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Down syndrome is one of the most common chromosomal anomalies affecting the world's population, with an estimated frequency of 1 in 700 live births. Despite its relatively high prevalence, diagnostic rates based on clinical features have remained under 70% for most of the developed world and even lower in countries with limited resources. While genetic and cytogenetic confirmation greatly increases the diagnostic rate, such resources are often non-existent in many low- and middle-income countries, particularly in Sub-Saharan Africa. To address the needs of countries with limited resources, the implementation of mobile, user-friendly and affordable technologies that aid in diagnosis would greatly increase the odds of success for a child born with a genetic condition. Given that the Democratic Republic of the Congo is estimated to have one of the highest rates of birth defects in the world, our team sought to determine if smartphone-based facial analysis technology could accurately detect Down syndrome in individuals of Congolese descent. Prior to technology training, we confirmed the presence of trisomy 21 using low-cost genomic applications that do not need advanced expertise to utilize and are available in many low-resourced countries. Our software technology trained on 132 Congolese subjects had a significantly improved performance (91.67% accuracy, 95.45% sensitivity, 87.88% specificity) when compared to previous technology trained on individuals who are not of Congolese origin (p

Helicobacter pylori disturbs the stomach lining during long-term colonization of its human host, with sequelae including ulcers and gastric cancer1,2. Numerous H. pylori virulence factors have been identified, showing extensive geographic variation1. Here we identify a ‘Hardy’ ecospecies of H. pylori that shares the ancestry of ‘Ubiquitous’ H. pylori from the same region in most of the genome but has nearly fixed single-nucleotide polymorphism differences in 100 genes, many of which encode outer membrane proteins and host interaction factors. Most Hardy strains have a second urease, which uses iron as a cofactor rather than nickel3, and two additional copies of the vacuolating cytotoxin VacA. Hardy strains currently have a limited distribution, including in Indigenous populations in Siberia and the Americas and in lineages that have jumped from humans to other mammals. Analysis of polymorphism data implies that Hardy and Ubiquitous coexisted in the stomachs of modern humans since before we left Africa and that both were dispersed around the world by our migrations. Our results also show that highly distinct adaptive strategies can arise and be maintained stably within bacterial populations, even in the presence of continuous genetic exchange between strains.‘Hardy’ Helicobacterpylori ecospecies shares the ancestry of ‘Ubiquitous’ H. pylori from the same region in most of the genome but has nearly fixed single-nucleotide polymorphism differences in 100 genes. [ABSTRACT FROM AUTHOR]

Background Cross-neutralizing capacity of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants is important in mitigating (re-)exposures. Role of antibody maturation, the process whereby selection of higher affinity antibodies augments host immunity, to determine SARS-CoV-2 neutralizing capacity was investigated. Methods Sera from SARS-CoV-2 convalescents at 2, 6, or 10 months postrecovery, and BNT162b2 vaccine recipients at 3 or 25 weeks postvaccination, were analyzed. Anti-spike IgG avidity was measured in urea-treated ELISAs. Neutralizing capacity was assessed by surrogate neutralization assays. Fold change between variant and wild-type neutralization inferred the breadth of neutralizing capacity. Results Compared with early-convalescent, avidity indices of late-convalescent sera were significantly higher (median, 37.7 [interquartile range 28.4–45.1] vs 64.9 [57.5–71.5], P <.0001). Urea-resistant, high-avidity IgG best predicted neutralizing capacity (Spearman r = 0.49 vs 0.67 [wild-type]; 0.18–0.52 vs 0.48–0.83 [variants]). Higher-avidity convalescent sera better cross-neutralized SARS-CoV-2 variants (P <.001 [Alpha]; P <.01 [Delta and Omicron]). Vaccinees only experienced meaningful avidity maturation following the booster dose, exhibiting rather limited cross-neutralizing capacity at week 25. Conclusions Avidity maturation was progressive beyond acute recovery from infection, or became apparent after the booster vaccine dose, granting broader anti-SARS-CoV-2 neutralizing capacity. Understanding the maturation kinetics of the 2 building blocks of anti-SARS-CoV-2 humoral immunity is crucial. [ABSTRACT FROM AUTHOR]

Copyright of Pan African Medical Journal is the property of Pan African Medical Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article offers information on TrypanoGEN biobank used for the elimination of human African trypanosomiasis (HAT). Topics discussed include efforts of World Health Organization in the elimination of the disease as a public health problem; role of TrypanoGEN network in understanding and eliminating the genetic basis of human susceptibility to trypanosomiasis; and characteristics and requirements of the HAT biobank;.

Copyright of Pan African Medical Journal is the property of Pan African Medical Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Pan African Medical Journal is the property of Pan African Medical Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Molecular methods have great potential for sensitive parasite detection in the diagnosis of human African trypanosomiasis (HAT), but the requirements in terms of laboratory infrastructure limit their use to reference centres. A recently developed assay detects the Trypanozoon repetitive insertion mobile element (RIME) DNA under isothermal amplification conditions and has been transformed into a ready-to-use kit format, the Loopamp Trypanosoma brucei. In this study, we have evaluated the diagnostic performance of the Loopamp Trypanosoma brucei assay (hereafter called LAMP) in confirmed T.b. gambiense HAT patients, HAT suspects and healthy endemic controls from the Democratic Republic of the Congo (DRC). Methodology/Principal findings: 142 T.b. gambiense HAT patients, 111 healthy endemic controls and 97 HAT suspects with unconfirmed status were included in this retrospective evaluation. Reference standard tests were parasite detection in blood, lymph or cerebrospinal fluid. Archived DNA from blood of all study participants was analysed in duplicate with LAMP. Sensitivity of LAMP in parasitologically confirmed cases was 87.3% (95% CI 80.9–91.8%) in the first run and 93.0% (95% CI 87.5–96.1%) in the second run. Specificity in healthy controls was 92.8% (95% CI 86.4–96.3%) in the first run and 96.4% (95% CI 91.1–98.6%) in the second run. Reproducibility was excellent with a kappa value of 0.81. Conclusions/Significance: In this laboratory-based study, the Loopamp Trypanosoma brucei Detection Kit showed good diagnostic accuracy and excellent reproducibility. Further studies are needed to assess the feasibility of its routine use for diagnosis of HAT under field conditions. [ABSTRACT FROM AUTHOR]

Background: Post-therapeutic follow-up is essential to confirm cure and to detect early treatment failures in patients affected by sleeping sickness (HAT). Current methods, based on finding of parasites in blood and cerebrospinal fluid (CSF) and counting of white blood cells (WBC) in CSF, are imperfect. New markers for treatment outcome evaluation are needed. We hypothesized that alternative CSF markers, able to diagnose the meningo-encephalitic stage of the disease, could also be useful for the evaluation of treatment outcome. Methodology/Principal findings: Cerebrospinal fluid from patients affected by Trypanosoma brucei gambiense HAT and followed for two years after treatment was investigated. The population comprised stage 2 (S2) patients either cured or experiencing treatment failure during the follow-up. IgM, neopterin, B2MG, MMP-9, ICAM-1, VCAM-1, CXCL10 and CXCL13 were first screened on a small number of HAT patients (n = 97). Neopterin and CXCL13 showed the highest accuracy in discriminating between S2 cured and S2 relapsed patients (AUC 99% and 94%, respectively). When verified on a larger cohort (n = 242), neopterin resulted to be the most efficient predictor of outcome. High levels of this molecule before treatment were already associated with an increased risk of treatment failure. At six months after treatment, neopterin discriminated between cured and relapsed S2 patients with 87% specificity and 92% sensitivity, showing a higher accuracy than white blood cell numbers. Conclusions/Significance: In the present study, neopterin was highlighted as a useful marker for the evaluation of the post- therapeutic outcome in patients suffering from sleeping sickness. Detectable levels of this marker in the CSF have the potential to shorten the follow-up for HAT patients to six months after the end of the treatment. [ABSTRACT FROM AUTHOR]

Background: Sleeping sickness due to Trypanosoma brucei (T.b.) gambiense is still a major public health problem in some central African countries. Historically, relapse rates around 5% have been observed for treatment with melarsoprol, widely used to treat second stage patients. Later, relapse rates of up to 50% have been recorded in some isolated foci in Angola, Sudan, Uganda and Democratic Republic of the Congo (DRC). Previous investigations are not conclusive on whether decreased sensitivity to melarsoprol is responsible for these high relapse rates. Therefore we aimed to establish a parasite collection isolated from cured as well as from relapsed patients for downstream comparative drug sensitivity profiling. A major constraint for this type of investigation is that T.b. gambiense is particularly difficult to isolate and adapt to classical laboratory rodents. Methodology/Principal Findings: From 360 patients treated in Dipumba hospital, Mbuji-Mayi, D.R. Congo, blood and cerebrospinal fluid (CSF) was collected before treatment. From patients relapsing during the 24 months follow-up, the same specimens were collected. Specimens with confirmed parasite presence were frozen in liquid nitrogen in a mixture of Triladyl, egg yolk and phosphate buffered glucose solution. Isolation was achieved by inoculation of the cryopreserved specimens in Grammomys surdaster, Mastomys natalensis and SCID mice. Thus, 85 strains were isolated from blood and CSF of 55 patients. Isolation success was highest in Grammomys surdaster. Forty strains were adapted to mice. From 12 patients, matched strains were isolated before treatment and after relapse. All strains belong to T.b. gambiense type I. Conclusions and Significance: We established a unique collection of T.b. gambiense from cured and relapsed patients, isolated in the same disease focus and within a limited period. This collection is available for genotypic and phenotypic characterisation to investigate the mechanism behind abnormally high treatment failure rates in Mbuji-Mayi, D.R. Congo. [ABSTRACT FROM AUTHOR]

Background: The polymerase chain reaction (PCR) has been proposed for diagnosis, staging and post-treatment follow-up of sleeping sickness but no large-scale clinical evaluations of its diagnostic accuracy have taken place yet. Methodology/Principal Findings: An 18S ribosomal RNA gene targeting PCR was performed on blood and cerebrospinal fluid (CSF) of 360 T. brucei gambiense sleeping sickness patients and on blood of 129 endemic controls from the Democratic Republic of Congo. Sensitivity and specificity (with 95% confidence intervals) of PCR for diagnosis, disease staging and treatment failure over 2 years follow-up post-treatment were determined. Reference standard tests were trypanosome detection for diagnosis and trypanosome detection and/or increased white blood cell concentration in CSF for staging and detection of treatment failure. PCR on blood showed a sensitivity of 88.4% (84.4-92.5%) and a specificity of 99.2% (97.7-100%) for diagnosis, while for disease staging the sensitivity and specificity of PCR on cerebrospinal fluid were 88.4% (84.8-91.9%) and 82.9% (71.2-94.6%), respectively. During follow-up after treatment, PCR on blood had low sensitivity to detect treatment failure. In cerebrospinal fluid, PCR positivity vanished slowly and was observed until the end of the 2 year followup in around 20% of successfully treated patients. Conclusions/Significance: For T.b. gambiense sleeping sickness diagnosis and staging, PCR performed better than, or similar to, the current parasite detection techniques but it cannot be used for post-treatment follow-up. Continued PCR positivity in one out of five cured patients points to persistence of living or dead parasites or their DNA after successful treatment and may necessitate the revision of some paradigms about the pathophysiology of sleeping sickness. [ABSTRACT FROM AUTHOR]

The article discusses the advantages and disadvantages of mini anion exchange centrifugation technique (mAECT) and modified single centrifugation (MSC) models which are used in the diagnosis and staging of sleeping sickness or human African trypanosomiasis (HAT). It notes that the improved mAECT model has more advanced analytical sensitivity, has robustness that does not need to mount collector tubes, and is applicable in field conditions, however, it requires specific centrifuge and material and has limited stability. It states that the advanced MSC model has short test times and has few manipulations, however, it is particular to a specific material and centrifuge and its cerebrospinal fluid (CSF) cannot be recovered to other tests. The developments of the models are cited.

Introduction: the aim of this study was to describe the socioemotional profile of children living in Konzo-affected areas, an epidemic toxico-nutritional palsy in sub-Saharan Africa., Methods: we evaluated the socioemotional profile of 210 children, 123 with Konzo and 87 presumed to be healthy (4-17 years) based on a structured interview conducted with their parents during an epidemioclinic survey of Konzo in Congo-Kinshasa in 2011. Neurocognitive profile was identified by the KABC-II, the BOT-2 and the global neurological symptom index of Konzo. Associative tests were carried out by using chi-square test, logistic regression and, where applicable, generalized linear model, at the significance threshold of 0.05., Results: in general, irritability, physical violence or inhibition with or without sadness were found in 46.0%, 30.2%, 18.7% of children respectively, with an increased risk of Konzo (OR = 2.6; CI95%: 1.4-4.8; p = 0.001). Socioemotional disorder was associated with underweight (OR: 0.49; CI95%: 0.31-0.78; p = 0.002) and with an elevated global neurological symptom index of Konzo (OR: 1.33; CI 95%: 1.1-1.63; p = 0.019); furthermore it exacerbated cognitive impairment in children with Konzo (interaction neurological status-socioemotional disorders D = 6.297; p = 0.013). High cognitive performances were observed in children without Konzo but with socioemotional disorders. The average concentration (standard deviation ± SD) of urinary thiocyanate was higher (554.8 ± 371.6 µmol/l) among children with Konzo associated with socioemotional disorders., Conclusion: children living in Konzo-affected areas have socioemotional disorders. Their psychopathological status and the effect of Konzo on cognition require in-depth studies., Competing Interests: Les auteurs ne déclarent aucun conflit d’intérêts.