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. 2014 Jan 4:7:6.
doi: 10.1186/1756-3305-7-6.

A tracking tool for long-lasting insecticidal (mosquito) net intervention following a 2011 national distribution in Benin

Roseric Azondekon  1 , Virgile Gnanguenon, Frederic Oke-Agbo, Speraud Houevoessa, Michael Green, Martin Akogbeto
Affiliations

A tracking tool for long-lasting insecticidal (mosquito) net intervention following a 2011 national distribution in Benin

Roseric Azondekon et al. Parasit Vectors. .

Abstract

Background: Following a mass distribution of long-lasting insecticidal nets (LLINs) in Benin, we used WHO guidelines to develop an assessment tool which is described in this report. It involved assessment of the three WHO indicators: survivorship, integrity and bio-efficacy.

Methods: To evaluate the assessment tool, we selected four communities, two in the Southern part of the country, and two in the North. One of the two assessment communities in each geographic setting had ready access to water and a higher reported frequency of washing LLINs. It was assumed that nets in communities with greater washing frequencies would show greater loss of durability. If the tool was sensitive enough to detect such differences, the field testing would confirm its suitability for general use in different settings in Benin. While durability indicators of survival and fabric integrity were quantified using standard WHO methodology, bio-efficacy was assessed using a 'new' alternative (to the WHO bioassay test), involving gas chromatography. Additionally, data management used current internet technology for 'real time' analysis at a central monitoring location.

Results: While no difference in survivorship was observed between sites with ready access to water for washing, both in the North and the South, there was a significant difference in integrity. In the South and in the North, nets from sites near water (Kessounou and Malanville) showed greater damage to integrity than did the nets from Allada and Kandi (sites far from water). As expected, LLIN integrity was significantly lower when a community was near water (p < 0.01). Bio-efficacy measurements, based on GC, were found to be so variable.

Conclusion: A rapid decrease of the LLINs fabric integrity was observed in areas near water for washing following the first 6 months post-distribution. Due to the way that the insecticide is incorporated into the LLIN fiber and its migration to the surface, confounding results were observed with the GC analysis suggesting that the WHO bio-efficacy method may also be similarly affected. The report of other assessments could help to better understand the durability of the LLINs.

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Figures

Figure 1
Figure 1
A map of Benin showing LLIN tracking sites: Kessounou and Allada in the South and Malanville and Kandi in the North.
Figure 2
Figure 2
Identification of sampling positions.
Figure 3
Figure 3
Sampling a mosquito net at Kessounou.
Figure 4
Figure 4
Mortality observed with WHO cone test and used to determine GC threshold.
Figure 5
Figure 5
ROC curves showing prediction of WHO cone bio-essay results by GC method.
Figure 6
Figure 6
Scatter plot of LLIN surface insecticide (permethrin) levels for 212 LLINs.
Figure 7
Figure 7
Net loss associated with bio-efficacy. Number of nets with insecticide levels below and above WHO threshold T0 versus T6.
See this image and copyright information in PMC

References

    1. Kitua AY, Ogundahunsi OAT, Lines J, Mgone CS. Conquering malaria: Enhancing the impact of effective interventions towards elimination in the diverse and changing epidemiology. J Glob Infect Dis. 2011;3:161. doi: 10.4103/0974-777X.81694. - DOI - PMC - PubMed
    1. NMCP. Benin’s strategic plan against malaria from 2006 to 2010. Cotonou: Ministry of health; 2006.
    1. Alonso PL, Lindsay SW, Schellenberg JRMA, Keita K, Gomez P, Shenton FC, Hill AG, David PH, Fegan G, Cham K, Greenwood BM. A malaria control trial using insecticide-treated bed nets and targeted chemoprophylaxis in a rural area of The Gambia, West Africa. Trans R Soc Trop Med Hyg. 1993;87:37–44. - PubMed
    1. Alonso PL, Lindsay SW, Armstrong JRM, de Francisco A, Shenton FC, Greenwood BM, Conteh M, Cham K, Hill AG, David PH, Fegan G, Hall AJ. The effect of insecticide-treated bed nets on mortality of Gambian children. The Lancet. 1991;337:1499–1502. doi: 10.1016/0140-6736(91)93194-E. - DOI - PubMed
    1. D’Alessandro U, Olaleye BO, McGuire W, Thomson MC, Langerock P, Bennett S, Greenwood BM. A comparison of the efficacy of insecticide-treated and untreated bed nets in preventing malaria in Gambian children. Trans R Soc Trop Med Hyg. 1995;89:596–598. doi: 10.1016/0035-9203(95)90401-8. - DOI - PubMed

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