapse efficacy of tafenoquine. We investigated the relationship between CYP2D6 activity status and tafenoquine efficacy in preventing P. vivax relapses retrospectively using plasma samples collected from Australian Defence Force personnel deployed to Papua New Guinea and Timor-Leste who participated in clinical trials of tafenoquine during 1999–2001. The CYP2D6 gene was amplified from plasma samples and fully sequenced from 92 participant samples, comprised of relapse ( n = 31) and non-relapse ( n = 61) samples, revealing 14 different alleles. CYP2D6 phenotypes deduced from combinations of CYP2D6 alleles predicted that among 92 participants 67, 15, and 10 were normal, intermediate, and poor metabolizers, respectively. The deduced CYP2D6 phenotype did not correlate with the corresponding participant’s plasma tafenoquine concentrations that were determined in the early 2000s by high-performance liquid chromatography or liquid chromatography-mass spectrometry. Furthermore, the deduced CYP2D6 phenotype did not associate with P. vivax relapse outcomes. Our results indicate that CYP2D6 does not affect plasma tafenoquine concentrations and the efficacy of tafenoquine in preventing P. vivax relapses in the assessed Australian Defence Force personnel.

Background Due to the relatively low numbers of households in high income countries experiencing food insecurity most studies conflate the levels of severity, which masks between- and within-country differences. This study aims to describe the characteristics of individuals living in high income countries who were moderately or severely food insecure and investigates temporal trends in prevalence. It assesses these characteristics in comparison to those who were food secure. Methods This is a secondary analysis of data collected by the FAO Voices of the Hungry between 2014–2018. The data were collected during the annual Gallup World Polls of nationally representative samples using the Food Insecurity Experience Scale. Data from 34 highly developed, wealthy countries were analysed. The age, gender, income, education, area of residence and household structure of individuals experiencing moderate/severe food insecurity (FI), and severe FI, were compared using ANOVA, Welch’s F, Pearson’s Chi-square, and Linear-by-Linear Association, dependent on the variable of interest. Hierarchical cluster analysis was used to group countries according to their prevalence of moderate/severe FI, and severe FI. Results Overall, 6.5% of the weighted sample were moderately/severely food insecure (M-SFI), while 1.6% were severely food insecure. M-SFI individuals were present in all 34 countries, in all years and across all education levels and income quintiles. The proportion of individuals experiencing moderate/severe FI varied between years and countries. Fifteen countries showed a significant downward temporal trend in prevalence of moderate/severe FI ( p < 0.001), while three countries demonstrated an increasing temporal trend driven by increasing prevalence in those aged 65 years or less ( p < 0.001). Comparing individuals experiencing moderate versus severe FI showed over-representation of males, single adult households and lower household income in the severe FI group. Conclusions Individuals across all income, education and age categories living in high income countries are experiencing moderate/severe food insecurity, but with higher prevalence in those experiencing more disadvantage. Over the study period some countries experienced escalating while others demonstrated decreasing moderate/severe FI trends. This comparison of countries with similar economic and human development indices highlights an opportunity to investigate subtle variations in social, economic and education policy that could have profound impacts on food insecurity.

Malaria rapid diagnostic tests (RDTs) are dominated by products which use histidine-rich protein 2 (HRP2) to detect Plasmodium falciparum. The emergence of parasites lacking the pfhrp2 gene can lead to high rates of false-negative results amongst these RDTs. One solution to restore the ability to correctly diagnose falciparum malaria is to switch to an RDT which is not solely reliant on HRP2. This study used an agent-based stochastic simulation model to investigate the impact on prevalence and transmission caused by switching the type of RDT used once false-negative rates reached pre-defined thresholds within the treatment-seeking symptomatic population. The results show that low transmission settings were the first to reach the false-negative switch threshold, and that lower thresholds were typically associated with better long-term outcomes. Changing the diagnostic RDT away from a HRP2-only RDT is predicted to restore the ability to correctly diagnose symptomatic malaria infections, but often did not lead to the extinction of HRP2-negative parasites from the population which continued to circulate in low density infections, or return to the parasite prevalence and transmission levels seen prior to the introduction of the HRP2-negative parasite. In contrast, failure to move away from HRP2-only RDTs leads to near fixation of these parasites in the population, and the inability to correctly diagnose symptomatic cases. Overall, these results suggest pfhrp2-deleted parasites are likely to become a significant component of P. falciparum parasite populations, and that long-term strategies are needed for diagnosis and surveillance which do not rely solely on HRP2.

To describe the demographics, presentation characteristics, clinical features and cardiac outcomes for Aboriginal and Torres Strait Islander patients who present to a regional cardiac referral centre ED with suspected acute coronary syndrome (ACS).

Background Rapid diagnostic tests (RDTs) that rely on the detection of Plasmodium falciparum histidine-rich protein 2 ( Pf HRP2) have become key tools for diagnosing P. falciparum infection. The utility of RDTs can be limited by Pf HRP2 persistence, however it can be a potential benefit in low transmission settings where detection of persistent Pf HRP2 using newer ultra-sensitive Pf HRP2 based RDTs can serve as a surveillance tool to identify recent exposure. Better understanding of the dynamics of Pf HRP2 over the course of a malaria infection can inform optimal use of RDTs. Methods A previously published mathematical model was refined to mimic the production and decay of Pf HRP2 during a malaria infection. Data from 15 individuals from volunteer infection studies were used to update the original model and estimate key model parameters. The refined model was applied to a cohort of patients from Namibia who received treatment for clinical malaria infection for whom longitudinal Pf HRP2 concentrations were measured. Results The refinement of the Pf HRP2 dynamic model indicated that in malaria naïve hosts, P. falciparum parasites of the 3D7 strain produce 33.6 × 10 −15 g (95% CI 25.0–42.1 × 10 −15 g) of Pf HRP2 in vivo per parasite replication cycle, with an elimination half-life of 1.67 days (95% CI 1.11–3.40 days). The refined model included these updated parameters and incorporated individualized body fluid volume calculations, which improved predictive accuracy when compared to the original model. The performance of the model in predicting clearance of Pf HRP2 post treatment in clinical samples from six adults with P. falciparum infection in Namibia improved when using a longer elimination half-life of 4.5 days, with 14% to 67% of observations for each individual within the predicted range. Conclusions The updated mathematical model can predict the growth and clearance of Pf HRP2 during the production and decay of a mono-infection with P. falciparum , increasing the understanding of Pf HRP2 antigen dynamics. This model can guide the optimal use of Pf HRP2-based RDTs for reliable diagnosis of P. falciparum infection and re-infection in endemic settings, but also for malaria surveillance and elimination programmes in low transmission areas.

IntroductionHousehold food insecurity and inadequate water, sanitation, and hygiene (WASH) contribute to ill health. However, the interactions between household food insecurity, WASH and health have been rarely assessed concurrently. This study investigated compounded impacts of household food insecurity and WASH on self-reported physical and mental health of adults in the Vietnamese Mekong Delta.Materials and methodsThis cross-sectional survey interviewed 552 households in one northern and one southern province of the Vietnamese Mekong Delta. The survey incorporated previously validated tools such as the Short Form 12-item Health Survey, Household Food Insecurity Assessment Scale, and the Access and Behavioural Outcome Indicators for Water, Sanitation, and Hygiene. Physical and mental health were quantified using the physical health composite score (PCS) and mental health composite score (MCS), respectively. These measures were the dependent variables of interest for this study.ResultsStatistical analysis revealed that household food insecurity and using <50 litres of water per person per day (pppd) were independently associated with lower PCS (p<0.05), after adjusting for socio-economic confounders. Household food insecurity and lack of food availability, using <50 litres of water pppd, and the use of untreated drinking water were associated with lower MCS (p<0.05), with water usage being an effect modifier of the relationship between household food insecurity and MCS. The results indicate that being food insecure and having limited potable quality water had a compounding effect on MCS, compared to being individually either food insecure or having limited water.ConclusionThis study is one of only a few that have established a link between potable water availability, food insecurity and poorer physical and mental health. The results also indicate a need to validate national data with fine-scale investigations in less populous regions to evaluate national initiatives with local populations that may be at higher risk. Adopting joint dual-action policies for interventions that simultaneously address water and food insecurity should result in larger improvements in health, particularly mental health, compared to targeting either food or water insecurity in isolation.

Aboriginal and Torres Strait Islander people, who experience cardiac events at younger ages compared to non-Indigenous Australians, have been underrepresented in research examining risk stratification pathways for patients who present to and emergency department (ED) with suspected acute coronary syndrome (ACS).

Abstract Background The World Health Organization recommends confirmatory diagnosis by microscopy or malaria rapid diagnostic test (RDT) in patients with suspected malaria. In recent years, mobile medical applications (MMAs), which can interpret RDT test results have entered the market. To evaluate the performance of commercially available MMAs, an evaluation was conducted by comparing RDT results read by MMAs to RDT results read by the human eye. Methods Five different MMAs were evaluated on six different RDT products using cultured Plasmodium falciparum blood samples at five dilutions ranging from 20 to 1000 parasites (p)/microlitre (µl) and malaria negative blood samples. The RDTs were performed in a controlled, laboratory setting by a trained operator who visually read the RDT results. A second trained operator then used the MMAs to read the RDT results. Sensitivity (Sn) and specificity (Sp) for the RDTs were calculated in a Bayesian framework using mixed models. Results The RDT Sn of the P. falciparum (Pf) test line, when read by the trained human eye was significantly higher compared to when read by MMAs (74% vs. average 47%) at samples of 20 p/µl. In higher density samples, the Sn was comparable to the human eye (97%) for three MMAs. The RDT Sn of test lines that detect all Plasmodium species (Pan line), when read by the trained human eye was significantly higher compared to when read by MMAs (79% vs. average 56%) across all densities. The RDT Sp, when read by the human eye or MMAs was 99% for both the Pf and Pan test lines across all densities. Conclusions The study results show that in a laboratory setting, most MMAs produced similar results interpreting the Pf test line of RDTs at parasite densities typically found in patients that experience malaria symptoms (> 100 p/µl) compared to the human eye. At low parasite densities for the Pf line and across all parasite densities for the Pan line, MMAs were less accurate than the human eye. Future efforts should focus on improving the band/line detection at lower band intensities and evaluating additional MMA functionalities like the ability to identify and classify RDT errors or anomalies.

Eritrea was the first African country to complete a nationwide switch in 2016 away from HRP2-based RDTs due to high rates of false-negative RDT results caused by Plasmodium falciparum parasites lacking hrp2/hrp3 genes. A cross-sectional survey was conducted during 2019 enrolling symptomatic malaria patients from nine health facilities across three zones consecutively to investigate the epidemiology of P. falciparum lacking hrp2/3 after the RDT switch. Molecular analyses of 715 samples revealed the overall prevalence of hrp2-, hrp3 -, and dual hrp2/3 -deleted parasites as 9.4% (95%CI 7.4–11.7%), 41.7% (95% CI 38.1–45.3%) and 7.6% (95% CI 5.8–9.7%), respectively. The prevalence of hrp2- and hrp3- deletion is heterogeneous within and between zones: highest in Anseba (27.1% and 57.9%), followed by Gash Barka (6.4% and 37.9%) and Debub zone (5.2% and 43.8%). hrp2/3 -deleted parasites have multiple diverse haplotypes, with many shared or connected among parasites of different hrp2/3 status, indicating mutant parasites have likely evolved from multiple and local parasite genetic backgrounds. The findings show although prevalence of hrp2/3 -deleted parasites is lower 2 years after RDT switching, HRP2-based RDTs remain unsuitable for malaria diagnosis in Eritrea. Continued surveillance of hrp2/3 -deleted parasites in Eritrea and neighbouring countries is required to monitor the trend.