Overview

Essential for the epidemiology of any vector-borne disease is the vector-host contact. A quantitative assessment makes it possible to predict epidemiologically dangerous situations and to take adequate measures of prevention and vector control. The extent of contact is strongly influenced by the feeding habit of the vector and the availability and activity of the hosts at the place and time of vector activity (WHO, 1972). Examples for hosts coming into contact with vectors have been observed in road building in Panama or agricultural development in Costa Rica which has brought men into contact with sand flies which inhabit the tropical forests without normally having contact with man (Lewis, 1971).
Sand flies have a limited chance to find a host while the distance they can travel is short compared with some flies or even mosquitoes. They often move in short hops. Most of them remain within 20-30 cm of the soil surface.
Whereas the maximum flight distance of Ph. ariasi in trials in France has been 2.3 km (Killick-Kendrick et al., 1984). Flight speed in Ph. ariasi was estimated to be around 1m/sec (Killick-Kendrick et al., 1986).
Sand flies are usually not found at great altitudes, but have been reported as vector of the uta called form of dermal leishmaniosis at 2800 m (in Peru). Sand flies often stay close to the ground, but some American forests sand flies bite in the canopy, some at all levels or in a middle zone while following their hosts (Shaw et al. 1972).