Variation in populations of chigger vectors of scrub typhus in developing oil palm areas of different ages.

The populations of scrub typhus vector chiggers were compared in two developing oil palm areas, one 5 years old and the other 7 years old at the inception of the study. Both areas were located within the same oil palm scheme in central Peninsular Malaysia. Leptotrombidium (L.) deliense, a principal vector of scrub typhus in Malaysia, was found in reduced numbers in the older oil palm habitat. This reduction is attributed to changes in the microhabitat, specifically the elimination of grasses between the oil palm trees due to canopy shading and to cultural practices.