Excerpt:

Granulocytic anaplasmosis (GA) and Lyme borreliosis are emerging
tick-borne diseases caused by infection with Anaplasma
phagocytophilum and Borrelia burgdorferi, respectively, and
maintained in rodent-Ixodes spp. tick cycles, including I.
pacificus in the western U.S. Ixodes pacificus has a
multiple-year life cycle and B. burgdorferi and A.
phagocytophilum are transstadially, but not transovarially,
transmitted within ticks, thus ticks function importantly in
maintaining infection in nature. In this study, the survival of
larval and nymphal I. pacificus was determined using ticks placed
in tubes in leaf litter from June 2005 to September 2006 at two
field sites in the California northern coast range mountains and
a laboratory control. In all three sites, nymphal and larval
survival ranged from 90-400 d, with differences in mean survival
among sites. Fewer ticks died in the autumn in the moister field
sites compared with the drier incubator control treatment.