Programme National Multisectoriel de Lutte contre le sida

BackgroundAccurate diagnosis is essential for achieving the 2030 goal of eliminating gambiense human African trypanosomiasis (gHAT) transmission. In recent years, novel screening and confirmatory laboratory tests, including rapid diagnostic tests incorporating recombinant antigens (2nd generation RDTs), an inhibition ELISA (iELISA) and RT-qPCR, have been developed. However, data on their diagnostic performance remain limited. This study aimed to evaluate the specificity of these newly developed tests, with particular emphasis on 2nd generation RDTs.MethodsDuring routine mobile team screening rounds in the Democratic Republic of the Congo, all consenting individuals aged ≥ 12 years provided a venous blood sample to screen for gHAT by Card Agglutination Test for Trypanosomiasis (CATT) and three RDTs (Abbott Bioline HAT 2.0, HAT Sero K-SeT and HAT Sero K-SeT 2.0). The remaining blood samples were shipped to the Institut National de Recherche Biomédicale, for further testing by iELISA, immune trypanolysis and RT-qPCR. gHAT cases were defined by the direct visualization of trypanosomes in blood or lymph.ResultsA total of 1503 participants were recruited in the Kwilu and Lomami provinces. Among the screening tests, CATT demonstrated the highest specificity at 98.3% (95% CI 97.6–99.0%). followed by HAT Sero K-SeT at 91.0% (95% CI 89.5–92.4%), HAT Sero K-SeT 2.0 at 87.1% (95% CI 85.4–88.8%) and Abbott Bioline HAT 2.0 at 76.4% (95% CI 74.3–78.6%). Among the laboratory tests, immune trypanolysis achieved a specificity of 97.8% (95% CI 97.1–98.6%) while iELISA reached 96.1% (95% CI 95.1–97.1%). RT-qPCR had the highest specificity at 99.9% (95% CI 99.7–100%). None of the RDTs met the 95% specificity threshold as recommended by the WHO target product profiles for gHAT, emphasizing the need for further improvements in their specificity.Trial registrationThe trial was retrospectively registered under NCT05637632 in clinicaltrials.gov on November 24, 2022.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12879-025-12278-3.

The Xpert assay has revolutionized the rapid detection of resistance to rifampicin. However, Xpert has its pitfalls. We explored potential determinants of false-positive rifampicin resistance when using Xpert, aiming to refine the precision of tuberculosis diagnostics and subsequently contribute to better patient outcomes. This is a retrospective cross-sectional analysis of archived Xpert files from the South Kivu province, used to diagnose Mycobacterium tuberculosis (MTB) between 2013 and 2018. Xpert cycle threshold was extracted for each molecular beacon probe, and ΔCt was calculated. We used the MTBDRplus line-probe assay, which covers the same 81-bp RRDR, as a reference test. Of 1900 samples positive for MTB, 220 (11.2%) were rifampicin resistant. Of the 141 patients' sputum samples that had results for both Xpert and MTBDRplus, 45 (31.9%) showed discordant results with Xpert, indicating rifampicin resistance while MTBDRplus indicated rifampicin susceptibility, suggesting false-positive rifampicin resistance detection by Xpert, predominantly in samples with very low (Ct > 28, odds ratio [OR] = 2.23, 95% CI: 1.30-3.82) or low (Ct 22-28, OR = 1.81, 95% CI: 1.21-2.71) bacterial loads. Probe E was the most frequently missed probe, followed by multiple probe dropouts or absence of probe binding (OR = 1.5, 95% CI: .731-3.076). Our findings indicate that low and very low MTB bacterial loads in sputum are strongly associated with discordant rifampicin resistance results when using Xpert. Further research into underlying mechanisms is needed to establish causality definitively.

Genomic analysis of parasites can deepen our understanding of their transmission, population structure, and important biological characteristics. Onchocerciasis (river blindness), caused by the parasitic nematode Onchocerca volvulus, involves adult worms residing in subcutaneous nodules that produce larval-stage microfilariae (mf), which are routinely detected in the skin for diagnosis. Whole-genome studies of mf are limited; most analyses have focused on the mitochondrial genome. We conducted a genome-wide analysis with 94% median nuclear genome coverage, analyzing 171, 37, and 98 mf from 16, 3, and 5 individuals from Ghana, Liberia, and the Democratic Republic of Congo, respectively. These data were used to investigate population differentiation, estimate the number of reproductive adult worms, and analyze genetic variation across chromosomes. Population genetic analyses across hosts and countries showed that nuclear genome diversity can reveal fine-scale genetic structure, even between geographically close countries, providing more resolution than mitochondrial haplotype data. By reconstructing maternal and paternal sibships, we estimated the number of reproductively active adult filariae. Comparisons between adult worm estimates from genetic data and nodule observations showed that genetics-based estimates were higher or equal to observed worm counts in 8 out of 9 hosts for female worms and 7 out of 9 hosts for male worms. Our analysis also revealed lower-than-expected X chromosome diversity, consistent with neo-X chromosome fusions in filarial species. This study represents an important step in using nuclear genome data from mf to support onchocerciasis elimination efforts and in developing genetic tools that could inform mass drug administration programs.

Background: Poliomyelitis is a vaccine-preventable disease, with oral poliomyelitis vaccines (OPVs) and injectable poliomyelitis vaccines. In the Democratic Republic of the Congo (DRC), circulating vaccine-derived polioviruses (VDPVs) persist due to intrinsic and extrinsic factors, including the quality of the cold chain, which may make the vaccines less effective. This study’s objective was to evaluate the cold chain’s quality of OPVs and its effect on the vaccine’s viability and potency at different levels in health systems in Kinshasa. Methods: A cross-sectional study was conducted in Kinshasa, collecting OPVs at different levels of the health pyramid. Vaccine viability was assessed by cell culture using a modified World Health Organization (WHO) protocol, and the viral titer was determined using the Karber formula. The vaccine titer was classified as “very good”, “good”, or “poor” according to the WHO standard’s viral titer. Results: A total of 53 vaccines were collected and analyzed, compressing 38 bivalent oral poliomyelitis (bOPV) vaccines and 15 novel oral poliomyelitis vaccines, type 2 (nOPV2). The viral titer ranged from log105.8 to log 107.3 and from log105.4 to log108.9 for the nOPV2 and the bOPV, respectively. Of these 53 vaccine samples, 10% of the bOPVs showed viral titers below the recommended WHO threshold (>106 CCID50/dose), 100% of the nOPV2 had viral titers within the WHO standards (>105 CCID50/dose), and a significant decline in the viral titer was observed for both types of vaccines (nOPV2 and bOPV) as the distribution progressed along the level of the health pyramid. Conclusions: This study demonstrated that the viral titer of OPV declined from central to peripheral areas in routine and campaign strategies in Kinshasa.

Abstract IntroductionMalaria is a public health threat in Mali, with high morbidity (37%) and mortality (25%) rates. Malaria risk stratification is needed to identify different transmission zones and prioritize the interventions, especially in resource-limited contexts. For the new National Strategic Plan, we updated stratification with World Health Organization (WHO) recommendation. This study presents the selection of interventions based on stratification.MethodData collection covered all the 75 Health Districts (HDs) in the country for the period 2018-2022. This was further supplemented by national survey data on parasitology and entomology in Mali. To estimate the adjusted incidence, the analysis considered health data reporting, malaria diagnostic positivity and health facility attendance rates at health district level to malaria cases estimated. Mixed interventions were defined based on adjusted incidence, prevalence, seasonality, vector resistance to insecticides and parasite distribution by Health Districts or region according to data available.ResultsFour strata have been defined according to the 2017 WHO Malaria Elimination Framework. Most HDs (54) fall within the highest and moderate transmission areas, covering 84% of the population (about 18 million) located in the southern and central regions. A total of 19 intervention packages were selected and adapted. We identified 61 out of 75 eligible HDs for the LLINs mass distribution campaign, 57 HDs for SMC, 67 for IPTp including community IPTp and 19 HD for vaccination.ConclusionA half of Malian population live in high-risk areas. These districts require a continuous intensification of interventions. Malaria stratification was critical for strategic planning and appropriate deployment of malaria control interventions in Mali.

<strong class="journal-contentHeaderColor">Abstract.</strong> Tropical forests play an important role in the greenhouse gas exchange between biosphere and atmosphere. Despite holding the second largest tropical forest globally, the Congo basin is generally understudied and ground based greenhouse gas flux data are lacking. In this study, high frequency measurements spanning of sixteen months from automated and manual soil chambers are combined, to characterize spatio-temporal variability in soil greenhouse gas fluxes from a lowland tropical forest in Yangambi, in the Congo Basin. Based on sub-daily continuous measurements, for CO_2, a total emission of 15.3 &plusmn; 4.4 Mg C ha^-1 yr^-1 was calculated, with highest fluxes at the start of the wetter periods and a decline in emissions during drier periods. For CH₄, the total uptake was -3.9 &plusmn; 5.2 kg C ha^-1 yr^-1. Over the whole period the soil acted as a sink however sporadic emission events were also observed. For N₂O an emission of 3.6 &plusmn; 4.1 kg N ha^-1 yr^-1 was calculated, which is higher than most previously reported tropical forest estimates. N₂O emissions decreased substantially during drier periods and emission pulses were detected after rain events. High spatial and temporal variability was observed for both CH₄ and N₂O, but less for CO₂. Higher spatial variability was assessed by the manual compared to the automated measurements. Overall, the tropical forest soil acted as a major source for CO₂ and N₂O and a minor sink for CH₄.

Plasmodium malariae is geographically widespread but neglected and may become more prevalent as P. falciparum declines. We completed the largest genomic study of African P. malariae to-date by performing hybrid capture and sequencing of 77 isolates from Cameroon (n=7), the Democratic Republic of the Congo (n=16), Nigeria (n=4), and Tanzania (n=50) collected between 2015 and 2021. There is no evidence of geographic population structure. Nucleotide diversity was significantly lower than in co-localized P. falciparum isolates, while linkage disequilibrium was significantly higher. Genome-wide selection scans identified no erythrocyte invasion ligands or antimalarial resistance orthologs as top hits; however, targeted analyses of these loci revealed evidence of selective sweeps around four erythrocyte invasion ligands and six antimalarial resistance orthologs. Demographic inference modeling suggests that African P. malariae is recovering from a bottleneck. Altogether, these results suggest that P. malariae is genomically atypical among human Plasmodium spp. and panmictic in Africa.

IntroductionIn the current study we assessed clinical laboratories’ staff ability across the city of Kinshasa with particular focus on their practices and performance regarding malaria microscopy.Materials and MethodsThis was a non-random cross-sectional study included clinical laboratories in Kinshasa and focused on cross-checking of blood slides, a questionnaire and checklist according to standardised analytic malaria microscopy procedures. Regarding the cross-checking of slides, participant responses were considered ‘corrects’ in cases of complete congruence with the reference; ‘acceptable’ for malaria-positive slides but no identification of Plasmodium species, stage of development, parasite density and/or reported as P. falciparum instead of ‘P. non falciparum’; and ‘incorrect’ if ‘false positive’ and ‘false negative’ cases.ResultsEighty-eight among the 90 targeted clinical laboratories (participation 97.8%) took part in the investigation from February to July 2019. The ability assessment revealed that individuals qualified to perform thick blood films (TBF) according to the national malaria control program (NMCP) procedures ranged from 48.6% to 100.0%. Overall cross-checking performance of 167 eligible routine slides was relatively low: 37.7%; 25.8% and 36.5% of correct, acceptable and incorrect responses, respectively. The first routine slide was correctly and acceptably scored respectively by 35.3% and 28.2% of participating laboratories (n = 85); and the second, by 40.2% and 23.2% respectively (n = 82). The sensitivity and specificity were found to be 79.4% and 53.8%, respectively. However, the relative high scores reported in relation with the ability needed to perform TBF based on NMCP standards contrasted with the poor performance from cross-checking slides. Consecutively, only one-third of the 88 participating laboratories reached a score > 60% in agreement with NMCP procedures and had acceptable responses to cross-checked slides.ConclusionsThe study was conducted as part of the activities relating to "Ensuring early diagnosis and prompt malaria treatment" component of the national malaria control strategy with NMCP support. More laboratories must implement clear and standardised malaria microscopy procedures, and need to include more rigorous quality control.