LLIN Care and Repair Abstracts

Updated January 21, 2013

Table of Contents

1Maintenance of Insecticide Treated Nets......

1.1An Observational Study of Material Durability of Three World Health Organization-Recommended Long-Lasting Insecticidal Nets in Eastern Chad.

1.2A stitch in time: a cross-sectional survey looking at long lasting insecticide-treated bed net ownership, utilization and attrition in SNNPR, Ethiopia.

1.3Loss of Household Protection from Use of Insecticide-Treated Nets against Pyrethroid-Resistant Mosquitoes, Benin.

1.4The efficacy and physical condition of olyset insecticide-treated nets after 5 years use in rural Lao PDR.

1.5Which nets are being used: factors associated with mosquito net use in Amhara, Oromia and Southern Nations, Nationalities and Peoples' Regions of Ethiopia.

1.6How much does malaria vector control quality matter: the epidemiological impact of holed nets and inadequate indoor residual spraying.

1.7Factors associated with mosquito net use by individuals in households owning nets in Ethiopia.

1.8Mosquito nets in a rural area of Western Kenya: ownership, use and quality......

1.9Determining and addressing obstacles to the effective use of long-lasting insecticide-impregnated nets in rural Tanzania

1.10Culturally compelling strategies for behaviour change: a social ecology model and case study in malaria prevention.

1.11Maintenance behaviour and long-lasting insecticide-treated nets (LLITNs) previously introduced into Bourapar district, Khammouane province, Lao PDR.

1.12Field issues related to effectiveness of insecticide-treated nets in Tanzania......

2Evaluation of Nets After a Period of Time......

2.1Evidence for a useful life of more than three years for a polyester-based long-lasting insecticidal mosquito net in Western Uganda.

2.2Evaluation of Interceptor long-lasting insecticidal nets in eight communities in Liberia......

2.3Loss of protection with insecticide-treated nets against pyrethroid-resistant Culex quinquefasciatus mosquitoes once nets become holed: an experimental hut study.

2.4An experimental hut evaluation of Olyset® nets against anopheline mosquitoes after seven years use in Tanzanian villages

2.5Evaluation of long-lasting insecticidal nets after 2 years of household use......

2.6Evaluation of Olyset insecticide-treated nets distributed seven years previously in Tanzania..

3Wash Resistance......

3.1Wash resistance and efficacy of three long-lasting insecticidal nets assessed from bioassays on Anopheles culicifacies and Anopheles stephensi.

3.2Evaluation of the wash resistance of three types of manufactured insecticidal nets in comparison to conventionally treated nets.

3.3Wash resistance of PermaNets in comparison to hand-treated nets......

3.4Evaluation of the effects of repeated hand washing, sunlight, smoke and dirt on the persistence of deltamethrin on insecticide-treated nets.

3.5A randomized and controlled comparison of the wash-resistances and insecticidal efficacies of four types of deltamethrin-treated nets, over a 6-month period of domestic use with washing every 2 weeks, in a rural area of Iran.

3.6Multi-country field trials comparing wash-resistance of PermaNet and conventional insecticide-treated nets against anopheline and culicine mosquitoes.

3.7Laboratory wash resistance of long-lasting insecticidal nets......

3.8Experimental hut comparisons of nets treated with carbamate or pyrethroid insecticides, washed or unwashed, against pyrethroid-resistant mosquitoes.

1 Maintenance of Insecticide Treated Nets

1.1 An Observational Study of Material Durability of Three World Health Organization-Recommended Long-Lasting Insecticidal Nets in Eastern Chad.

A total of 876 nets (229 Interceptor(®), 363 Olyset(®), and 284 PermaNet(®)) were collected 14 months post-distribution of long-lasting insecticidal nets (LLINs) from 811 households of internally displaced and host communities in Dar Sila District in eastern Chad to examine their physical condition. Holes were recorded by using three hole categories (average diameter = 2, 3.5, and 15 cm) and a Proportionate Hole Index (pHI). A total of 69.5% were in poor or very poor condition. There was no significant difference in the performance between the polyester 75 denier LLINs, but they had 4.22 times the odds of having a pHI ≥ 175 (poor or very poor condition) than polyethylene 150 denier LLINs; and 39.2% were unserviceable (pHI ≥ 300) compared with only 7.7% of the polyethylene LLINs. These results provide the first comparative data on LLIN material durability to guide procurement and replacement practice, and to inform urgently needed changes in LLIN international minimum specifications and product standards.

Allan R, O'Reilly L, Gilbos V, Kilian A. An Observational Study of Material Durability of Three World Health Organization-Recommended Long-Lasting Insecticidal Nets in Eastern Chad. Am J Trop Med Hyg 2012,

1.2 A stitch in time: a cross-sectional survey looking at long lasting insecticide-treated bed net ownership, utilization and attrition in SNNPR, Ethiopia.

ABSTRACT: BACKGROUND: Since 2002/03, an estimated 4.7 million nets have been distributed in the Southern Nations, Nationalities and Peoples Region (SNNPR) among an at risk population of approximately 10 million people. Evidence from the region suggests that large-scale net ownership rapidly increased over a relatively short period of time. However, little is known about how coverage is being maintained given that the last mass distribution was in 2006/2007. This study sought to determine the status of current net ownership, utilization and rate of long lasting insecticide-treated nets (LLIN) loss in the previous three years in the context of planning for future net distribution to try to achieve sustainable universal coverage. METHODS: A total of 750 household respondents were interviewed across malarious, rural kebeles of SNNPR. Households were randomly selected following a two-stage cluster sampling design where kebeles were defined as clusters. Kebeles were chosen using proportional population sampling (PPS), and 25 households within 30 kebeles randomly chosen. RESULTS: Approximately 67.5% (95%CI: 64.1-70.8) of households currently owned at least one net. An estimated 31.0% (95%CI 27.9-34.4) of all nets owned in the previous three years had been discarded by owners, the majority of whom considered the nets too torn, old or dirty (79.9%: 95%CI 75.8-84.0). Households reported that one-third of nets (33.7%) were less than one year old when they were discarded. The majority (58.8%) of currently owned nets had 'good' structural integrity according to a proportionate Hole Index. Nearly two-thirds of households (60.6%) reported using their nets the previous night. The overriding reason for not using nets was that they were too torn (45.7%, 95% CI 39.1-50.7). Yet, few households are making repairs to their nets (3.7%, 95% CI: 2.4-5.1). CONCLUSIONS: Results suggest that the life span of nets may be shorter than previously thought, with little maintenance by their owners. With the global move towards malaria elimination it makes sense to aim for sustained high coverage of LLINs. However, in the current economic climate, it also makes sense to hark back to simple tools and messages on the importance of careful net maintenance, which could increase their lifespans.

Batisso E, Habte T, Tesfaye G, Getachew D, Tekalegne A, Kilian A, Mpeka B, Lynch C. A stitch in time: a cross-sectional survey looking at long lasting insecticide-treated bed net ownership, utilization and attrition in SNNPR, Ethiopia. Malar J 2012, 11:183.

1.3 Loss of Household Protection from Use of Insecticide-Treated Nets against Pyrethroid-Resistant Mosquitoes, Benin.

Pyrethroid resistance is becoming widespread in Anopheles gambiae mosquitoes, coinciding with expanded use of insecticide-treated nets (ITNs) throughout Africa. To investigate whether nets in use are still protective, we conducted household trials in northern and southern Benin, where An. gambiae mosquitoes are susceptible and resistant, respectively, to pyrethroids. Rooms were fitted with window traps and monitored for mosquito biting and survival rates before and after the nets were treated with pyrethroid. Sleeping under an ITN in the location with resistant mosquitoes was no more protective than sleeping under an untreated net, regardless of its physical condition. By contrast, sleeping under an ITN in the location with susceptible mosquitoes decreased the odds of biting by 66%. ITNs provide little or no protection once the mosquitoes become resistant and the netting acquires holes. Resistance seriously threatens malaria control strategies based on ITN

Asidi A, N'guessan R, Akogbeto M, Curtis C, Rowland M. Loss of Household Protection from Use of Insecticide-Treated Nets against Pyrethroid-Resistant Mosquitoes, Benin. Emerg Infect Dis 2012, 18:1101-6.

1.4 The efficacy and physical condition of olyset insecticide-treated nets after 5 years use in rural Lao PDR.

We assessed the insecticidal efficacy of Olyset nets after 5 years of use in rural villages of Lao PDR and evaluated the relationship between the physical condition of the nets and their insecticidal effect. Our results showed that most of the Olyset nets remained effective after 5 years of use; however, there was no significant relationship between the physical condition of the nets (ie, presence of holes, level of stains) and the insecticidal effect. The presence of large holes in polyester nets compared to the Olyset nets suggest the Olyset nets are stronger; however, nearly half of Olyset nets had small holes or had been previously repaired. Interestingly, the insecticide concentration and knockdown (KD) rate for 3 stored nets was low compared to the other nets routinely used in the house. To maintain the effectiveness of Olyset nets in rural villages of Lao PDR and other areas, residents should be advised to repair and store the nets appropriately and avoid exposure to high temperatures and direct sunlight for long periods.

Tsuzuki A, Khamlome B, Kawada H, Eto H, Phompida S, Takagi M. The efficacy and physical condition of olyset insecticide-treated nets after 5 years use in rural Lao PDR. Southeast Asian J Trop Med Public Health 2011, 42:268-73.

1.5 Which nets are being used: factors associated with mosquito net use in Amhara, Oromia and Southern Nations, Nationalities and Peoples' Regions of Ethiopia.

ABSTRACT: BACKGROUND: There has been recent large scale-up of malaria control interventions in Ethiopia where transmission is unstable. While household ownership of long-lasting insecticidal nets (LLIN) has increased greatly, there are concerns about inadequate net use. This study aimed to investigate factors associated with net use at two time points, before and after mass distribution of nets. METHODS: Two cross sectional surveys were carried out in 2006 and 2007 in Amhara, Oromia and SNNP regions. The latter was a sub-sample of the national Malaria Indicator Survey (MIS 3R). Each survey wave used multi-stage cluster random sampling with 25 households per cluster (224 clusters with 5,730 households in Baseline 2006 and 245 clusters with 5,910 households in MIS 3R 2007). Net ownership was assessed by visual inspection while net utilization was reported as use of the net the previous night. This net level analysis was restricted to households owning at least one net of any type. Logistic regression models of association between net use and explanatory variables including net type, age, condition, cost and other household characteristics were undertaken using generalized linear latent and mixed models (GLLAMM). RESULTS: A total of 3,784 nets in 2,430 households were included in the baseline 2006 analysis while the MIS 3R 2007 analysis comprised 5,413 nets in 3,328 households. The proportion of nets used the previous night decreased from 85.1% to 56.0% between baseline 2006 and MIS 3R 2007, respectively. Factors independently associated with increased proportion of nets used were: LLIN net type (at baseline 2006); indoor residual spraying (at MIS 3R 2007); and increasing wealth index at both surveys. At both baseline 2006 and MIS 3R 2007, reduced proportion of nets used was independently associated with increasing net age, increasing damage of nets, increasing household net density, and increasing altitude (>2,000m). CONCLUSION: This study identified modifiable factors affecting use of nets that were consistent across both surveys. While net replacement remains important, the findings suggest that: more education about use and care of nets; making nets more resistant to damage; and encouraging net mending are likely to maximize the huge investment in scale up of net ownership by ensuring they are used. Without this step, the widespread benefits of LLIN cannot be realized.

Ngondi JM, Graves PM, Gebre T, Mosher AW, Shargie EB, Emerson PM, Richards FO, Ethiopia EM. Which nets are being used: factors associated with mosquito net use in Amhara, Oromia and Southern Nations, Nationalities and Peoples' Regions of Ethiopia. Malar J 2011, 10:92.

1.6 How much does malaria vector control quality matter: the epidemiological impact of holed nets and inadequate indoor residual spraying.

Background: Insecticide treated nets (ITN) and indoor residual spraying (IRS) are the two pillars of malaria vector control in Africa, but both interventions are beset by quality and coverage concerns. Data from three control programs were used to investigate the impact of: 1) the physical deterioration of ITNs, and 2) inadequate IRS spray coverage, on their respective protective effectiveness. Methods: Malaria indicator surveys were carried out in 2009 and 2010 in Bioko Island, mainland Equatorial Guinea and Malawi to monitor infection with P.falciparum in children, mosquito net use, net condition and spray status of houses. Nets were classified by their condition. The association between infection and quality and coverage of interventions was investigated. Results: There was reduced odds of infection with P.falciparum in children sleeping under ITNs that were intact (Odds ratio (OR): 0.65, 95% CI: 0.55-0.77 and OR: 0.81, 95% CI: 0.56-1.18 in Equatorial Guinea and in Malawi respectively), but the protective effect became less with increasingly worse condition of the net. There was evidence for a linear trend in infection per category increase in deterioration of nets. In Equatorial Guinea IRS offered protection to those in sprayed and unsprayed houses alike when neighbourhood spray coverage was high ($80%) compared to those living in areas of low IRS coverage (,20%), regardless of whether the house they lived in was sprayed or not (adjusted OR = 0.54, 95% CI 0.33-0.89). ITNs provided only personal protection, offering no protection to non users. Although similar effects were seen in Malawi, the evidence was much weaker than in Equatorial Guinea. Conclusions: Universal coverage strategies should consider policies for repair and replacement of holed nets and promote the care of nets by their owners. IRS programs should ensure high spray coverage since inadequate coverage gives little or no protection at all.

Rehman AM, Coleman M, Schwabe C, Baltazar G, Matias A, Gomes IR, Yellott L, Aragon C, Nchama GN, Mzilahowa T, Rowland M, Kleinschmidt I. How much does malaria vector control quality matter: the epidemiological impact of holed nets and inadequate indoor residual spraying. PLoS One 2011, 6:e19205.

1.7 Factors associated with mosquito net use by individuals in households owning nets in Ethiopia.

BACKGROUND: Ownership of insecticidal mosquito nets has dramatically increased in Ethiopia since 2006, but the proportion of persons with access to such nets who use them has declined. It is important to understand individual level net use factors in the context of the home to modify programmes so as to maximize net use. METHODS: Generalized linear latent and mixed models (GLLAMM) were used to investigate net use using individual level data from people living in net owning households from two surveys in Ethiopia: baseline 2006 included 12,678 individuals from 2,468 households and a sub-sample of the Malaria Indicator Survey (MIS) in 2007 included 14,663 individuals from 3,353 households. Individual factors (age, sex, pregnancy); net factors (condition, age, net density); household factors (number of rooms [2006] or sleeping spaces [2007], IRS, women's knowledge and school attendance [2007 only], wealth, altitude); and cluster level factors (rural or urban) were investigated in univariate and multi-variable models for each survey. RESULTS: In 2006, increased net use was associated with: age 25-49 years (adjusted (a) OR = 1.4, 95% confidence interval (CI) 1.2-1.7) compared to children U5; female gender (aOR = 1.4; 95% CI 1.2-1.5); fewer nets with holes (Ptrend = 0.002); and increasing net density (Ptrend < 0.001). Reduced net use was associated with: age 5-24 years (aOR = 0.2; 95% CI 0.2-0.3). In 2007, increased net use was associated with: female gender (aOR = 1.3; 95% CI 1.1-1.6); fewer nets with holes (aOR [all nets in HH good] = 1.6; 95% CI 1.2-2.1); increasing net density (Ptrend < 0.001); increased women's malaria knowledge (Ptrend < 0.001); and urban clusters (aOR = 2.5; 95% CI 1.5-4.1). Reduced net use was associated with: age 5-24 years (aOR = 0.3; 95% CI 0.2-0.4); number of sleeping spaces (aOR [per additional space] =0.6, 95% CI 0.5-0.7); more old nets (aOR [all nets in HH older than 12 months] = 0.5; 95% CI 0.3-0.7); and increasing household altitude (Ptrend < 0.001). CONCLUSION: In both surveys, net use was more likely by women, if nets had fewer holes and were at higher net per person density within households. School-age children and young adults were much less likely to use a net. Increasing availability of nets within households (i.e. increasing net density), and improving net condition while focusing on education and promotion of net use, especially in school-age children and young adults in rural areas, are crucial areas for intervention to ensure maximum net use and consequent reduction of malaria transmission.

Graves PM, Ngondi JM, Hwang J, Getachew A, Gebre T, Mosher AW, Patterson AE, Shargie EB, Tadesse Z, Wolkon A, Reithinger R, Emerson PM, Richards FO. Factors associated with mosquito net use by individuals in households owning nets in Ethiopia. Malar J 2011, 10:354.

1.8 Mosquito nets in a rural area of Western Kenya: ownership, use and quality.

Background Insecticide-treated nets (ITNs) are regarded as one of the most effective strategies to prevent malaria in Africa. This study analyses the use and quality of nets owned by households in an area of high net coverage. Methods A structured questionnaire on ownership and use of nets was administered to the households of individuals sampled from a local health centre in south Kisii district, Kenya. A physical inspection of all the nets in the households was done and their conditions recorded on spot check forms designed for that purpose. Results Of the 670 households surveyed, 95% owned at least one net. Only 59% of household residents slept under a net during the night prior to the survey. 77% of those who slept under a net used an insecticide-treated net (ITN) or long-lasting insecticide-treated nets (LLIN). Out of 1,627 nets in the survey households, 40% were deemed to be of poor quality because of holes. Compared to other age groups, children aged 5-14 years were most likely to have slept under nets of poor quality (odds ratio 1.41; p= 0.007). Conclusions Although net ownership was high following increased delivery of ITNs, continuous promotion of effective maintenance and routine use is needed and efforts to replace damaged nets must be implemented.