Table 2 Characteristics of the included 57 studies

Sangoro et al. [21]

Tanzania

A cluster-randomized, placebo-controlled trial

To assess whether 15% DEET topical repellent used in combination with LLINs can prevent greater

malaria transmission than placebo and LLINs

6 months and above

LLIN + DEET topical repellent

LLIN + placebo lotion

14 months

Rapid diagnostic test (RDT) confirmed malaria measured by passive

case detection (PCD)

The placebo group comprised 1972.3 person-years with 68.29 (95% CI 37.05–99.53) malaria cases/1000 person-years

The repellent group comprised 1952.8 person-years with 60.45 (95% CI 48.30–72.60) malaria cases/1,000 person-years, demonstrating a non-significant 11.44% reduction in malaria incidence rate in this group (Wilcoxon rank sum z = 0.529, p = 0.596)

Protopopoff et al. [22]

Tanzania

A cluster randomized controlled trial

To evaluate impact on malaria transmission comparing two rounds of IRS with bendiocarb plus

universal ITN coverage, with ITNs alone

General population

IRS + ITN

ITN alone

21 months

Mosquito density monitored using CDC light traps during one night

Mean An. gambiae s.l. density in the ITN + IRS arm was reduced by 84% (95%CI 56–94%, p = 0.001) relative to the ITN arm. In the clusters categorised as high anopheline density at baseline EIR was lower in the ITN + IRS arm compared to the ITN arm (0.5 versus 5.4 per house per month, Incidence Rate Ratio: 0.10, 95% CI 0.01–0.66, p-value for interaction)

Okumu et al. [23]

Tanzania

Experimental study design (comparative field evaluation)

To evaluate combinations of LLIN and IRS, relative to either method alone, for malaria prevention in an area where the main vector is Anopheles arabiensis

Male volunteers aged between 18 and 35 years

LLIN + IRS or IRS + untreated nets

LLIN alone or untreated nets alone or unsprayed huts

13 months

Indoor mosquito bites, malaria vectors mortality, proportions caught exiting

All the net types, used with or without IRS, prevented > 99% of indoor mosquito bites. Adding Permanent 2.0 and Icon Life, but not Olyset nets into huts with any IRS increased mortality of malaria vectors relative to IRS alone. However, of all IRS treatments, only pirimiphos-methyl significantly increased vector mortality relative to LLINs alone, though this increase was modest. Overall, median mortality of An. Arabiensis caught in huts with any of the treatments did not exceed 29%. No treatment reduced entry of the vectors into huts, except for marginal

reductions due to PermaNet 2.0 nets and DDT. More than 95% of all mosquitoes were caught in exit traps rather than inside huts

Maia et al. [24]

Tanzania

A household- cluster-randomized, placebo-controlled

To measure if diversion occurs from households that use repellents to those that do not use repellents

General population over 6 months

15% DEET + LLIN

Placebo

10 weeks

Mosquito densities

Repellent-users had consistently fewer mosquitoes in their dwellings. In villages where everybody had been given 15%-DEET, resting mosquito densities were fewer than half that of households in the no coverage scenario (Incidence Rate Ratio [IRR] = 0.39 (95% CI 0.25–0.60); p < 0.001). Placebo-users living in a village where 80% of the households used 15%-DEET were likely to have over 4-times more mosquitoes (IRR = 4.17; 95% CI 3.08–5.65; p < 0.001) resting in their dwellings in comparison to households in a village where nobody uses repellent

Killeen et al. (2017) [25]

Tanzania

Experimental study design

To assess window screens and eave baffles (WSEBs), which enable mosquitoes to enter but not exit houses, as an alternative to indoor residual spraying (IRS) for malaria vector control

General population

IRS using insecticides + LLIN + WSEBs

IRS using water + LLIN

Not clear

Mosquito vector mortality

Compared with IRS containing the same insecticide, WSEBs killed similar proportions of Anopheles funestus mosquitoes that were resistant to pyrethroids, carbamates and organochlorines and greater proportions of pyrethroid-resistant, early exiting An. arabiensis mosquitoes. WSEBs with pirimiphos-methyl killed greater proportions of both vectors than lambda-cyhalothrin or lambda-cyhalothrin plus pirimiphos-methyl and were equally efficacious when combined with binding agent. WSEBs required far less insecticide than IRS, and binding agents might enhance durability

Sternberg et al. [26]

Tanzania

Experimental study design

To evaluate “eave tubes”—a technology that combines house screening with a novel method of delivering insecticides for control of malaria mosquitoes

General population

LLIN + eave tubes (closed eaves and eave tubes treated with bendiocarb) or LLIN + open eaves

Untreated bednet (control group)

9 months

Larval densities, mosquito in-door host seeking densities

In the model village, introducing LLINs led to an approximate 60% reduction in larval densities and 85% reduction in indoor catches of host-seeking mosquitoes relative to pre-intervention values. Installing eave tubes and screening further reduced larval density (93% relative to pre intervention values) and virtually eliminated indoor host-seeking mosquitoes. When the eave tubes and screening were removed, larval and adult catches recovered to pre-eave tube levels

Protopopoff et al. [27]

Tanzania

A 4-group cluster randomised controlled trial using a two-by-two factorial design

To evaluate the effectiveness of Piperonyl butoxide (PBO)

long-lasting insecticidal nets versus standard long-lasting insecticidal

nets as single interventions and in combination with the indoor residual spraying of pirimiphos-methyl

Children aged 6 months to 14 years

Standard LLIN + IRS or PBO LLIN + IRS

Standard LLIN alone or PBO LLIN alone

34 months

Malaria infection prevalence

Malaria infection prevalence after 9 months was lower in the two groups that received

PBO LLINs than in the two groups that received standard LLINs (odds ratio [OR] 0·37, 95% CI 0·21–0·65; p = 0·0011). At the same timepoint, malaria prevalence in the two groups that received IRS was lower than in groups that did not receive; OR 0·33, 95% CI 0·19–0·55; p < 0·0001) and there was evidence of an interaction between PBO LLIN and IRS (OR 2·43, 95% CI 1·19–4·97; p = 0·0158), indicating redundancy when combined. The PBO LLIN effect was sustained after 21 months with a lower malaria prevalence than the standard LLIN; OR 0·40, 95% CI 0·20–0·81; p = 0·0122)

West et al. [28]

Tanzania

A cluster randomised controlled trial

To investigate whether the combination provided added

protection compared to ITNs alone

General population

ITN + IRS

ITN alone

48 months

Plasmodium falciparum parasite rate (PfPR) in children 0.5–14 years old, Anaemia in children 5 years old

In intention-to-treat analysis, mean PfPR was 13% in the ITN + IRS arm and 26% in the ITN only arm, odds ratio = 0.43 (95% CI 0.19–0.97, n = 13,146). The strongest effect was observed in the peak transmission season, 6 months after the first IRS. Subgroup analysis showed that ITN users were additionally protected if their houses were sprayed. Mean monthly entomological inoculation rate was non-significantly lower in the ITN + IRS arm than in the ITN only arm, rate ratio = 0.17

(95% CI 0.03–1.08)

De Castro et al. [29]

Tanzania

Case description of before and after

To describe and evaluate a control program that operated from 1988 to 1996 as a consequence of a bilateral agreement between the governments of Tanzania and Japan

General population

Chemical larviciding + Indoor residual house spraying (IRHS) + Space spraying of insecticides at ultra-low volume + ITNs + Environmental management

None, before and after data

96 months

Malaria prevalence, number of mosquito breeding sites

Reduced number of breeding sites. Malaria prevalence rates among school age children were reduced by approximately 50% over the eight-year period that the UMCP was operative (1988 – 1996)

Masalu et al. [30]

Tanzania

Experimental study design

To measure the additional benefits of combining transfluthrin-treated sisal decorations and LLINs with an aim of extending protection against early evening, indoor-biting malaria vectors when LLINs are ineffective

Male volunteers

Transfluthrin-treated sisal baskets + LLINs:

(i) four transfluthrin-treated (2.5 ml) sisal baskets and one permethrin-treated LLIN; and (ii) four transfluthrin-treated sisal baskets (5 ml) and one permethrin-treated LLIN

Untreated sisal baskets + permethrin-treated LLIN

1 month

(i) Mosquito deterrence (reduction in the density of indoor mosquitoes) (ii) Indoor human mosquito biting rate (proportion of mosquitoes landing and attempting to bite volunteers) (iii) Insecticide-induced 24 h mortality

Sisal decorative baskets (0.28 m2) treated with 2.5 ml and 5.0 ml transfluthrin deterred 3/4 of Anopheles arabiensis mosquitoes from entering huts (relative rate, RR = 0.26, 95% CI 0.20–0.34, P < 0.001 and RR = 0.29, 95% CI 0.22–0.37, P < 0.001, respectively). Both treatments induced a tenfold increase in 24 h mortality of An. arabiensis mosquitoes (OR = 12.26, 95% CI 7.70–19.51, P < 0.001 and OR = 18.42, 95% CI 11.36–29.90, P < 0.001, respectively). Sisal decorative items treated with spatial repellents provide additional household and personal protection against indoor biting malaria and nuisance mosquitoes in the early evening, in absence of conventional indoor vector control tools

Menger et al. [31]

Kenya

Field experimental study design

To quantify the effects of eave screening in

combination with a push–pull system based on the simultaneous use of a repellent (push) and attractant-baited traps (pull)

Male volunteers

Eave screening + outdoor, attractant-baited traps

No eave screening

33 consecutive nights

Mosquito house entry

Eave screening, whether used in combination with an attractant-baited trap or not, was highly effective in reducing house entry by malaria mosquitoes. The magnitude of the effect varied for different mosquito species and between two experiments, but the reduction in house entry was always considerable (61–99%). Using outdoor, attractant-baited traps alone did not have a significant impact on mosquito house entry but the high number of mosquitoes trapped outdoors shows that attractant-baited traps would enhance outdoor plus indoor protection against mosquito bites. As eave screening was effective by itself, addition of a repellent was of limited value, but could help in reducing outdoor malaria transmission in domestic areas

Mutero et al. [32]

Kenya and Ethiopia

A factorial, cluster-randomized, controlled trial

To assess the effect of supplementing LLINs with either larviciding with Bacillus thuringiensis israelensis (Bti) or community education and mobilization, or with both interventions in the context of

IVM

School children

LLINs and Bti (arm 2);

LLINs and community education and mobilization (arm 3); and,

LLINs combined with Bti

and community education and mobilization (arm 4)

LLINs only (arm 1)

36 months

Indoor mosquito density

There was no significant reduction in adult anopheline density at each of the three sites, which could be attributed to adding of the supplementary interventions to the usage of LLINs. Malaria prevalence was significantly reduced by 50% in Tolay when using LLINs

coupled with application of Bti, and community education and mobilization. The two other sites did not reveal significant

reduction of prevalence as a result of combining LLINs with any of the other supplementary interventions

Fillinger et al. [33]

Kenya

A controlled trial (pre-post, control group design was used)

To assess the contributions of both microbial larvicides and ITNs in terms of reducing malaria

incidence in an integrated vector management programme in an area moderately endemic for malaria in the western Kenyan highlands

Children 6 months to 10 years old

Microbial larvicides + ITNs

ITNs alone

Not clear

Incidence of Plasmodium infections in children 6 months to 13 years of age

ITN use was associated with a 31% reduction in the risk of new malaria infections (OR: 0.69, 95% CI 0.48–0.99), while residence in an area with additional larviciding reduced the risk of new infections by 56% (OR: 0.44; 95% CI 0.23–0.82). Vector control with microbial larvicides enhanced the malaria control achieved with ITNs alone

Hamel et al. [10]

Kenya

A non-randomized prospective cohort study

To determine protective efficacy of IRS with ITNs compared with ITNs alone in preventing Plasmodium falciparum parasitemia

General population

IRS + ITNs

ITNs alone

Participants were followed for 1,197 person-years, 627 and 570 person-years in the ITN + IRS and ITN only groups, respectively

Incidence of P. falciparum parasitemia, Adjusted protective efficacy

Incidence of P. falciparum parasitemia in the ITN + IRS and ITN only groups was 18 and 44 infections per 100 persons-years at risk, respectively (unadjusted rate ratio = 0.41; 95% CI = 0.31–0.56). Adjusted protective efficacy of ITN + IRS compared with ITN only was 62% (95% CI = 0.50–0.72)

Gimnig et al. [34]

Kenya

Cross-sectional-Surveys

To evaluate the impact of an IRS program on malaria related outcomes in western Kenya, an area of intense perennial malaria transmission and moderate ITN coverage

General population

IRS + ITN

ITNs alone

24 months

Prevalence of malaria parasitemia, prevalence of clinical malaria

At baseline and after one round of IRS, there were no differences between the two districts in the prevalence of malaria parasitemia, clinical malaria or anemia. After two rounds of IRS, the prevalence of malaria parasitemia was 6.4% in the IRS district compared to 16.7% in the comparison district (OR = 0.36, 95% CI = 0.22–0.59, p < 0.001). The prevalence of clinical malaria was also lower in the IRS district (1.8% vs. 4.9%, OR = 0.37, 95% CI = 0.20–0.68, p = 0.001). Multivariate models incorporating both IRS and ITNs indicated that both had an impact on malaria parasitemia and clinical malaria but the independent effect of ITNs was reduced in the district that had received two rounds of IRS

Bousema et al. [35]

Kenya

A Cluster-Randomized Controlled Tria

To determine the impact of interventions targeted to serologically defined malaria hotspots on malaria transmission both inside hotspots and in surrounding communities

General population

Larviciding + LLINs + IRS + Focal mass drug administration

Malaria control following Kenyan national policy (IRS, routine case management at clinics, and bednet distribution at antenatal clinics)

7 months

Nested PCR (nPCR) parasite prevalence, Prevalence of clinical malaria, Mosquito density

Hotspot-targeted interventions did not result in a change in nPCR parasite prevalence outside hotspot boundaries (p ≥ 0.187). An average reduction in nPCR parasite prevalence of 10.2% (95% CI − 1.3 to 21.7%) inside hotspots 8 wk post-intervention was statistically significant after adjustment for covariates (p = 0.024), but not 16 wk post-intervention (p = 0.265). No statistically significant trend in the effect of the intervention on nPCR parasite prevalence in the evaluation zone in relation to distance from the hotspot boundary 8 wk (p = 0.27) or 16 wk post-intervention (p = 0.75). Thirty-six patients with clinical malaria confirmed could be located to intervention or control clusters, with no difference between the study arms. In intervention clusters, an average of 1.14 female anophelines inside hotspots and 0.47 in evaluation zones was caught; versus the control clusters with average of 0.90 female anophelines inside hotspots and 0.50 in evaluation zones, with no apparent difference between study arms

Okech et al. [36]

Kenya

Cross-sectional study

To investigate the potential factors that could have contributed to the decline of malaria cases in the hospital by analyzing the malaria control knowledge, attitudes and practices that the residents in Mwea applied in an integrated fashion

Children between 41/2 – 10 years

ITN + environmental management + mosquito repellent and smoke + insecticide canister sprays + window and door screens

None

Not clear

Malaria cases

Over the last 4 years prior to this study, the malaria cases in the community hospital reduced from about 40% in 2000 to less than 10% by 2004 and by the year 2007 malaria cases decreased to zero. The usage of a combination of malaria control tools in an integrated fashion by residents might have influenced the decreased malaria cases in the district hospital and in the school children

Bekele et al. [37]

Ethiopia

A cross-sectional study

To assess the effect of IRS and ITNs control

strategies in Aneno Shisho kebele compared with Kamo Gerbi (supplied ITN only) and Jela Aluto (no IRS and ITNs), with regards to the prevalence of malaria and mosquito density

Under 5 years, and above 15 years

IRS + ITN

Single intervention

8 months

Malaria prevalence, Mosquito density

The difference in overall malaria prevalence and mosquito density between the three kebeles was significant (P < 0.05). The malaria prevalence rate in October/November 2006 in Jela Aluto, which was not covered by ITNs or IRS was significantly higher (10.4%) than Kamo Gerbi which was covered by ITN (5.4%) and in Aneno Shisho (1.7%), which was covered both by ITNs and IRS. In the under five years of age, malaria prevalence of October/November 2006 and April 2007 was 26.2% in Jela Aluto; 6.0% in Kamo Gerbi and 1.2% in Aneno Shisho. The difference in the under five years of age in prevalence among the three kebeles was statistically significant (P < 0.05). Malaria prevalence in the age group above 15 years was 9.5% in Jela Aluto; 10.2% in Kamo Gerbi and 3.7% in Aneno Shisho. The densities of An. gambiae s.l. were 11(73.3%) in Jela Aluto, 3(20%) in Kamo Gerbi and 1(6.6%) in Aneno Shisho

Asale et al. [11]

Ethiopia

A before and after cross-sectional study

To assess the impact of Integrated Vector Management (IVM) for malaria control in Botor-

Tolay district, southwestern Ethiopia after three years (2016–2018) of IVM implementation

General population

Larva source management and environmental management + LLIN + IRS

None, before and after data

36 months

Malaria cases, Mosquito population

Significantly fewer adult mosquitoes were collected in 2018 (0.37/house/trap-night) as compared to 2015 (0.73/house/trap-night)

(P < .001). Malaria cases significantly declined in 2018 (262) when compared to the record in 2015 (1162) (P < 0.001)

Deressa et al. [38]

Ethiopia

A community-based clustered-randomised trial

To determine the effect of combining community-based mosquito repellent with LLINs in the reduction of malaria

General population

Mosquito repellent + LLINs

Single intervention

4 months

Malaria infection

Compared with the control arm, the combined use of mosquito repellent and LLINs significantly reduced malaria infection of all types over time [OR = 0.66; 95% CI: 0.45–0.97]. Similarly, a substantial reduction in P. falciparum malaria infection during the follow-up surveys was observed in the intervention group (OR = 0.53, 95% CI 0.31–0.89). The protective efficacy of using mosquito repellent and LLINs against malaria infection of both P. falciparum/P. vivax and P. falciparum was 34–47%, respectively

Loha et al. [39]

Ethiopia

A 2 × 2 factorial, cluster-randomized, controlled trial

To evaluate whether the combined use of LLINs and IRS with propoxur provides additional protection against Plasmodium falciparum and/or Plasmodium vivax among all age groups compared to LLINs or IRS alone

General population

LLINs + IRS

LLINs alone OR IRS alone

29 months

Incidence of clinical malaria and anaemia prevalence

The overall malaria incidence was 16.5 per 1000 person-years of observation time, and similar in the four arms with 17.2 per 1000 person-years of observation time in the LLIN + IRS arm, 16.1 in LLIN, 17.0 in IRS, and 15.6 in the control arm. There was no significant difference in risk of anaemia among the trial arms

Musoke et al. [40]

Uganda

A qualitative cross-sectional survey

To assess the experiences of households using integrated malaria prevention as part of impact evaluation of the

project 2 years after implementation

General population

LLIN + screening + removing mosquito breeding sites + closing of doors early

None, before and after data

12 months

Mosquito density, malaria prevalence

The major benefits reported from using integrated malaria prevention were reduction in mosquito populations in their houses and less occurrence of malaria especially among children

Katureebe et al. [41]

Uganda

Prospective observational study- before and after interventions-cohort studies, cross-sectional Community Surveys

To measure changes in key malaria indicators following universal LLIN distribution in three sites, with the addition of IRS at one of these sites

Children

LLIN + IRS

LLIN alone

28 months

Malaria test positivity rate (TPR), incidence of malaria, Human biting rate (HBR)

In Walukuba, over the 28-month post-intervention period, universal LLIN distribution was associated with no change in the incidence of malaria (0.39 episodes PPY pre-intervention versus 0.20 post-intervention; adjusted rate ratio [aRR] = 1.02, 95% CI 0.36–2.91, p = 0.97) and non-significant reductions in the TPR (26.5% pre-intervention versus 26.2% post-intervention; aRR = 0.70, 95% CI 0.46–1.06, p = 0.09) and HBR (1.07 mosquitoes per house-night pre-intervention versus 0.71 post-intervention; aRR = 0.41, 95% CI: 0.14–1.18, p = 0.10). In Kihihi, over the 21-mo post-intervention period, universal LLIN distribution was associated with a reduction in the incidence of malaria (1.77 pre-intervention versus 1.89 post-intervention; aRR = 0.65, 95% CI 0.43–0.98, p = 0.04) but no significant change in the TPR (49.3% pre-intervention versus 45.9% post-intervention; aRR = 0.83, 95% 0.58–1.18, p = 0.30) or HBR (4.06 pre-intervention versus 2.44 post-intervention; aRR = 0.71, 95% CI 0.30–1.64, p = 0.40). In Nagongera, over the 12-mo post-intervention period, universal LLIN distribution was associated with a reduction in the TPR (45.3% pre-intervention versus 36.5% post-intervention; aRR = 0.82, 95% CI 0.76–0.88, p < 0.001) but no significant change in the incidence of malaria (2.82 pre-intervention versus 3.28 post-intervention; aRR = 1.10, 95% 0.76–1.59, p = 0.60) or HBR (41.04 pre-intervention versus 20.15 post-intervention; aRR = 0.87, 95% CI 0.31–2.47, p = 0.80). The addition of three rounds of IRS at ~ 6-mo intervals in Nagongera was followed by clear decreases in all outcomes: incidence of malaria (3.25 pre-intervention versus 0.63 post-intervention; aRR = 0.13, 95% CI 0.07–0.27, p < 0.001), TPR (37.8% pre-intervention versus 15.0% post-intervention; aRR = 0.54, 95% CI 0.49–0.60, p < 0.001), and HBR (18.71 pre-intervention versus 3.23 post-intervention; aRR = 0.29, 95% CI 0.17–0.50, p < 0.001)

Rek et al. [42]

Uganda

Cohort study

To measure recent changes in house design in rural Uganda and evaluate their association with malaria in relation to a mass scale-up of control efforts

All children aged 6 months to 10 years

IRS + ITN + House improvements

ITN alone

74 months

Parasite prevalence, malaria incidence, HBR

IRS was associated with significant declines in human biting rate/HBR (33·5 vs 2·7 Anopheles per house per night after IRS, p < 0·0001), parasite prevalence (32·0% vs 14·0%, p < 0·0001), and malaria incidence (3·0 vs 0·5 episodes per person-year at risk, p < 0·0001). Compared with traditional houses, modern houses were associated with a 48% reduction in HBR before IRS (adjusted incidence rate ratio [aIRR] 0·52, 95% CI: 0·36–0·73, p = 0·0002), and a 73% reduction after IRS (aIRR 0·27, 0·17–0·42, p < 0·0001). Before IRS, there was no association between house type and parasite prevalence, but after IRS there was a 57% reduction in the odds of parasitaemia in modern houses compared with traditional houses (adjusted odds ratio 0·43, 95% CI 0·24–0·77, p = 0·004). House type was not associated with malaria incidence before or after IRS

Oguttu et al. [43]

Uganda

Observational retrospective analysis

To assess malaria incidence, test positivity rates and outpatient attendance due to malaria before and after vector control interventions

Children and adults

LLINs + IRS

LLINs alone

48 months

Malaria incidence, malaria test positivity rates

A rapid reduction in malaria incidence was observed in the district following the introduction of IRS in addition to LLINs. -Following universal LLINs coverage, the annual mean monthly malaria incidence fell from 95 cases in 2013 to 76 cases per 1000 in 2014 with no significant monthly reduction (OR = 0.99, 95% CI 0.96–1.01, P = 0.37). Among children < 5 years, the malaria incidence reduced from 130 to 100 cases per 1000 (OR = 0.98, 95% CI 0.97–1.00, P = 0.08) when LLINs were used alone in 2014, but declined to 45 per 1000 in 2015 when IRS was combined with LLINs (OR = 0.94, 95% CI 0.91–0.996, P < 0.0001). Among individuals aged ≥ 5 years, mean monthly malaria incidence reduced from 59 to 52 cases per 1000 (OR = 0.99, 95% CI 0.97–1.02, P = 0.8) when LLINs were used alone in 2014, but reduced significantly to 25 per 1000 in 2015 (OR = 0.91, 95% CI 0.88–0.94, P < 0.0001). Malaria test positivity rate reduced from 57% in 2013 to 30% (Chi = 15, P < 0.0001) in 2015. Slide positivity rate reduced from 45% in 2013 to 21% in 2015 (P = 0.004) while RDT positivity declined from 69 to 40%

Musiime et al. [44]

Uganda

A cross-sectional study before and after

To compare malaria transmission indoors and outdoors, before and after

mass deployment of LLINs and IRS

General population

LLIN + IRS

LLIN

96 months

Human biting rate, annual entomological inoculation rate, proportion of mosquitoes collected outdoors

The interventions were associated with a decline in human biting rate from 19.6 to 2.3 female Anopheles mosquitoes per house per night (p < 0.001) and annual entomological inoculation rate from 129 to 0 infective bites

per person per year (p < 0.001). The proportion of mosquitoes collected outdoors increased from 11.6 to 49.4% (p < 0.001). Before interventions, the predominant species was Anopheles gambiae sensustricto (s.s.), which

comprised 76.7% of mosquitoes. Following the interventions, the predominant species was Anopheles arabiensis, which comprised 99.5% of mosquitoes, with almost complete elimination of An. gambiae s.s. (0.5%)

Galatas et al. [45]

Mozambique

A before and after cross-sectional study

To evaluate a multi-phased malaria elimination project to interrupt Plasmodium falciparum

malaria transmission

General population

Mass Drug Administration + IRS + LLIN

None-before and after

Not clear

Malaria prevalence and incidence rates. Yearly parasite surveys and routine surveillance data were

used to monitor the outcomes of the study at

baseline and annually since the onset of the project

Parasite prevalence declined from 9.1% (95% CI: 7.0–11.8) to 2.6% (95% CI 2.0–3.4), representing a 71.3% (95% CI 71.1–71.4, p < 0.001) reduction after phase I, and to 1.4% (95% CI 0.9–2.2) after phase II. This represented an 84.7% (95% CI 81.4–87.4, p < 0.001) overall reduction in all-age prevalence Case incidence fell from 195 to 75 cases per 1000 during phase I (61.5% reduction) and to 67 per 1000 during phase II (65.6% overall reduction). Phase I interventions were associated with a significant immediate reduction in cases of 69.1% (95% CI 57.5–77.6, p < 0.001). Phase II interventions were not associated with a level or trend change. An estimated 76.7% of expected cases were averted throughout the project (38,369 cases averted of 50,005 expected)

Temu et al. [46]

Mozambique

Cross-sectional community-based surveys

To assess the impact of IRS and ITNs, the effects of keeping farm

animals and of the construction material of roofs of houses and other potential risk factors associated with malaria infection

in children

Children (ages 1–15 years)

LLIN + IRS

LLIN alone

36 months

Malaria prevalence, protective factors independently associated with malaria infection

Prevalence of malaria infection was 47.8% (95% CI 38.7–57.1%) in children 1–15 years of age, less than a quarter of children (23.1%, 95% CI 19.1–27.6%) were sleeping under ITN and almost two thirds were living in IRS treated houses (coverage 65.4%, 95% CI 51.5–77.0%). Protective factors independently associated with malaria infection included: sleeping in an IRS house without sleeping under ITN (OR = 0.6; 95% CI 0.4 – 0.9); additional protection due to sleeping under ITN in an IRS treated house (OR = 0.5; 95% CI 0.3–0.7) versus sleeping in an unsprayed house without a ITN was noted

Chaccour et al. [47]

Mozambique

A two-arm, cluster randomized, controlled study design

To provide evidence on the incremental epidemiological benefit of using third-generation IRS product in a highly endemic area with high ITN ownership

Children under 5 years were enrolled in the cohort

ITN + IRS

ITN alone

36 months

Malaria incidence rate, malaria prevalence

Children in the IRS arm experienced 4801 cases (incidence rate of 3532 per 10,000 children-month at risk) versus 5758 cases in the no-IRS arm (incidence rate of 4297

per 10,000 children-month at risk), resulting in a crude risk reduction of 18% and an incidence risk ratio of 0.82 (95% CI 0.79–0.86, p-value < 0.001). Facility and community passive surveillance showed a malaria incidence of 278 per 10,000 person-month in the IRS group (43,974 cases over 22 months) versus 358 (95% CI 355–360) per 10,000 person-month at risk in the no-IRS group (58,030 cases over 22 months), resulting in an incidence rate ratio of 0.65 (95% CI 0.60–0.71, p < 0.001). In the 2018 survey, prevalence in children under five in the IRS arm was significantly lower than in the no IRS arm (OR 0.54, 95% CI 0.31–0.92, p = 0.0241)."

Makoutode et al. [48]

Benin

A cross-sectional study

To see if adding the IRS to the LLINs

(municipality of Kouandé) strategy is cost-effective, as compared to the LLINs-only strategy (municipality of

Copargo)

General population

IRS + LLIN

LLIN alone

N/A

Cost-effectiveness ratio by malaria case, annual incidence of malaria

After LLINs + IRS intervention, (1) the annual incidence of malaria in health facilities decreased significantly at Kouandé-Centre. In the same period, it increased significantly at Copargo- Centre. (2) The average cost per malaria case prevented (CE) was respectively 85,572.4 FCFA at Copargo Centre, 38,932.6 FCFA at Kouandé Centre. The CE ratio at Kouandé-Centre was lower than the CE ratio at Copargo- Centre. The LLINs + IRS strategy was more cost effective in urban areas than the LLINs-only strategy. The opposite result was observed in rural areas

Corbel et al. [49]

Benin

A cluster randomised

controlled trial

To Investigate whether the combination of LLINs with IRS or carbamate-treated plastic sheeting (CTPS)

conferred enhanced protection against malaria and better management of pyrethroid-resistance in vectors than did

LLINs alone

Pregnant women and children under 6 years

4 interventions

1- TLLIN (LLIN targeted coverage to pregnant women and

children younger than 6 years), 2- ULLIN (LLIN universal coverage of all sleeping units), 3-

TLLIN plus full coverage of carbamate IRS applied every 8 months (TLLIN + IRS), 4- ULLIN plus full coverage of CTPS lined up to the upper part of the household walls (ULLIN + CTPS)

TLLIN

18 months

Clinical incidence density of malaria in children younger than 6 years

The clinical incidence density of malaria was not reduced in the children from the ULLIN group (incidence density rate 0·95, 95% CI:0·67–1·36, p = 0·79), nor in those from the TLLIN + IRS group (1·32, 95% CI 0·90–1·93, p = 0·15) or from the ULLIN + CTPS group (1·05, 95% CI 0·75–1·48, p = 0·77) compared with the reference group (TLLIN). The same trend was observed with the prevalence and parasite density of asymptomatic infections (non- significant regression coefficients). Finally, fewer mosquitoes entered the houses containing both IRS + LLINs than houses with LLINs alone

Ngufor et al. [50]

Benin

Experimental study design

To compare the efficacy of Interceptor® G2 LN, a newly developed LN treated with a mixture of chlorfenapyr (a pyrrole) and alpha-cypermethrin (a pyrethroid), to a combined chlorfenapyr IRS and Interceptor^® LN (a standard alpha-cypermethrin LN) intervention

Human volunteer sleepers

ITNs + IRS

Untreated nets

4 months

Mosquito mortality, blood feeding inhibition,

Mortality in the control (untreated net) hut was 5%. Mortality with Interceptor^® LN (24%) was lower than with chlorfenapyr IRS alone (59%, P < 0.001). The combined Interceptor^® LN and chlorfenapyr IRS intervention and the mixture net (Interceptor^® G2 LN) provided significantly higher mortality rates (73 and 76%, respectively) and these did not differ significantly between both treatments (P = 0.15). Interceptor LN induced 46% blood-feeding inhibition compared to the control untreated net, while chlorfenapyr IRS alone provided none. Both mixture/combinations also induced substantial levels of blood-feeding inhibition (38% with combined interventions and 30% with Interceptor^® G2 LN). A similar trend of improved mortality of pyrethroid-resistant An. gambiae s.l. from Cove was noted with Interceptor® G2 LN (79%) versus Interceptor LN (42%, P < 0.001) in WHO tunnel tests

Aregawi et al. [51]

Ghana

Cross sectional study

To assess the impact of

interventions on malaria cases, admissions and deaths using data from district hospitals

General populatoin

IRS, ITN, and artemisinin-based combination therapy

Non-IRS districts

10 years

TPR, malaria admissions, malaria deaths

Difference in IRS and non-IRS districts: In the regions where IRS was implemented during 2006–2015, the TPR in all ages decreased significantly by 89% (77–95%); malaria admissions and deaths decreased significantly by 68% (21–87%) and 88% (71–95%), respectively. The decrease in trends of malaria indicators in the non-IRS districts (34 within the same regions) was smaller. The TPR decreased only by 38% (16–54%); malaria admissions showed little change, 35% (− 15 to 63%), and malaria deaths decreased by 44% (16–62%). The decreases in proportion of malaria outpatients, inpatients and deaths of all-cause conditions were much higher in the IRS districts compared to the non-IRS district

Okyere [52]

Ghana

Cross-sectional study

To examine the interaction effects of household use of bed nets and

insecticide products on self-reported malaria prevalence using panel data collected from two administrative districts and a doubly robust estimation technique

General population

ITNs + household insecticide

products

ITNs alone

Not clear

Malaria prevalence

The use of bed nets was associated with lower malaria among household members. Household use of insecticide products singly shows no statistically significant negative relationship with malaria. Indicating some evidence that adopting the two measures jointly increases the efficacy of insecticide products—combining bed nets and household insecticide products reduce malaria for all individuals, females and children under five years

Afoakwah et al. [53]

Ghana

Cross-sectional study (data sourced from the current round of the Ghana Demography and Health Survey)

To investigate the association with use of large-scale malaria interventions such as: IRS, ITNs, and Behaviour Change Communication strategies, and the prevalence of malaria among children under-five in Ghana 2014 survey

Children under-five years

ITN and IRS

ITN alone OR IRS alone data

Not clear

Malaria prevalence

The dual use of both ITN and IRS, does not provide an added protection;—IRS offers much more protection than ITN use. The odds of malaria infection among children in IRS was significantly lower (OR = 0.312; 95% CI − 1.47—0.81; p = 0.00) compared to those not protected. This association was even high (OR = 0.372; 95% CI − 1.76—1.02; p = 0.00) among children in poor households protected by IRS compared to those with no IRS protection. ITN use did not have a significant association with malaria infection among children, except among children whose mothers had at least secondary education. For such children, the odds of malaria infection were significantly lower (OR = 0.545; 95% CI − 0.84—0.11; p = 0.011) compared to those who not protected

Prakash et al. [54]

India

Operational research study

To develop an effective malaria control strategy

for the oil personnel working in these areas, a 1-year pilot study

(April 2000 to May 2001) was carried out in the Jorajan camp of

OIL

Oil employees

Deltamethrin-treated mosquito nets + Mosquito repellent cream + Weekly chemoprophylaxis with 300 mg chloroquine

None, before and after data

12 months

Mean landing rate of Anopheles dirus, incidence of malaria, malaria mortality

The mean landing rate of Anopheles dirus, the vector mosquito in the camp area, was 5.03 per person per night during monitoring. The incidence of malaria in the camp was reduced by > 90% as compared to previous years and the number of malaria cases came down from 6.7 per 1000 man-nights in 1998–99 to 0.06 in 2000–01. Mortality due to malaria was completely eliminated

Dutta et al. [55]

India

Household survey, surveillance, and Entomological and parasitological baseline and follow-up

To evaluate the preventive efficacy of ITNs and mosquito repellent in a malaria-endemic foothill area of Assam, India, with forest ecosystem, 2003 – 2006

General population

During the second year, intervention measures were implemented in the four sectors as follows: A- ITN + repellent B- ITN; C- repellent; D- Information, Education and Communication activities were carried out in sectors A, B and C

No intervention

36 months

Malaria protective efficacy, vector population

The most effective intervention was in sector A (ITN + repellent), followed by sectors B and C. Sectors A and B exhibited significantly higher (P < ;0.001) malaria protective efficacy during both the first and second years of intervention compared with sector D. The total vector population in the three intervention sectors decreased significantly compared with that of the non-intervention one

Singh et al. [56]

India

Cross-sectional surveys, pre- and post-intervention surveys

To assess the impact of intensified malaria control interventions in an ethnic minority community in Betul using existing tools

Children up to 10 years of age and an older age group > 10 years

2 rounds of IRS + larvivorous fish + intensive surveillance for early detection of Plasmodium falciparum with rapid diagnostic tests and prompt treatment with sulphadoxine pyrimethamine

None, before and after data

Not clear

Malaria cases, Mosquito population

Pre-intervention surveys revealed a very high fever rate in the community in all age groups with a slide positivity rate of > 50% with > 90% P. falciparum. The post-intervention phase showed a sharp steady decline in number of malaria cases (β 0.972; p < 0.0001, 95% CI 0.35–0.47). Monitoring of entomological results revealed a significant decline in both Anopheles species and An. culicifacies (p < 0.0001)

Nwaneri et al. [57]

Nigeria

A cross-sectional descriptive study

To document

factors that influence regular use of ITNs in under-fives and impact of vector control methods on malaria outcome (severe malaria prevalence and mortality) in under-fives presenting in a tertiary health institution in Nigeria

Under 5 years

ITN + indoor insecticide spray + netting of doors/window + regular environmental sanitation (clearing bushes and drainages around the house)

None

14 months

Severe malaria prevalence and mortality in under-fives

Prevalence of severe malaria was 36.2% and

mortality was 52 per 1000. Combination of regular use of insecticide treated nets, environmental sanitation, indoor insecticide

spray and netting of household doors/windows significantly predicted low prevalence of severe malaria compared to each of the malaria vector control methods used singly by the caregivers (β = 1.66, OR = 5.0, p = 0.04)

Agomo et al. [58]

Nigeria

A cross-sectional study

To identify the factors associated with risk of malaria infection in pregnant

women

Pregnant women

Insecticide spray + ITN

Single intervention

12 months

Malaria prevalence

Malaria preventive practices associated with a significant reduction (P < 0.05) in the malaria infection was the use of insecticide sprays (RR = 0.36, 95 CI 0.24—0.54), and the combined use of insecticide spray and insecticide-treated

nets (ITN) (RR = 6.53, 95% CI 0.92–46.33). Sleeping under ITN alone (RR = 1.07, 95% CI 0.55–2.09) was not associated

with significant reduction in malaria infection. Young maternal age (< 20 years) (RR = 2.86, 95% CI 1.48–5.50), but not primigravidity (RR = 1.36, 95% CI 0.90–2.05), was associated with an increased risk of malaria infection during pregnancy. After a multivariate logistic regression, young maternal age (OR = 2.61, 95% CI 1.13–6.03) and the use of insecticide spray (OR = 0.38, 95% CI 0.24–0.63) were associated with an increase and a reduction in malaria infection, respectively

Kawada et al. [59]

Malawi

A before and after cross-sectional study

To examine the effect of the

combined use of metofluthrin-impregnated spatial repellent devices (MSRDs) and LLINs (Olyset® Plus)

on malaria prevalence and vector mosquitoes were examined in malaria endemic villages in south-eastern

Malawi

Children

MSRDs + LLINs (Olyset Plus)

LLINs alone (Olyset Plus)

24 months

Infection rate in children, Number of vector mosquitoes

The intervention reduced the infection rate in children as well as the No. pyrethroid resistant vector mosquitoes. In the preliminary field study, significant reduction in

the number of mosquitoes was observed in the houses treated with MSRDs in combination with Olyset^® Plus compared to that of the control houses. The reduction in the number of mosquitoes was highest in the houses treated with Olyset^® Plus + MSRDs. Significant reduction in the number of mosquitoes compared to the control houses was observed at 3 months after the abovementioned intervention regimes were

implemented, although the mosquito numbers slightly resurged after 3 months of intervention

McCann et al. [60]

Malawi

A two-by-two factorial, cluster-randomized controlled trial

To assess the effects of community-based house improvement and larval source management (LSM) as supplementary interventions to the Malawi National Malaria Control Programme interventions in the context of an intensive community engagement

General population

(i) Malawi National Malaria Control Programme (IRS + ITNs + intermittent preventative therapy for pregnant

women, and malaria case diagnosis and treatment with

artemisinin-based combination therapy

(ii) larval source management (LSM- consisted of draining, filling and larviciding) + house improvement

(i) House improvement alone,

(ii) LSM alone

36 months

Entomological inoculation rate (EIR), Mosquito density, P. falciparum prevalence

The mean nightly EIR fell from 0.010 infectious bites per person (95% CI 0.006–0.015) in the baseline year to 0.001 (95% CI 0.000–0.003) in the last year of the trial. Over the full trial period, the EIR did not differ between the four trial arms (p = 0.33). Similar results were observed for the other outcomes: mosquito density and P. falciparum prevalence decreased over 3 years of sampling, while haemoglobin levels increased; and there were minimal differences between the trial arms during the trial period. -In the context of high insecticide-treated bed net use, neither community-based house improvement, LSM, nor house improvement + LSM contributed to further reductions in malaria transmission or prevalence beyond the reductions observed over two years across all four trial arms

Furnival-Adams et al. [61]

Côte d’Ivoire

Experimental study design

To evaluate the efficacy of indoor ATSB® traps treated with 4% boric acid (BA ATSB)

or 1% chlorfenapyr (CFP ATSB) in combination with untreated nets or LLINs (holed or intact), against pyrethroid resistant Anopheles gambiae sensu lato

General population

Arm 1- Boric acid 4% ATSB + untreated polyester net holed

Arm 2- Boric acid 4% ATSB + PermaNet 2.0 LN holed

Arm 3- Chlorfenapyr 1% ATSB + untreated polyester net

holed. Arm 4- Chlorfenapyr 1% ATSB + PermaNet 2.0 LN holed

Arm 5- Chlorfenapyr 1% ATSB + PermaNet 2.0 LN intact

Arm 6-Untreated polyester net holed

Arm 7-PermaNet 2.0 LN holed

4 months

Mosquito mortality

The addition of ATSB to LLINs increased the mortality rates of wild pyrethroid-resistant An. gambiae from 19% with LLIN alone to 28% with added BA ATSB and to 39% with added CFP ATSB (p < 0.001). Anopheles gambiae

mortality with combined ATSB and untreated net was similar to that of combined ATSB and LLIN regardless of which insecticide was used in the ATSB. The presence of holes in the LLIN did not significantly affect ATSB-induced An. Gambiae mortality. Comparative tests against pyrethroid resistant and susceptible strains using oral application of ATSB treated with pyrethroid demonstrated 66% higher survival rate among pyrethroid-resistant mosquitoes

Deparis et al. [62]

Coˆ te d’Ivoire

Experimental study design

To assess the field efficacy of the impregnated battlefield uniforms (BFUs) and their resistance to

washing

French military personnel

Impregnated BFU + 50% DEET Topical repellent

Impregnated BFU alone, or DEET alone

2 months

Malaria incidence, protective effects of DEET

The protective effects of the use of DEET skin repellent was not significant, perhaps due to the high density of Anopheles mosquitoes during the night catching sessions and an

average time of effective repellency of 2 or 3 h in the field. The analysis indicated that the industrial impregnation of permethrin of the BFU offered some protection from mosquito bites but not enough to reduce significantly the incidence of malaria among nonimmune troops. No positive or negative interaction was noted when DEET and the impregnated BFUs were used together

Allcock et al. [63]

Namibia

A cross-sectional study

To explore the coverage of two vector control methods: IRS and ITNs

2–10 years

IRS + ITN

Single intervention data

Not clear

PfPR. PfPR 2–10 (the proportion of the population

aged 2–10 years carrying asexual blood parasites)

PfPR2–10 ≥ 5% was strongly associated with IRS (RR 14.54; 95% CI 5.56–38.02; p < 0.001), ITN ownership (RR 5.70; 95% CI 2.84–11.45; p < 0.001) and ITN and/or IRS coverage (RR 5.32; 95% CI 3.09–9.16; p < 0.001). Transmission intensity was strongly associated with intervention coverage, with households in the PfPR2 –10 ≥ 5% category the most likely to have at least one intervention (RR 6.10; 95% CI 3.74–9.97; p < 0.001)

Rojas et al. [64]

Colombia

A cross-sectional study

To implement and evaluate an Integrated Malaria

Control Program

General population

Drainage filling + bromelias removal

None

36 months

Malaria deaths, cases of cerebral malaria, malaria incidence, and length of sick leave

The project: (1) avoided deaths from malaria (no fatal cases in the 3-year period, compared to 5–8 deaths a year previously); (2) avoided cases of cerebral malaria (no cases, as compared to 90–110 per year previously); (3) reduced malaria incidence by 45.36%; (4) decreased length of sick leave from 7.52 to 3.7 days

Chen-Hussey et al. [65]

Lao People’s Democratic Republic

A double blind, household randomised, placebo-controlled trial

To determine whether the use of repellent and LLINs could reduce malaria more than LLINs alone

6–60 years

LLIN + DEET lotion

Placebo lotion

11 months

Malaria incidence

Intention to treat analysis found no effect from the use of repellent on malaria incidence (hazard ratio: 1.00, 95% CI 0.99–1.01, p = 0.868)

Pinder et al. [66]

Gambia

Two-arm cluster, randomised, controlled efficacy trial

To assess whether the addition of IRS to LLINs provided a significantly different level of protection against clinical malaria in children or against house entry by vector mosquitoes

Children, aged 6 months to 14 years

LLIN + IRS

LLIN alone

24 months

Incidence of clinical malaria, density of vector mosquitoes

Incidence of clinical malaria was 0·047 per child-month at risk in the LLIN group and 0·044 per child-month at risk in the IRS plus LLIN group in 2010, and 0·032 per child-month at risk in the LLIN group and 0·034 per child-month at risk in the IRS plus LLIN group in 2011. The incident rate ratio was 1·08 (95% CI 0·80–1·46) controlling for confounders and cluster by mixed-effect negative binomial regression on all malaria attacks for both years. No significant difference was recorded in the density of vector mosquitoes caught in light traps in houses over the two transmission seasons: the mean number of A. gambiae sensulato mosquitoes per trap per night

was 6·7 (4·0–10·1) in the LLIN group and 4·5 (2·4–7·4) in the IRS plus LLIN group (p = 0·281 in the random-effects linear regression model)

Sluydts et al. [67]

Cambodia

A cluster randomised controlled trial

To assess the epidemiological efficacy

of a highly effective topical repellent in addition to long-lasting insecticidal nets in reducing malaria prevalence in

this setting

General population

LLIN + topical repellent

LLIN alone

24 months

Plasmodium species prevalence

No post-intervention differences in PCR plasmodium prevalence were observed between study groups in 2012 (4·91%

in the control group vs 4·86% in the intervention group; OR 1·01 [95% CI 0·60–1·70]; p = 0·975) or in 2013 (2·96% in the control group vs 3·85% in the intervention group; OR 1·31 [0·81–2·11]; p = 0·266). Similar results were obtained according to Plasmodium species [Plasmodium falciparum; OR 0·83 [0·44–1·56]; p = 0·561; and Plasmodium vivax; OR 1·51 [0·88–2·57]; p = 0·133)]. 41 adverse event notifications from nine villages were received, of which 33 were classified as adverse reactions (11 of these 33 were cases of repellent abuse through oral ingestion, either accidental or not)

Martins-Campos et al. [68]

Brazil

Cross-sectional study

To investigate the fauna of anopheline mosquitoes and verify the impact of integrated vector management in two colonization projects in the Careiro Municipality, Western Brazilian Amazon

General population

ITNs + IRS

ITNs alone

20 months

HBRs, EIRs, malaria incidence rate, plasmodium carrier’s prevalence

An. darlingi HBRs showed a notable decreasing trend from the start to the end of the study. Conversely, An. albitarsis increased its contribution to overall HBRs throughout the study. For An. darlingi there was a significant positive correlation between HBRs and malaria incidence rate (p = 0.002). Anopheles albitarsis HBRs showed a significant negative correlation with the corresponding malaria incidence rate

(p = 0.045). EIR from total anophelines and from An. darlingi and An. albitarsis presented decreasing patterns in the successive collections. Four species of anophelines (An. darlingi, An. albitarsis, An. braziliensis and An. nuneztovari) were naturally infected with Plasmodium, albeit at very low infection rates. There was a decrease in the malaria incidence rate for both vivax and falciparum malaria and in the prevalence of Plasmodium vivax and Plasmodium falciparum carriers during the period of study

Hill et al. [69]

Bolivia

A double blind, placebo-controlled, cluster-randomised clinical study

To determine the effectiveness in reducing malaria of combining an insect repellent with insecticide treated bed nets compared with the nets alone in an area where vector mosquitoes feed in the early evening

General population

LLINs + plant-based insect repellent

Placebo

7 months

Episodes of Plasmodium falciparum or P. vivax malaria, Numbers of P. falciparum cases

Analysed 15 174 person months at risk and found a highly significant 80% reduction in episodes of P. vivax in the group that used treated nets and repellent (incidence rate ratio 0.20, 95% CI 0.11 to 0.38, P < 0.001). Numbers of P falciparum cases during the study were small and, after adjustment for age, an 82% protective effect was observed, although not significant (0.18, 0.02 to 1.40, P = 0.10). Reported episodes of fever with any cause were reduced by 58% in the group that used repellent (0.42, 0.31 to 0.56, P < 0.001)

Kane et al. [70]

Mali

A comparative study, cross-sectional and passive case detection surveys

To assess the added value of IRS to LLINs on the prevalence of parasitaemia and malaria incidence among children under 10 years old

Children from 6 months to 10 years old

IRS + LLINs

LLINs only

Not clear

Malaria prevalence and incidence

There was an increase of 220% in malaria prevalence from June to October in the control area (14% to 42%) versus only 53% in the IRS area (9.2% to 13.2%). Thus, the proportional rise in malaria prevalence from the dry to the rainy season in 2016 was 4-times greater in the control area compared to the IRS area. The overall malaria incidence rate was 2.7 per 100 person-months in the IRS area compared with 6.8 per 100 person-month in the control areas. The Log-rank test of Kaplan–Meier survival analysis showed that children living in IRS area remain much longer free from malaria (Hazard ratio (HR) = 0.45, 95% CI 0.37–0.54) than children of the control area (P < 0.0001)

Lee et al. [71]

Island of Príncipe

Cross- sectional survey, before and after study

To evaluate a five-year integrated control programme

General population

IRS + LLINs + IPT for pregnant women + early diagnosis and prompt treatment with artemisinin-based combination therapy

IRS alone, LLIN alone

60 months

Protective effect against malaria, malaria incidence and prevalence, malaria mortality, slide positivity rate was used as an indicator of any increase of malaria cases during and after the control programme

Combined use of IRS and LLINs has no additional protective effect against malaria when compared to the use of IRS alone (OR = 1.108, 95% CI 0.594–2.066, p-value = 0.747 > 0.05). Being unprotected increases the odds by 3.5 (OR = 3.496, 95% CI: 1.473–8.300, p-value = 0.005) of that for IRS protection alone, while using LLINs alone, when compared with IRS protection alone, increased the odds by almost 3-times (OR = 2.979, 95% CI 1.113–7.975, p-value = 0.030). Meaning that there is no statistical evidence that living in an IRS treated house with a bed net has any additional protective effect against malaria infection

- A steep decline by 99% of malaria incidence was observed between 2003 and 2008, with an incidence risk of the population of five per thousand, in 2008. No malaria mortality reported since 2005. Species shift from falciparum to non-falciparum malaria was noted after a five-year intensive control programme

- Before the intervention was taken, higher incidence of clinical and severe malaria was noted in under-five years of age children and a reduction (from 40 to 20%) observed

Mathews et al. [72]

Cameroon

Cross- sectional study. Pre-and Post-intervention medical survey

To examine different mosquito control interventions applied to entire villages to assess their impact on vectors, malaria incidence and the quality of life of the communities

Children and adults

IRS + ITN, OR Improved screening of houses + outdoor/intradomiciliary misting

A village received no treatment

8 months

Malaria incidence, numbers of mosquitoes

IRS + ITN using ICON CS (lambda-cyhalothrin capsule suspension formulation) or improved screening of houses combined with outdoor misting reduced the numbers of mosquitoes collected from exit traps compared to the other treatments. More sporozoites were detected in mosquitoes sampled in exit traps in the untreated village than in the treated villages. Malaria incidence several months after treatments was not significantly different from pre-treatment levels. Blackfly adult populations were reduced for several weeks following larvicide application but recovered when treatment was halted

Protopopoff et al. [73]

Burundi

Cross-sectional surveys

To present the impact of these targeted vector control activities on the prevalence of malaria infection

Children between 1- 9 years

IRS + LLIN

LLIN alone

48 months

Prevalence of malaria, parasite density, risk of malaria infection, histories of malaria illnesses and antimalarial drug use

After the intervention and compared with the control valleys, children 1–9 years old in the treated valleys had lower risks of malaria infection (OR: 0.55), high parasite density (OR: 0.48), and clinical malaria (OR: 0.57). The impact on malaria prevalence was even higher in infants (OR: 0.14). When intervention with control valleys were compared, children of age 1–9 years had a significantly lower risks of malaria infection [OR: 0.55, 95% CI 0.42–0.72, P < 0.001], high-density parasitemias (OR: 0.48, 95% CI 0.33–0.70, P < 0.001), and clinical malaria (OR: 0.57, 95% CI 0.41–0.81, P = 0.001). Histories of malaria illness (OR: 0.66, 95% CI 0.52–0.83, P < 0.001) and antimalarial drug use (OR: 0.65, 95% CI 0.49–0.85, P = 0.002) were lower in the intervention valleys compared with the control valleys. According to surveys, malaria prevalence was reduced in intervention valleys compared with control valleys by 12–64% in the ≤ 9 age group and by 14–59% in > 9 age group. These differences were significant in children ≤ 9 years old for surveys 3, 5, and 9 and in individuals > 9 years old for Surveys 3–6 and 9. No difference in malaria prevalence was observed between intervention hilltops and control hilltops, where using nets did not confer an additional protective effect to spraying. Targeted vector control had a major impact on malaria in the high-risk valleys but not in the less-exposed hilltops

Hiwat et al. [74]

South America

Cross-sectional study, before and after evaluation

To evaluate both on account of the targets established within the programme and on account of its impact on the malaria situation in Suriname

General population

Interventions grouped by strategic areas: vector control (including IRS, LLNs, re-/impregnation of nets and entomological surveillance); case management (diagnosis and treatment); Behaviour Change Communication/Information, Education and Communication (mass media, outreach programme) and Surveillance, Monitoring and Evaluation (including epidemic detection, passive and active case surveillance, mobile/fixed malaria service deliverers, M&E)

None, before and after data

60 months

Malaria vector populations, malaria incidence and transmission

Malaria vector populations, monitored in sentinel sites, collapsed after 2006 and concurrently the number of national malaria cases decreased from 8618 in 2005 to 1509 in 2009. Malaria transmission risk shifted from the stabile village communities to the mobile gold mining communities, especially those along the French Guiana border

Bradley et al. [75]

Equitorial Guinea

Cross-sectional study

To examine the effect of the short residual life of bendiocarb insecticide and of children spending time outdoors at night, on malaria infection prevalence was

Children 2–14 years

ITN + IRS

ITN

6 months

Prevalence of malaria infection

Prevalence of malaria infection in 2 to 14-year-olds in 2011 was 18.4%, 21.0% and 28.1% in communities with median time since IRS of three, 4 and 5 months respectively. After adjusting for confounders, each extra month since IRS corresponded to an OR of 1.44 (95% CI 1.15–1.81) for infection prevalence in 2 to 14-year-olds. Mosquito mortality was 100%, 96%, 81% and 78%, at month 2, 3, 4 and 5 respectively after spraying. Only 4.1% of children spent time outside the night before the survey between the hours of 22.00 and 06.00 and those who did were not at a higher risk of infection (OR 0.87, 95% CI 0.50–1.54). Sleeping under a mosquito net provided additive protection (OR 0.68, 95% CI 0.54–0.86)