Insecticide space spraying for preventing malaria transmission

Area of Science:

• Public Health
• Entomology
• Vector-borne Disease Control

Background:

• Space spraying disperses insecticide fog outdoors to eliminate adult insects.
• It's a common practice in public health and pest control, including emergency responses to malaria outbreaks.
• This review assesses space spraying's impact on malaria transmission for vector control programs.

Purpose of the Study:

• To evaluate space spraying's effect on malaria transmission, alone or combined with other methods.
• To identify and summarize effective, promising, and unfeasible space spraying strategies for future research.

Main Methods:

• Searched multiple databases (Cochrane, PubMed, Embase, etc.) and clinical trial registries up to April 2018.
• Included cluster-randomized controlled trials, interrupted time series (ITS), and controlled before-and-after (CBA) studies.
• Two authors independently assessed eligibility, risk of bias, and extracted data; GRADE approach used for evidence certainty.

Main Results:

• Two ITS studies met criteria; one quantitative analysis from India (18,460 people) showed no immediate effect on malaria incidence but a 15% monthly reduction (slope rate ratio 0.85).
• Estimated 12-month impact: reduction from 6 to 1 case/1000 population/month (very low-certainty evidence).
• A second ITS study in Haiti lacked data for temporal trend adjustment; two CBA studies examined various spraying methods and insecticides.

Conclusions:

• Limited evidence from a 30-year-old Indian study suggests space spraying may impact malaria incidence.
• The certainty of this evidence is very low.
• Further high-quality research across diverse settings is crucial to determine the intervention's true value.