Failure of artemether-lumefantrine therapy in travellers returning to Belgium with Plasmodium falciparum malaria: an observational case series with genomic analysis

BACKGROUND

Failure of artemisinin-based combination therapy is increasingly reported in patients with Plasmodium falciparum malaria in sub-Saharan Africa. We aimed to describe the clinical and genomic characteristics of recent cases of P. falciparum malaria failing artemether-lumefantrine in Belgium.

METHODS

Travel-related cases of malaria confirmed at the national reference laboratory of the Institute of Tropical Medicine, Antwerp, Belgium, were reviewed. All cases for which attending clinicians reported persistence (beyond Day 3 post-treatment initiation, i.e. early failure) or recrudescence (from Day 7 to 42, i.e. late failure) of P. falciparum parasites despite adequate drug intake were analysed. Both initial and persistent/recurrent samples were submitted to next generation sequencing to investigate resistance-conferring mutations.

RESULTS

From July 2022 to June 2023, eight P. falciparum cases of failure with artemether-lumefantrine therapy were reported (early failure = 1; late failure = 7). All travellers were returning from sub-Saharan Africa, most (6/8) after a trip to visit friends and relatives. PfKelch13 (PF3D7_1343700) mutations associated with resistance to artemisinin were found in two travellers returning from East Africa, including the validated marker R561H in the patient with early failure and the candidate marker A675V in a patient with late failure. Additional mutations were detected that could contribute to decreased susceptibility to artemisinin in another three cases, lumefantrine in six cases and proguanil in all eight participants. Various regimens were used to treat the persistent/recrudescent cases, with favourable outcome.

CONCLUSION

Within a 12-month period, we investigated eight travellers returning from sub-Saharan Africa with P. falciparum malaria and in whom artemether-lumefantrine failure was documented. Mutations conferring resistance to antimalarials were found in all analysed blood samples, especially against lumefantrine and proguanil, but also artemisinin. There is a pressing need for systematic genomic surveillance of resistance to antimalarials in international travellers with P. falciparum malaria, especially those experiencing treatment failure.

Evaluation of the AIX1000 Automated Rapid Plasma Reagin Assay in a High-Prevalence Setting

BACKGROUND

Manually performed nontreponemal assays, such as rapid plasma reagin (RPR), are labor intensive and time consuming. Recently, commercial automated RPR assays gained attention. The aim of this study was to compare the qualitative and quantitative performance of the AIX1000 (RPR-A; Gold Standard Diagnostics) to a manual RPR test (RPR-M; Becton Dickinson Macrovue) within a high-prevalence setting.

METHODS

A retrospective panel of 223 samples was selected for comparison between RPR-A and RPR-M, including 24 samples from patients with known syphilis stages and 57 samples from 11 patients in follow-up. In addition, 127 samples obtained during routine syphilis diagnosis with RPR-M were analyzed prospectively with AIX1000.

RESULTS

Overall qualitative concordance (percent agreement) between both assays was 92.0% in the retrospective and 89.0% in the prospective panel. Of 32 discordances, 28 were explained by a treated syphilis infection still positive in one assay and already negative in the other. One sample was false positive with RPR-A, 1 infection remained undetected by RPR-M, and 2 remained undetected by RPR-A. A hook effect was apparent on the AIX1000 at RPR-A titers from 1:32 onward; however, no infections were missed. Accepting a ±1 titer difference, quantitative concordance between both assays reached 73.1% and 98.4% for the retrospective and prospective panels, respectively, with an upper limit of reactivity for RPR-A at 1:256.

CONCLUSIONS

The AIX1000 showed a similar performance to Macrovue RPR with the exception of a negative deviation for high-titer samples. Within the reverse algorithm used in our high-prevalence setting, AIX1000's main advantage is automation.

Presymptomatic viral shedding in high-risk mpox contacts: A prospective cohort study

The risk of infection after exposure to clade IIb mpox virus (MPXV) is unknown, and potential presymptomatic shedding of MPXV remains to be demonstrated. High-risk contacts of mpox patients were followed-up in a prospective longitudinal cohort study. Individuals reporting sexual contact, >15 min skin-to-skin contact, or living in the same household with an mpox patient were recruited in a sexual health clinic in Antwerp, Belgium. Participants kept a symptom diary, performed daily self-sampling (anorectal, genital, and saliva), and presented for weekly clinic visits for physical examination and sampling (blood and oropharyngeal). Samples were tested for MPXV by PCR. Between June 24 and July 31, 2022, 25 contacts were included, of which 12/18 (66.0%) sexual and 1/7 (14.0%) nonsexual contacts showed evidence of infection by MPXV-PCR. Six cases had typical mpox symptoms. Viral DNA was detected as early as 4 days before symptom onset in 5 of them. In 3 of these cases, replication-competent virus was demonstrated in the presymptomatic phase. These findings confirm the existence of presymptomatic shedding of replication-competent MPXV and emphasize the high risk of transmission during sexual contact. Sexual contacts of mpox cases should abstain from sex during the incubation period, irrespective of symptoms.

Characteristics of confirmed mpox cases among clinical suspects: A prospective single-centre study in Belgium during the 2022 outbreak

Background

The presentation of mpox clade IIb during the 2022 outbreak overlaps with a range of other diseases. Understanding the factors associated with mpox is important for clinical decision making.

Methods

We described the characteristics of mpox patients who sought care at Belgian sexual health clinic. Furthermore we compared their characteristics to those of patients with a clinical suspicion of mpox but who tested negative on polymerase chain reaction.

Results

Between May 23 and September 20, 2022, 155 patients were diagnosed with mpox, and 51 patients with suspected symptoms tested negative. All mpox patients self-identified as men and 148/155 (95.5%) as gay or bisexual MSM. Systemic symptoms were present in 116/155 (74.8%) patients. All but 10 patients (145/155, 93.5%) presented with skin lesions. Other manifestations were lymphadenopathy (72/155, 46.5%), proctitis (50/155, 32.3%), urethritis (12/155, 7.7%), tonsillitis (2/155, 1.3%). Complications involved bacterial skin infection (13/155, 8.4%) and penile oedema with or without paraphimosis (4/155, 2.6%). In multivariable logistic regression models, the presence of lymphadenopathy (OR 3.79 95% CI 1.44-11.49), skin lesions (OR 4.35 95% CI 1.15-17.57) and proctitis (OR 9.41 95% CI 2.72-47.07) were associated with the diagnosis of mpox. There were no associations with age, HIV status, childhood smallpox vaccination, number of sexual partners and international travel.

Conclusions

The presence of proctitis, lymphadenopathies and skin lesions should increase clinical suspicion of mpox in patients with compatible symptoms.

Accuracy of malaria diagnosis by clinical laboratories in Belgium

BACKGROUND

The Belgian Reference Laboratory for Plasmodium offers a free-of-charge reference testing of malaria-positive or doubtful samples to clinical laboratories.

METHODS

The final malaria diagnosis from the Reference Laboratory (microscopy, rapid diagnostic tests (RDTs) and Plasmodium species-specific PCR) were compared with the final diagnosis from peripheral Belgian laboratories. The Reference Laboratory reports were analysed for all samples submitted between 2013 and 2017. Criteria assessed included the diagnosis of malaria, Plasmodium species identification including mixed infections, and in case of Plasmodium falciparum, the parasite density and the presence of sexual and asexual stages.

RESULTS

A total of 947 non-duplicate samples were included. Reference testing confirmed 96.3% (893/927) and 90.0% (18/20) samples submitted as positive and negative, respectively, the two missed diagnoses were samples with Plasmodium ovale and Plasmodium malariae. Submitting laboratories had correctly identified P. falciparum in 95.1% (508/534) samples with P. falciparum single infection. They had correctly diagnosed the species in 62.9% (95/151) single non-falciparum samples and had reported 'non-falciparum' in another 26 (17.2%) samples; most errors occurred among P. malariae (n = 8/21, 38.1%) and P. ovale (n = 14/51, 27.5%). Only one of the 21 mixed Plasmodium species infections had been diagnosed as such by the submitting laboratories; in three of them, P. falciparum had been overlooked. Taken single and mixed infections together, P. falciparum was diagnosed in 98.6% (546/554) samples. Among 471 single P. falciparum samples available for comparison, laboratories had correctly reported parasite densities above 2% in 87.5% (70/80) samples; they had incorrectly reported parasite densities > 2% in an extra 52 (8.9%) samples. Laboratories had correctly reported P. falciparum schizonts and gametocytes in 25.6% (11/43) and 56.7% (17/30) samples, respectively.

CONCLUSION

Diagnostic laboratories in a malaria non-endemic setting provided excellent diagnosis of malaria and P. falciparum, reasonably good diagnosis of non-falciparum infections and acceptable calculation of P. falciparum parasite density.

Clinical and microscopic predictors of Entamoeba histolytica intestinal infection in travelers and migrants diagnosed with Entamoeba histolytica/dispar infection

Background

Amebiasis is a protozoal infection caused by Entamoeba histolytica, while the morphologically indistinguishable E. dispar is considered as non-pathogenic. Polymerase chain reaction (PCR) assays are necessary to differentiate both species. The most common clinical presentations of E. histolytica disease are amebic colitis and amebic liver abscess, but asymptomatic infection is also possible. We assessed the frequency and pattern of clinical symptoms and microscopic features in travelers/migrants associated with E. histolytica intestinal infection and compared them to those found in individuals with E. dispar infection.

Methods

We conducted a retrospective study at the travel clinic of the Institute of Tropical Medicine, Antwerp, Belgium on travelers/migrants found from 2006 to 2016 positive for Entamoeba histolytica/dispar through antigen detection and/or through microscopy confirmed by PCR. All files of individuals with a positive PCR for E. histolytica (= cases) and a random selection of an equal number of Entamoeba dispar carriers (= controls) were reviewed. We calculated the sensitivity, specificity and likelihood ratios (LRs) of clinical symptoms (blood in stool, mucus in stool, watery diarrhea, abdominal cramps, fever or any of these 5 symptoms) and of microscopic features (presence of trophozoites in direct and in sodium acetate-acetic acid-formalin (SAF)-fixed stool smears) to discriminate between E. histolytica and E. dispar infection.

Results

Of all stool samples positive for Entamoeba histolytica/dispar for which PCR was performed (n = 810), 30 (3.7%) were true E. histolytica infections, of which 39% were asymptomatic. Sensitivity, specificity and positive LRs were 30%, 100% and 300 (p 0.007) for presence of blood in stool; 22%, 100% and 222 (p 0.03) for mucus in stool; 44%, 90% and 4.7 (p 0.009) for cramps and 14%, 97% and 4.8 (p = 0.02) for trophozoites in direct smears. For watery diarrhea, fever and for trophozoites in SAF fixated smears results were non-significant.

Conclusions

E. histolytica infection was demonstrated in a small proportion of travelers/migrants with evidence of Entamoeba histolytica/dispar infection. In this group, history of blood and mucus in stool and cramps had good to strong confirming power (LR+) for actual E. histolytica infection. Trophozoites were also predictive for true E. histolytica infection but in direct smears only.

In the present work, we found that E. histolytica intestinal infections are rarely diagnosed among travelers and migrants presenting in a national reference travel clinic in Europe. Microscopic finding of cysts or trophozoites and antigen testing cannot discriminate between Entamoeba histolytica/dispar infection, which leads to overdiagnosis of E. histolytica infections in low resource settings where PCR is not available. We found visualization of trophozoites under the microscope helpful in discriminating between E. histolytica and E. dispar infection in direct smears. Hematophagy is a very rare finding but in our experience was always associated with E. histolytica infection. In a context where only microscopy is available, a patient presenting with blood or mucus in stool or cramps should anyhow be treated as amoebiasis if Entamoeba histolytica/dispar cysts/trophozoites are found. Nevertheless it is worth noting that a sizeable proportion of E. histolytica cases were asymptomatic. Last, our study suggests that E. dispar might be pathogenic but symptoms in E. histolytica infected patients were clearly more often suggestive of intestinal tissue invasion.

Instabilities of High Speed Dislocations

Despite numerous theoretical models and simulation results, a clear physical picture of dislocations traveling at velocities comparable to the speed of sound in the medium remains elusive. Using two complementary atomistic methods to model uniformly moving screw dislocations, lattice dynamics and molecular dynamics, the existence of mechanical instabilities in the system is shown. These instabilities are found at material-dependent velocities far below the speed of sound. We show that these are the onset of an atomistic kinematic generation mechanism, which ultimately results in an avalanche of further dislocations. This homogeneous nucleation mechanism, observed but never fully explained before, is relevant in moderate and high strain rate phenomena including adiabatic shear banding, dynamic fracture, and shock loading. In principle, these mechanical instabilities do not prevent supersonic motion of dislocations.

A systematic review of different jump-landing variables in relation to injuries

AIM

Injuries of the lower extremity tend to be associated with jump-landing movements. This review provides an overview of the kinematic variables and malalignments during jump-landing, which could be attributed to overuse or acute injury occurrence.

METHODS

We searched ISI Web of Knowledge, SPORTDiscus, PubMed, EMBASE and SCOPUS for all studies, published before October 2012, which looked at the relation between kinematic risk factors and malalignments of jump-landing and injuries. An article was included 1) if the article was an observational, retrospective or prospective study; 2) if the article investigated the relationship between injuries and the visible and easily measurable kinematic variables or malalignments of the jump-landing technique; 3) if the article met a predefined quality cut-off score.

RESULTS

Ten studies met all inclusion criteria. Literature shows that several kinematic factors are related to lower acute and overuse injuries.

CONCLUSION

A stiffer jump-landing technique is a risk factor in the development of overuse injuries and acute injuries. This is caused by less active motion in the lower extremity joints and by the increased valgus position of the knee during the jump-landing maneuver which creates an unfavorable alignment of the lower extremity. A valgus position of the knee during landing was also a predictor of acute lower extremity injuries. Future intervention programs should focus on the jump-landing technique and the performance of the athlete.

A customizable 3-dimensional digital atlas of the canary brain in multiple modalities

Songbirds are well known for their ability to learn their vocalizations by imitating conspecific adults. This uncommon skill has led to many studies examining the behavioral and neurobiological processes involved in vocal learning. Canaries display a variable, seasonally dependent, vocal behavior throughout their lives. This trait makes this bird species particularly valuable to study the functional relationship between the continued plasticity in the singing behavior and alterations in the anatomy and physiology of the brain. In order to optimally interpret these types of studies, a detailed understanding of the brain anatomy is essential. Because traditional 2-dimensional brain atlases are limited in the information they can provide about the anatomy of the brain, here we present a 3-dimensional MRI-based atlas of the canary brain. Using multiple imaging protocols we were able to maximize the number of detectable brain regions, including most of the areas involved in song perception, learning, and production. The brain atlas can readily be used to determine the stereotactic location of delineated brain areas at any desirable head angle. Alternatively the brain data can be used to determine the ideal orientation of the brain for stereotactic injections, electrophysiological recordings, and brain sectioning. The 3-dimensional canary brain atlas presented here is freely available and is easily adaptable to support many types of neurobiological studies, including anatomical, electrophysiological, histological, explant, and tracer studies.

Reporter gene-expressing bone marrow-derived stromal cells are immune-tolerated following implantation in the central nervous system of syngeneic immunocompetent mice

Background

Cell transplantation is likely to become an important therapeutic tool for the treatment of various traumatic and ischemic injuries to the central nervous system (CNS). However, in many pre-clinical cell therapy studies, reporter gene-assisted imaging of cellular implants in the CNS and potential reporter gene and/or cell-based immunogenicity, still remain challenging research topics.

Results

In this study, we performed cell implantation experiments in the CNS of immunocompetent mice using autologous (syngeneic) luciferase-expressing bone marrow-derived stromal cells (BMSC-Luc) cultured from ROSA26-L-S-L-Luciferase transgenic mice, and BMSC-Luc genetically modified using a lentivirus encoding the enhanced green fluorescence protein (eGFP) and the puromycin resistance gene (Pac) (BMSC-Luc/eGFP/Pac). Both reporter gene-modified BMSC populations displayed high engraftment capacity in the CNS of immunocompetent mice, despite potential immunogenicity of introduced reporter proteins, as demonstrated by real-time bioluminescence imaging (BLI) and histological analysis at different time-points post-implantation. In contrast, both BMSC-Luc and BMSC-Luc/eGFP/Pac did not survive upon intramuscular cell implantation, as demonstrated by real-time BLI at different time-points post-implantation. In addition, ELISPOT analysis demonstrated the induction of IFN-γ-producing CD8+ T-cells upon intramuscular cell implantation, but not upon intracerebral cell implantation, indicating that BMSC-Luc and BMSC-Luc/eGFP/Pac are immune-tolerated in the CNS. However, in our experimental transplantation model, results also indicated that reporter gene-specific immune-reactive T-cell responses were not the main contributors to the immunological rejection of BMSC-Luc or BMSC-Luc/eGFP/Pac upon intramuscular cell implantation.

Conclusion

We here demonstrate that reporter gene-modified BMSC derived from ROSA26-L-S-L-Luciferase transgenic mice are immune-tolerated upon implantation in the CNS of syngeneic immunocompetent mice, providing a research model for studying survival and localisation of autologous BMSC implants in the CNS by real-time BLI and/or histological analysis in the absence of immunosuppressive therapy.

Dynamic bioluminescence imaging for quantitative tumour burden assessment using IV or IP administration of D: -luciferin: effect on intensity, time kinetics and repeatability of photon emission

INTRODUCTION

In vivo bioluminescence imaging (BLI) is a promising technique for non-invasive tumour imaging. D: -luciferin can be administrated intraperitonealy or intravenously. This will influence its availability and, therefore, the bioluminescent signal. The aim of this study is to compare the repeatability of BLI measurement after IV versus IP administration of D: -luciferin and assess the correlation between photon emission and histological cell count both in vitro and in vivo.

MATERIALS AND METHODS

Fluc-positive R1M cells were subcutaneously inoculated in nu/nu mice. Dynamic BLI was performed after IV or IP administration of D: -luciferin. Maximal photon emission (PE(max)) was calculated. For repeatability assessment, every acquisition was repeated after 4 h and analysed using Bland-Altman method. A second group of animals was serially imaged, alternating IV and IP administration up to 21 days. When mice were killed, PE(max) after IV administration was correlated with histological cell number.

RESULTS

The coefficients of repeatability were 80.2% (IV) versus 95.0% (IP). Time-to-peak is shorter, and its variance lower for IV (p < 0.0001). PE(max) was 5.6 times higher for IV. A trend was observed towards lower photon emission per cell in larger tumours.

CONCLUSION

IV administration offers better repeatability and better sensitivity when compared to IP. In larger tumours, multiple factors may contribute to underestimation of tumour burden. It might, therefore, be beneficial to test novel therapeutics on small tumours to enable an accurate evaluation of tumour burden.

Prediction of head-up tilt test result by analysis of early heart rate variations

BACKGROUND

Head-up tilt testing is a useful test for investigating vasovagal syncope. The determination of early, accurate, predictive criteria for a negative result would permit a reduction in the duration of the tilt test.

METHODS AND RESULTS

Patients with no drug use and no illnesses other than recurrent unexplained syncope were recruited. In an initial study (110 consecutive patients), we aimed to determine a predictive criterion based on heart rate variations during the first minutes of upright tilting that could distinguish between patients with positive and negative tilt tests (patients with an early continual decrease in heart rate or blood pressure were excluded). Then we tested the predictive value of the established criterion in a second independent sample of patients with unexplained syncope (109 consecutive patients). An early sustained increase in heart rate < or = 18 bpm during the first 6 minutes of upright tilting at a 60 degree angle allowed us to predict negative tilt tests with 100% specificity, 100% positive predictive value, and 88.6% sensitivity. This criterion was validated in the second, prospective arm of the study (96.4% specificity, 98.4% positive predictive value, and 87.3% sensitivity), even with subsequent use of isoproterenol in low doses.

CONCLUSIONS

In patients with no drug use and no illnesses other than recurrent unexplained syncope, a simple clinical criterion identifies patients who will not develop syncope during a prolonged upright tilt.

A comparison of single doses of bucindolol and oxprenolol in hypertensive patients

Single doses of bucindolol 50, 100 and 200 mg were compared to placebo and single doses of oxprenolol 40, 80 and 160 mg in seven patients with mild hypertension, in a double-blind randomized study. Both bucindolol and oxprenolol inhibited exercise induced tachycardia. The mean maximum inhibition of exercise heart rate was similar after each dose of both drugs (20%, P less than 0.001). Bucindolol produced a significantly greater reduction in blood pressure than either oxprenolol or placebo. This was most apparent in standing systolic and diastolic and post-exercise systolic blood pressures between 1 and 2 h after dosing and was dose-related. All seven patients experienced adverse effects related to hypotension within the first 2 h after ingestion of bucindolol 200 mg. Plasma concentrations of oxprenolol, bucindolol or 5-hydroxy-bucindolol, sampled 2 h after dosing, could not be related to either the changes in blood pressure or to the occurrence of symptoms. The results emphasise the need for careful dose-finding of new drugs prior to their more widespread evaluation in phase 3 studies.