Vector control for yellow fever around an airpo is done upto a distance of -

<p> international vector control for yellow fever. Aircraft and ships arriving from endemic areas are subjected to aerosol spraying with prescribed insecticides on arrival for destruction of insect vectors. Airpos and seapos kept free breeding of insect vectors over an area extending at least 400 metres around their perimeters. The Aedes aegypti index kept below 1. {Reference: park&;s textbook of preventive and social medicine, 23rd edition, pg no.284}</p