The safety and applicability of synthetic pyrethroid insecticides for aircraft disinsection: A systematic review.

BACKGROUND: Air travel contributes to the global spread of vectors and vector-borne infections. Although WHO provides guidance on methods for disinsection of aircraft, there is currently no harmonized or standardized decision-making process to decide when disinsection of an aircraft should be conducted. It is however compulsory for flights arriving in certain countries. Concerns have been expressed about the usefulness of disinsection for preventing the international spread of vectors and vector-borne diseases via air travel and possible toxicity for passengers and flight crew. METHODS: We performed a systematic literature review using the databases PubMed, Embase, Medline, Scopus and CINAHL to evaluate all research findings about the applicability and safety of chemical-based, aircraft disinsection. Official reports from the WHO were also screened. This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and meta-analysis (PRISMA) statement. The literature search strategy included "disinsection, airplane/plane/aviation/aircraft" and several other search items including d-phenothrin, permethrin, insecticide. Papers in English, French and German were reviewed. Reports of adverse events attributed to the disinsection of aircraft were also searched. AMP and PS screened all papers of relevance and agreed on a final selection. RESULTS: Our search resulted in 440 papers of possible relevance. After screening, we included a total of 25 papers in this systematic review. Ten papers reported possible human toxicity and 17 papers addressed the applicability of disinsection and 2 papers addressed both topics. Chemical disinsection at recommended insecticide concentrations was found to be highly effective against a broad range of arthropods. Three papers reported passenger or crew illness possibly associated with insecticide spraying in passenger cabins - one describing a single passenger, the other two papers describing occupational illness of 12 and 33 aircrew members respectively, possibly due to aircraft disinsection. Another paper evaluating exposure of flight attendants to permethrin found higher levels of urinary metabolites in those working in planes that had recently been sprayed but this could not be linked to adverse health outcomes. CONCLUSION: Our analysis confirmed that disease vectors are carried on international flights and can pose a threat particularly to island populations and certain airport hub areas. Disinsection with permethrin or d-phenothrin was shown to be highly effective against vectors. Despite several hundred million passenger and crew exposures to chemical disinsection, very few proven cases of toxicity have been reported. There is limited evidence linking exposure to insecticide spraying with negative health impact.