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. 2022 Apr 11;22(1):719.
doi: 10.1186/s12889-022-13051-w.

Survival of eight LLIN brands 6, 12, 24 and 36 months after a mass distribution campaign in rural and urban settings in Senegal

Mbaye Diouf  1 , Babacar Thiendella Faye  2 , El Hadji Diouf  3 , Abdoulaye Kane Dia  3 , Abdoulaye Konate  3 , Fatou Ba Fall  4 , Doudou Sene  4 , Mame Birame Diouf  5 , Libasse Gadiaga  4 , Lassana Konate  3 , Demba Anta Dione  6 , Roger Clément Tine  5 , Ousmane Faye  3
Affiliations

Survival of eight LLIN brands 6, 12, 24 and 36 months after a mass distribution campaign in rural and urban settings in Senegal

Mbaye Diouf et al. BMC Public Health. .

Abstract

Background: Long lasting insecticidal nets (LLIN) are one of the core components of global malaria prevention and control. The lifespan of LLIN varies widely depending on the population or environment, and randomized studies are required to compare LLIN inaccording to arbitrary thresholds households under different field conditions. This study investigated survival of different LLIN brands in Senegal.

Methods: Ten thousand six hundred eight LLINs were distributed in five regions, each stratified by rural and urban setting. As part of the longitudinal follow-up, 2222 nets were randomly sampled and monitored from 6 to 36 months. Using random effects for households, Bayesian models were used to estimate independent survival by net type (Interceptor®, Life Net®, MAGNet™, Netprotect®, Olyset® Net, PermaNet® 2.0 R, PermaNet® 2.0 C, Yorkool® LN) and by area (rural/urban). In addition to survival, median survival time and attrition of each LLIN brand was determined. Attrition was defined as nets that were missing because they were reported given away, destroyed and thrown away, or repurposed.

Results: Three net types had a proportion of survival above 80% after 24 months: Interceptor®87.8% (95% CI 80-93.4); conical PermaNet® 2.0 86.9% (95% CI 79.3-92.4) and Life Net® 85.6% (95% CI 75-93). At 36 months, conical PermaNet® 2.0 maintained a good survival rate, 79.5% (95% CI 65.9-88.8). The attrition due to redistributed nets showed that the two conical net types (PermaNet® 2.0 and Interceptor®) were more often retained by households and their median retention time was well above 3 years (median survival time = 3.5 years for PermaNet® 2.0 and median survival time = 4 years for Interceptor®). Despite this good retention, Interceptor® had weak physical integrity and its median survival due to wear and tear was below 3 years (median survival time = 2.4 years). The odds ratio of survival was 2.5 times higher in rural settings than in urban settings (OR 2.5; 95% CI 1.7-3.7).

Conclusions: Differences in survival among LLIN may be driven by brand, shape or environmental setting. In this study in Senegal, conical PermaNet® 2.0 were retained in households while rectangular PermaNet® 2.0 had lower retention, suggesting that net shape may play a role in retention and should be further investigated. Distribution of preferred LLIN shape, accompanied by good communication on care and repair, could lead to increased effective lifespan, and allow for longer intervals between universal coverage campaigns.

Keywords: LLIN; Median survival time; Retention; Senegal; Survival.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Location of study sites (map created by using ArcGIS software)
Fig. 2
Fig. 2
Probability of survival of different LLIN brands. Abbreviations: PermaNet 2.0 cir: PermaNet 2.0 Curcilar, PermaNet 2.0 rect: PermaNet 2.0 Rectangular
Fig. 3
Fig. 3
Survival rate in rural and urban areas at 6, 12, 24 and 36 months
Fig. 4
Fig. 4
Retention rate in rural area at 6, 12, 24 and 36 months
Fig. 5
Fig. 5
Survival rate of different LLIN brands at 6, 12, 24 and 36 months. Abbreviations: PermaNet 2.0 C:PermaNet 2.0 Circular, PermaNet 2.0 R: PermaNet 2.0 Rectangular
Fig. 6
Fig. 6
Retention rate of different LLIN brands at 6, 12, 24 and 36 months. Abbreviations: PermaNet 2.0 C: PermaNet 2.0 Circular, PermaNet 2.0 R: PermaNet 2.0 Rectangular
Fig. 7
Fig. 7
Median survival rate time of different LLIN brands. Abbreviations: PermaNet 2.0 C: PermaNet 2.0 Circular, PermaNet 2.0 R: PermaNet 2.0 Rectangular
Fig. 8
Fig. 8
Median retention time of different LLIN brands. Abbreviations: PermaNet 2.0 C: PermaNet 2.0 Circular, PermaNet 2.0 R: PermaNet 2.0 Rectangular
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