The primary objective of the study is to demonstrate and quantify the protective efficacy (PE) of a single SR product, in reducing DENV infection and active Aedes-borne virus (ABV) disease in human cohorts. The study design will be a prospective, cluster randomized controlled trial (cRCT). Although not a specific objective of this project, an overall goal is to allow for official recommendations (or not) from the World Health Organization (WHO) for the use of SRs in public health. A WHO global policy recommendation will establish evaluation systems of SR products to regulate efficacy evaluations, thereby increasing quality, overall use and a consequent reduction in disease.

The study will be a prospective, cRCT, participant and observer-blinded, placebo-controlled trial in a site endemic for ABV to measure the impact of a SR product on new ABV virus infections. Clusters of households, each cluster containing 110-120 residents testing negative for antibodies against DENV (seronegative) or positive to a single DENV infection (monotypic), will be selected from three MOH areas in the district of Gampaha: Negambo, Wattala, Kelaniya. All participating houses in each cluster will be monitored entomologically for adult Aedes aegypti surveys for 3 months before deployment of the SR intervention and monthly after the intervention is in place. Entomological surveys will include monitoring of indoor Ae. aegypti adult population densities and blood-fed status. DENV infection in study participants will be assessed by serologic testing of scheduled longitudinal blood samples (primary outcome) and passively by monitoring febrile persons for acute Dengue illness (secondary outcome). Seroconversion to DENV from baseline (pre-intervention) and follow-up (post-intervention) samples as well as ABV active disease rates will be compared between active intervention and placebo (control) clusters. Testing and confirmation of Zika virus (ZIKV) and Chikungunya virus (CHIKV) infection at baseline and during the intervention phase of the trial will be dependent on circulation history/detection in study area during study period.

The spatial repellent (SR) will be a new formulation of transfluthrin. This active ingredient (AI) is widely used in mosquito coils and other household pest control products worldwide. The new formulation is a passive emanator that will release the AI over a period of up to four weeks, Mosquito ShieldTM. The emanator will consist of a pre-treated piece of cellulose acetate or other medium, which will be positioned within consenting households according to manufacturer specifications of 2 units/9m2. A placebo product of matched design with inert ingredients will be applied similarly. The Mosquito ShieldTM and placebo products for this study will be designed and provided by S.C. Johnson, INC. A Family Company.

LONGITUDINAL SEROCONVERSION Individual Level

Inclusion Criteria:

• ≥ 4 - 16 years of age
• Plans to stay in residence and/or study area for a minimum of 24 months
• Resident of household or frequent visitor (~20% of day hours in house / month)

Exclusion Criteria:

• < 4 and > 16 years of age
• Plans to leave residence and/or study area within next 24 months
• Temporary visitor to household (<20% of day hours in house/ month)

FEBRILE SURVEILLANCE Household Level

Inclusion Criteria:

• Adult head of households agrees to census, health visits and logging resident symptoms when febrile (or in the case of suspected Zika in the absence of fever, presenting with rash, arthralgia, arthritis or non-purulent conjunctivitis).
• Individuals spend a minimum of 4hrs per week during the daytime hours or sleep in the house.

Exclusion Criteria:

• Adult head of households does not agree to census, health visits or logging symptoms of residents.
• Households where study personnel identify a security risk (i.e., site where drugs are sold, residents are always drunk or hostile).
• Sites where no residents spend time during the day (i.e. work 7d a week outside the home).

FEBRILE SURVEILLANCE Individual Level

Inclusion Criteria:

• ≥ 6mo of age.
• Fever at the time of presentation or report of feverishness within the previous 24 hours or presenting with a rash, arthralgia, arthritis or non-purulent conjunctivitis (suspicion of ZIKA determined by project physician)
• Individual who spends a minimum of 4 hours per week within the household or sleeps in the house.

Exclusion Criteria:

• < 6mo of age.
• No fever at time of presentation or report of feverishness within the previous 24 hours or not reporting with a rash, arthralgia, arthritis or non-purulent conjunctivitis
• Individuals who have spent less than 4 hours in the household during the week prior to illness.

ENTOMOLOGICAL MONITORING Household Level

Inclusion Criteria:

• Adult head of household agrees to surveys.
• Properties where study personnel do not identify a security risk (i.e., site where drugs are sold, residents are always drunk or hostile).

Exclusion Criteria:

• Adult head of household does not agree to surveys.
• Properties where study personnel identify a security risk (i.e., site where drugs are sold, residents are always drunk or hostile).

SPATIAL REPELLENT INTERVENTION Household Level

Inclusion Criteria:

• Adult head of households agrees to have intervention applied inside the home and to provide access to team member at 4-week intervals to change products.
• Properties where study personnel do not identify a security risk (i.e., site where drugs are sold, residents are always drunk or hostile).

Exclusion Criteria:

• Adult head of household does not agree to Mosquito ShieldTM deployment or study team access.
• Properties where study personnel identify a security risk (i.e., site where drugs are sold, residents are always drunk or hostile).

Analytical datasets will be anonymized and GPS tag-blurred to remove sensitive information prior to sharing.

The data and supporting information will be made available 12 months following completion of data analysis and will remain open access in the public domain.

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