Study setting {9}
The study will be conducted in three southern Africa countries; Zambia, Zimbabwe and Mozambique. Study areas were selected in malaria transmission hotspots where the use of LLINs is promoted by the Ministry of Health, but IRS is not routinely implemented. The project countries had similar profiles in terms of malaria incidence/prevalence, primary malaria vectors, parasites transmitting malaria, vector resistance to insecticides, tools employed in malaria control and transmission season (Table 1).
Table 1
Malaria epidemiology in the project countries
Countries
|
Zambia
|
Mozambique
|
Zimbabwe
|
References
|
Malaria prevalence/incidence
|
Prevalence 9% in 2018 for under 5’s.
|
Weighted prevalence of 38.9 % in 2018
|
Incidence 20.5 /1000 population in 2016
|
[28–30]
|
Primary vectors
|
An. funestus
An. gambiae s.s
An. arabiensis [31]
|
An. gambiae s.l.
An. funestus s.l.
|
An. gambiae s.l.
An. funestus s.l.
|
[28, 32, 33]
|
Secondary vectors
|
An. coustani, An. squamosus, An. pretoriensis
An. rufipes
|
An. coustani, An. tenebrosus, An. ziemanni.
|
An. coustani, An. natalensis, An. pretoriensis
|
[34–38]
|
Primary parasite prevalence
|
P. falciparum (95%)
P. ovale (2%)
P. malariae (3%)
|
P. falciparum (90%)
P. malariae (9%)
P. ovale (1%)
|
P. falciparum (98%)
P. ovale &
P. malariae (2%)
|
[28, 29, 33]
|
Insecticide resistance
|
Both An. funestus and
An. gambiae s.s. resistant to deltamethrin, lambda-cyhalothrin, permethrin and DDT.
|
Both An. funestus s.l. and
An. gambiae s.l. resistant to deltamethrin, alphacypermethrin, lambda-cyhalothrin, permethrin and DDT in some areas of Mozambique.
|
An. arabiensis reported to be resistant to DDT and permethrin. An. funestus was reported to be resistant to carbamates and pyrethroids. An. gambiae s.l. reported to be resistant to bendiocarb and lambda-cyhalothrin.
|
[29, 33, 39]
|
Malaria control tools
|
IRS, LLINs, IPTP, RDTs and case management using ACTs [40].
|
IRS, LLINs, RDTs, case management using ACTs, Social & Behaviour Communication Change (SBCC) and entomological monitoring and surveillance.
|
IRS, LLINs, RDTs, case management using ACTs, therapeutic efficacy testing (TET), Community-based management of malaria, IPTP and entomological surveillance.
|
[29, 33, 40]
|
Transmission season
|
January – April
|
January - April
|
January – April
|
[28, 30, 33]
|
Nyimba, Zambia.
The house screening trial will be conducted in Nyimba District located 350 km East of Lusaka in Eastern Province, Zambia. Nyimba has a cool dry winter from May to August and a warm wet season from December to April, which is the main malaria transmission season [41]. Plasmodium falciparum in Nyimba is vectored by An. funestus which mediates an entomological inoculation rate (EIR) of 70 infectious bites per unprotected user of LLIN [42]. The average annual temperature is 25°C and the annual average rainfall was 175 mm from 2009 – 2020 [43].
Chiredzi, Zimbabwe:
The evaluation of house-screening will be explored in Chiredzi District located in Masvingo province in South-Eastern Zimbabwe situated at 21°02′20″ S 31°40′40″ E. Chiredzi district receives on average 78 mm of annual rainfall and has an annual average temperature of 26°C [43]. The main malaria vector found in this area is An. funestus. An. quadriannulatus was found to be the most predominant of the An.gambiae. s.l. complex. Other anophelines present in the area were An. pretoriensis, An. squamous, An. rufipes, An. coustani and An. pharoensis. The major control measures employed in the area are IRS, LLINs, larval source management (LSM) and prompt case management [44].
Chokwe, Mozambique:
The house-screening trial will be conducted in Chokwe District, Gaza Province, specifically within the study area of the Chokwe Health Demographic Surveillance System (CHDDS), at 24°33′37″S, 33°1′20″E in southern Mozambique. Chokwe district receives on average 72 mm of annual rainfall and has an annual average temperature of 26 °C. The major P. falciparum vectors are An. funestus and An. gambiae s.l. An. funestus are recorded to be highly resistant to pyrethroids in Chokwe [45] and as a result, IRS using DDT has been used for malaria control in this area since 2006 [45].
Eligibility criteria {10}
The households to be enrolled into the study will be assigned the following inclusion criteria:
-
Houses that have either a tin or tiled roof; mud, stone or wooden walls and earthen or cemented floors (*semi-modern) with few open spaces for potential mosquito entry and screening; the houses should not be in such a debilitated state that it’s impossible to cover up the mosquito entry points.
-
Houses are at least 50 meters apart to prevent diversion of mosquitoes from the treatment to control houses.
-
Houses have at least 1 resident children between 6 months and 13 years of age.
-
The resident child recruited into the study cohort will stay in the study area for the whole study period and will not be allowed to travel out of the study area during the project period.
-
Houses in which the household head/guardian has signed the study informed consent.
Who will take informed consent? {26a}
Once all houses (800) to be enrolled in the study have been identified, consent will be sought from the household heads/guardians for a resident child between 6 months – 13 years, to join the study cohort for the malaria incidence (clinical malaria) and prevalence (parasite density) surveys.
Written and verbal information will be provided to household heads/guardians on the objectives, benefits and potential risks of the study using a local language with which they are familiar. The household heads/guardians will be advised that participation is voluntary. Only children whose parents have given written consent for their child to be included in the study will be enrolled.
The participant child will be selected randomly among those aged 6 months to 13 years from the 800 houses enrolled. During the blood specimen collection for clinical malaria infection and parasite prevalence, assent will be sought from children above 8 years, and if assent is denied, this child will be excluded from data collection. No distinctions will be made regarding the gender or ethnic group of the household.
Consent will also be sought from household heads for their houses to be used as sentinel stations for sampling of adult mosquitoes using CDC light traps and PSC techniques.
Any child testing positive for malaria parasites will be treated as per respective national malaria diagnosis and treatment guidelines [46].
Additional consent provisions for collection and use of participant data and biological specimens {26b}
On the actual day of blood specimen collection, the household heads/guardians will be presented with another consent form before a blood specimen is collected from the study children. If consent is obtained, then the field workers will collect the data. However, if consent is denied, blood specimen will not be collected from the child.
Interventions
Explanation for the choice of comparators {6b}
Long lasting insecticidal nets (LLINs) will be the comparator in this study. This is because LLINs are the current recommended intervention by the study countries’ NMCPs and by WHO. Universal coverage of LLINs for personal protection is also the gold standard malaria intervention and the only ethical comparator that can be used when testing new malaria control tools as is has been demonstrated to be both effective and readily available. Therefore, we will ensure universal access to LLINs and then evaluate the additional benefits of house screening against malaria transmission.
Intervention description {11a}
House screening
In the target areas of all three countries, 400 houses will be screened with non-insecticide PVC-coated fiber glass netting by trained artisans recruited from each study village. The installations are expected to take about 2-3 months to complete. House residents will be trained on the care needed to keep the screens intact and avoid activities that could damage the screens. Screened houses will be examined by field assistants during entomological sampling of adult mosquitoes in sentinel households when conducting active case detection of malaria incidence every fortnight during the transmission season and during the cross-sectional parasite density surveys (parasite prevalence). The integrity of the screens will be recorded during these observations. Other routine procedures to reduce mosquito entry into houses, such as shutting the door whenever an occupant enters or leaves the house between 18.00h and 06.00h, will be emphasized and adherence to these practices monitored passively by the study field team during the above activities. These observations will be recorded in structured forms in order to quantify the frequency of their occurrence over time.
Criteria for discontinuing or modifying allocated interventions {11b}
Withdrawals may also occur if a study subject has any significant adverse events such increase in upper respiratory tract infections (URTi’s) in household members in screened households compared to non-screened households.
Strategies to improve adherence to interventions {11c}
Household heads and residents will be trained on the care needed to keep the screens effective, such as avoiding activities that may poke holes onto the nets or cause damages that will create spaces that would allow mosquito entry into the houses. Other routine procedures that reduce mosquito entry into houses such as closing windows and doors early will be emphasized and adherence to this practice monitored passively by the study team during entomological, clinical and parasitological data collection as described above. The community members in the study areas will also be continually engaged on the benefits of participating in the study and the importance of following the recommended procedures above through community meetings to encourage adherence to malaria and parasitological surveys.
Relevant concomitant care permitted or prohibited during the trial {11d}
As this study aims to assess the additional impact of house screenings to LLINs in preventing malaria transmission, use of IRS in the study target area will be prohibited.
Provisions for post-trial care {30}
At the end of the study, households in the control arm will be given the option of screening their households at project cost. Also, households in the intervention arm will be given the option of having the screens removed from their houses if they so wish.
Outcomes {12}
Clinical endpoints
The primary endpoint will be the incidence of clinical malaria in children between 6 months and 13 years. Clinical malaria will be assessed by active case detection over the main transmission season (January- April). The axillary temperature will be taken every fortnight by CHWs from all enrolled study children and if ≥ 37.5 °C or history of fever in the past 48 hours is reported, the child will be tested for malaria using a rapid diagnostic test kit (RDT). Blood specimens will also be collected using thick and thin blood slide smears for parasite identification and a dry blood spot (DBS) using a filter paper for later malaria analysis using PCR techniques.
The secondary endpoint will be the prevalence of malaria parasitaemia in the study children and the average parasite density in each study arm will be determined. Cross-sectional surveys will be done before (November) and after the main transmission season (May). A finger prick sample will be taken for an RDT and a thick and thin blood smear and DBS prepared for microscopy and molecular analysis in the laboratory.
RDT positive children will be provided with a full dose of Artemether-lumefantrine (AL) for treatment by a trained health worker following in-country national guidelines [47].
Entomological endpoints
The primary entomological endpoint will be the relative indoor mosquito density, expressed as the average number of mosquitoes caught per trap night in each study arm. The secondary endpoint will be the entomological inoculation rate (EIR) incorporating the blood meal source (human biting rate) and the mosquito sporozoite positivity per study arm.
A total of 30 sentinel houses per study arm (N=60) per country will be randomly selected for adult mosquito collections. The household selection will be stratified by village and geographical area so that an equal number of sentinel houses are selected in each village and equally spread over the study area. This stratified randomization by village will reduce the likelihood of imbalances between study arms. Indoor host-seeking mosquitoes will be collected for 5 days of each month using CDC UV light traps from 15 sentinel households. The CDC light trap will be placed next to the sleeping space of the study enrolled child and will be raised 1.5 metres from the ground. The light trap will be set up at 7:00 p.m. and mosquitoes collected at 7:00 a.m. the next morning.
Indoor resting mosquitoes will be collected using pyrethrum spray catches (PSC) in the remaining 15 sentinel households in each arm of the study. The collections will be done inside the room where the child recruited into the study cohort sleeps. Mosquito sampling using PSC will be conducted early in the morning between 06:00 and 08:00 hours. All the exit points to the sleeping area will be shut and a white sheet spread on the floor. An insecticide will then be sprayed in the room to knock down mosquitoes which will then be collected after 10 minutes. This sampling will be conducted one day for each month in the fixed sentinel households throughout the study period.
All the mosquito collections will be preserved in silica gel and transported to the respective national health laboratories where they will be stored in a freezer for identification using morphological and molecular methods. Morphological identification will use morphological keys for afro tropical vectors [48]. Molecular analysis of mosquito samples will be based on the polymerase chain reaction (PCR) to assess sporozoite infections in the mosquitoes and enzyme-linked immunosorbent assays (ELISA) for analysis of all blood-fed female Anopheles mosquitoes. A material transfer agreement (MTA) will be signed between the Ministries of Health of the project countries and icipe to allow for a sample of the collected mosquitoes to be transported to icipe, in Nairobi Kenya for quality assurance. In case there is no in-country capacity to process the collected samples, then all collected mosquitoes will be transported to icipe for morphological and molecular analysis.
Cost effectiveness endpoints
To determine the cost effectiveness of house screening, the costs associated with house screening will be collected from the implementing organizations (WHO and The NMCPs of the project countries). The per capita costs of house screening will be estimated by dividing the average cost of house screening per house by the household size and this will be compared to the per capita costs of LLINs. Daily Adjusted Life Years (DALY) will be estimated for each household using standard methods on the basis of the number of malaria cases averted [49]. The Cost Effectiveness Ratio (CER) will be computed as the per capita costs of house screening per DALY averted.
The acceptability of house screening as a mosquito abatement tool will be evaluated using qualitative surveys that include key informant interviews and focus group discussions as the secondary endpoint.
Participant timeline {13}
Sample size {14}
Clinical
The sample size used in this study is based on simulation models described in Hayes and Bennet et al. for incidence rates [50]. Routine data collected from all health facilities in Nyimba district in Zambia estimated an incidence rate of 0.312 cases per person from January to June 2019. Using these estimates in equation 1 [50], we estimated that in order to detect a reduction of 35% on malaria incidence, with 80% power at the 5% significance level, 338 houses were required per study arm when following one child per household per year [51]. A total of 400 households with one child each were recruited per treatment arm. The additional households were enrolled to account for households lost to follow up.
Data collected from all health facilities in Chokwe district, Mozambique, estimated an incidence rate of 0.325 cases per person from January to June. Using the same formula, we estimated that 324 children were required per treatment arm to observe a 35% treatment effect with 80% power at the 5% significance level [50]. A total of 400 households were also recruited in Mozambique.
Equation 1
Entomological
House screening is projected to reduce indoor malaria vector collections by at least 50% [51]. We used the Hayes and Bennet model for sample size calculation when using means to determine the number of households required to demonstrate a 50% reduction of indoor-entering mosquitoes associated with house screening, with 80 % power at the 5 % level of significance [50]. A study assessing different mosquito sampling schemes using light traps and human biting catches in Nyimba district, Zambia in 2014, estimated that 2.6 An. funestus were caught using CDC light traps per night [52]. Using equation 2 below, we estimated that we would require 17 houses in each arm of the study. An additional 12 households were recruited for mosquito sampling to make a total of 30 households per study arm to allow for sampling of mosquitoes using both the CDC LTs and PSC techniques. Each sampling technique was used to sample mosquitoes from 15 households per study arm. As the standard deviation (SD) for this data was not reported we assumed a SD of 1.96 for the sample size calculation.
Mosquito data from Chokwe in Mozambique was not available, and there we used the same sample size as that of Zambia of 30 households per treatment arm.
Equation 2
Recruitment {15}
Study participants will be recruited by the national project team in consultation with local health workers. The project staff will obtain verbal and written informed consent using ethical review committee (ERC)-approved language that outlines the objectives, benefits and potential risks of the study and the data and biological samples that will be collected. Household heads will be briefed about the study, provided with an information sheet and asked for their written consent to have their children involved in the study. Assent will be sought from all children above the age of 10 years. Household heads/guardians who do not want their children to participate in the study will be free to refuse participation. On the survey day, children will be informed about the survey procedures, making it clear that their participation is voluntary and that they might opt out at any time if they chose to. Children unwilling to participate or whose parents did not give consent will be excluded from the selection procedure, with assent obtained from selected children before samples are collected. Participants’ names will be removed in the final database to ensure anonymity. Children with a positive malaria RDT will be treated for malaria according to national guidelines.
Participants will be free to withdraw from the study at any time without giving a reason. In the unlikely event that homeowners require their house to be returned to the pre-intervention state, items added will be removed. No replacements will be made during the surveillance period in either year, but in Year 2 children who have withdrawn or are no longer in the study for any reason will be replaced by a child within the age range of 6 months – 13 years in the same household. If another child within this age range is not present in that house, then another household with a child within this age range will be sampled in the same village. If a household withdraws consent, no further follow up will be made in that household. If the house was participating in the entomology collections, it will be replaced by a neighbouring house of the same type and intervention status.
Assignment of interventions: allocation
Sequence generation {16a}
Households were used as the unit of randomization. For allocation of the households, a computer-generated list of random numbers was used. Households were randomly assigned following simple randomization procedures (computerized random numbers) to either the intervention or control group. The allocation was stratified by village. The randomization sequence was created using Excel 2007 (Microsoft, Redmond, WA, USA) by the Co-PI’s in the project countries.
Concealment mechanism {16b}
All eligible households will be uploaded into an Ms Excel spreadsheet. The simple randomization formula will then be used to assign the households to the intervention and control groups. The Co-PI’s therefore did not know which household would be assigned to the intervention or control group before the allocation of the interventions.
Implementation {16c}
The simple randomization was done by a computer-generated random number list that was prepared by the Co-PI’s in each of the study countries. The randomization was stratified by village so that there was an equal number of intervention and control households in each village.
Assignment of interventions: Blinding
Who will be blinded {17a}
This study cannot be blinded since house screening will be visible to all including data collectors and the researchers involved. However, staff involved in reading the blood slides will be blinded to the intervention. Statisticians analyzing the primary endpoints of the study will also be blinded to the intervention.
Procedure for unblinding if needed {17b}
Datasets will be unblinded after all primary and secondary analysis have been conducted.
Data collection and management
Plans for assessment and collection of outcomes {18a}
Study endpoints will include clinical, entomological and cost-effectiveness data. Data will be collected electronically using Open Data Kit (ODK) software which was programmed and uploaded on mobile phones. Once households have been enrolled in the study, a household survey using a WHO standardized Malaria Indicator Survey (MIS) questionnaire will be administered to capture baseline demographic, behavioural and socio-economic household indicators. Each household will be assigned a unique identification code at the time of questionnaire administration.
Baseline household data will be collected between April-October, after the long rains in southern Africa.
Entomological sampling will be undertaken throughout the study period and initiated after the baseline socio-demographic household data collection. Clinical malaria baseline data will also be collected after the household baseline survey (November-April) and in subsequent malaria transmission seasons at similar time points after the intervention implementation (Figure 2).
Plans to promote participant retention and complete follow-up {18b}
Once a household and child are enrolled or randomized, the study team will make every reasonable effort to follow the child for the entire study period.
Data management {19}
Data will be stored by the NCMP/NMEC at their national offices in a secure database as they are the custodians of the Demo project. A unique ID number will be assigned to each participant. The NCMP/NMEC team will be responsible for overseeing data management. Data will be collected electronically and synced daily through 3G enabled Wi-Fi hotspot with the database at the NMCP/NMEC offices by the study supervisors. Collected data will remain on the tablets until the end of data collection to ensure that it is backed up. The NCMP/NMEC team will also ensure that the questionnaires uploaded to the database are backed up regularly to prevent any loss of data. At the end of the survey, all the data will be into an aggregated master database. The NCMP/NMEC team, WHO, and icipe staff will check the data for inconsistencies and will make necessary corrections.
After all the primary and secondary analysis of the project data has been conducted, the database will be archived for the minimum NMCP/NMEC retention period and disposed of as per ERC guidelines. The ERC will be notified in writing of the intention to dispose of the project data by filling the ERC destruction form outlining the data disposal method and invited to witness the destruction of the hard disc that contains the project database.
Confidentiality {27}
Data confidentiality will be strictly kept with the data stored on an access-restricted/password locked database accessible only to authorized personnel, and the data used for analysis will be de-identified so that they cannot be traced back to any individual. To maintain confidentiality, a system of coding will be used to link the name and data.
Plans for collection, laboratory evaluation and storage of biological specimens for genetic or molecular analysis in this trial/future use {33}
During the cross-sectional surveys, clinical surveys will be done on all study children. A finger prick sample will be taken and an RDT used to test for presence of malaria parasites. Thick and thin blood smears will be taken for later detection and quantification of Plasmodium parasites. Blood films will be stained in the field by project staff, transported to the in-country laboratory, and read independently by two microscopists blinded to the identity of the child. Any discrepancy will be resolved by a third senior microscopist. A sample of the blood films will be transported to icipe for quality assurance after signing the material transfer agreement (MTA) between icipe and the Ministries of Health of the Project countries. Children with malaria will be referred for treatment if they have not received any treatment already.
All the mosquito collections will be preserved in Eppendorf tubes with silica gel and transported to the laboratories where they will be identified to species level and examined for sporozoite infection and blood meal analysis. A sample of the mosquito specimen will also be transported to icipe for quality assurance. Blood slides and mosquito DNA will be stored in a -20 °C non-frost-free freezer until DNA extraction. This data will be made available for future studies after all the guidelines and conditions for secondary data use have been met at both icipe and the project countries.
Statistical methods
Statistical methods for primary and secondary outcomes {20a}
A mixed-effects model will be used to compare clinical malaria incidence rates between the intervention and control arms, to allow for repeated measures within household, villages and the effect of year. Possible confounders such as age of child, gender, ethnicity, and season will be included in the models.
Differences in abundance of mosquitoes caught indoors and outdoors will be made between the study arms to evaluate the impact of house screening on mosquito density. Mixed-effects models will be used to estimate differences in the numbers of mosquitoes, adjusting for repeated measures (i.e., within houses, villages) and other possible covariates such as the child’s age, gender, ethnicity and rainfall. A Poisson distribution model with a log link function will be used and, a random factor for each data point will be included in the model to adjust for excess variation between data points (over-dispersion) All mean counts per treatment and their 95% confidence intervals (CIs) will be modelled as the exponential of the parameter estimates for models with no intercept included.
Interim analyses {21b}
Interim statistical data analyses will be implemented annually to monitor the progress of the project and a comprehensive data analysis will be implemented at the end of the project.
Methods in analysis to handle protocol non-adherence and any statistical methods to handle missing data {20c}
A per-protocol and an intention-to-treat analysis will be conducted.
Plans to give access to the full protocol, participant level-data and statistical code {31c}
The study team members will have access to records. The authorized representatives of the sponsor, the ethics committee(s), or regulatory bodies may inspect all documents and records required to be maintained by the PI, including but not limited to medical records (office, clinic, or hospital) for the participants in this study. The clinical study site will permit access to such records. The results of the study will be made publicly available.
Oversight and monitoring
Composition of the coordinating centre and trial steering committee {5d}
A regional Project Steering Committee (PSC) of 6 members was established to provide oversight of this multi-country study. The PSC’s main mandate is the monitoring of the participating countries’ progress towards the implementation of the planned project activities as outlined in the protocol. The PSC will also ensure WHO and national patient safety guidelines are followed and adhered to, review reports on adverse events reported in the study and that patient's rights are upheld.
Composition of the data monitoring committee, its role and reporting structure {21a}
A DMSC will provide overall supervision of the study and ensure that it is conducted to the standards set out in Good Clinical Practice (https://www.mrc.ac.uk/documents/pdf/good-clinical-practice-in-clinical-trials/). In particular, the DSMC will concentrate on the progress of the trial, adherence to the protocol, patient safety, and the consideration of new information, and the SSC will formally report to the sponsor (UNEP). The DSMC will determine if additional interim analyses of trial data should be undertaken and assess any additional safety issues that may arise during the study. They will ensure the safety, rights, and well-being of the study participants and will report to the SCC at regular intervals.
Adverse event reporting and harms {22}
Adverse events and serious adverse events will be recorded during both transmission seasons. Sick children will receive referral notes to the nearest health facility, and treatment will be documented.
Frequency and plans for auditing trial conduct {23}
The trial implementation and progress will be reviewed yearly during the project steering committee meetings and way forward agreed upon.
Plans for communicating important protocol amendments to relevant parties (e.g. trial participants, ethical committees) {25}
In case of protocol amendments, this will be communicated to participants through community meeting and field assistants. This information will also be communicated to the DSMC through the established organogram.
Dissemination plans {31a}
The results of the study will be made publicly available through peer-reviewed publications and presentations international conferences.