Characteristics of malaria vector populations and transmission before a randomised controlled trial assessing the efficacy of next-generation insecticide-treated nets in Côte d’Ivoire
Bibliographic record
Abstract
Abstract Background The World Health Organization (WHO) recommends mass distribution of insecticide-treated nets (ITNs) to prevent malaria transmission. Unfortunately, resistance to pyrethroids affects the efficacy of standard ITNs. To overcome this resistance and continue to protect the population, the WHO has recommended new types of ITNs that combine a pyrethroid insecticide with either a synergist (PBO) or a second insecticide, such as chlorfenapyr. This study examines the baseline characteristics of malaria vectors prior to the distribution of three types of insecticide-treated nets as part of a three-arm randomised controlled trial: Interceptor G2 (pyrethroid–chlorfenapyr), VEERALIN (pyrethroid–PBO), and MAGNet (pyrethroid only). Methods The study was carried out in 40 villages (grouped into 33 clusters) of Tiébissou district in central Côte d’Ivoire. To assess biting rate and biting behaviour, human landing catches were conducted hourly indoors and outdoors in six randomly selected houses in each cluster, starting at 18:00 and continuing until 08:00 the next morning. Adult mosquitoes collected were morphologically identified, and a subset of Anopheles gambiae sensu lato (s.l.) and An. funestus s.l. were speciated by quantitative PCR (qPCR). Plasmodium sporozoite infections were detected by qPCR to estimate infection rates. The entomological inoculation rate was calculated as the product of the mosquito biting rate and the sporozoite infection rate. Results Among the 10,698 mosquitoes collected, An. gambiae s.l. was the predominant species, accounting for 62.5% (n = 6683) of the catch, followed by An. funestus s.s., which accounted for 19.8% (n = 2120). Of the sub-sample of An. gambiae s.l. processed by PCR, 79.0% (n = 1291/1635) were An. coluzzii and the remaining were Anopheles gambiae s.s. Malaria vectors were highly aggressive, with an average of 14.8 bites/person/night for An. coluzzii, 2.0 b/p/n for An. gambiae s.s. and 5.4 b/p/n for An. funestus, representing an overall average of 22.2 b/p/n (95% CI 17.2–27.2 b/p/n). No significant difference was found in biting activity between indoor and outdoor environments (Z = −0.25, P = 0.803). Plasmodium sporozoite infection rate was 2.4% (95% CI 1.3–3.6%) for An. coluzzii, 1.5% (95% CI 0.3–2.6%) for An. gambiae s.s. and 2.7% (95% CI 1.2–4.3%) for An. funestus. The estimated overall entomological inoculation rate was 0.4 infected b/p/n (95% CI 0.3–0.6) and varied between 0.0 and 0.2 infective bites/person/night according to species. There was no difference observed in entomological infection rate (EIR) between capture locations (indoors versus outdoors; Z = 1.521, P = 0.128). Conclusions This study shows that An. coluzzii and An. funestus were the main malaria vectors and showed similar biting patterns both indoors and outdoors. Anopheles funestus was found in high density in a limited number of villages. Malaria transmission was high despite universal distribution of pyrethroid-ITN in the district. Graphical Abstract
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.008 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".