Background
Initial experimental development and evaluation of insecticide-treated housing materials
Field site, country, trial type | Intervention(s) | Insecticide (dosage) | Intervention coverage | Control(s) (dosage) | Major malaria vector speciesresistance status
| Entomological parametersb
| References | |||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Mortality | Deterrence | Exiting rates | Blood feeding inhibition | Personal protection | Impact on insecticide resistance | |||||||
Afghan refugee camp, Pakistan, experimental platforms | Impregnated polythene tarpaulins | Deltamethrin | Full coveragea
| Untreated polythene tarpaulin |
An. subpictus
ND, An. stephensi
ND
| High mosquito mortality (86–100%); no significant differences between interventions | ND | ND | No impact on blood feeding (~20% for all interventions) | ND | ND | [36] |
(45 mg/m2) | ||||||||||||
Sprayed polythene tarpaulins | (30 mg/m2) | |||||||||||
Impregnated polythene tents | (45 mg/m2) | |||||||||||
Afghan refugee camp, Pakistan, experimental platforms | Polyethylene canvas | Deltamethrin (ND) | Full coverage | Untreated canvas tent |
Anophelines (spp. grouped)ND
| Increased mosquito mortality relative to control (51 vs. 26%, respectively) | No significant reduction in mean no. of mosquitoes relative to control (7 vs. 19, respectively) | ND | Reduced blood feeding relative to control (9 vs. 46%, respectively) | ND | ND | [37] |
Bobo Dioulasso, Burkina Faso, experimental West African huts [50] | Polyethylene sheeting | Permethrin (2% w/w) | Ceiling only | Untreated polyethylene sheeting |
An. gambiae
r
| Mortality correlated with coverage (20% for two walls; 45% for four walls; 46% for four walls + ceiling covered) | Deterrence correlated with coverage (28% for two walls; 43% for four walls; 46% for four walls + ceiling covered) | All treatments highly repellent (induced-exophily 68–78%) | No significant impact on blood feeding; level of inhibition correlated with surface area covered (10% for two walls vs. 27% for four walls + ceiling) | ND | Mortality and blood feeding inhibition kdr
r/kdr
r < kdr
r/kdr
s + kdr
s
/kdr
s (19 vs. 64% and 12 vs. 62% for four walls + ceiling, respectively) | [38] |
Two walls | ||||||||||||
Four walls | Untreated control | |||||||||||
Four walls + ceiling | ||||||||||||
Cotonou, Benin, experimental West African huts | Polypropylene mesh | Bendiocarb (200 mg/m2) | Top thirds of walls | Deltamethrin-treated mosquito net (ITN; 45 mg/m2) |
An. gambiae
r
| Mortality proportional to wall surface area covered (80% vs. 100% for upper third of wall or full coverage, respectively) | No significant reduction in mean no. of mosquitoes in full coverage hut relative to control (202 vs. 206, respectively) | ND | High levels of blood feeing inhibition; no significant increase when combining wall treatments with ITNs compared to ITNs alone (100% vs. 94%, respectively) | ND | ND | [39] |
Full coverage | Untreated mosquito net | |||||||||||
Bobo Dioulasso, Burkina Faso, experimental West African huts | Polypropylene sheeting (ITPS) | Bendiocarb (400 mg/m2) | Upper thirds of walls | Deltamethrin LLIN (PermaNet® 2.0; 55 mg/m2) |
An. gambiae
r
| Significantly higher mosquito mortality when interventions used in combination (ITPS + LLIN: 73% vs. ITPS alone: 53%) | ND | Significantly higher vector exophily when interventions combined (LLIN + IRS: 61%; ITPS + LLINs: 50%) | Significant blood feeding inhibition only when ITPS combined with LLIN (58%) relative to untreated control | ND | Frequency of ace-1
R
allele significantly higher among heterozygote survivors from individual IRS and ITPS treatments but not when combined with LLIN | [41] |
IRS (bendiocarb; 400 mg/m2) | Mortality similar for partial coverage of ITPS vs. full coverage with IRS (53% vs. 42%, respectively) | |||||||||||
Untreated mosquito net | ||||||||||||
Bobo Dioulasso, Burkina Faso, experimental West African huts | Polyethylene sheeting (ITPS) | Permethrin (2% w/w) | Full coverage | Holed permethrin LLIN (Olyset®; 2% w/w) |
An. gambiae
r
| Significantly higher mosquito mortality when ITPS used in combination with LLIN (60%) compared to alone (34%) | No significant reductions in mean no. of mosquitoes in ITPS huts without (443) or with untreated nets (309-315), relative to control (422) | Significant increase in exophily for single (ITPS alone: 80%; LLIN alone: 77%) and combined interventions (ITPS + LLIN: 79%) | Combined use of ITPS + LLIN did not significantly increase blood feeding inhibition over LLIN alone (75% vs. 82%, respectively) | Combined use of ITPS + LLIN significantly increased personal protection over LLIN alone (88% vs. 16%, respectively | Significantly more kdr
r/kdr
r dead with LLIN (55%) and ITPS + LLIN (67%) than ITPS alone (17%) | [42] |
Intact or holed untreated mosquito net | ||||||||||||
Untreated control | ||||||||||||
Muheza, Tanzania, experimental East African huts [51] | Polyester wall hangings (NWH) | Pirimiphos methyl (1 g/m2) | Ceiling only | Untreated control |
An. gambiae s.l.s/r(c)
, An. funestus
|
An. gambiae and An. funestus mortality significantly higher for p-methyl NWH than deltamethrin NWHs (92% vs. 11% and 78% vs. 6%, respectively for two walls) | Significant reductions in mosquito entry for p-methyl (65–95%) and deltamethrin (50–56%) treated NWH | Significantly increased exiting rates in NWH huts compared to untreated control | Limited effect on blood feeding rates (52–77%) relative to untreated control (64–67%) | ND | ND | [46] |
Two walls | ||||||||||||
Four walls |
An. gambiae and An. funestus mortality significantly higher for two walls than ceilings only (59 and 39%, respectively) | Deterrence increased with increasing coverage (65–77% vs. 92–95% for two walls vs. four walls + ceiling) | ||||||||||
Four walls + ceiling | ||||||||||||
No improvement in mosquito mortality when coverage increased beyond two walls | ||||||||||||
Deltamethrin (55 mg/m2) | Two walls | |||||||||||
Tiassalé, Côte d’Ivoire, experimental West African huts | Polyethylene wall lining (WL) | Pirimiphos methyl (1 g/m2) | Four walls | Holed deltamethrin LLIN (PermaNet® 2.0; 55 mg/m2) |
An. gambiae s.s.r
| Significantly higher mortality with p-methyl WL than pyrethroid WL (66% vs. 32%, respectively) | Significant reductions in mosquito entry for p-methyl WL/NHW only when combined with LLIN (59%/65% vs. 28%/3%, respectively) | Significantly increased exiting rates for p-methyl WL (53%) and p-methyl NWH + LLIN (59%), relative to untreated control (29%) | Limited effect on blood feeding rates (82–94%) relative to untreated control (95%), unless combined with LLIN (9–13%) | Limited personal protection for p-methyl WL/NWH relative to untreated control (4%/0%), unless combined with LLIN (93%/92%) | Significantly higher numbers of ace-1
R
heterozygote (RS) and homozygote (RR) survivors compared to susceptible homozygotes (SS) following exposure to p-methyl WLs/NHWs | [47] |
Four walls + ceiling | ||||||||||||
Holed untreated mosquito net | No improvement in mosquito mortality when p-methyl WL/NWH coverage increased from walls only (66%/49%) to walls + ceilings (56%/69%) | Combined WL and LLIN did not limit the selection of ace-1
R
compared to WL alone | ||||||||||
Nylon NHW | Pirimiphos methyl (1 g/m2) | Four walls | ||||||||||
Four walls + ceiling | Untreated plastic sheeting | No increase in mosquito mortality when WL/NHW combined with LLINs (72%/61% vs. 61%/53%, respectively) | ||||||||||
Polyethylene WL (ZeroVector®) | Deltamethrin (175 mg/m2) | Four walls | ||||||||||
Bobo Dioulasso, Burkina Faso, experimental West African huts | Polyethylene WL | Pirimiphos methyl (1 g/m2) | Four walls | Holed deltamethrin LLIN (PermaNet® 2.0; 55 mg/m2) |
An. gambiae s.s.s/r(c)
| Significantly higher mortality with p-methyl WL than pyrethroid WL (>95% vs. 40%, respectively) | Largest reductions in mosquito entry for pyrethroid WL and p-methyl WL when used in combination with LLIN (74 and 62%, respectively) | Significantly increased exiting rates for p-methyl WL (53%), relative to untreated control (33%) | Blood feeding significantly reduced when p-methyl WL/NWHs combined with LLIN (91%/90% vs. 50/50%, respectively) | Personal protection for p-methyl WL/NWH relative to untreated control (56%/72%), increased when combined with LLIN (95%/94%) | Significantly higher numbers of ace-1
R
survivors (100%) following exposure to p-methyl WL alone, compared to susceptible vectors (32%) | [48] |
Four walls + ceiling | ||||||||||||
Holed untreated mosquito net | Significantly higher mortality with p-methyl WL/NHW either alone or in combination with LLIN (100% for all) | Combined WL and LLIN limited the selection of ace-1
R
compared to WL alone | ||||||||||
Nylon NHW | Pirimiphos methyl (1 g/m2) | Four walls | ||||||||||
Four walls + ceiling | Untreated plastic sheeting | No significant increase in mortality when pyrethroid WL combined with LLINs (48% vs. 40%, respectively) | ||||||||||
Polyethylene WL (ZeroVector®) | Deltamethrin (175 mg/m2) | Four walls | ||||||||||
Four walls + ceiling |
Initial community-level trials of insecticide-treated housing materials
Field site, country, trial type | Intervention(s) | Insecticide (dosage) | Intervention coverage | Control(s) (dosage) | Major malaria vector speciesresistance status
| Impact on vector populationsc
| Impact on disease incidencec
| References |
---|---|---|---|---|---|---|---|---|
Orissa, India, community-levela
| Polyethylene sheeting (ITPS) | Deltamethrin (55 mg/m2) | Full coverageb
| Untreated plastic sheeting |
An. culicifacies
s, An. fluviatilis
s
| Significant reductions in mosquito house entry (80–89%), vector indoor population density (95–100%), blood feeding (75%) and parity rates (74–77%) | Significant reduction in malaria incidence (65–70%) | [40] |
Untreated control | Increased immediate (56%) and delayed (100%) mosquito mortality and induced exophily (41%) | |||||||
Human blood index decreased to 0 | ||||||||
Uttar Pradesh, India, community-level (temporary labour shelters) | Polyethylene sheeting (ITPS) | Deltamethrin (265 mg/m2) | Full coverage | Untreated plastic sheeting |
An. culicifacies
s, An. fluviatilis
s
| Significant reductions in indoor vector population density and blood feeding, both to 0% | Significant reduction in malaria incidence to 0% | [43] |
Liberian refugee camps, Sierra Leone, community-level (temporary shelters) | Polyethylene sheeting (ITPS) | Deltamethrin (55 mg/m2) | Ceiling + roof | Untreated plastic sheeting |
An. gambiae s.l.s, An. funestus s.l.s
| ND | Protective efficacy from malaria infection of 60% and 15% for full or partial ITPS coverage, respectively | [44] |
Four tent walls + ceiling | Significant increase in time to first malaria infection among full ITPS coverage group | |||||||
Significant increases in mean Hb concentration in both intervention groups | ||||||||
Ouidah-Kpomassè-Tori Bossito, Benin, community-level | Polypropylene sheeting (ITPS) | Bendiocarb (200 mg/m2) | Upper thirds of walls | Deltamethrin LLIN (PermaNet® 2.0; 55 mg/m2) (targeted coverage to pregnant women and <6 years) |
An. gambiae s.l.s/r, An. funestus s.l.ND
| No significant reductions in human biting rate, sporozoite rate or EIR for all interventions | No significant reductions in malaria incidence, prevalence or parasite density for ITPS + LLIN, UC of LLIN or LLIN + IRS compared to targeted LLIN | [21] |
Significantly greater proportions of parous mosquitoes and indoor resting vectors in ITPS + LLIN villages | ||||||||
IRS | Bendiocarb (400 mg/m2) | All house walls |
kdr allele frequency increased in all intervention groups | |||||
PermaNet® 2.0 LLIN | Deltamethrin (55 mg/m2) | Universal coverage | ||||||
Balombo, Angola, community-level | Polyethylene sheeting (ITPS) (ZeroFly®) | Deltamethrin (360 mg/m2) | Full coverage | Deltamethrin LLIN (PermaNet® 2.0; 55 mg/m2) |
An. funestus
ND and other minor anopheline spp. | Significant reductions in indoor vector population density (82% for ITPS + LLINs; 78% for IRS; 73% for WL) and intensity of mosquito bites in most intervention villages, measured using anti-Anopheles saliva IgG antibodies levels | Significant reductions in malaria incidence (58% for ITPS + LLINs; 54% for IRS; 51% for WL) | [45] |
IRS (lambdacyhalothrin; 25 mg/m2) | ||||||||
Polyethylene WL (ZeroVector®) | Deltamethrin (175 mg/m2) |
Commercial development of insecticide-treated housing materials
A potential role for insecticide-treated housing materials in resistance management
Key determinants of community-level ITWL acceptability
Field site(s), country (sample size) | Intervention (insecticide) | Study duration | Key determinants of intervention acceptability | Supporting quotations | Additional observations | References |
---|---|---|---|---|---|---|
Huambo province, Angola (60); Enugu (60), Kano (57) and Lagos (61), Nigeria | Blue polyethylene woven shade cloth (ZeroVector®) (Deltamethrin) | 12 months | Immediate entomological efficacy |
‘The thing is picking insects the way I can’t explain. It’s picking them like a magnet. It was very very effective.’ (Female 18–29 years, rural Enugu) | ITWL was commended for being a single preventative measure which could alleviate the use of multiple strategies incorporated into daily routine | [52] |
Aesthetic value |
‘Since we have put that thing, it has beautified my house.’ (Female 18–29 years, rural Enugu) | Higher levels of acceptability in Nigeria may be attributable to overall greater awareness of malaria and preventative measures | ||||
Blue laminated polyethylene plastic sheeting (ZeroFly®) (Deltamethrin) | Angolan participants, despite reporting positive feedback, ultimately removed their ITPS once it was perceived as ineffectual | |||||
A dichotomy emerged between rural and urban householders; the latter rejected the use of wall linings based on objections to their aesthetics and installation feasibility | ||||||
Blue polyester netting (Deltamethrin) | Of the three prototype materials, ZeroVector® was the most popular because of its ease of installation and resemblance to local materials | |||||
Río Muni, Equatorial Guinea (40), Obuasi municipality, Ghana (60), Koulikoro, Mali (24), Mpumalanga South Africa (12) and Hoa Binh province, Vietnam (12) | Blue polyethylene woven shade cloth (ZeroVector®) (Deltamethrin) | 12–15 months | Immediate and sustained entomological efficacy |
‘This fabric was very helpful because the mosquitoes have fled. The flies also leave us alone.’ (Mali, female) | Majority of participants expressed interest in keeping the ITWL for decoration even if it did not kill mosquitoes or other nuisance insects | [53] |
Aesthetic value |
‘The textile is very good because in addition to its insecticidal activity, it makes the room more beautiful.’ (Mali, female) | When offered the choice of other vector control interventions (IRS or insecticide-treated curtains), ITWL was the most popular, irrespective of earlier household allocation | ||||
Potential protection from malaria |
‘Since the textile arrived I have not seen a case of malaria.’ (Mali, female) | |||||
Highland and lowland, Papua New Guinea (40) | Blue polyethylene woven shade cloth (ZeroVector®) (Deltamethrin) | 1 month | Immediate and sustained entomological efficacy |
‘The first day after [ITPS]
a
installation I saw mosquitoes flying into the house, contact the material and then just fall off and die. The cockroaches climbed up the [ITPS covered] wall and died instantly.’ (Lowlands village, male) | Participants appreciated the ITPS acting as additional building material, blocking holes in walls, reducing draughts, noise and dust entering the house | [57] |
Potential protection from malaria |
‘We do not want to be sick with malaria. If the kids are sick, we will struggle to walk a long way to go to the hospital. We do not want this to happen. This plastic sheeting will help protect us and our children from getting sick with malaria.’ (Lowlands village, male) | Many recipients ceased LLIN use, perceiving the ITPS to be sufficient and/or superior for protection | ||||
Aesthetic value |
‘When I opened the door and went into the house it looked a lot different [following ITPS installation]. My house looked beautiful and was glowing.’ (Highlands urban, male) | It was difficult to establish ‘routine’ installation due to heterogeneous house size, shape and construction | ||||
Ownership prestige |
‘One of my sisters came and saw the durable lining sheets and liked it and said she wished she could have got one like this too.’
(Islands village, female) | Householders raised concerns about the products flammability, fragility and possibility of theft by the installation team | ||||
Few observable side effects |
‘I have a small child and I was worried that the insecticide on the durable lining sheet might have a bad effect on my child.’
(Islands village, female) | ITPS was exposed to smoke from internal, unventilated fires which may result in more rapid degradation, reduction in aesthetic appeal and impact insecticidal longevity and potency | ||||
Highland and lowland, Papua New Guinea (38) | Blue polyethylene woven shade cloth (ZeroVector®) | 36 months | Immediate and sustained aesthetic value |
‘Yes, initially it [the DL] looked very nice. It made the house look nice, but now that it is losing its colours or maybe the dust covered it so its colours are fading. But it’s still looking nice on the wall as it is.’ (Highlands urban, 36 months) | Despite reductions in perceived effectiveness over time, householders did not remove the material and most expressed interest in obtaining a new one | |
Despite reductions in perceived aesthetic value over time, householders still felt their home interior was enhanced. However, no participants expressed interest in installing a DL for appearance sake alone, suggesting perceived entomological effectiveness was important for initial and continued acceptability | ||||||
(Deltamethrin) | Potential protection from malaria |
‘For myself, when this thing [DL] was there I see that me or my family members had never been sick with malaria since this thing was installed. Not one of us was infected with malaria. This is why I like that thing.’ (Islands village, 36 months) | Householders from the cooler highland region suggested that the material warmed the house, which was considered a desirable function. This ‘warming’ benefit was not reported by those in the lowlands | [58] | ||
Ease of use and perceived effectiveness compared to other malaria control methods |
‘Previously we used to do the work of tying up nets and sleep and even in the night to wake up and tie up nets and now this green net is here, sorry blue net [DL], that we do not have the hard work of tying the nets. It’s [DL] on the wall helping us to kill mosquitoes so we just sleep relaxing’
(Highlands village, 36 months) | Many recipients reported ceasing LLIN use, perceiving the ITPS to be sufficient and/or superior for protection. Householders made no indication to suggest awareness that this reduction in net use might increase risk of malaria | ||||
‘[DL] is better than the mosquito net and the other thing is that I can breathe properly when I’m sleeping, but in the mosquito net I feel that I am breathing in all the medicine/treatment from the net. Now that we are using this [the DL], we don’t want to use the mosquito net, our nets are piling up there. I am ready to sell mine. We don’t really like mosquito nets. These nets [DL] are better than mosquito nets. For me and my families good I’m saying this.’ (Islands village, 12 months) | ||||||
Few observable side effects compared to other malaria control methods |
‘I don’t like using the mosquito net. Sometimes I have shortness of breath.’ (Islands village, 12 months) | Due to the type of housing material used in PNG, DL durability may be longer than average house lifespan, suggesting that effective duration would be largely determined by the age and condition of the house at the time of installation, rather than the product itself | ||||
Bioefficacy testing demonstrated no loss in insecticidal activity after 36 months indicating that participant perceptions of reduced product effectiveness are not necessarily synonymous with actual ineffectiveness | ||||||
Limpopo province, South Africa (40) | Green, orange, brown, or purple polyethylene monofilament (deltamethrin or alpha-cypermethrin) | 6 months | Immediate and sustained entomological efficacy |
‘Net
b
helps a lot because there are not as many mosquitoes like before. Like nets for both rooms.’ (Female, age 28, house with green lining) | Majority of participants ceased using other methods to prevent malaria, including spraying insecticides and burning mosquito coils and other materials | [59] |
‘The net is helping us because mosquitoes are not as many as before when there is no lining.’ (Female, age 73, hut with brown lining) | Householders disagreed over whether ITWL should cover the entire wall or only the top portion, out of reach of children and potential damage | |||||
Smoke damage and soot accumulation from cooking over open, unventilated fires was raised as an issue which might impact ITWL long-term aesthetic appeal and insecticidal efficacy | ||||||
Aesthetic value | ‘The net is too much good. It decorate my room and it kill mosquitoes and cockroaches.’ (Female, age 48, house with orange lining) | The ability to remove and re-install ITWL would overcome logistical problems associated with IRS in the area, namely the annual or bi-annual mud re-smearing, re-painting or washing of walls that occurs during the festive season |