Longitudinal analysis of the prevalence of minor <i>Plasmodium</i> spp. in the reservoir of asymptomatic infections through sequential interventions in Northern Sahelian Ghana
Notice bibliographique
Résumé
ABSTRACT Current interventions targeting malaria control in sub-Saharan Africa (SSA) are focused on Plasmodium falciparum , the most prevalent species infecting humans. Despite renewed efforts for malaria elimination in SSA, little attention has been paid to the neglected parasites P. malariae and P. ovale spp. and the impact of interventions like long-lasting insecticidal nets (LLINs), indoor residual spraying (IRS) with non-pyrethroid insecticides, and/or seasonal malaria chemoprevention (SMC) on these minor Plasmodium spp. To address this research gap, this study was undertaken to assess the efficacy of two sequential interventions, IRS and SMC combined with LLINs, on minor- Plasmodium spp. infections in Bongo District, an area characterized by high seasonal transmission in the Northern Sahelian belt of Ghana. Using an interrupted time-series study, five age-stratified surveys, each of ∼2,000 participants, were undertaken at the end of the wet seasons between 2012 and 2022. Across this 10-year study period, infections with P. malariae and P. ovale spp. were detected using a species-specific PCR targeting the 18S rRNA gene. In 2015, following IRS, the prevalence of the minor Plasmodium spp. declined in all ages from baseline in 2012, with participants being significantly less likely to be infected with P. malariae (13.7% vs 1.4%) and P. ovale spp. (5.7% vs 0.4%). Despite this decline, in 2017, 32 months after IRS was discontinued and SMC was introduced, the prevalence of P. malariae (2.9%) and P. ovale spp. (4.0%) rebounded 2- and 10-fold, respectively. This rebound in the minor species was observed in all age groups, except for the younger children (< 5 years) targeted by SMC. Finally, when we examined this population in 2020 and 2022 after sustained deployment of SMC, the prevalence of P. malariae continued to increase (7.4% and 5.8%), while the prevalence of P. ovale spp. declined (2.6% and 1.3%). Results show that both IRS and SMC were effective not only against P. falciparum but also reduced the prevalence of P. malariae and P. ovale spp. in Bongo District. Going forward, molecular diagnostics will be critical to identify changes in the submicroscopic reservoir of the minor Plasmodium spp. found in adolescents and adults and to achieve malaria elimination in this region of Ghana. AUTHOR SUMMARY To achieve malaria elimination, the use of molecular diagnostics for surveillance of the Plasmodium spp. reservoir is essential. Such diagnostics are critical to detect hidden reservoirs of submicroscopic minor-species infections with P. malariae and P. ovale spp. Here we examine the impact of two sequential malaria control interventions, indoor residual spraying (IRS) with non-pyrethroid insecticides and seasonal malaria chemoprevention (SMC) with sulfadoxine-pyrimethamine plus amodiaquine administered to all children < 5 years, combined with long-lasting insecticidal nets (LLINs) impregnated with pyrethroids to reduce the reservoir of Plasmodium spp. infections where P. falciparum is dominant and the minor species, P. malariae and P. ovale spp., were also found. This interrupted time-series study, undertaken over 10 years (2012-2022) in Bongo District, located in the Northern Sahelian belt of Ghana, identified that IRS and SMC reduced the prevalence of all Plasmodium spp. IRS significantly reduced the prevalence of single- and mixed- Plasmodium spp. infections across all age groups. However, following its discontinuation a rebound was observed for P. falciparum and minor-species infections, especially in adolescents and adults. Although SMC maintained a near-zero prevalence of all Plasmodium spp. infections, its impact was limited to the target age group (< 5 years). Furthermore, this study showed that following the discontinuation of IRS, the older children, adolescents, and adults, not eligible for SMC, continued to harbour Plasmodium spp. infections, including minor species, thus sustaining the reservoir. These results show that by combining vector control inventions as well as targeting all age groups with chemoprevention, high-burden countries in sub-Saharan Africa, including Ghana, could bring the Plasmodium spp. reservoir closer to elimination more rapidly.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,002 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».