Implementation and operational feasibility of SAMBA I HIV-1 semi-quantitative viral load testing at the point-of-care in rural settings in Malawi and Uganda.

OBJECTIVE: We monitored a large-scale implementation of the Simple Amplification-Based Assay semi-quantitative viral load test for HIV-1 version I (SAMBA I Viral Load = SAMBA I VL) within Médecins Sans Frontières' HIV programmes in Malawi and Uganda, to assess its performance and operational feasibility. METHODS: Descriptive analysis of routine programme data between August 2013 and December 2016. The dataset included samples collected for VL monitoring and tested using SAMBA I VL in five HIV clinics in Malawi (four peripheral health centres and one district hospital), and one HIV clinic in a regional referral hospital in Uganda. SAMBA I VL was used for VL testing in patients who had been receiving ART for between 6 months and ten years, to determine whether plasma VL was above or below 1000 copies/mL of HIV-1, reflecting ART failure or efficacy. Randomly selected samples were quantified with commercial VL assays. SAMBA I instruments and test performance, site throughput, and delays in communicating results to clinicians and patients were monitored. RESULTS: Between August 2013 and December 2016 a total of 60 889 patient samples were analysed with SAMBA I VL. Overall, 0.23% of initial SAMBA I VL results were invalid; this was reduced to 0.04% after repeating the test once. Global test failure, including instrument failure, was 1.34%. Concordance with reference quantitative testing of VL was 2620/2727, 96.0% (1338/1382, 96.8% in Malawi; 1282/1345, 95.3% in Uganda). For Chiradzulu peripheral health centres and Arua Hospital HIV clinic, where testing was performed on-site, same-day results were communicated to clinicians for between 91% and 97% of samples. Same-day clinical review was obtained for 84.7% across the whole set of samples tested. CONCLUSIONS: SAMBA I VL testing is feasible for monitoring cohorts of 1000 to 5000 ART-experienced patients. Same-day results can be used to inform rapid clinical decision-making at rural and remote health facilities, potentially reducing time available for development of resistance and conceivably helping to reduce morbidity and mortality.

OBJECTIF: Nous avons suivi une mise en œuvre à grande échelle du test de la charge virale semi-quantitative du VIH -1 basé sur de Test de Simple Amplification version I (SAMBA I Viral Load = SAMBA I VL) au sein des programmes VIH de Médecins Sans Frontières au Malawi et en Ouganda, afin d'évaluer sa performance et sa faisabilité opérationnelle. MÉTHODES: Analyse descriptive des données du programme de routine entre août 2013 et décembre 2016. L'ensemble des données comprenait des échantillons collectés pour le suivi de la CV et testés à l'aide de SAMBA I VL dans cinq cliniques VIH au Malawi (quatre centres de santé périphériques et un hôpital de district), et une clinique VIH dans un hôpital régional de référence en Ouganda. SAMBA I VL a été utilisé pour le test de la CV chez les patients qui recevaient l'ART depuis 6 mois à dix ans, afin de déterminer si la CV plasmatique était supérieure ou inférieure à 1000 copies/ml de VIH-1, reflétant l'échec ou l'efficacité de l'ART. Des échantillons sélectionnés aléatoirement ont été quantifiés avec des tests de CV commerciaux. Les instruments de SAMBA I et les performances des tests, le débit du site et les délais dans la communication des résultats aux cliniciens et aux patients ont été suivis. RÉSULTATS: Entre août 2013 et décembre 2016, un total de 60.889 échantillons de patients ont été analysés avec SAMBA I VL. Dans l'ensemble, 0,23% des résultats initiaux de SAMBA I VL étaient invalides; ceux-ci ont été été réduits à 0,04% après avoir répété le test une fois. L'échec global du test, y compris l'échec de l'instrument, était de 1,34%. La concordance avec les tests quantitatifs de référence de la CV était de 2620/2727; 96,0% (1338/1382; 96,8% au Malawi; 1282/1345; 95,3% en Ouganda). Pour les centres de santé périphériques de Chiradzulu et la clinique VIH de l'hôpital d'Arua, où les tests ont été effectués sur place, les résultats ont été communiqués le jour même aux cliniciens pour entre 91% et 97% des échantillons. Un examen clinique le jour même a été obtenu pour 84,7% de l'ensemble des échantillons testés. CONCLUSIONS: Le test SAMBA I VL est réalisable pour le suivi de cohortes de 1.000 à 5.000 patients déjà sous ART. Les résultats le jour même peuvent être utilisés pour éclairer la prise de décision clinique rapide dans les établissements de santé ruraux et éloignés, réduisant potentiellement le temps disponible pour le développement de la résistance et contribuant éventuellement à réduire la morbidité et la mortalité.

Point-of-care viral load monitoring: outcomes from a decentralized HIV programme in Malawi.

INTRODUCTION: Routinely monitoring the HIV viral load (VL) of people living with HIV (PLHIV) on anti-retroviral therapy (ART) facilitates intensive adherence counselling and faster ART regimen switch when treatment failure is indicated. Yet standard VL-testing in centralized laboratories can be time-intensive and logistically difficult in low-resource settings. This paper evaluates the outcomes of the first four years of routine VL-monitoring using Point-of-Care technology, implemented by Médecins Sans Frontières (MSF) in rural clinics in Malawi. METHODS: We conducted a retrospective cohort analysis of patients eligible for routine VL- testing between 2013 and 2017 in four decentralized ART-clinics and the district hospital in Chiradzulu, Malawi. We assessed VL-testing coverage and the treatment failure cascade (from suspected failure (first VL>1000 copies/mL) to VL suppression post regimen switch). We used descriptive statistics and multivariate logistic regression to assess factors associated with suspected failure. RESULTS AND DISCUSSION: Among 21,400 eligible patients, VL-testing coverage was 85% and VL suppression was found in 89% of those tested. In the decentralized clinics, 88% of test results were reviewed on the same day as blood collection, whereas in the district hospital the median turnaround-time for results was 85 days. Among first-line ART patients with suspected failure (N = 1544), 30% suppressed (VL<1000 copies/mL), 35% were treatment failures (confirmed by subsequent VL-testing) and 35% had incomplete VL follow-up. Among treatment failures, 80% (N = 540) were switched to a second-line regimen, with a higher switching rate in the decentralized clinics than in the district hospital (86% vs. 67%, p < 0.01) and a shorter median time-to-switch (6.8 months vs. 9.7 months, p < 0.01). Similarly, the post-switch VL-testing rate was markedly higher in the decentralized clinics (61% vs. 26%, p < 0.01). Overall, 79% of patients with a post-switch VL-test were suppressed. CONCLUSIONS: Viral load testing at the point-of-care in Chiradzulu, Malawi achieved high coverage and good drug regimen switch rates among those identified as treatment failures. In decentralized clinics, same-day test results and shorter time-to-switch illustrated the game-changing potential of POC-based VL-testing. Nevertheless, gaps were identified along all steps of the failure cascade. Regular staff training, continuous monitoring and creating demand are essential to the success of routine VL-testing.

Therapeutic drug monitoring of nevirapine in resource-limited settings.

BACKGROUND: We developed a simple and inexpensive thin-layer chromatography (TLC) assay for semiquantitative detection of saliva concentrations of nevirapine in resource-limited settings. The method was validated in an African target population. METHODS: Paired plasma and saliva nevirapine concentrations were assayed by high-performance liquid chromatography (HPLC); saliva concentrations of nevirapine were also assayed by TLC. The rate of false-positive results was the proportion of subtherapeutic nevirapine saliva and plasma concentrations determined by HPLC that were judged to be therapeutic in saliva specimens by TLC. The rate of false-negative results was the proportion of therapeutic nevirapine saliva and plasma concentrations determined by HPLC that were judged to be subtherapeutic in saliva specimens by TLC. The extent of agreement in TLC readings between 5 technicians and 2 batches of TLC sheets was evaluated. RESULTS: Twenty-five (9%) of 286 African adults had a subtherapeutic plasma nevirapine concentration. The median ratio of nevirapine concentrations in saliva to those in plasma was 0.51:1. The rate of false-positive results for TLC was 0% (0 of 23 specimens) when TLC results were compared with HPLC results for saliva specimens and 8% (2 of 25 specimens) when TLC results were compared with HPLC results for plasma specimens. The rate of false-negative results for TLC was 1% (3 of 263 specimens) when TLC results were compared with HPLC results for saliva specimens and 1% (3 of 261 specimens) when TLC results were compared with HPLC results for plasma specimens. The extent of agreement of TLC results was substantial for the 5 technicians (Fleiss's kappa = 0.77) and for the 2 batches of sheets (Cohen's kappa = 0.80). CONCLUSIONS: The TLC assay was found to be sensitive, specific, and robust in the detection of subtherapeutic nevirapine concentrations in saliva specimens obtained from African HIV-infected adults. It is an attractive alternative to HPLC for therapeutic drug monitoring of nevirapine in resource-limited settings.

Randomized double-blind controlled Phase I/IIa trial to assess the efficacy of malaria vaccine PfCS102 to protect against challenge with P. falciparum.

The aim of this Phase I/IIa double-blind controlled trial was to test the efficacy of the sporozoite-based malaria vaccine PfCS 282-383 (PfCS102) to protect against Plasmodium falciparum parasitaemia. 16 volunteers were randomized to receive twice 30 µg of PfCS102 formulated in Montanide ISA 720 or ISA 720 alone (control). Two weeks after 2nd immunization, volunteers were challenged using 5 infected mosquitoes. All vaccinees developed antibodies against PfCS102 versus none control. 8/8 vaccinees and 6/6 controls challenged developed malaria parasitaemia. The duration from infection to onset of patent parasitaemia was similar in both groups (214 h in vaccinees and 216 in controls). PfCS102 is safe and immunogenic but provides no protection against artificial challenge in its current formulation.

Submicroscopic Plasmodium falciparum gametocyte carriage is common in an area of low and seasonal transmission in Tanzania.

OBJECTIVE: Recently developed molecular gametocyte detection techniques have shown that submicroscopic Plasmodium falciparum gametocytes are common in symptomatic patients and can infect mosquitoes. The relevance for the infectious reservoir of malaria in the general population remains unknown. In this study, we investigated submicroscopic asexual parasitaemia and gametocytaemia in inhabitants of an area of hypoendemic and seasonal malaria in Tanzania. METHODS: Two cross-sectional malariometric surveys were conducted in the dry and wet seasons of 2005 in villages in lower Moshi, Tanzania. Finger prick blood samples were taken to determine the prevalence of P. falciparum parasites by microscopy, rapid diagnostic test and real-time nucleic acid sequence-based amplification (QT-NASBA). RESULTS: 2752 individuals participated in the surveys, of whom 1.9% (51/2721) had microscopically confirmed asexual parasites and 0.4% (10/2721) had gametocytes. In contrast, QT-NASBA revealed that 32.5% (147/453) of the individuals harboured asexual parasites and 15.0% (68/453) had gametocytes. No age dependency or seasonality was observed in submicroscopic parasite carriage. DISCUSSION: Molecular detection techniques reveal that carriage of submicroscopic asexual parasite and gametocyte densities is relatively common in this low transmission area. Submicroscopic gametocytaemia is likely to be responsible for maintaining malarial transmission in the study area.

Real-time nucleic acid sequence-based amplification is more convenient than real-time PCR for quantification of Plasmodium falciparum.

Determination of the number of malaria parasites by routine or even expert microscopy is not always sufficiently sensitive for detailed quantitative studies on the population dynamics of Plasmodium falciparum, such as intervention or vaccine trials. To circumvent this problem, two more sensitive assays, real-time quantitative nucleic acid sequence-based amplification (QT-NASBA) and real-time quantitative PCR (QT-PCR) were compared for quantification of P. falciparum parasites. QT-NASBA was adapted to molecular beacon real-time detection technology, which enables a reduction of the time of analysis and of contamination risk while retaining the specificity and sensitivity of the original assay. Both QT-NASBA and QT-PCR have a sensitivity of 20 parasites/ml of blood, but QT-PCR requires a complicated DNA extraction procedure and the use of 500 microl of venous blood to achieve this sensitivity, compared to 50 microl of finger prick blood for real-time QT-NASBA. Both techniques show a significant correlation to microscopic parasite counts, and the quantification results of the two real-time assays are significantly correlated for in vitro as well as in vivo samples. However, in comparison to real-time QT-PCR, the results of real-time QT-NASBA can be obtained 12 h earlier, with relatively easy RNA extraction and use of finger prick blood samples. The prospective development of multiplex QT-NASBA for detection of various P. falciparum developmental stages increases the value of QT-NASBA for malaria studies. Therefore, for studies requiring sensitive and accurate detection of P. falciparum parasites in large numbers of samples, the use of real-time QT-NASBA is preferred over that of real-time QT-PCR.