Academic journal article Bulletin of the World Health Organization

Why Aircraft Disinsection?

Academic journal article Bulletin of the World Health Organization

Why Aircraft Disinsection?

Article excerpt

Voir page 1001 le resume en francais. En la pagina 1002 figura un resumen en espanol.

Introduction

Since the inception of international air traffic there has been concern that mosquito vectors and the diseases they transmit might be introduced by aircraft into countries where they were not previously found (1, 2). Thus, consideration was already being given in the early 1930s as to how aircraft might be disinsected so as to prevent this from happening.

In conjunction with its Collaborating Centres, WHO conducted field trials on various materials and methods for the disinsection of aircraft and developed recommendations on this basis. Foremost among the recommended methods is "blocks away" disinsection, in which an insecticide aerosol spray is applied to the interior of aircraft just before they begin taxiing for take off (3, 4).

Many countries insist that arriving aircraft be disinsected, especially if they have come from areas where vector-borne diseases are endemic. It is common for an arriving aircraft to be sprayed by the health services of the country of destination if there is any doubt as to whether treatment has been applied earlier in the flight. Moreover, there have been instances in which the suspension of landing rights has been proposed unless evidence of disinsection was provided by the crews of arriving aircraft.

Concern has been expressed about possible adverse effects on passengers and crews of the application of pyrethroid aerosol sprays for the disinsection of aircraft. A detailed review conducted by WHO led to the conclusion that no toxicological hazard was attributable to any of the materials or methods recommended for use in aircraft disinsection and that they were safe to use in the presence of passengers and crew (5).

There have been reports that the "blocks away" method and other types of aerosol disinsection used with passengers on board, such as the "top of descent" method (6), are of limited effectiveness and that live mosquitoes have arrived in aircraft following blocks away disinsection (7). Mosquitoes can conceivably survive if treatments are not properly effected and if aerosols do not reach all areas where the vectors rest, for instance in overhead baggage racks. There is a need to improve disinsection methods (8).

Vectors introduced by aircraft

There have been frequent instances of insects of public health importance being introduced from one country to another, with occasional dire consequences. Until the advent of passenger aircraft in the 1920s such occurrences were mainly associated with ships. For example, Anopheles gambiae, a major vector of malaria, was probably introduced into Brazil in 1930 from Senegal by a French naval vessel, although the possibility that an aircraft was responsible cannot be excluded. This mosquito was first observed in a flooded field 2.5 km from the port of Natal and subsequently spread rapidly to other parts of Brazil. As a result, there was a great increase in the transmission of malaria and a sharp increase in mortality from the disease in the country. The importation and subsequent establishment of this highly efficient vector led to an epidemic of malaria involving ca. 300 000 cases and 16 000 deaths. A costly campaign was successfully conducted to eradicate the vector from Brazil (9).

The Government of Brazil was concerned about the possibility of A. gambiae being reintroduced into the country. After eradication was achieved, therefore, aircraft arriving in Brazil from Africa continued to be inspected. Over a nine-month period in 1941-42 the vector was found on seven occasions on such aircraft. During the inspections, 132 mosquitoes and two live tsetse flies were found. This led the government to insist that all aircraft arriving from Africa be disinsected by means of pyrethrum spray before the passengers disembarked.

The first reported occurrence of insects in an aircraft was in 1928 when a quarantine inspector boarded the dirigible Graf Zeppelin on its arrival in the USA: 10 species of insects were discovered on plants (10). …

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